Light transport and general aviation aircraft icing research requirements

TABLE OF CONTENTS Title Page Section i [ SL_,I_IRY INT'_DUL"TION [I Backgro_"ld a Objective Scope and Approach Pro roam Payoff III RESE.LRO{ DATA ACQUISITION Literature Search ii Data Management File Indu__try/Government/University Survey Questionnaire IV TE_[NIC_L DISt_USSION OF TASKS Ice Sensiti,'e Component Categorization [Task P, ice Protection Methocks Categorization (Task l] Component and Ice Protection ._Dthod PenaLty Io _ssessment and Evaluation (Task 37 _neral Relative Penalties _te to Effecr_ of lcm_.'Ice 2S Protection S?'st em_ 3" Ice Protection System Weight Penalty Maintenance Safer," ._se_s,7_nt of the E.werirnental Data Base [Task 4 _ Droplet Collection Efficiencies Ice Accretion Size and Shape S- ice Shedding Effects of ice Accretion on the Aemdynamic t_aracteristics of the Components Assess,meat of the ice Accreeion predicti,m o0 Methods _Task 57 O0 ..Xnalvtical _redlction Methods E.rperi.ment,d Prediction Dethods .tsses_,.'_-nt of New Ice Protecti,_n _ethod.,_ _Task o', "2 Electroimpulse ice Protection System Microwave Ice Protection Concept S3 rcephob tc )[tteriai> ii[ Title Page TEfI_N[Ca£ DIScXJSSION OF TASKS (continued) Reduced Ice Protection Requirement and Icing Instrt_ntation ._sessment [Task r) General Reduced Ice Protection Requirement Assessment of Aircraft Icing Instrumentation - Existing and Under Development .Assessment and Recommendations for Icii2g Facilities [Task 8) ._hk.qA Altitude Wind Tunnel (AWT) _ Icing Research Tunnel (IRT] Instr_ntation Requirements for Icing Research Testing Techniques i13 Recommended Usage of .NASA Icing Wind Tuhnel Facilities RECCM_N_ED NASA ICINC RESE4R(._ PROGI_[ (TASK 9) Genera/ Ice Protection Systems Icing Forecasting and Icing Definitions Icing Intensity, Definitions Forec&_ting and Icing Envircrm_nt ._,bdels Instrumentation .amab't ical )_ethods II0 Icing _'ind ,_u_nel ?esting NASA Short and Long Term Icing Research Plan Research [terns Ranking and Scheduling Funding Requirement s V[ CONCLb_I NG R_ b_KS %'[[ AP P D.l} I XT..S A-[ Li_t of References A--I 4-2 Bibliography - Sorted by Subject A-18 B X_ok_-p gables of Ccde_ Used in Icing Research _ta Ftle B--I C rcing Research Data 7tie Interrogations C--i D Stmmary of Industry"C_verr_ent Survey k_lestiotmaire F Sum'ev of Mrcraft icing Simulation Facilities in North America _md Europe E--[ iv LIST OF ILLUSTRATIONS Figure Title Page Task Flow Description Sample Page From ,XASA Search Sample Page From DDC Search How to Create A File Using _lark I%'System 15 S A Sample ,_lark I_ r Icing File Sample Input Sheet Use of Data _tanagement to Accomplish Tasks Effect of SLmu/ated Hoar Frost on the ,Maximum Lift for NACA 65 A /IS Wing Section, From Reference 53 Effects on ,%_ximum Lift and Cruise Drag of Simulated Large Leading Edge Io: Shapes Considered of Importance for Light .a/C, Ref. 53 3O !0 the Effect on CL(_] and CL max of Ice Shapes From the Icing Tunnel Corresponding to Icing in Cruise for the No Flap Configuration, Ref. 55 i1 7he Effect on CL(a) and CL m_-x of Ice Shapes From the icing Turmel Corresponding to Icing in Cruise but Nith Trailing Edge Flap Extended, Ref. 53 Ice Protection System Neight Penal_* Definition of Analysis Parameters, Ref. 105 Electroi_pulse System Details, Ref. 102 -5 Guidance of Hicro_ave Energ 2. by Conposite Ice-Dielectric Surface %_'ave_uide, Ref. 115 I0 MicPowave Deicer Rotor Blade Concept i" • \verage Shear Force per Ablation Test, Ref. 10" 8" [cephobic C_cting Flight Tests 8" [FR Departures of Single Eqgines .aircraft, Ref. 1 2O IFR Departures o£ _alti-engine Mrcraft, Reg. 1 Icing Encotmter Frequency ?s A]titude, Ref. I ;_'ater Content as a Ftmctton af ._bient Te._perature at Different ;_ater Content \'uantities _Stratus Clouds_ 9O 1" Title Page Figure Outside Air Temperature F-xceedance Probability Below 9Z i0,000 Ft, Ref. 102 Liquid Water Content Exceedance Probability Below 10,000 Ft, Ref. 102 25 Continuous _ _M_ximum (Stratiform Clouds) - Atmospheric Icing Conditions, FAA FAR Part 25 26 Intermittent _xim_ (Cum_liform Clouds) - Atmospheric Icing Conditions, FAt FAR Part 25 Recommended Continuous Y___in_/m[Stratiform Clouds) Atmospheric Icing Conditions, Liquid Water Content Vs _an Effective Drop Diameter, Ref. 102 and 134 28 Intermittent _k%_imtm (Cun_liform Clouds) Atmospheric Icing Conditions, Liquid Water Content Vs _lean Eff_tive Drop Diameter, Ref. 102 and 134 29 ._T Flow Circuit 3O AWT _mracteristics 31 Comparison of a Typical General Aviation Aircraft Operational Envelope With the ANT Capabilities 3_ ° .klCF Flow Circuit (Option] 33 (h'erlayof C_neral Aviation Operation Envelope (54,0C0 HP Drive) 3_ Flow Chart of Integrated Icing Research TecY_ical ,4rea_ Short Term and Long Term Research Plan 36 Estimated Funding Requirements in Thousands of 1980 Dollars vi

LIST OFTAB!_S

Table Title

Page

I SearchTermsfor the DDC Search 9

II

Log of Questiom,aire Re_ponses

Ill 23

MatrL_ of Components Vs Ice Protection 5Mthods

I%' 33

Penalties of Icing Effects on Aircraft by _del

V 34

Penalties of Icing Effects on Aircraft by Components

%q 35

Penalty Assessment of the Protection Systems

Aircraft Type (Typical E_amples of Weight Class)

VIII 40

Aircrmft Ice Protection SystemCodes

IX _3

WLndshieldDefog/Anti-icing Reliability

X 44

Wing/F_ennageBleed .Sir Anti-icing Reliability

XI 45

Electrical Empennage Deicing Reliability

XII

Bleed Air Engine Inlet Anti-icing Reliability

XIII

Electrical Propeller Deicing Reliability

Ice Detection SystemReliability

k%"

PneumaticRadome Anti-icing Reliability

_q

Bleed Air on _gine Components - Reliability

k%q I

_ri_ of Components Vs Data Base/Facility l_/pe

k%q I [

._trix of Components Vs Data Base/Facility Type

XIX

_tri_x of Components Vs Data Base/Facility Type

.LX

Assessment of the Icing Facilities by Relative Ranking

KXI 99

A-ssessment of Icing Instrumentation

L'XI[

Suggested Research Program_ vii

Section !

SH_kRY A study was conducted to define for the ,NASA Lewis Research Center, both a long term and a short term icing research and tecnnology program which is responsive to the needs and desires of members of the light transport and general aviation industry. Included were assessments of the current state- of-the-art in prediction and test techniques and facilities, as well as the adequacy, of the existing data base and aircraft instrumentation under icing conditions.

In order to facilitate the overall objectives, the program w_s divided into ten separate but related tasks as follows: I. Identif7 ice sensitive components.

2. List existing ice protection systems for components.

3. Assess ice protection system penalties.

4. Assess experimental data base.

5. Assess ice accretion prediction methods.

6. Assess new ice protection methods.

7. Define a reduced ice protection system requirement.

8. Assess _%SA LeRC icing research facilities and recormnend Lmprovements.

9. Scm_uariae results and reco_end research program.

10. Reporting effort.

The stud)" was accomplished utilizing a comprehensive literature search to obtain the current published information and an industrywide survey to solicit highly specific opinions and answers to questions directly related to the program tasks.

In order to ald the inp!ementation of the specific vro_ram tasks and te organize the material obtained from the literature search, a computerized data nanagement file _s used for both the storing and retrieving of information, The biblio_rraphy of references assembled from the literature search, the Lists of ice sensitive components and current methods of ice protection, and tables of codes used for data storage and interro_ation were directly used in the report.

The results of the study programrevealed that the techniqu_ anl

methods developed in the 1940 and 1950's are still being used today through- out the general aviation industry, l]_e major improvement has been in the tree of computer codes (mostly individually company developed) for calcu/ating flow fields about wings and body shapes, droplet trajectories, ice accretion quantities, and subsequent heat transfer characteristics involved with ice protection system design and certification. Further research is required to develop codes beyond the 2-D programs and also codes for ice shedding, ice shapes, accretion with ice buildup, and aircraft penalties.

Ice protection systems currently used are the same conventional systems that have been use_ over the past 20 to 30 Fears, with perhaps some improve- ments in design and utilization. New systems such as icephobics, electro-- impulse, microwave, and acoustic are only in the conceptual and research phases.

A reD" great concern has been shown throughout the general aviation industry for improvements in instrumentation, icing forecasting, qumltita- tire ich_g definitions that can be related to G/A aircraft, standard certification required for all FAA regions, and a reevaluation of the FAR 25 Appendix C envelopes.

.kn assessment of the .NASA (LeRC) icing facilities _ nade including a list of fourteen suggested improvements sumnarized from the industry survey.

From the results of the study, a list of thirty three research items were a.sse.,_bled for laying out a short tern a_.d long term research program.

For purposes of the program, the short tern is three to five years and the long term five to ten years, The starting times and program costs were coordinated with probable facilities refurbishing dates and estimated reasonable budgets. Research and technology areas are ranked in accordance with the ,most needed listed first.

Section II LNTRODUCT I ON BACKGROUND The .nature of icing problems and advances in technology related to icing and ice protection methods have changed considerably since the 1950's, when the last major thrust in icing research by NACA (now NASA) was terminated.

Although industry has accomplished some work in applied RgD, most of the effort has been direczed to specific designs for certification of large transport aircraft. ._re recently, exparmion in the use of private business and co_uter aircraft has emphasized the ._roblems that restdt from applying the icing requirements of large commercial aircraft to the smaller, light transport segment of the industr/. General aviation told light transport air- craft have operational a_d utilization problems resulting in relatively higher exposure to icing conditiop_s ard greater penalties for ice protection systems. These are due to: (_ the smaller physical d_nension_, which produce r_latively heavier ice _cretions and, thus, aerodyrmmic performarce degradatlon, (2) weight and cost penalties of icing systems relative to their payload and cost baselines, and (3) the perceived inappropriateness of weather forecasting methods, told (4] lack of parti_i/lJJnited tyl_e cer_ifica- ti_,n require._nts to this calss of aircratt.

Current icing problems result from increased air traffic _01'mne, r_re e_ensive w_rld_ide and seasonal operations, proliferation of low-altitude shuttle operations wh_re icing is _re likely for both civil ant industrial use, a_:d an increased threat to general populace from accidents that occur in highly populated areas.

In the meantLme, advances in tech_nolo_, have been extensive in _an/ areas and particularly in electronics and optics with the proliferation of microprocessors, computers, new t_1_es of sensors, radar, laser_, holography, and microwave. A major effort is needed to resolve the icing proble_ns with the aid of these new tec_hnologles. Recognition of these factors has resulted in X_SA reestablishing an icing research function dedicated to both short and long term research progTa_s, hncludin_ _dating of icing tumanel and instr[mentat ion capabilities.

The research problem is not ertirely new, since man)" tec.hnique_ e_m[ved in the 19S0's, refined since that ti_e, and applied primarily to large transports, are accurate. In particular, tDe correlation of ice collection equations, as well as heat ,and mass "ransfer equations over airfoils and windshields, has been quite good. Since these quantities are also required for light transport and general aviation, some cormlonality exists. This commonality lies in the areas of the following.

I.

The same ice sensitive components, such as flight surface leading edges, engine inlets, pitots, etc. The similarity exists in the areas of function, shapes, and certain ice protection methods.

Z.

Icing physics associated with ice accumulation and heat and mass transfer are identical and can be related by common scaling parameters.

3. Operational exposure in those regions of operational space which are cormnon, i.e., during transitional flight and at lower altitudes.

_bst of the differences result fTOm size, performmnce, mission, and payload differences, where the general a._ation and light transport aircraft are penalized in all these respects.

It is seen that the major problems which need to be resolved are: (I) reduction in operational (certif:.cation requirements) constraints in order to improve the use of the e×isting and growing body of general aviation and light trmnspoz% aircraft, (2] i_,rovement in safety while operating in icing conditions, and [3) reduction in manufacturing and mainter2_nce costs of ice protection systems as a basis for i_proving the operational opportunities of short distance shuttle services. It is evident that to solve these problems, a new, concerted effort ._ast be initiated to combine the advancements in instrumentation, ice protection capabilities and methods, weather forecasting techniques, etc., so as to provide a sound and current technological basis for the design and ce,_tificatioh of light transport and general aviation aircraft.

OBJECTI\_ The objectives of this program were to define for .NASA both a long and a short term icing research and technology program responsive to the needs and desires of members of the light transport and genera/aviation industD,.

Included are assessments of the current state-of-the-art in prediction and test techniques and facilities, as well as the adequacy, of the existLng data base and aircraft inst_nentation under icin_ operation.

SCOPE :L\_ %PPROA_ The program was accomplished by laving out a detailed and relevant foundation fcr acaumulation of _ta'_i_h defines the current and future icing prediction, testing, protection methods, and instrumentation that are applicable to the probiem3 ef hght transport and general a_iation aircraft.

This foundation estahhshed a basis for determining the requirements for future icing research anJ technolo_, efforts.

As shown in figure i, the program consisted of ten separate, but related tasks. The first six of these are related, in tLat the results of each task correspond on a one-to-one basis with the list of ice sensitive components defined in task I. The outputs of these tasks are similar in format, each generating parameter lists which apply to the task I components. The results of the first six tasks were used with the additional assessments of tasks VII and VIII to provide the conclusions and recommendations of task IX. Task X is a reporting task.

The general approach consisted of the division of each task into an initial definition phase and a final assessment phase, including conclusious and recommendations for each task. The intermediate effort, _hich involved data gathering, data relating, sorting, and interim evaluation was accomplished concurrently by means of a computerized data management system.

This step permitted a major increase in program analysis efficiency by: (i) data search and recording of all parameters concurrently, and (2) data combinations, sorting, relating, etc., by computer, based on the use of specialized parameters derived from the objectives of each task. Additional data were obtained from the results of a survey of Government and industry relating to the objectives of this program.

For the purposes of the study program, light transport is defined as fLxed wing 31rcraft of up to 30 passengers, having an annual utilization of about Z500 hours in scheduled operations, and operating primarily at altitudes below 19,000 feet. General aviation refers to fixed wing aircraft utilized in non-milita_, and unscheduled airline operations. Aircraft with the following types of engines are being considered: jet and fan engines, turboprops, and piston enzines.

P R06_.<_IPAYCFF The Lntent of this program is to provide gui#ance regarding areas for icing research and tec>_ology _ich have the greatest potential for advance- ment of the ice protection state-of-the-art as applicable to light transport and general aviation aircraft. The short term and long term icing research programs developed from the result_ of the literature search, questionrmire returns, and task studies of this prod-am, along with discussions with other icing authorities will help define a la_je scale effort for NASA facility _mprovement and for N_L_A in-house and/or _ontracted research and technolo_.

activity. _lese efforts should cul,_[nate .n an increased utilization of _eneral aviation a_,d light transport aircraft with attendant improvements in safety and econorm" of operation.

L II Ill

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--_ ICE-PROTECTION SISTENS SYSTEq PENALTY l FOR P._(7_ CO_ONEVr ASSES_IENT IV

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IDENTIFY , l DATA EASE ASSES_ENT ICE-SEVSITIVE _-- FOR EA(_ CO_NEVF I_- INTER'_CTION COMPONENTS I V ICE-ACCRETION PREDICTION - ASSESS_T OF METHODS i PROPOSE & EK_LUATE N_W .k_/0R AD_\TCED ICE-PROTECTION _THODS CCNDITION OPERATION DEFINITION I }.EDE_%TE TO LIGHT ICING '_II _ASA/LH_XS ICING FACILITY USE S_fb_" IX [ DE%TLjP FL'.TJRf K-k_.4 _CING Fi_rdre [. Task Flow _escriptlon Sect ion II I RESEARCH DATA ACQUISITILIN LITERATURE SEARCH From the very beginning of this study, it was recogni:ed that a fairly extensive search of the literature wDuld be required to provide a basis for assessing the current state of icing technology and future icing research requirements. .is noted in the introduction, the last major efforts in this field were spearheaded by NAC% in the early 1950'5. _bst of the literature resultung from those efforts _has been in circulation for some time, and reviewing such documents would not result in information of which _e are not already well aware. (For example, Rockwell already has an in-house file of about I00 icing related documents published circa this period, r_stly by NACA._ On the other hand, a search of the more recent literature _Duld provide an indication of the problems and solution5 which currently exist in the genera/ aviation and light transport industr F. .As a result, the search .was linited to documents published since 1968, and to subjects concerning aircraft related icing only. Helicopters were eKplicit!y omitted since it was felt that this area would be studied under a similar but separate _ASA _ponsored contract.

The scope and effort of the search was quite large, since it was intended that the literature would provide the support required for the research _rograra recz,_endations. Three search sources were utilized - K:_SAo Natlonal Technical Information Service (NTIS), and the Defense Dooanentation Center tDDCT. Abstracts were requested of all documents in these files which addressed aircraft icing and m%ti-.icing.

Fi_re 2 present3 a sample page from the GLSA literature search. A total of 221 references were cited by K.LSA as pertinent to aircraft icing and anti-icing methods. Note that abstracts were not available for all of the references, although in many cases, at least a partial description of the contents was included. Doctanents published in a foreign [an_n_age (excluding translations) were not considered for the purposes of this contract, due to tJ_e and man power constraints. However, it was noted that eight of these ',,ould pertain to the objectives of this program :rod might be included in future studies. Based on t_he abstracts, -9 references _mre determined to bo of further interest to :his program, ;rod _,ere ordered.

The 3FC search turned up only 3" doctm_ents which net the search ::nstraints. Table [ presents the "first" and "second leveI search term._s" :_ed by DDC to extract dccuv, ents of interest from its files. In essence, the search requires t.hnt at least one term from each level appear in the descrip- tars for each dee',mont. _us ,-_a>" be seen to be the case m the DDC search s:Lwle ,if fi;are 3. Th, :rteen decoments _ere ordered from the Drc for further examinat ion.

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• _, ? , lO '!G_;I?,.-%I. tL._GH I,_ '>;' I: "_T{ _2_;.\l.r'l-y The .NTIS cited 122 docLments. Thirty seven were considered of interest to the program. Seven were found to be duplicates, so thirty documents were ordered.

[n all, 380 documents were cited by the three services, and 122 were ordered. However, the ntmVoer actually reviewed totalled 141, since: (I) some of the doclanents which were received contain a number of separately referenceable articles of interest to the program, and (2) there were doc_nents not listed in any of the searches which were already in Rockwell's possess ion.

A computerized bibliography of the references which have been reviewed as part of this program was developed. This file stores the reference titles in standard bibliography format, but also keeps tr,_ck of t_he year of publication, the source of the do_ent (e,g., USA_, USN, cor_panv, country., etc.), a subject (assigned by the user), and the Government accession n_nber (NASA, DDC, NTIS, or other). The most current output of the biblio_Taphy is presented in Appendix A.

A manipulation of this reference file was made to sort the above reports by sabject. This was done in order to identify those areas where icing work and studies are currently being conducted which have application to ,'_kSA research objectives. It would also point to areas where such work is lacking.

The results of this file search are presented Ln Appendix A. It was fo_d that in general, there was good balance among the separate subjects. .As exvected, the bulk of t_he references could be classified as pertaining to gener_l aircraft Icing. _-ere were also quite a few ¢oncernLng anti-icing and deicing systems, chnlv three accident reports relating to icing were revie_;ed, plus three on fuel additives, and _hree on carburetor icing. Cnly five out of the i_i reports dealt entirely with an analytical model for air- craft icing. The literature searches turned up a number of do_n_nents on helicopter icing, but these were not ordered unless they appeared to have application to the general aviation segment of the industrw as well. .As a result, only six docam,ents are listed under "helicopter icing" in Appendix B.

Some reports such as the accident reports which were not specifically sought, turned trp in the literature search due to the key" code _Drds used in the search. The," _ere reviewed for their possible contribution to the program and recorded. It is suspected, from the review of aany documents, that much gocd data may remain hidden due to: _.[> the use of nondescript titles, or ,2" the fact that a reFort _lv contain icing data which is not properly" identified via either the title or key search terms.

[IAY% _IAK_IFiJ Fits Review of the literature has to be acco,,_plished in a consistent, repeat- able _aumer, with certaLn questions being asked of each document which related explicitly to the objectives of the progran. In the process, the reviewer obtains a feel for the content of the literature and its application Ii potential for the various tasks of the program. However, after reviewing more than i00 documents, it becomes difficult to efficiently remember or sort out which of the documents ,_as applicable to what purpose. .Also, this procedure al_st requires that the reviewer also be the primary, investigator for the effort, if he is to know what is contained in each document.

In order to get around this problem, a computerized data management system was used in this program. The idea behind this system is to provide a means of storing the information fotmd in the literature into an easily retrievable file. In this way, the reviewer quickly scans and reviews each document, answering a number of pertinent questions in code form on computer data sheets. The data sheet information is then punched into cards and entered into the icing research data file.

For this study, the _PdIK IV File _nagement System was used. ,_nis is a system proprietary to Informatics, Inc., but _ich is on line as part of the Rock_'ell computer system. ._ the name implies, the primary.,concept of ._DdZi IV is the ability to manipulate files of data. Basically, what the user must do when startlng out, is to decide what informatlon he wants to store from each record (or reference), how he wants to store it, and un _t_at format he wants to input the data into the system. Thxs "file creation" process is depicted in figure 4, and can be broken down into "file definition," "transaction definition" [input format), and "file creation" phases, it is important to choose the categories of information to be stored carefully when first developing the file because it becomes increasingly difficult to go back and restr_acture the file as the number of records (or references) inserted into the file grows.

u_noe the files and their transactions have been defined, the user has the ability to solve his information _mlagement requirements. In _RK IV, this is done through the use of "requests." In general, requests are the mea_:_ bv which a user selects records from a file, selects specified data from "he records for computation and logical processing, and _,q_ecifies the desired output. This output normally takes the form of reports, inte,'nnediate result files, subsets of the original file, or combinations of all of these.

A _wr>' s umplified scheme for a _%ARK _" file is sho_n in figure S. [n this example, the total file length allocated for data storage is 2- locations per record, or reference. The first three are allocated to the reference nigher, ,'md the next fifteen to the aircraft type discussed m that reference. _e last three sets of three locations are for filing the lee sensitive ce,,'zponent, if _W, addressed in the reference, the anti-ice system discussed, and the .!ata base vi.e., _/_nd tunnel testing, anal>_izal, etc._.

Note tN_t for the iatter three, a code number is stored, instead of a _vrd description. _is is done to reduce the file si:e requirements. For e×;tmpie, i: each of those three parameters _ere allocated 20 locations each in the file. then the file length _2uld be -S per reference, instead of the 2-

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1 [. i i Table of Components I00 NCh]_ 200 YfNDSHIELDS 500 AIRFOILS 4OO RA_ObES 500 ._t&\H" Table of Anti-ice Systems 10 HOT AIR 2O THEKqO- ELECTRI C 30 NON_ 40 _ta&X Table for Data Base 1 wIN_ I1.NN_L 2 FLIGHT TEST 3 .ZNALtTICeG 4 NON_ k Sample ._hrk P,- Ichqg Fkke Fi_are 5.

locations shown in the figure. The code numbers are chosen from tables of components, ,_nti-ice systems, and data base which the analyst constructs at task initiation.

The file used to actually accomplish this effort was rmch larger than the sample file in figure 5, but the basic principles are the same. A number of questions were developed for classifying and storing the informa- tion found in the references. These questions were based on the investiga- tor's interpretations of the task objectives, and deal with a number of items required by these tasks.

Figure 6 presents a t}_pical _rk sheet used during the review of the literature. The work sheet breaks down into four different parts. The first part deals with the reference in general, and includes codes for a reference number, the component types, anti-ice methods, and the availability of the reference. The tables of codes which were used are presented in Appendix B.

The "data base" describes the tyloe of data in the report, such as commentary, statistical, operational experience reporting, type of test facility, computer progTsm, etc. The 'hnethod of expression" describes or classifies any" specific equations, or notes whether there are computer programs/data or experimental measurements included, lqle "research status" allows the reviewer to note whether the reference suggests that research is either needed or not needed, as well as how badly it is needed. A code is included for the "icLng conditions" discussed in the reference, such as liquid water content, altitude, drop size, flight test under natural or tanker icing, combinations, flight profiles, cerzification data, and many others. The "state-of-the-art" code really' applies to the method of anti-icing or ins_%ruments which r_easure icing. Using this code, the reviewer assesses where the state-of-the-art lies; i.e., off the shelf, new' concept, etc.

Provision is made for indicating the aircraft discussed in each reference, if applicable. Finally, up to four lines of co.n_nents are allc_ed regarding the overall reference. Here the reviewer can rate the source, or simply provide a mini-abstract, if he wishes.

The second part of the work _heet deals with the icing phenomena in the reference, such as heat transfer mm!yses , water drop trajectory/collection efficiencies, ice shedding, aircraft effects, etc. Once the phenomenon has been coded, questions regarding its data base, method of expression, research status, and icing conditions are considered, rE icing phenomena are not discussed, all the attendant codes and comments which follow may be left bhmk.

The third part of the work sheet addresses the penalties discussed in the reference. 7hose are coded to siTufy whether the}" address components, or are aircraft associated [weight, speed, drag, r_ge, etc.). A rating of the penalty is also coded: no effect, small effect, moderate effect, _evere effect, etc.

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_-------.._.--.---____+.---_ _ ___u__,---+_...._ + • • i _ 1TM , , ,.+.,+- ._ < _" The same questions are asked in the penalty section as were asked in previous ones. The data base, method of expression, research status and icing conditions are noted. Up to four lines of co_nent regarding the penalty information in the reference are allowed. Again, if penalty informa- tion is not discussed, all the attendant codes and comments are omitted.

The fourth part of the work sheet, which was an addition made after a considerable number of references ha_ been reviewed, addresses the instrumen- tation associated with icing which are discussed in each reference. Again, the s_me questions are ssked in the inst_mentation section as were asked in the previous ones. A/lowances are made for additional instrumentation when '%here than one" code is used. The principle of operation and utilization of the instruments are also indicated by code number. Again, up to four lines of con_nents regarding the instrument information are allowed. A component code number in the first par_ of the work sheet uvmediately indicates to the computer and reviewer when the main subject of the reference is instrumentat ion.

The questions sad codes used are meant to reflect the task requirements.

Some additions or changes were made, such as the addition of a section regarding instrumentation. However, as more and more of the literature was reviewed, it became more difficult to make changes, since one would then have to go back and rereview the documents already incorporated into the files.

_i 141 references were reviewed from the standpoint of these questions, and the resulting information was input into the >_RK IV system to create a file o£ data pertaining to icing research requirements. _he entire process, including the literature search, file creation, and file manipulation is schematically depicted in figure 7. As expected, the file >ms an efficient tool for ,.naaipulating the findings of the literature so as to address the requirements of the various program tasks.

During the course of this effort, the computer file was interrogated in a number of different ways, and the results _:ere used in the fulfillmen_ of each task, as required. The computer outputs from these interrogations are included in this report as Appendix C.

LXDUSTRY/CC_'ER.',_'_I_T/UN!_.-ERSITY SLTR\_" Q[_STIOk_41RE Early in the program, it was decided by the NA_SA that a vet worthwhile addition to the program _ould be a survey of the general aviation industry _md those concerned Government agencies involved in aircraft icing tecS_nolo_,, to solicit their views with regard to a number o£ the progrm-_ tasks.

I- DEVELOP CRITERIA _ ' i ROCKWELl < LITERATURE SEAR[}{ DATA ACQUISITION i DB_AaLOP C0b_UTER , i L'_2UT ______pROTECTION , PROGRAM IN?U'r DATA

, I

IcI ,I i 'I : p)./_A_[TERS _ORKSHEET

/ BY C&TEGORY i i DATA FILE CRE%TION DEFINE

] Fi_ I

FILE i _--_L CO_L_ 7 STRU_n'bT_i

k

!

[_ , i [ I ' i ANALY2E AND [ ._ i DE\_LOP P • TIT ASSESS TO FLLF._*- OUTPUT ?_NIPULATE I I D.SK OR/ECTI_S FI_S SEXRG{ BY ,AS_ ; i r_RCUP[NGS FOR i / DAT.a RETRIEVAl. .-ix,I) xi&LYS[S Figure " Use of Data ),t_uagement to _,ccomFlish Tisks The major objectives of the survey/questionnaire were threefold, as follows : 1.

To solicit the latest up-to-the-minute information on many different aspects of icing technology including ice protection system design and operational techniques used by the general aviation aircraft industry and related Government agencies.

To solicit the views, comments and reconmendatious from the experts in industry and Government, concerned with icing problems and their resolut ion.

, ro give the icing technology erperts in industry, and Government an opportunity to voice their concerns relating to icing and icing protection and to influence the direction of future NASA research.

These inputs would allow the reflection of the broader view of the general aviation indust_z in the reeommencmtions given to ,xi$SAfor short and long term research plans.

A copy of the survey/questionnaire and the letter of transmittal sent to industry, and Gove.-n_ment agencies is contained within the report inAppendix D. The survey/questionnaire _s sent to eight Government agencies and fifty- two general aviation aircraft companies and universities.

The questions in the survey were grouped into eight basic sections dealing with: I. Ice _rotection Systems 2. lee Protection Penalties 3. Propulsion System IcLng I. Airframe Icing S. Testing Tec.hniques O. Calculation Techniques -. h'eather Data 8. FLqal Recommendations _zese eight section> went right to the heart of the important naterial of the study program in an effort, not only to obtain the most current infor- .nation available frcm those experts from industry and 'Cevernment agencies '_orking in the a_rcraft icing field, but in the case of penalties data, to obtam data not readily available in the general literature, An initial IIi____ review of the literature obtained in the study, program indicated that there was only a limited amount of icing, icing component, or anti-icing system penalty data available in usable form. Anti-icing protection system penalty data is usually aircraft model oriented and _-ystem oriented rather than anti- iced component oriented.

7dso noted in the general literature was a lack of specific data base information regarding specific computer codes used for ana_ sis. This may, of course, be due to the proprieta_, nature of nm_ny computer programs developed in the private industry, sector. Specific information on data base was requested, not only to obtain direct and current information on the subject, but a/so due to the fact that in much of the literature reviewed the data base was poorly defined or merely inferred.

Each questionnaire was sent out with a letter of trans_nittal. B,'c basic letters were used, differing only in one or t_o sentences depending upon ",hether the letter was being sent to a representative of the aviation industry or to a Government agency. In general, the questionnaires were not necessarily sent directly to the icing expert, but to a company official who _muld be in a position to see that any information presented was in accord- ante with the individmti ¢ompm_- policies.

_proximateb" 55 percent of the companies, universities, and <_vernment agencies receLving the questionnaire responded. A list of the respondents is sho_n _n table it. _hich indicates that a good cross section of beth indicts- and J_vet_ent contributed generously to the program.

Permltv data presented in the rescenses were in the form of tabulations on ice protection syste_ and components. _Iost of the data were relative ranking of penalties with respect to the various aircraft model.-- listed. All of the other data presented were prunarily in the form of _Titten answers to the specific questions. _bst organizations ;,'ere extremely heleful by presenting their answers directiv m the same format as they were asked, The information from the survey was carefully evaluated mqd then folded into the ,|pplicable 3ectiens of the report. Since manv of the respondent_ ['resented sixnilar ,tra_'.ers :rod ideas to _mx of the same question , no atttnnpt '*_b :rode :o sinKie out _m individual in the body of the rer_ort for credits, _ather, ,I :;_raF," or" the data and infor-natlcn from :m evai[uition of :!'e 5(.'F.-e v ,,_ils ,ls_eFbled ,lnd is presented -a \['pendix F of the report.

FIRM TYPE 06/11/80 Rockwell, Genera/ Aviation Division Aircraft 07/28/80 Key Industries Corporation Systems, Operations 08/01/80 Teledyne-Ryan Aeronautical Systems, Operations 08/01/80 General Dvnam/cs ' Convair Division .Aircraft / - 0S 0/80 Cessna Aircraft Aircraft 08/11/80 Cre_ Systems Consultants Systmes, Operations 08/14/80 Gulfstream American Aircraft 08/:4/80 AiResearch _£g. Co. of Ari=ona Engines 08/15/80 Bendix Avionics Division Systems, Operations C8/15/80 Beech Aircraft Corporation Aircraft 08/15/80 b_iversity of Kansas University 08/12/80 Dept. of Transportation, F.<4 Government ']8/'" lql] _ .

....... B.F. q_odrlch Systems, Operations 08, 22/80 A.F. IVright Aeronautical Labs Government 08 ' _a / .-. 80 L°ckheed-Georzia Company .Aircraft 09/02/80 A%Co,- [.._'comlng Division Engines 09/05,'S@ Piper Aircraft Corp., Lakeland Division Airc_-af_ 09/08/80 Detroit Diesel .-tllison Engines 09,"!1,/_0 KASA, }._rshal Space Fli_h_ Center O._FC) Government 09/16/_0 Douglas )drcraft Company Alrcraft i.... O, 80 Piper Aircraft ,Corp. , Santa "[aria, Calif. .Aircraft 1-, )_,31] _oe[nK Co_ercial .Airplane, Co., Seat_ [e, Washin<ton tircraft _.e _ HavilIand Aircraft of ..anada, Cntario, Canada Aircraft

Section FV TE(]qNICAL DISCUSSION OF TASKS in the following _echnical discussions, are the assessments and evalua- tions of the many facets of icing technology referred to in the specific program stud}- tasks. It was the considered opinion of both NASA and Rockwell that these assessments and evaluations would play a very necessary part in the development of the requirements for a short term and long term icing research program.

ICE. SD4SITI%Z CQ_E_OhT-\T C%TECORIZATION tTASK I] 1"he logical first task requirement in this program was t_ identify and list all light transport and general aviation aircraft components which are ice sensitive, particularly those which need to be considered _'ith respect to ice protection. Ice sensitive refers to those components which: l. Ac_nm_late ice in the presence of an icing conducive atmosphere.

2. Are '_roblem oriented" with respect to aircraft performance, safer>', ,_mintenance, design cost, life cycle cost, or other t>_e of penalty.

[he ice sensitive component list developed for the stud}- program is one of the prL,_ar%- codes for the data file and is show_ in its entirety in Appendix 3 as the first table in the series of 15 "lookup" tables. This code list not only lists the ice sensitive qomponent but also gives answers to the followLn< questions for each component.

i. ;_here and,,'orhow does the ice form?

i. %_hen does the ice term'7 3. Is it a problem? _hv7 7he list is cons[tiered quite deflnitLve and wus updated _everal tbnes durtn< the pro;r:m_. _he component [_st is the basis for aid of the other task< of the ?rog_rmn. Each succeedin_ t_<k concerns all, or at least several of the co_,np,onents on the l i_t, dependin_ upon the technology subject :m,t the avaihlbilitv of the data.

Table ][[ i_ a natrlx ot co,_.?enents versus ice ?rotect[on :_ethods. ]_e cc_onent__ are listed _m,ler seve:'ll Kene'.'al titles _hich divide them into Olttlral :ate<cries _s feilc_,s: iet on<rues, f:m 'et _en_ines], turhe!_ro/, ,engines , ?iston on<inca, li:'c:'aft instr't_ents fli<ht'. (tu, ehhle, tail TABLE III MATRIX OF COMPONENTS VS ICE PROTECTION METHODS ICE-PROTECTION METHOD CODE: I Continuous RLUID OTHER HOT AIR I ELEC. I 2 Cyclic ' 1 3 Intermittent ¢ "Cne-Shot" Io _ v Z COMPONENT JET ENGINES I. Main Inlet 2,3J 2. Slow :n Doers !

2. Inlet Noise Su:cression _. Nose CaDs I 1 S. Screens I 5. Inlet Guide Vanes I I 7. Ro:or Blades _. Frame Struts F_N JET : i items I 7o _ And B 7a 7 From i : Cet Engines Fin 8yoass TSRBOPROP Items I, _, Zn¢ S "o _ From Jet Zngines Particle SeDara:ors Scree,s l,C 3 l _usn P-o_ellers l,Z 3 Zngiqe :awliqg 1,2 _ST_N E?_GINES i _arbure_r , l _u!l P'o_eiie-s l,Z 3 'l ,i Engine ,]Cwi_g _b TABLE III _ATRIX OF COMPONENTS VS ICE PROTECTION METHODS _continued) ICE-PROTECTION METHOD

r

CODE: I Continuous ELEC. FLUID OTHER HOT AIR 2 Cyclic 3 Intermittent "One-Shot" z I

-

-

COMPONENT A/C INSTRUMENTS _itot Static Tube I Aft. Rate-of-Climb Orifice Yaw Vanes Total Head Prsbe II ,2 Total Temo mrobe i ' !

FUSELAGE 1 3 -_ 1 1 Wincsh!eld Wing/Fuselage Junc:ure Static Vents ] ; Scoops grains Cther Junc:ures Antennas 3 3 l 1 Radomes I Elactro-O_tical Tr_ms_ar.

TAIL SURFACES :I,Z 1,2i 3 3 ,2,_! I _orizont_, E_evat3r 1,2! 3 3 '2,31 [ I Vertical, Ru_¢e_ -.Tail

f

'/-'a_l _i_erons _13_s I,'_3 Slats Slots 1,2 ;,i3 ,l Canard The ice protection method or methods used with each of the ice sensitive components is shown on the matrix and is discussed in the next section of the report. The effects of ice on the unheated components and the penalties associated with the ice protection systems are the subjects of discussion in subsequent sections of the report.

ICE PROTECTION ._THODS CATEGORIZATION (TASK 2) Ice protection methods for the ice sensitive components identified for Task r were itemized and utilized for the matrS-E of combinations shown in table Ill. A list of all of the various ice protection methods currently used or in research and development stages have been included in the second table of .Appendix B. There is a computer file code number for each method and there is a cohmm parameter established for the code in the data file.

The ice protection methods sho_m in the matrix of table III have been further detailed in that they have been coded to indicate the type of system such as continuous, cyclic, intermittent, or "one shot," thal are normally used for a specific component.

In general, ice protection systems fall into the following categories : I. Hot Air " Electrical 3. Fluid 4. Pneunat ic = Other (Acoustic. Hicrowave. Vibratory, Icephobics) The first four categories are in cot, men use today, and have been for some tL_ in the past. The systems tunder the heading "other" are still Ln the concep- ttutl ant'or research ,rod devetopment stages.

All of these categories of systems fall into one or hoth of t_c possible t',_es of protection svsteras: LI_ deicing syste_, or .2 _, anti-icing svstem,_.

Deicing refers to the removal of ice accretion after it has built up.

Deicing can be accomplished b?- ,my of the categories of sy'ste_ listed.

Anti-icing refers te the prevention of ice for_,altion before it c_ start to build u_, In <choral. anti-icLng c&n only be accomplished by the first three categories of sx'ster_, ba>icallv fluid or thermal neans, It r_>" be noted here that _ll of the he;, conce"tuai and research :rod develc!'ment systems are ietcl:_ <'.'_,tem t,.Tes. This is not considered tmusual since one of the main concerns is to reduce the po_er requirements of these ne_, systems. [_2iCillg systems, by the nature of their operational characteristics, which are a[_,avs intemittent, use less ?m,er thin1 mt:-_cing svste_.

-'3 Descriptions and discussions of the conventional methods of ice protection and of ice protection systems may be found in many of the documents listed in the bibliography of references herein, in particular, refe-ences 75, i05, and 1O8 contain design data, descriptions and discussions of both deicing and anti-icing systems.

COMPON_-NT A,\q3 ICE PROTECTION ,_ETHOD PENALTY .a_$SESSMF_NT .aND E%La/UATION (T.aSK 3] 6"D;ERAL The objectives of this section are to identify ice protection systems and related factors whi-_h have the greatest payoff for L_proving the icing condition operational capability of general aviation and light transport aircraft.

In order to achieve the objectives that are desired, an assessment of the penalties associated with the ice sensitive aircraEt components and the ice protection systems utilized or contemplated for these components was _mde insofar as data were available. A literature search was conducted to obtain data with respect to penalty data associated with the ice sensitive components or ice protection systems. Five lines (12 through 16] _ere allowed for penalty associated data on the cemp. uterized master file computer code fonn. k'uestions and fill-in -_harts were included with the industry-/ Government su.,wev questionnaire in order to solicit the desired information from general aviation aircraft manufacturers, univcrsities, and experts in goverr_,,ent agencies associated ;,ith aircraft icLng problems and technolo%D..

]_e literature search was conducted for penalty factors which concerned both unprotected aircraft ice sensitive components _nd ice protection systems _uch as the followhng: i. Power Requirements 2. Initial Cost o, Safety The literature search was disappointing in that very little information on penalties is published in the general literature, particularly under the general title of component penalties. Certain t>-pes of information, such as electrical power requirements and heat requirements can be extracled from published analyses made on specific systems for specific aircraft. However.

specific penalties such as electrical power required or heat required (which is sometimes translated into an engine bleed air flow available) are "difficult to assign a relative ranking because they are intimately involved with the type, size, and capabilities of the specific aircr&ft/engine _ype involved. The ice protection system requirement for a particular ice sensitive component which may i_pose a severe penalty to one ,type of aircraft may impose only a minor penalty to another type of aircraft.

It is logical, then, to make penal_" assessments on a basis of ice protection system(s) for a specific aircraft and/or type of aircraft where ice protection systems are provided and data are available. Different kinds of ice protection systems for the same ice sensitive component are evaluated with respect to each other. The same logic holds true with respect to ice accretion on tmprotected components regarding the impact on aircraft aero- dFnamic perfor_mace. The unpact of icing on aircraft performance due to icing of unheated surfaces such as the leading edges of the wings, horimontal and vertical stabilizers, w_ng struts, engine cowl propeller, etc. is in the form of increased drag, reduced lift and rate of climb, and increased stall speed. Fl!ght tests have indicated thal only i/4 inch of glaze ice on the leading edges of the wing can reduce climb speed by 300 fpm (reference I).

This _me reference mdicates that wing icing can contribute _0 to 60 percent of the total icing drag on an airplane. Propeller efficienQ" on a typical G/A alrcraft can be reduced by as _]ch as lO to 19 percent (reference l and _AC_ _ 1398_ by ice buildups. For business jet _pe aircraft '_ith new wing LapproxL_ating sup_ercritical_ cross sections, less than 1/4 inch of ice on the leading edge "hi-lite" or stagnation point can increase the stall speed by i0-15 hnots. Propeller driven G/A aircraft also exhibit the same 10-15 k_,ot stall speed increase for I/8 to 1/'4 inch ice buildup on the wing leading edge. Icing accretions on the engine cowl, aircraft nose, .-dscellaneotts anterma, and other protuberances can contribute as much as .'0-25 percent of the total increased drag due to aircraft icing.

Recent tests with simulated ice representing l0 minutes of _oderate 0.5 gr_s mS_ icing on the leading edges cf the Sabreliner 05 wing, increased the -tall speed by 13 k_ots. Although handling quatities of the aircraft _e:'e vet--" satisfactory, some buffeting was ex_perienced with the ice shapes.

Bata on a Z_I-21D aircraft taken from reference _1 indicate that at 1-C kCb_. an ice acctr_alatien of _5 re 1.9 inches moderate icing _ cn ti_e flight surface lead,n; c4ges will result Ln a 10-3¢ i_et Loss in $peed at the same _ewef setting.

A very excellerlt study of the effects of simulated hoar frost and Joe

on three basic wing configurations of the NACA 65A215-wing section is cnntained in reference 53 by Sundberg mud Trunov. Figure 8, taken from reference 53, shows the effect of slmulated hoar frost on maximum lift. The loss in CLm_ x can be greatly reduced by cleaning the first 18 percent of the chord. The effects on maximum lift and cruise drag of si-_ilated large leading edge ice shapes considered of importance for light aircraft are shown in figure 9, taken from reference 53. The effects on CL[_) and CLma x of ice shapes simulating cruise conditions for no flap and for trailing edge flaps e_ended are shown in figures I0 and ii, taken from reference 53. A third configuration with leading edge slats was tested, but is not shown here since most all general aviation aircraft and most light transports do not use leading edge slats, whereas, many use flaps of one ,type or another. Of key interest in these figures, is the fact t_mt the big reduction in CL[_) or CLms_x at the higher angles of attack occurs with a minimum accretion (hoar frost sirm//ation) and increase somewhat from that point. At low angles of attack for the no fflap configuration and at negative angles of attack for the flaps extended configuration, vePJ little change occurs in CL(a) or CI_x for any of the sL_ulated ice shapes. For sustained exposure to icing conditions, an aircraft loitering with a relatively high angle of attack must have an ice protection system that keeps the flight surfaces relatively clean in order for the system to be effective.

RELATII'E PENALTIES [TJE TO EFFECTS OF ICING/ICE P_TI'ECTiON SYSTEm5 Data from the results of the questionnaire were reviewed and selected penalty data on the icing effects o11 aircraft or cor_ponents or penalties due to tee protection systems were tabulated. Table IV lists the aircraft penalties and tcble V the components, by the .nanufacturer's name, aircraft m_del, and by component nm-ne. The penalties are given a relative ranking as: (I) severe penalty. I[2) noderate penalty, and (3) small penalty. The majority of the rankings for both total aircraft and components were either moderate or small. The only severe penalties were related to the effects of icing of wing leading edge surfaces.

Table V! is a penalty assessment of the protection systems b_sed on data from the results of the sur%'ev/questionnaire. Penalty rankin_s are given for beth aircraft and cemDonents in terms of Dower, cost, weight, range .educe.on. etc. ,-he table lists the data by the manufacturer's name and aircraft name and/or model nu_,ber. In some instanc2s, actual values for the power or engine bleed data are _iven.

L . i ' ..... Iiii ........

__,* ..... lilt W ?

I./SL _f _-I I Cnecl PQ_'tLO_Iy r_ved It@s1 _OOJ/e _fro$_" C. OVC¢4d _FIaD" 200 _e::._.lO 8 % $0 lo s.,d_ _ Figure _. Effect ,of Sit,fated [{oar Fro_t on the _h__i;:_n Lift _L_.lon, From Reference 33 for _-\C-\ b3 A ZIS Win_ c.-* $9 Ot*S CD0. 2 _,04.

_ou_.es S o[t W'30 k/'c= 1,/13OO ,, leadi:_ ed_;e = 1/13OOO i //T

__' __L_t

at C. = O, "_ I . -C D

o__ ! I

CDo, 2- wz$ w 30 w3_ Lu .,,a__. _ons_cered ot [_,ort_nce 63r L_ht .\'C, Re: _3 _d_e ice < ..... " " " , CL I l° ICLEAN AI IL .

Ro#_h_e$_ I/I_00 ol _ae chord

F

, f . / ,/ \! _' !, /, , l I

C

Io :5 20 ..,_t on ' of ice ShaDes 7tom Fi_:re i0, the [cmK T[mmel CorresocndLng to Icin_ in Cr_lise _or the No Flap Configuration, Ref 53 3i C L C. ° - _ _ 5 ,_ 15 22 I ..... c. on CL _ and CL max 0£ Ice Sha,_es From _':e _m_ T_'_r, el Correspondin_ to Icin_ fn Cr_ise but With -_;l[lin_ £d_e Flap H,xte:_.ded, Ref 33 3Z TABLE IV [I.I PENALTIES OF ICING EFFECTS ON ._IRCRAFT BY ,_DDEL Pk-NALTIES DUE TO ICING Use Actual Values or Relative Penalties: l=Severe Penalty; 2*}l_derate; 3=Small ,', STM.,L ,_ Wg [SPEED LIFf DRAG SPEED IZ_GE I i ' i ROCk%IZLL 2 i _ I 1 i Z >Ddel 700 3 2 i _ 1 2 _bdel 690 Series CESSX_ 2 2 2 " CE-441 L'E- S00 __-530 In general detailed research on these Engine [3"ions, Wing ] unprotected areas needs to be accomplished Fillet, Wing Tip, Radome

I

in all areas of question 5 in Section IV.

Antennas: VCPJLC'C GS, ADF] _lore research on performance _sense _ [,_cp, LlgF, \l.F/ | penalties required.

Cessna 121 3' Wing & 5,mercqage Boots L Prop Deice Boots Heated ;t/S Heated Pitot a i Heated Stall V:me ! Very little information available All tmp:xntected surfaces ! on performance degradation due to kacIudtng nose caps, ; ice accurmlat_on.

nacelles, wmg tips, *Each cong,onent by itself has a small wt penalty but _ith them combined the wt penalty becomes sMnlficant- <L%FSTP, CA_ I .<_R h'k< I ; ;ulfstre_n [['III : 3 2 : 2 2 5 3 ,]ulfstre.m I [C i 3 2 2 3 3 PIgEF, F\3l/ <erie_ 5 3 5 2 2 2 3 3[!','T_¢[ 7- .-\[.L [ ";,_N 73_ 3at [h<ine 3 , 3 : 5 2 TABLE V II.i PDNALTIES OF ICING EFFE_fS ON .OdRCRAFT BY C_ONDgrS pF_NALTIES DUE TO ICING ASSL_E ,NO ICE PROTECTION Use Actual Values or Relative Penalties: l=Severe Penalty.; 2=bDderate; 3=Small AIRCRAFT OR CObfl:'O_ i k

A

SAFE7"[ D_G STALL A SPEED K%NGE WT SPEED BEEC_ 1 I 1 1 i Wu_g Surface 2 3 3 3 3 Tail Surface I 3 3 1 Falg ine Inlets

3 !"

3 3 3 Windshield 3 _ 3 3 5 Radome i 3 2 Propeller 3 3 3 3 3 Antenna 3 a 3 5 5 Control Surface Balance Horn All relative penalties assume ,.me loss.

*Considers the potential of en no ice protection.

I K_SA - ,_7 l

!

Frost on .drfoil I _L'CLkS A! RC?JC-"T I 5 3(.k) 5(A) 5 5(A) I Horizontal Tail 3 3 3 3 ! 3 Vertlca[ Fail 3 2-3(B) 3 -'-_(B) 5 12-3(B!

Inboard Span of Win_ 3 3 .3 3 3 3 Fvlon 3 3 3 3 5 3 Flap HLnge Fairim_s 3 3 3 3 3 Wing Tips 3 3<1 3 3 3 3 5Liscelh'meous Antenna _ htghts 2 1 2 1 3 ].

C_ter WLng Panels _ 3 2 3 2 3 dear Extended penalties are severe.

'\! If desismed to inc!ude ice effects, if not the edge geometry'.

iB: Strong fvmctior: or." sFmmise extent .lnd leading _C_ if shed ice clear_ aircraft.

I ,'-E: 1-{_3,_ - RY._.\ _d{,_C ;_in<s 3 1 I I 1 ,Tar2L_ret ion 2 3_

: i

I _et Star _ _ l X _ l ........................ I _ts : C-ill I 1 1 % l l i [ l / l 1 1 I 1 1 l / I l I 3_ I_ "I_'I,%1. A/RCR_ 3"f INITILL . : T:ON _!_E_ SPEED M LI'Pf kI RCIV6_ _'_PIL ji,, : N_NE, _t WCII.L , i i ! i 3 2 C_tAt$on I _ iI --2% _g h_eed Xi,-I.-i-, -- .... 7557 _ttt_ :1 'X, X -'-: " } :t _| ble_d C,a-,qu_t (_-_41) x x x x x x i [ s ._ : s • ................. 3t _'xg bind X; .... :........

X -.I .......... }_i% *nil bXecd X - ......... 234 _tts Cessaa *21 i x X X X: x 3 : : ml x ....... ] [oada itr_ i_Ot tZ_iriCll_l i 3 3 ,_J, f_l t ,=otto :I/ill iX X X X X I 3 ! 3 3 3 Oal f_t _'_m :,IC iX X g X X X 3 3 !

X 3 3 x: ] 3

i .'-3 2-_ :-3

X 3 3 1 !

X _ X _ x t C90, Z_O, FQ_'. _JO 3 3 _,._ BY _ertt $ 3 3 X X 3 1 L 1 :.3 a:'t] 3v -de_c_e'nt X _rt _ vodat :00 ts _ttL_i by _tro _v .kmptm_t % Ice protection system weight depends upon the ty_e of system used, the ice sensitive components protected, the extent or area of each component protected and the design of each protective system that is provided.

It has been found that in general the ice protection system weight of all aircraft except large wide body, transports ranges from 0.2 to 1.5 percent of the vehicle empty weight. This ice protection system weight for piston engine aircraft ranges from 0.6 to 1.0 percent of the aircraft takeoff weight. Also, it ha_ been calculated that in general, ice protection systems neigh in the order of 0.4 to 1.6 pounds per square foot of protected area [reference IG2].

Because of the discrepancies m the "bookkeeping" ut_ed to assign ice protection system weights and those associated systems weight that may have a portlon attributed to ice protection, exact weights are sometLmes diffiumlt to come by.

In percentage ratios of ice protection system weight to aircraft weight from heaviest to tightest, the sequence is as follows: i. General Aviation (Piston or Turboprop _Igines] 2. ZtL_ ines s iets 3. .\S;_' Patrols and Trainers =. Commercial transports :md Helicopters 5. Fighters and Bombers o. .km_bojets \ _ur_:ev _,as .,'mtde of gener:d .lviation ;rod light trnnsporl :lircraf_ to determine the :,'eight of the standard or optienal ice ?rotectien svsterL_ used on eaah aircraft. Each aircraft chosen _&s representative of a partiuuhr class ,_f urcraft, in fi<ure 12, the ice protection s_'stem _,el_:hts are ?',erred ._<aznst the akrcrat't total ._,-oss _ei>zht for each t_7"e of aircraft for ',d_tch 3,_t._ :,ere .t_allable. table VI presents in code form. the protection sv_te%_ '_kich ;,ere zmed to .!ete:'nine the>e ',ei_ktq..rod tabke VII dcfknes these cedes. _i:'.'u_g the t'.Te ..'f a'.stem .w.,i c._Tenent protected.

70 ,4> LE GT_\-D ?YPIC%L A/C 'l"fPES .5 AZTEC F 6O © NAVAT0 _, C_L=yENN£ 1 X 600A AEROST._J_ _7 CObB_NDER 700 SABRELIN_R 65 SO- A L-13-F LT. _T.

i L-Z3-D ST.%\'DARD O L'23-F ELEC. .%i[ 'V LEkKTET 24F 4.0- '1_ CHALLENGER >< CHALLENGER E %b GULFSTRE_?,! 3 ADS-4 A", ,-.,< 3= Jx ADS-4 B \ _k O .ktqS-4 C ' ,< i t k-' --WEIGHT 0F AVF[-[CING ,b'I'5_!

DEPENIXS LTCN I_TE [ELEC., _T AIR, LIQUID, ETC.), CC6_¢NEX_5

/

PROT_CI_..D, 7_T_ CF r2h'ERbq" AVAIL_Bh2 IBLEED AIR, ELFLq'. _ / / &" x,_ / i .j.t I 3J [ !L' 1.S_ ,-(} ,, .r ..........

; '-urc if, 'ce Prctc,'th'n <','_tcm '4¢icht Fcna:,_,," ,b . _ I TABLE %ql _dRCRAFT TYPE (TFPICAL EXA\IPLES OF WEI(I-ff CLASS) IPS hT ICE PROTECTION _'STF_\I CODES ] MA_NIIFACTURER- NAME (Ibs) (See Table VIII] ] I NO. I SYmbOL 48.8 i Ix Piper - Aztec F BW,D#S,EP 6Z.0 HDF, EW/S ,WW,BW,BV,BH,EP O Piper - Navajo 39.4 BW,BH,BV,Lights 3 H Piper - Cheyenne 1 73.9 HDF, BW,BH, BV,EP, _H'//S, EPT, 4 x Pil.er - 600A Aerostar Lights 78.3 Rock_-e 11 - Co_ander 700 EW/S ,EPT,EP ,WW,BN,BH,BV, 5 _7 Lights 86.'0 6 O Rockwell - Sabreliner 65 cU_'/S, HW,HE,EPT j_W/S 123.0 - & BW,BH,BV,EW/S, EP Beech - L-23F 1-14.0 Beech - L-13D BW,BH, BV, BV/S ,EP S • 107.0 Beech L-/3F EW,EH,EV,D_/S,EP 9 • SO. 0 I0 • :-,_, Eq ,G',FR,_T ,H_. ,_IS ,HDF Gates - Learjet IlF 83.!

_¢/S, HW,HV, h_, HE, EPT ii • C_nadair - ::allenger 93. i F,_'/S, hI% HV ,,u?I, HE, EPT Canadair - Challenger E Crummmn - _ulfstremn 3 _'/S, h%', EPT (Est) 108.0 ! -5.0 BW, BH, BV,_'/S, EP la 8 I I ! _0.0 BW,BH,BV,E_/S, EP F I l 80.0

© BW,BH, BV,EW/S,HK

1o O I *F_othetical a:rcraft for ice protection system penalty assessment, ref. F..bk .KII%--_ T)d3LE %_II MRLT-AF[ ICE pRtrrEt_rION SYS_I CODES CODE TYPE SYSTEXl BW PneLnT_t ic Boots Wing BH Horizontal Stabilizer BV Vertical Stabilizer HW Hot Mr Wing Hori'-ontal Stabilizer Vertical Stabilizer HW/S Wingshield AfI HDF W/S Defrost HE Engine Inlet EN Electrothermal _Lng F_H Horizontal Stabilizer G" Ver_ ical Stabilizer E_/S Windshield EP Propeller EPT Pitot EID Ice Detecter EC Carburetor El Engine Inle_ F_' FLuid !PS F_'/S Windshleld Horizontal Stabilizer F," Vertlcal StabLll--er FR Rado_e Prope: ler Wipe r._ Windsii_e ld K,ferences: 8, "'. S8, 89. 1,_5 >tini- 5u_we','. d,mada:r :eleccn Sahrel [:',er ;;eL_hts _r_'_,._ It can be noted in figure 12 that the ice protection system weight for jet aircraft does not change appreciably with aircraft sine/weight in the range of aircraft of interest in this study. The biggest scatter in ice protection system weight is for the smaller aircraft. This is due to the fact that there is a variation in t?pes of ice protection systems used, there is a variation in which components are provided with protection between types of aircraft, and variations due to the state-of-the art changes.

For new ice protection systems, considerable weight savings are anticipated as well as great savings in power penalties. Reference IE4 shows the following advantages of a microwave ice protection concept relative to an electrothermal concept for the same component: i. Power, 80 percent less.

2. Weight, 17 to 30 percent less.

3. Ice detection is inherent in the microwave system.

,1. Reduced complexity.

5. Cost, 2- percent less.

The latter z_o ite_ require the proof _hat _te_ from a complete research and development progrmm estimated to require about " to 8 years ti_e. 3hinta±nability, durability, and _daptabili_: all need to be proven as yet, xiththis _vstem.

Another new ice protection system, the electroi._pulse system, has also been sho_n to have considerable advantage over the electro- thermal system relative to weight and power penalties and other a_pects as follo_s I. Power, 90 percent less.

2. ;_eight, 3 to 2._ percent less.

3. Cost, 29 percent ie_s.

4. Less ce_vlex.

5. SLm_Ie :mdificat_en kits _an be used for many application<.

iQ_ls svsten will requi:'e from three to four years to de_Iop in this -otmt_,'. So far, only" the RtL_S_,ms have acttmlly used t_hese s)'ste,_s on air- craft. A t'.Ticat system : refere::ce 29. co_,ares ,m electrothcrpal sx_tem :,lth ,m ei_u_.v_ .,i._.._v3tem :Lr deicin_ .......

• g_ _ewer requirements. 7b, e el_,,.v, the,'_,_l s_stem usea 3.25 to 15.7 _atts'ia.- corapared to ).,)ie to ,_.0_2

watts/in. 2 for the electroiz_ulse system. The payoffs for the development of

systems with this sort of power savings are obviously very, good provided that the concepts are proven to be feasibly sound for fixed wing general aviation aircraft.

_IN'IT-'4_NCE In assessing the overall penalties associated with ice protection systems, the probability of failure and complexity of the systems n_/st be considered. The probability of hot air thermal systems failing is very.

small. ,\_q!functioning of the valves and associated controls are about the only possibility, l_e electrothermal systems are much mere complex with all of their contactors and controls, therefore, their failure is more probable.

Electrothermal systems are more efficient generally, thus causing less power loss to the engine than the aerothermal systems. Maintenance is less on aerotherm_l systems, therefore, maintenance costs are less. However, the possibilit'y of burnout arid G%_age to the electrical heating elements has not been completely eliminated by design as vet. .an excellent listing of ice protection system components sho_-ing mean time between failures (3rrBF], mean time betnceen unscheduled replacements _fP.rR], and corrective maintenance man hours ((l\] that are at 90 percent confidence level (CL) for wh%dshield /clogging/anti-icing, wing and empennage anti-icing, empennage deicing, propeller deicing, and engine inlet anti-icing are contained in reference 102. Lxanples of these data, sho_,_%here in tables IX through k%q, point out problem areas and places where improvements should be made with ice gretection subsystem components.

SAFE_" Carburetor icing caused 300 general aviation accidents in a five year period [reference l'_ with 40 fatalities, l@O injured, and 4- aircraft destroyed. Some 613 persons were exposed to death and injury" and 313 a_rcraft were d:mmged. Carburetor icing caused 44 accidents kn 19_0-6" time period (reference _I. These statistics indicate the seriousness of carbure- tor icing problems and their effects on aircraft safety. It also helps to e,,_phasi:e the requirement for continued research into the carburetor icing :_reblem. At :_resent, research is continuing on the use <f fuel additives 5L_ch as ethylene circe( monemethv!ether _EL?_2_ for ice protection. ,_b,.e tk-e of earl'ureter !teat caP, catase a !5 Percent loss in _e_er in light air- craft, so :nethcd:_ .u:d tec!miques wi_ich do not extract from the already mini'-_ _c_,er avaLkabLilt'.- of smai'_ aiecraft are :path needed.

7he '.;ir_dshieid of ,m aircraft may hold a charge of several thousand yetis relative to its _ountmg stracture preference "2]. The electrostat:_ char;e can be mduced onto the _urface ef the windshield by certain t_,-pes of precipitation including ice c_'stals, if the wlndshield is provided _ith _m e!ectrical['." heated :rail-icing system _conductive coatln_ or _lres1 it t__ 4_"

TABLE IX

WINDSHIELD DEFOC/ANTI- ICINC P_LIABILI_"

SL_S_fS_M: W'LNDEP-_LD DEFOGGING/A/WdI-ICiNG (ELECTRICAL)

X/CA

MrBF _BM MTUR @ (m) (._) 9o_ cL ',ompo ne n_ Description 16.5 513,832 85,638 256,916 Relay 1.0 128,_ 126,_58 Rheo st a'_ _,_29 2.5 _,429 Thermistor !2.0 64,329 10,704 32,1!4 Tr-__u sformer 3.1 55,000 1,73_ = 51,383 Control Box i00,0 O0 3.1 1,167 Heating Element 3.6 14,273 Other 14,273 6.0 55,5oo _43 18,518 Subsystem Complete L_in 3-3 96,280 320,936 Relay, High/Norm 2.8 6o,175 Control Box 5,8h2 26,163 6.3 601,755 35,397 200,585 Tr _n sfc rm_e r 19,969 5.5 6,656 19,969 Wiring 1,163 7h ,468 He_ting Element > lh, 492 2,785 iC,ai6 _.5 Subsystem Complete 13.8 infln 6,656 Switch In fin 7.6 19,969 39,938 Control Box (Side) 2.5 =nfln 59,907 Ccntrc! Box _ W'izldshie id) i!.7 39,93@ 13,313 39,938 Xfmr. (Si_e) i0.1 infin 19,969 39,93_ Xf=r. (_'indshiei_ _ infin 19, .69 5.9 .Relay !nf!n 5.'_ "_,_96 Wiring _ _crmec_cr: I_. C infin Other 39,93_ _6 _ a,_¢O Su_ _'ste _-- Cc--p!ete k ?k73!{ -memn time bet_,een TaLntenance }_,_- mean time bet_,een tmscheduked replacements hq_F - me_m ti=e !7e_%een failure )l_{'Ll\ _ _' C L - :_an-hours per cor-rective action at Or'{ confidence level data From Referen=e Ir_2 a5 TABLE X WING/D[PKkNAG_ BLEED .AIR ._NTI-ICING RELIABILITY EL_SYZTEM: BLE_ A.I_. D!STR!EL_ICN - W_;G A.'ffI-ICING AiD D4PENEAGE ._;TI-ICI:;G M_/CA* .V_._F * or.

Component Description 8.2 25,691 7,556 1,173 Valve-lsolat ion 22,3_0 8.9 10,932 Va!ve -An=!-icir_, WLug !2.g L_8,_58 32,115 17,718 Valve -Check 32,1!4 7.7 11,170 3,_a5 Valve A_nt i-Icing ; _mpenr.ag e Infln 9-1 128 ,_58 i$,35i Ex_ans ion Be iJ_ow_ 39,525 3.5 3,471 T.-. _ulat ion B lar_ket llr_fin 25,691 1,976 I-1.6 Duct ing Infin 64,229 6 "9 _,75r T'_b Lug Infln 214,C96 8.6 a5,8_7 Cc_en_a= or 6,173 Subsystem Cc_lete "u1,107 i 8.5 infln 137, _L_ Valve, Check 17,193 2,407 Valve_ Wing isolation 5,_7C I 7.5 4_,_76 _,o6_ 5- 5 _,689 Valve, Mcd'.CLating 361,053 103,156 5,5 80,234 Sensor. Ten-p. Control Ir_fln 1,6_b,,9l _ 3.3 _ '_12,327 Duct _ Dif:_ser 213,957 1_,12 _' _.7 29,176 Camp, Duct 30,C_7 12,035 3._ 5,Cla Lnsulat icn Blari<e t 601,755 2CO, _=_5 iC .9 Ducting _,_C _.7 2,71C I,IC2 Sub s_'st ___ Cczple_e *See table IX for definitions.

TABLE XI ELECTRICkL z_SNqNAGE DEICING RELIABILITY SLVBo_f _SI_: _SrENKAGE DEICING (ELEC%K4. !CAL) i _w_/CA_ MTBF* @ MTUR* MT=_ * 9o_ cL Component Description 2.8 8,596 1,972

Controller 53o 1

96a,8o8 26,7h/* ._mater, Leading Edge 925,616 !.7 962,808 962,8o8 Relay In f _.

7.2 60,175 6,33g Indicator Light Asa__ & Wiring 8,575 $65 1,779 5.0 Subsystem Complete * See table IX for definitior_.

TABLE XII BLEEDAIRDGIN_ IhlZT ANTI-ICING RELIABILITY SL_SYSTLM: LNGLNE _" _ " _ '" @ MT__M* 9o% CL Desc. _-Cn i Coz_nen: -_'-

F

ze,556 Valve 2, ,_3 12,235 Pr. cbe/_ce Detector l':'!, 277 6k,229 Shut-Off V_l"ve (_tor Lufku 5-) .... 5.5 36,702 _act Infin 6k,229 Other 32,25__ _6,393 6.O 5,681 Sub_'_tem Complete 3!,91_ 3,902 Valve, ._u_-ice ] k..4 Duc_, ihceLie Nose 3owl 127,66C Relay -- -_-' - k 9 223,_C6 Rectifier, Engzne A:I _ i <_ 6.7 Aetuatcr_a-lve Eng.

inlet 223 ['_= 5.1 Actuator, Nace_-le A,'!

t k 5.2 Saksy_to_n - fez?fete Ducking [_ata From Reference ID2 aS TABLE XIII ELECrP/CAL PROPELLER DEICING RELIABILITY SZ'BSYST_M: FROPELi/.R, Ag_ZI-TCRQb_ A_ND DEICING SY STLM (ELECTRICAL) MMH ,/CA* MTBM * MI"/R* _ MTBF * Ccm;onent Descr_._tion (Y.r) (F.:') 9G_ C L (Hr) I !.0 infin Element Assy., Nose 1.0 infln Heater Assy., U'_ff Ira.fin 13,351 Element-Hea_¢r, Sp_.nner 2.0 Control Panel 64,229 lh0,658 2.0 !nfin Transformer 128,458 Infln 8_6,386 7.6 Relay 2.2 35,16_* Timer 6_,229 InfLu B_o_ - Blade _,6T? 293,618 i 3,58a 9o,9co 3-3 28,131 Subsystem Ccmp!ete ; * See table IX for definitions.

TABLE XIV I_ DETECTION SYSTDI ,RELLXBILITY SUBSY_: T_- _u:_ DETECTION 5Y. ST_-L_M _F/__F * _m_o.._nt Description _O_ C L (*_) 2._ 2l_,O76 3_z,!_5 Relay 8.9 _5,638 32,11a 6_,229 In%e.-Tre_er IrWin Rec_tfier 256,916 770,7u8 _.6 Detector 10,276 21,_C9 2_,5a6 "_5.5 Other Det_ctor 613 16_ _wi%eh_ 3cntrcl 5C_ • Subsy_t_z _etal Deteztcr 799 _ll_ P-T.

.:" ,Zc Su_sys_-m - Tct_l [ .Data From Reference _']fi _6 TABLE k%" PNEt_b\T[C RAIXNf! ..%\'FI-It.lXt, RI.LL.\BILI£_ _o_.S .... .RADC_ A,_Ii-!C_IG _PNEL_tATIC_ MN_i/CAe MTBM* MTLrR * @ MTBF* Component Desc:ipt ion (_,r) _._ _'_ CL (flr) Valve, ,_res_um_ Relief 2!,L09 2.9 128,h5@ 2,21& o,760 5.9 25,691 Valve Modulating 6,7_?

0_,229 6,5 IrWin Regulator @ •l Inf Ln The nnestat 15,'___2 $fi,63@ i8,351 Ejector 3.2 i inf[n I Subsystem CompLete 1,153 5,2_@ * See tlb[e IX for de t-lI'tt_ tons.

;u2, cv2 [ , '.'-- ] • "v. 7.3 2." .f3_ '._-v-,, 3ie,_i Jo::'_:- " a a , _',1- _75L.; it" 25L,:l.

R:. 2- !

"$!1]_"-_, A::t L- [?'_ 1.,". 13t: 11 , "L',- ,_. i'! .!

['_l:.l } :'_'T2 \_. l< :<. • v , _ possible that tile _indsi_ield uill act a._ a t_ plate capacitor cetmected to the [,o_,ersupply, if there is sufficient static charge, the resist:mce to current flow r_v breakdo_l_ and the ci_arge will be discharged into the :_ir- craft electrica( system by way of the _indshield heating elelnent co]metiers, caust[:g a failure. It is possible to reproduce thi_ complete electrical phenome_ in the iaborato1?" icing research tu_mel at modest costs. Research in this area is recorr_nended in order to learn more about the '_mech_ics" of windshield electrification by ice crystals.

Current solution._ to the problem Ixave been through the u._e of _mt t static coatings, Hl_ch are metal oxides. ,rod the t_e of suI_pressiou devices st:oh ._ air cored c_hokes, capacitors, :rod resistors. I_le d_okes are not easy to install ,me are often omitted Hlich shorte:_s windshield service liCe.

thee ','e t Lea i lv.

Icing of _he flight control surfaces extx_<ed to direct hnpinge_'nt of water droplets or to _nmback ice c:m impose a severe safety problem if careful desi_7_ cons[donation has not been given to such possibilities during: the concel,ttkll design sta_tes of tile aircraft, khne example Is ill the dest_tn of e[t,V:llOf [,,l[,ulc_" !ferns. ice accretion on the leading edge> of the bombs n_v pt'evellt ful't}ler tip oF do_,ll movelnent of the elevators, with possible ,tisasrer- OLI-_ I, eqL,_[_.., t.*OTT_llx2n deJ i{n prilctl.ct" has l_eell tO leave at qll_Jtilllt ial :-ap i'et_,een the t txed ,rod _weabte part> of the hori:ontal stabt[t-'er in tile v_cir, itv of :he bal,mce bo_ms. Hcated:mdnonheared shield> haxe also bccn :_t:lized ,,,tth -uccess. !lo_,evcr. t!:e problem has :lot {,cell CoUlplete[v solved [o .i,l_O, .Idld rescAic!l k:; qti.[[ :-e,tt:{I'ed l.t .1 ,2olllp].ote]-\ _.&I'lqf.lC[OlV ,_dlS;_t.I" 15 t,, _,e retard.

\.';Si S>'?,'J}:£{" ,T i!{F ::M'{,RBFN"-\I '#:\i'\ 3'\-qF , {'ASK "_'!

i. Pt-ot'Iet ,,,i'cvt :,'1% eft'.cie:'_cle>;.

"['ABLE k'VII • _L\TRIXOF CC_[PONL-NTS _,_ _'_TA iL\_'I/IAC'LITY I_'PE m DATA B,%SE/FAC[LITY TYPE O!_CTI\_S OF TESTS: 1. Nature a Extent of Icing 2. rPS Performance 3. ,,VC Perroi',_mce k.a Pena[ t ies

=_1_1_

_I_1 _- [ ct_ rt_T.\'r u3

I i .... I

I x I x

o l

X t X X \ X X O X X 0 '< X X !

X t) X 0 \ X X I X X X O X X ¢ X X X .... i ..... _-.-+-_h ",[ X 0 X X X X X t_ X X c' X X X t' X ,_ X X 0 X • - ['i-tY,lI'_ ._'41tA ".",15i!

• ,,1<,l :.1 _td .rl<I .,tl,or TABLE XNXII _TRIX OF CCBN@;L_CTS\_ DATA BASE/FACILITY T_E DATA BASE/FACILITY T_E OBJECTt%_ES OF TESTS: 1. Nature & Extent ef Icing 2. IPS Performance i b2 3..Q'C Perfo_ance Penalties -- -, i----, ! ! _ ! i TLT_3QP RCP )_aLn [nlet X X o x X X c Nose Caps Inlet Cuide V,_les X X o x Rotor Blades I o X Frame St _dts X o : X K o Part Icle _<epar:Itors Screens X O h:ll Propellers O ¢ D, Ish Propellers Engine Cowl b_{ 0 x PISTON EN(;INTS ' I Carbu re t or : _ ; X I x X ' X X X 0 i , 1 i I I h:ll Propellers ¢ ' X O I ) ] , i i , !

h ;s ',', Propellers C 0 ', × i ; _LqK ine Co_I in_" 0 I X 0 ' WL",dS S_,ep t S_ r _L,.'hr X _ X ×. 0 X K .\ile:'ons X X Q Flaps k X X © \ <_ots X # X X !7orlce_< j _,OFIOX ",.'I], X X X 7< Cmar.!

X X X • - PI'I21;I, "_." ._;lt.t !_tse T.M3LE XIX HATRIX OF C_lt_NT2_'I'S VS I3ATA B,_SE/F,,\CILITY TYPE flAT..\ RASF/FACtLI'D( TYPE ORIE.CTIVES OF TESTS: 1. Nature _ Extent of Icing I 2. IPS Performance 3. &_C Verfor,_mce Penalties D- aa e-, .a

9 =

7, CCgII_bW2','T --÷ i 7.\I L SURI:Ac_2S X x X 0 O X L Horizontal. Elevator )" 0 0 X X x i Vertical, Rt:J.der 0 O X X ; I'- Tail 0 0 X X V- ?ail X X O Balance He _ ,'ns ! ,r_;SEL\GE X 0 0 0 hindsh fe "d C X O X ;gi_g, Ftk_e[a_e .rkmcture X X 0 0 Stattc Vent:_ X X X 0 X bCOOpS O X X X Prain._ X 0 X X X "_PF ,rt'j1C_tlres 0 X X :\rl t CPJla 0 O , X X _ildOEC'; I X X ! \ !

I 7r;msrarenc it'> A 7 [_STRD.2.\':'S Pttet St,it!,: 7u!,e \It. :i 2ate ,,t C_::nb X L_,,'_. f { Ce:a k X \ X 7ct._" !(e,k! F:'_!,e X X :',,t,t'. _e:'::'. i':"}-c , ; r :_.1 , '.klt3 P.1Se "- " ,'oat rtbt_tor 4. Effects of ice accretion on the aerod>mamic characteristics of the components.

The last _:em (a) is also dis_sed in the previous section which assesses the available information on aircraft penalties due to ice accretion on unheated surfaces or aircraft penalties due to the ener_" and weight requirements of the ice protection systems provided.

The data base associated pr_arily with ice accretion is also the sub- ject of the see:ion on ice accretion siae and shape.

D_PLET CCLLEL-T[ON EFFIC[_CIES i-me collection efficiency', Era, is defined <from reference 105) as the ratio of the actual water impingement stremn tube thkc_ess to the nmvL_um value that could occur (straight line trajectories).. The actual t_-ater ir_Lqgement stream tube thickness 0"] is determined from the difference bet_aeen the starting Y-values (YIu and YIL) of the:_article trajectories that are tangent to the upper (Su) and lower (S L) body" surface, respectively (see ficare 13_. The straight lime trajectories _very heart drops} stre_an in,be thickness is ..,_ereLy the projected height of the body'.

\'ere little qt_mtitative experLmentai data. with regard to droplet collection efficiency, has ever been acqurred withany facility other than _m icin_ research'tt_el. U_e _aioritv of nhis data, as far as the data that are published is concerned. _ere obtained by x,nrk accon_plished in the oft x '_ ft [RT at _L:_& Lewis Research Center. _,'umntitative data on collection effiencv have been obtained with m_ticvlinder instr_amentation during :'lights in natural icLn_ which have been used .%-my thnes to confirm the theoretical collection efficiencies for cylinders, in a similar fashion, collection efficiencies on other conventional body shapes <spheres, ellipsoids, i.e., bodies of re_mlution _ have been detemined, but not to the smee extent as with the cylinder, xh:antitative data on collection effic:enc?" for airfoils from flight in natural ice is extremely d_fficult to obtain, so consev_uentlv, little is m existence.

Coil/orion efficiency is a time,ten of _ight steed, droplet sl:e, body <eo_er_, ambient temperature, :rod pres.<ure, in the literature, Em is i,ceser, tcd versus various [ir_enslonle>> 7a::_:_eters, but :,._._t gene:-aflv it :s _orrelate! _,ith the di;r.ensLonies_ _,_dif_ed mertS.t parameter _. Ihe use of this ?ar;L"_,eter results in e_dentiallv .1 single valued cu_'e of E m versus _ for berlin.- 2f the s,=ne geometrical shape. 7h.e error involved [n theuse of the _) par:L_eter for torte!at:on of -{m i> less th_ul -'I0 percent re:" nest airfo'.iq md bo,hes, for :!',e no_a[ :':m<e ef flksht conditlor_s reference i¢- _" .

• ..... ; -_ _ _,<, bet:,een "_'_''' 1cI[ ,tile! exPerl- LX_-_ • .L. • • .

.t._,al .Lira .,n _..._._nv_ ot catch .::iv l,e fot_d in the bi!qto<ra:mv l-ofeTenco5 _ _jo _;, &nd 1- _-I . _IeF.e references Sl_rf_.lrlz6 o\-_t, ri!:ienlai dat,l 3,2 I !

-2 2O largely obtained in icing tests conducted by the .'iACAduring the 1950's Ln the 0 ft x 9 ft [RT at _SA LeRC.

._my investigators solved the _,_ter drop trajectory equations and determined the impingement limits and the collection efficiencies for a variety of airfoil shapes. It _s found that the accuracy of their solutions w_s very much dependent on how accurately they could predict the flow field.

For JoukowskJ airfoils, _'linders, ellipses, and spheres, exact potential flow solutlans exist and the agreement between anal>_tical and e.rperimental data is good. However, a great majority of practical airfoils do not have exact potennal f-aw solutions, and the agreement between ar_al_ical _nd experhnental data ',_a_ not as good, indicating that water catch calculations are ver_" sensitive to the airflow field.

Computerized techniques are utilized for solving the water drop trajectories ¢_quations for reasonably shaped, 2-D and _._ept airfoils, and axis}'_netric engine inlets at angles of attack. They solve the _ter droplet trajecto_- equations by a nt_nerical technique _md then use the water drop trajector7 resists to calculate the water catcA data; i.e., local efficieno" distrib,.:tious, local '^ater catch distribution, impingement limits, total collection efficiency, and the total ',_ntercatc.h. These ,,_ethodsOUtFut all of the water catch data discussed above, given the body coordinates, angle of attack, free-stre:L_ '.'elec_tv, altitude, free-stream temperature, chord length.

thickness of the body. droplet size, and liquid water content.

5ta_y respondents to the sur-;ev'questionnair: indicated that they use ce,._uter tec?"_nRtt;es to solve the droplet tra_ect'r_" equatlons and for subsequent calculations Lncluding collection efficiency. _he co:_uter ?regr._ns. although similar in 6mction, are generally proprietary to the indivldual cenp;mies. [n other b:st;mces, some respondents indicate that they use the techniques at ..K_S-1 with charts and _r_'es of data to sL_'_plify h:md calculations. _tanv indicated t_utt APS-4 should be updated to include :_;mv new airfoils desi_,ed fn recent )'ears. N_e collection efficiency verst_ Ko for the new airfoils cakulated by cer_'uter ;mnalysis .rod backed by icinq tt_rme! test data ts :_ :zuch needed z,_,,rovement to _he data base.

ILT ACCRETION SIIE ._\]) S_{_PE Ice accretion will occur on a_,y object (ice sensitive component) moving through a cloud when the temperature is below freezing.

The rate of ice buildup _ili _-ary,with the following: i. The water density, of the cloud, i.e., liquid _ter content (LWC).

2. The velocity of the object with respect to the air.

3. The size and shape of the object (component).

4. The temperature of the air and Lhe temperature of the object/ component.

5. Duration of the encounter, The shape and consistenc_." of the ice buildup will vary widl the foI io_ hlg: I. Temperature of the object (componentS,, the cloud, and the water drop size.

2. [he velocity of the object, as it affects the surface temperature (adiahatic te,rperature rise).

3. 7h.l_ne._ ratio of the obiect (collection efficieno'_ and "sweep" w_th respect to tae free-stream.

_. .Lngle of attack of the object.

Ice shapes are generally classified as glaze (mt._shroom], intermediate, and rLne. A correlation of ice shape in terms of liquid _ater content, mnbient ten_'erature, _md _qight speed _s developed by Tom Dickey usrng the "freezing fraction" concept developed by ._kssinger. A _eneral discussion of the correlation for lee shape is found m reference lOS. In general terms, it can be stated that fine Lee is l:kel)" to occur at total air t_.nperatures of about lO°F and beiow, while glaze ice usually occurs at total te_eratures of 25°F to 32_F. 3et'_een IO°F and 25_F, a glaze-rime fot-_ltion _ill ustmilv occur, with clear glaze ice at the stagnation region and nilka' white ,._:_,e ice in the aft re_iom_.

Correlation of ice accretion _Lze and 5hape h:k_ never been experi- ':entallv ter!f'ed for the full r:mge of vah:es for the associatei Far:'_t'ter_.

Also, even thou<h a K_r<e m_ber of ?hoto<rai-hs cf ice shapes on <mXneated bodies have ]_een taken and are available in tile literature, ve_w fet_ cross sectiet_ e{ the" ;.co are slne_n, cr critical 4i:_n=;tcns ;lyon. Rime ice fo,,_as _5

Ln a marmerthat is ,_ore easily predicable than glaze ice. l]le drops freeze

on impact and the rate of _ro_th is generally linear becausethe ice shape

does not alter the flow field sig_nificantiY - The gla:e ice e_<hibits the

t_-oical "double horn" shape that results from water tZowin the stagnation

region. The exact shape of glaze ice is difficult to predict a_nd the growth

is nonlinear because the ice affects the flow field (NACA TN 4151).

On highly swept airfoils, glaze ice tends to form as a series of discontinued cu_nps (cup shapes), sometimes referred to as "lobster tails."

These shapes are repeatable for tests using the same conditions all around, but there is no empirical eqtmtion or theoretical prediction method for determining the size and shape of this type of ice configuration.

The ice accretion information available from published d_ta for deter- mining the ice shapes is applicable to unswept airfoils at limited angles of attack, for the most part. However, reference 121 does contain a discussion •_- _. progrmm, isponsored bv the FAA and conducted in of the Boeing .ki_cra_ Company - ' the NASA 0 ftx 9 ft IRT) to obtain basic ice accretion and ice shedding data on t,,Tical jet transport swept airfoils.

:ce accretion tests were conducted on two swept airfoil sedtions representative of the inboard _md outboard _ing or horizontal stabilizer airfoil sections of t}mical jet transports. I1_e size and shape of these ice accretions were measured through photo_rap hs and actual plaster casts of the ice caD. Tests were conducted over a range of s;mmlated flights _nd icing csndit_iens desi_.med to give __he rough or _laze shape, which results in the • te.,_ results ",,ere satisfactorily correlated with highest drag penalty. _le _" theoretical _,ater i.,npLu_ement _armneters obtained from a digital computer sro<rSm. _ce accretion characteristics mid test data were found TN _151 rand _L_A _nmaraDle _o limited published data _,hich include NAG\ 7N D- Z166.

Xlthough this _rk was conducted for large transport aircraft win£ sect[ons, the tecb_o[e_X," is applicable to general aviation and light trans- port aircraft. The empirical relationships develoFed which correlate measured ice accretion rates with theoretical impingement parameters are not restricted to any 2articular size of airfoil, although the complex t-ends of airfoil the data m'eciude a {enera_ ice accretion relationship _ith other sk_mes ,involving c:m_ber, tmg!e of attack, etc.).

Future re,_earch ks ree.uired to obtain the s:m_e t)T,e of data on m_n)" ' * base which exists t.t.e_ _Ir_o_- and body <hapes to upd_te the limited ,_a_a at the ?resent tlne.

Fhotog_raphs and qualitative data havebeen obtained over the years for

ice accretion tests utilizing aircraft flying in natural icing conditions,

aircraft flying behind tanker aircraft, and for full scale an_ subscale

models in icing wind turLnels. Quantitative data, to a limited extent, were

obtained by specially equippedaircraft with instrurr_nted airfoil shapes

extending vertically from the fuselage section of the aircraft (i.e., Canadian "ice wagon" and USA/: B-2_ test aircraft). These aircraft were flown in natural icing conditions. Considerable data in natural icing conditions related to ice accretion were obtained with multiple cylinders in order to relate the airfoil catch characteristics with the multiple cylinder accretion characteristics. However, the bulk of the published quantitative data on ice accretion on airfoils and all other body shapes tested have been obtained from icing wind tunnel tests.

[_ SHEDDING Ice shedding from aircraft components on _hich ice has been accreted is a f_nction of ma_y, many variables and sometimes occurs in a totally random fashion, lee shed@ing is some function of the shape or confi_°uration of the body or airfoil to which the ice has adhered. It is a function of the type and shape of ice, which in turn, is a ftmction of temperature, LWC, droplet size, airstre_ velocity, and duration of exposure. The angle of attack and the _'eep angle pla(' an extensive role in both the shape and sJ'' of the ice accretion. Any discussion of ice shedding must necessarily address ice shed from unprotected surfaces, passively protected surfaces, and surfaces proteczed with active ice protection systems.

For those surfaces which are unprotected, the accreted _ce or some portion of it will shed for the following reasons: I. Some oortion of the ice btiildup is _aker than the aerodyna,'nio forces acting trpon it.

i. Natural flexing and/or vibration of the ice aecreted surface is sufficient to break the bGnd with the ice.

The aircraft, due to acceleration, altitude change, or meteorologi- cal changes, flies into an area where the air temperature and subsequent component surface temperature reach 5_°P or above.

For those surf:ices _hich are _,assively protected by hav_ng a surface '*hich either has a.n icephobic :nateria! covering it, or itself is icephobic in nature, the ice will shed for the s_e reasons _iven in the previous :_a[a!._ra?h. _',e main difference is that the ice will probably shed before it builds to the s_me si-e, because the adhesive forces are .inch less, thus requiring less aerod_1".,_n, ic force for ice rer._oval.

For the ice accreted surfaces which are protected by active ice orotection systems only deicing syste_ are of concern. For these surfaces, some portion of the ice will shed for the following reasons: i. Iie bond between the ice and the surface is disturbed by mechanically changing the surface by vibrating it or expanding it, as with pnetm_tic boots. Aerodynamic forces assist in the final removal of the ice.

2. The layer of ice being brittle, fractures due to vibration or change in surface area.

3. 7ae temperature of the interface between the ice and the body surface is made to exceed 52°F by a heating system, thus eliminating the ice adhesion. ._erodFnamic forces then re_ve the ice.

The experimental data that has been published on ice shedding is extremely limited, particularly that which is related to fragment sizes. The _mjority of the data or information is related to qualitative assessments as to w,hat component the ice sheds from, and how soon did it shed after leaving the icing cloud which was Fenetrated. Testing for ice shedding ha_ been accomplished during flight in natural icing conditions, flight behind.

tanker aircraft, and in icing wind tunnels. The majority of the testmg for which quantitative data have been obtained i_a_ been by tanker tests _,d from icin? _.d t,_mnel tests.

Reference 121 contains a discassion of a Boeing Aircraft Company method of calc'alatlng the airfoil/ice interface temperature and predicting the tL,_e at which the ice wil_ shed. This method was developed asing icing tunnel test data in conjunctior with a heat transfer analysis. The ice shedding cai_nalation procedure was demonstrated and sho_r, to be censer _:ative from natural icing flight test data. S_ibsequently. a computer program was developed by the Boein_ _ircraft Corcpa.ny to compute the leading edge skin temperature beneath ice accreted on ,_mheated airfoil surfaces. This program also determined from the calculated transient temr'rature profiles (reference 133_ the altitudes _t which shedding _ould oct-at during a descent.

Ice shedding characteristlcs are of interest in determining the requkred £rccuency of appkic.atien of the deicing system. .affso, ice shedding _:redlccicns _:an be used to .tete:_ine the need for ice ,_rotection ate to the ..... e and.'or aft-netmted engines. Shed ice from hazard to do_71stre_J_- 5_l_l_u_ • wings, etc. nay strike the taii see=ion or be ingested by aft-_tmted jet - of shed ice from enfines. 7_ .-_;_ _ _slow_ecge ot the s_ze and traiectories the- foP,,ara " "*; - of the aircraft are required. Reference 127 ,.[,_scusses ::l_ scale r.edel :es:_- of shed ice tra_ectori es from the unrrotected radone of a _T,_ ,_i'. Zae results matc_,ed theoretical calculatzons. _mamic sk_tlarity _n,d scalh_ factors were used in the scale :nodel tests.

ice shed from the leading edges of the wings or tail in an unsymmetrical

ir_Jnnermay cause aircraft control problems which could be hazardous if it occurred during landing. Testing of such a situation is extremely difficult or impossible in natural ice, but can be simulated with tanker tests, dry air tests 'with sLmulated ice shapes, or in large icing wind tunnels such as the .NASA Altizude Wind Tunnel (AWl), after the planned rehabilitation is completed.

There is very little published data on ice shedding including the conditions for shedding, ice fragment sizes, and the trajectories of the fragments. Although the effects of ice shedding can be different fo_ each aircraft, depending on its design configuration, there is a requirement for more research to build up the experimental data base of general infomation on these factors. There is a need for e.rpanding methods for determining ice shedding characteristics for straight and swept airfoils and other _ody shapes based on the various types of acoreted ice, including the mmxunum and average size of the ice fragments. Theoretical methods for determining trajectories and impact velocities of shed ice are required which can acco,mt for the shape and size of the ice fragments.

EFFEt_S OF IC_ ACCR_TICN ON 7]iF kEROD'_k\[IC CHAP_%CTERISTICS OF T_C CO!.90N_VTS The experL_,ental data base for the effects of ice accretion on the aero- J>_m_/c characteristics of components comes largely from wind t_mnel tests.

Sirmlated ice shapes dete_.i_ed from i¢e accreted during icing wCnd tunnel re<is are used in dry air wizld turn]el tests for me_surln_ char, go s in lift, dra_, and pitching moments on the airfoil or body configuration. In this nznner quantitative data ._my be ob[aLned readily without the difficulties involved with below freezing temperatures for the e_perL_entees and other such problems as une.xpected ice shedding or melting, etc.

I_hL_antitative_ita _rom flight tests in natural icing conditions or t_ulker tests other than i71creased angle of attack, increosed power to _tin- rain altitude, and _ch member, are relatively imFossible to obtain.

<,kmlitative data on handling and control characterlstics are obtaLqed with t-light tests in natural icing conditions or tanker tests. This t?_pe of data could be obtained for small aircraft In a large wind t._mmel such as the A]_T _mder si_llated condi_ion_.

_]e effects ef ice accretion on an aircraft is to increase dra_, red_cc wing stal!in.< angle amd rn_xlmum lift coefficient, and create adverse pitching moments. The upper horn of a glaze ice acts as a spoiler to destroy the s,-ooth flow over the upper __urfacz of the wing, causing premature stall. "_ lo_er horn sere'ca to incre_se the ira f.

A recent survey (1979) o£ uhe state-of-the-art in aerodynamicpenalty

prediction wasmadeby the Air Force Flight Dynamics Laboratory and referred

to in a technical memorandum (reference 125) on Air Force aircraft icing

needs. The following conclusions were made: I. At present, there are no theoretical methods available that can be used to provide numerical lift and drag increment values. Yhere has never been any attempt made in the past to develop the capability from a purely theoretical standpoint.

2. _bst of the existing methods a_'e empirical and are based on very limited test data. Drag estimates for other airfoils are extrapolated from these data and the accura_f of the results are -_proven.

5. There are n_nerous references available on uhe subject of the methods of calculating water droplet trajectories relative to aera- d'_mmnlc bodies and to determine impingement limits and distribution.

There are only very limited attempts to directly relate meteoro- logical data to drag or lift increment numbers. .No attempts were made to understm]d the exact manner in which the ice grows and to develo F a detailed geometry description. The capability exists to estimate the rate of water catch (ibs/hr/ft of span) on a given exq_osed surface.

:kSSES_[F_NT OF T/_ ICE ACCRETION PREE[CT!ON _q_OD5 (TASK 5) A,KILYT[C<L PREDICTION METHODS The vast majority ot _rk on icing statistics and ice accretion predic- tion was ocnduc',ed during the late 19_0's and 1950's by the NACA. 5_st of this material has a]readv been reviewed _.md stu_narized as a result of a Federal Aviation Agent7 study and published in their report ADS-I (reference i05) in Y_rch lgbI.

0nly a limited muount of work has been done since the publication o£ Al_S-_ that is available to the public. A substantial portion of this most recent _,ork is contauned within the reports called out in the bibliography and reference list of ._Fendix \.

The amain'sis _theds in use today are chie£_y based on the above- mentioned XACA icing research conducted mlder natural icin Z conditions over a 7eriod oT" ma_qv >'ears _late IQl0's rLnd early 1950's_ as stmmlarized in section [ _f .LPL;-!. _br_ rece"_iy [9-3" the '_ork ",,asupdated 'p," ',<e:mer reference [)2h to h:ch_dc ccrTari ons '.,it! l much more recent data taken Ln [iurope and >,:ss_a.

The early work ,.,as performed by specially equipped research aircraft m;mg rotating rmlticylinders to measure icing intensitT. Later data were obtained by motmtLng icing rate meters on commercial and militam/ aircraft, thus obtaining icing data related to routine FLight operations. These data form the major part of icing statistical data that are still in use today.

The vaiidity of these statistical data, having been recorded more than 50 years ago, have been questioned many times in recent years, e_,cept for a few" instances, the NkCx data b_ve stood the test of time and are still considered valid. Also, the European and _sian data discussed in reference i02 verify the _G\ statistical data. However, the trae test awaits the time when new "ia_stpxaentation is developed :rod utili:ed in real time with continuous readout, thus providLng a much more complete plctare of each icing Fenetration made for statistical model verLfication.

The si-'e _md shape of _m ice accretion are ftmctions of the airfoil or component shape, flight speed, :ingle of attack, attitude, component surface temperature, and properties of the icmz cloud in terms of liquid water content LL;_C?, drop si:e, temperature or" the air, and horizontal and/or vertical extent.

Section T[ of :tgS-2 present_ a sL_rrmrv of droplet i_qa_gement &_ta.

These data _md the icing _'lomt &_ta of section I of the report c:m he used to deter*hi.no rates of water catch and L,-_<un.<ement limits fop >pecLfic fli<ht condLtions a.nd airfoiT or comgonent geemetra'. "Pae data are presented in correlated foi-m in a series of graphs. Kp, owing the airfoil, /li_ht speed, aitLtude, temperature, drot_let si:e, [;<, :rod angle of attack, the _,ater _atcb, and i::;'£ngemcnt L kmi.)s can be aFproxi_lrod from the various _:raphs.

_ae lata are clai:=ed to 5e generall'," accurate _ithin %0 percent _refereilce lOS?.

The nethod is Lh:_ited to those ai':fo_Ls or [,odv shapes for _,hich data have been lcctm_utated :rod plotted. For ,my other case, the contour of the airfoil or V'odv must !,e 'N_tched" to .ul ai,.'foil of known characteristics, at Least in :he fi:'lavai-,I Llcading edgo_ portion. A second _,thod iq to :attch the :,ressure or velocttv/ dlstrlbntien ,_f the airfoil of interest _ith the i,ressu:'e ;or velocity > distributton ,_f m airfot! havin_ _oM_ charactorLst LOS.

v'_qtoLll" :qa[ch[II_ iS Ilot .l_{eQtla_e in [_le oil> t-_ or eil_i['te lille,:; ,?r [OF h,,.c.hiv s;,e_'r a::':-oils. _!etheds kave bee:', 2evel,,ped for c._nver:::_,', <_ai<h_.

',,in< data t._ ;:,e_t _,_n_ .Lat,_, but _i:h l i:nL:ed t>e:"aL;',ess.

}:_<'P.O '.n'.et ice accretion .ln_ _'r,'_oc[ion tCqkl_re _'eTlt5 !:a'.e t!le i,!01_t: c.l_ !_l',_b_ei:!_ all" _)Ic CI!;CF ,iL:[rLE:;e _v'Tn_'_'l:¢iI_>. T",el l,i}_[e .[at.1 _TI ',_.|ler C {._Ct,: .m,i _:=i,;:',<e:=c:_t ',c:,<ths are [i:::ited to :hat ',,tUc'._ have been ,.e,,'ified _,v _*ro\'l©tL5 tost'21C.

>I Mmlv aiccr:lt't comp,mies ,rod tkwerm:_mt agencies have dcvc',oped computer codes tc t_red£ct ,,rater catch and impingeraent l im{ts for air:'oils :rod other body sha_es. I2",e adv,mta._e of :hose programs ts that c_:ce developed, they c,m input ,my 2-dunensionM. body shape Lai.rfoil2 Lnto the progr_m_ tilI'ouRh a gL_-en set of X. ¥ coordinates. Then through the use of a potential t'lo,_ field progr;_n amd the rest_tant physical t'lo_ data, _m input to a droplet traiectorv t_rov, ram ks _Me. Ult£_tety, the program t?utputs water catch character'istics, the tmper :rod lo_er (airfoil] ia_mgemtmt l traits, efficiencv o£ catch (by _d:atever definrt£on is used), cmd sometimes the modified parameter, .Ko.

Some of tile ,_lown cowuter progrmns related to ice _ccret_on ,rod icing techno'_o},.y m general are as follow, s: '_. RooM, ell proprietary progr:un de, ::nented in a rht'ee x_q_une report, .'¢\- - 2- Sa9.

Vol. [ A computer progr,un that >ets up on-_dv :_lld oft-body point> for icing ,uutlvs[s.

\ok. il .\Fp[kCat;,on or" _he P_mg'_.ts Netu:_:um computer i'_ogrmn to deternme _.he fto_, field .trt_utd ,_. t_,o-di:',,ensio[_al body tot _cttlg ,ula[v Sis.

• _.\2q.\ Dyoc:lt.o, I, ,1[- ',],lllIlck! COrlpLIteY CO_$OS.

_,l'e', ._.l-_'pi:'t :,:.1'¢c=o1-_c> :,?t ;_,lIcr ,::ItCh ,-%,• ,tn, t lmT'tn:der*._nt , ,I ,. Oll1 _,O.t_. _, ,,t.L lie,L{" ,*_'&IlS_'OY :O1' ,LI:[ '- kv'ki',_ LlLL[\:zi:: , • . , , •, , , ire ,LvCIC_ICI% 2o,'.e[ 111( ,-!l _i,,_ >. I:ll.ots, ,tll_[ t-otoI',;.

:'1"0_$: i,'11 ,'_ LOI'C :" •!,L;2LC _'eILt' " ' ,{;_, to t_e v_ I < '.o11, , v L'A-; IC:I, _ !IC,I *, *, : :l[15 i OY , ,'t',c > :',:" ,.C iv L,, l,.l,,',l :.

Kev Industries Corporation proprietary programs "PLY," defines this 3.

flew field ahead of and around t_.o-dLmensional or axis?_netric mode is.

"DROP," utilizes the tqow field generated by progr_l "FI_T" to compute model L_pingement limits and water loading.

4. Air Force Flight _namics Laboratory program, AEROICE (._&FDL-I_I-'9- 91-'*_S]. A computer progrmm which evaluates the aerodynamic penalty due to icing.

5. A t_ dimensional particle trajectory computer program _,Titten by Boeing 5ti!itarx" Airplane Co., Kansas for [!_e Bureau of Naval geapons, 9 .',_arch I9o5.

Reference I25 discusses nmny of the general needs for icing researd_ as well as the specific needs of the U. S. Air Force. lhe need for extending the exis_in< methods of calculating the L_pmgement distribution on aero- dye.amic bodies and the problems with theoretical methods are given fellows: i. =,xa¢_ geometric F,hapes are difficult to define for some components.

2. Full potential _Zow equations are no,lLnear and c:mnot yet be solved.

3. [-vistin< linearized equations are not applicable to the leadin_ ed<es.

1. ]2re solution is accurate for onl'," one inst:mt of tLme.

Existu_g aerody_,_aic prcxlfction cedes recuire a i_.owledge cf the body contour in order to a!',ply the proper _undary" conditions. In additkon, the geometry l qurface coordinates, cm=ber shape, [eadhng edge radius] ntL_t re:;_l:n fixed durLn< the duration of the flow. I]_u__, a theoretical lpgroach _s complicated bv the _'.,1¢, .... that the geometry," of an iced airfoil continuously - l,,, or drag char:_es _,ith the duration ot the ex-;oF,ure ,rod the calcuhtted ;"" values ,ire tn_e for only one [nst_mt of time.

_lOther fAc[or t]:at COlP.l]l[cate5 the t[so ,)f ,malvt kcal :__,thod_ at iLL • _,'.e <h_ :_o_'ioll 3z_[ olu" pt-esent c[lPa[)i[I "_" _ t,."',< :_ the ",,a_,,tv*''" ,_f ' uationF, of . .....

serve ...¢.. ]2_i-; Dt-cg_e]:] L _ ti<ie ,tcl'os5 t.he onttre <pectv_:l o. _ .lero,.l\_l_E_li_ [ t 01_ , , ,_- i-eqo_Lrljh. __,',e ",,1,_ I. uo_eIl_La[ ¢_Ii_it ions for [T1vIscld *_ and *_'" f',:iI N,l\-[e:'-f._,,_e5 etxxi[IOllF, for "_lJCOtlS flc_ ,ire hi_i',[v nonlinear and ;_i{hOIl[ *' ' • -,--,_,-x.. • as::z_,tions, the_e e_;t_tt[ons cannot vet be :nt-,>dtac,_icn 2f >_.,e ,-- l']s • ,_, _ I irleai'iTe,_ fol'?b 5ob,ed. _x:_t::l< ....... ._ ._ -.,-To • : - [v on O{ $,e>e .._l_l, .,n .... :e p:'IC_2F, F, ,If [ ;" " _4- _, , ; "- _ ".'_ ! i_it,i_ kOIIS ,O ,,!e u_:qic•tbii:tv o: the Frof,:'.n$. For vXA:.,_[-, *,or lnv1-;c[.[ ._ _1_ -'_e , 1' >,,_i_a., q,",l:'_,tIlvC " • ,_Y,e _-_l,_ f'O[.[ _'R: t'_" '" r4,, "; , '._et't_Ir_zlT'.otl ve!ocitv to the free-stream velocity is considerably less than one. Examina- tion of" this boLmdary condition shows that it does not apply in the region close to the airfoil leading edge, where we are primarily interested in an icing investigation.

F_XTERLMEAT,-%L PREDICTItlN METHODS There are basically four methods of testing aircraft and aircraft components for ice accretion and icing effects. These are icing tests in m_tural icing conditions, icing tests behmd a tanker aircraft, icing tests Ln icing wind tunnels, and tests using ground spray systems. T_v kinds of tests accomplished in icing wind tunnels are full scale model tests and sub- scale ,,model tests.

Current prediction methods for ice accretion are 1L_Lited due to the difficulties caused by a limited data base, uncertain accuracy, _o- dimensional a_atysis, and uncertahl effect of the fuselage nacelles and finite span of the airfoils. .-%11of these difficulties limit the choice to experimental empirlcal _ethods. lrhis approach seems to provide the only nossible answer to the prediction problem at the present time. In order to enhance the level of confidence, the current data base must be expanded. A systematic investigation of airfoils of dlfferent thicMlesses .q_-stbe mmde tO L_prove the accurao" of the resulting empirlcal eqttations and to avoid generalized e×trape!at ions.

]T,e ex]_erlmenta! methods also have their o_n problem_ t_hat _ast be resolved before .my me_mingfu2 ttumel _md _aight test data correlation ts pessib!e. ,h.=,onv the Lmediate requirements <reference 1-_5] are the fo i !owin< : Fu_llv inst_nented nlmnel capable of controlling the icing param- eters .rod closely simulating the Flight icing conditions. It is otten dlfficult to estimate aerodynamic penalties Ln icing condtt _ons dtfferent from those specifically investigated for a part:cular airfo'A. .'m accurate control of the parameters in the tunnel may provide greater flextbii:ty in simu/ating different f!ight condltiens.

._derst_mding of the effects of scalmlg. Many of the current avail- able data are based on fttil scale airfoil tests. Though this aFpreach si_Iifies the problem, Full scale testing is not ah,av- possible, particularly for complete aircraft _-onfi#:rations. [f .L sradler >tale ncdel is to be tested, the icing parameters .,_v also have :o be scaled h; :o:::e 7_umer. .an i,,-Fort.mt question i3 '.d:et!:er the ice £eene[p/ obtained in the tzau_el ,a:Ii be _dentical to the <eemetrv in flicht if the 2eteero[ogical parmT_eters are the s,u-_" or as close ._s 7oq_ible. 22:is ,lt[:l_n _int5 out the necessity ,)f :mder.<tandin< the T.l;iner in ;,hich ice builds up ,'n a sz;rf:t_e.

Icing tests in natural icing conditions are limited in that it is rarely

possible to find actual design icing conditions for adequate testing, even

with ,modern weather satellite pictures, weather radar, etc. A typical icing search will invOlve 50-60 hours of flight to obtain one to two hours of actual icing erperience, resulting in high costs. ]bus, because of the hiEh cost sand the fact that design ¢onditic 5 are hard to find, the usual proce- dure is to find icing conditions of wbmtever severity is available and to use previous analytical and test data to e_vtrapolate the natural icing test data to the desi_ ex-tremes. .aiso, determination of the characteristics of the icing conditions encountered (L;_E, drop size, etc.) is extremely difficult mud subject to error. _us, natural icing tests are of dubious value when weighed against the cost of conducting these tests (_tDonnell-Douglas paper "Flight Testing in ibex" Air and Icing Cloud," reference 111).

T_,n methods of tanker icing tests have been employed in the past. The first, which is not used very. often, is to motmt a water spray rig ahead of the aircraft Wing, engine, or other component to be tested. The aircraft is then flown at an altitude with the desired ten_erature, and water from the spray rig is Sprayed over the component to cause icing. This method has many problems associated with it includin_ size, weight, and acre turbtuence eft ....

_e_-, caused by" the spray rig.

In the second method, a tanker aircraft equipped wi_u spray nozzies . creates mu artifical cloud into whic& the test aircraft is flown to expose _or_.ons or the entire aircraft to icing conditions. In most cases the cloud is not lar<e enough to enveiop the entire aircraft. This met.hcd is limited in its usefulness and accuracy-, in that it is diffioxlt to simulate acttml desi,_n conditions and to accurately measure the conditions that are produced zn a spray- rig. In _mav cases the drop sizes produced are e×cessive and not representative of those encotmtered m natural conditions The cloud behind the tmker is turbulent due to the tanker aircraft and the spray rig itself.

Research tests have been conducted in the last few years to try to briz.g the droptet size from tanker spra_ rio_ more in line with desired desi_ lmz_, but w:t.hout conple:e success ,reference 61_.

rcing _ind :_qel testing has been, and still is the best ,method for determinin< ice accretion rates and _a .

_,.a_e_. The icing environmen_ and _.

parameters ca:: be caref,'Jlv controlled and varied as desired to permit _ta to be obtained at as mar:?, conditions _s required, in this t,,ay, con-c_lete data cm_ be oi'taiaed for any airfoil, body si_ape, or other corg'onent that will tit into _:, , " " _,,e parti.-:dar - -"" tacl_:t,. The ?_aior limitation, -' " the turmel an2 the .';- the " ,.neretore. is the size of -.__e of ._odel or cerement ta be tested. _'." icin_ t',mmels are ar-_os,nheri c _,-_ =e&nhn_ that they cannot dtmlicate al. _-_e conditions, alth,-u_h-_ ' • " _'"_ _.,zs 1< net .m ex:re,nelv ;-_-_ ...... _c. _nt factor in -a:c) -: the ;_.n< "-_* "';''_' ^u._t_ have a pore ._mific:mt eff,-ct for • - _ , _,I_ _r_'Lqster - -g - • - +",-_-: ' . _oet.t_len;_ are &.-C_._C., '£v derlSl_v cnan_e.

e_5 There are several t_]pes of gTCur, d spray systems thet are used in icing tests with jet engines, fLxed wing aircraft, and helicopters. The spray systems are either right at ground level (for tests with jet engines) or mounted in a tower for creating an icing cloud for low hovering helicepters.

.%lso, these clouds can be used to simulate ground fog type conditions for fixed wing aircraft. In any case, the systems rely on the seasonal low temperatures to produce below freezing conditions necessary for icing tests.

The desired spray cloud conditions are difficult to produce and are often used in conjunction with a large fan er blower to move the cloud ever the vehicle being tested. ._asurements of the icing parameters is particularly difficult with this t3_e of spray system due to the minimum velocity condit ions.

The general literature contains very. little data with regard to scaling parameters relat£qg the similarity betw'een a scale model and full scale prctot_3;e (aircraft or coraponent) with respeC: to icing.

Reference 94 Lntroduces the fundamental relations,hips for dynamic s_ilarity," between ,model and protot>_pe which ;m_st be satisfied in order to measure ice catch distribution, airflcw, and heat load requirements for an -:'-_ m _..%ereport, however, L_qposes certain limitations as anti-icin_ _,s_e • fo[io_s: i. The mcde! is tested at the same pressure altitude and ambient .

temperature as the airpl_me flight altitude. This limits ialvest_ga tionS to flight altitudes equal to tunnel altitudeS.

2. _ne heat trnnsfer rate on the .model is the _s,_ne as on the protot2cze.

3. The model is tested at the same water catch per unit area and acquires the same ice accretion thic k_ness on an unheated surface as the prototym_e. However, even if the above conditions are ,met, the et,ec_ of ice buildup cannot be determined due to _d_e aerodynamic "; "_ " relat'ive difference in si:c of the formation of protot>_P e versus _cale model.

Reference 93 is at. extension of the work accoraplished in reference 91 m_d el L_inates the .,modeltesting l h_itations by two developmental _t_p Foac_L_5 ; models under condi ", ",he ad tm_,,,_n_ of variables to test :mti-icin< tiens _h[ch account for nearly all ._ltitude effects _md allow for any ratio bet'_,eenbeat tr:m>fer rate on the model to that on the pretor3._e.

The adjustment of variables to test unheated models under conditions which allo_, ice accretion in the proper aanount to produce a geometric distortion of the n_del proportional to that of the protot>_e.

Reference 130 describes the scale model testing at the French St _Ddane Tunnel. The French have had excellent results with scale models down to 1/12 scale when icing similitade laws were respected. Since it is not possible to vary the tunnel altitude or temperature at this wind tunnel, the prototype flight conditions of altitude and temperature have to match the tunnel available condltions, The SI _dane Ttmnel uses the winter season low" temperature conditions for icing tests. Also, it is an atmospheric type t_nel.

The operating parameters of the experimental facilities are given in the survey of aircraft icing sinilation facilities in NorSh .America and Europe, fotmd in Appendix E. The tables of data on the facilities contain not only the range of operating parameters, but the size and location of the facili- ties as well. The tx-pes of fatalities are defined in sketches accompanying the lists of facilities.

Some of the characteristics of the various test facilities selected from the lists, inc!udinf icm_ pars.meter measurin< instrmnentation, ranges mid accuracy, :rod general test pmgr_ are discussc_d below.

[n reference 15-. data are presented qonceming the A_mold En,:ineering ?_velopment Center _.-_X] with regard to atroraft engine testing in icing conditions. .'vl! instrz_,entation and data acquisition systems used by :_DC to doc'_=nent engine perform.,ance are described in the .a£,._ test faci,ities hand- book. All tra-nsducer :rod system calibrations are traceable to the National _ureau of St:mdards. 5peeiali:ed unstr_entat_on sysrem_- are used to :,easure the state of the icing cloud at the engine _nlet. i!eated total te_aFerature and total pressure probes are installed zrest:em_ of the engine mlets.

hlrbule flo_,_.eters measure de:ine,,'ali:ed _ater flow rate in qpray water syste,_v ;,h_ch dete:-n:nes water lo:ldmg of the icing cloud. :hn in-line holography system _s treed to deter-une three-dhrensienaI ',rater droplet ,htta.

part:tie >ice. paetic!e distribution ,rod leith double laser pldse, part_c:e veIoctt'.'. \_7 feels helowaghv nell"otis are superior to aid other; t_ed for =e,_surin,.: droph': md L;_C 2ata.

[n reference 21. other factors aboL:t the test tnstmunentat:en ::sod _t L;i[k? factl[ties ._re closer:bed havi:l< Go dc with conventional 'te:l<u:'e,_,nts.

_OT1ve;lticP, A[ [:lslT&_eIl_'.ltLdn is used t,:, _2astlre en<ine __]_eed,. te17-crat,dr¢ ' ?reqs:_re#. _cale force. :rod other ca;in, e par&%,'tcrs. Special mstr%ments are _:sed for :zoastlri.qg tOt.t[ p?'e_sure md te:'_e:'tture _n the icing en,.-ir?n;-_,nt _f the inlet duct. bh_itiprob_ pr¢-_sure rake calibrates heated total pressure probes. Electrically heated temperature probes are calibrated to measure inlet total temperature. Special portholes are provided for use in photo- gTaphing the inaccessible areas. Willbanks and Sehulz of ._EI£ developed a math model of the inlet flow (therrno and kinetic properties) to the engine test article.

Engine icing reserach at AEDC has the following objectives: (I) to develop improved measurLng techniques for defining water droplet number, size, and velocity, and (2] to use the measuring techniques to obtain a data base fez" _proving the anal v_ical model. The ._EDC progrmm _s of 1978 _as divided into four phases: I. Development of _ icing research test cell.

2, A survey of available particle size instrumentation systems.

3. Selection of the devices which might meet the measurement requirements.

i. Evaluation of the selected particle measurement devices in the icing research test cell.

t'nl?" ",turkon the fourth phase continued af:er 19"8. The first three phases _,ere completed earlier.

[he icin_ Lnstm_nentation survey looked for a particle diag_nostic system which provided the means to measure panicle diameters in the range of 3_ to l_0u at concentrations up to OO0 particies/cc. :klso, the system would meet the follo_¢ing requ:.rements: I. Acquisition of data in real time, nearly.

3. Konperturbing to the flow field.

in-line holocmmera wasselected as the baseline device for the experimental

portion of the evaluation.

Icing test measurement uncertainties _ical of icing tests at .__DC test

cells are:

P._A_[__R

UNCERTAI,YIY _ PE RCLNT ±15 Liquid Water Content, gm_/m3 ±36 _ean Effective Droplet Diameter, _m Engine Face Temperature, °K -_1.2 General Electric Fagine Test Facilities Also from reference [37, the instrt_nentation used at the General Electric, Peebles, Ohio test facilities mnd comparative accuracies experi- enced with that Lnstmanentation are discussed below.

Real time measurement of both cloudLKC _nd dron size/distribution characteristics at the General Electric Peebles, @hie Test Center Free Jet Engine Ground Test Facility _s obtained from t_D laser driven spectrometers bqnollenberg probes) which were direct-connected to on-line computers for data reduction and displa F. Water droplet sizes are also determined from I@0X photographs of an oil coated slid_ which is _nnted to a retractable boom. Zotating o;linder systems are used to measure LWC (_ Q'linders - 5 in. diameter _nd 9.125 Ln. diameter). With 85 data points, the spread in laser Frebe. oii slile, _nd rotating cylinder measurements of drop size and L;_C _ns as foiicws: Liquid hhter Content Droplet Size 3-4 Hicrons Temperature 0.2 °C In the !O-SJu range, the tmcorrectcd oil slide data are large by a factor of [.8 .agrees with ._ test i_ta]. _e causes ,of oil slide error are e_nFora- tion ;_f s:_111 drops, c_alescence errors, and L_pact errors itqatteninp.

?k_iti;'le cylinders e.d_ibit mm off at hi:<h ,.i-°F ] temFerature rand are limited to lo',_erte-_'eratures for accdracv.

......_cun< '.,i:_d _u,nnel tustmE at -_,o_.. _atlonal Aeronautical Establishment ,.._. ._ .t .... _c en__,u_u that natural IJlnC. condit_on_ Ot ] are used with little or no choice of the conditions of the test. In simulated icin_ L%_'C,droplet size, etc., cm_ be changed or controlled as can the tenmerature and air velocity. In bo_h cases measurement of the icing parameters is difficult and inconvenient and are more expensive when done in an aircraft. Tests in t_mnels have not as yet been able to reproduce the higher speed, low turbulence levels, and natural ht_nidity conditions. In the wind tu_mel, due to turbulence or a degree of supersaturation (either true supersaturation or semisaturation caused by presence of large numbers of very minute droplets), frost is usually deposited aft of the true ice formation. The tunnel tests give the impression that the ice formation is of greater extent than would be obser_'ed in flight. Intermittent icing from broken clouds cannot be satisfactorily reproduced in a _ind tunnel as it involves transitlons from saturated to drier air. This is _h) a pressure t>-pe ice detector may function in a _,ind tunnel and give no signal in natural icing, since the" holes may not plug in intermittent (broken cloud) icing. Total aero drag effects cannot be satisfactorily measured in icing tunnels, due to disturbances of spray rigs and interferences of full scale _odels, etc., plus major drag effects are often on unprotected parts of the fuselage, wing tips, antennas, etc. Good practice dictates prudent use of both wind ttumel and natural ice tqight tests and good engineering judgement.

Naval Air Pr?pulsion Test Center (NAPTC) Facilities Referent a3 discusses the facilities, inst_-_nentation, and ice tunnel testing at K%P,C, Trenton, New Jersey. The facility at Trenton is capable of supplying complete environmental sLmulation for experLmental and production turbojet and turbof_m engines. The test wing houses six major test areas.

l_nere"are three altitude chambers, two sea level cells, and a ten foot diameter subsonic Lnduction wind tunnel.

Control of water droplet size in the icing system is considered to be probably the most critical factor required. The icing systems are calibrated in the test cells prior to each engine evaluation. It has been found that droplet sizes vary due to variations in the cell geemet_'. Consequently, parameters sxch as nozzle water/air pressure ratio tor various droplet sizes are letermined for each new installation.

7he followLng icLn_ parmneter in._trL_rxentation is provided at the K)dWC facii Lt)-: l. _ _ *: ,- Cylinders _5 2vlinder3 ., CiI ,_llce_ with ",tl_con ;tease .:. j-W L',_C !,k-ter -0 5. Closed Circuit _" upstream of spray rig 6. IO nm High Speed Camera 7. 53 ram Robot Camera The most effective w_y of detemLining LNC was by calculation, _owing the total water and air mass flow in the spray rig. This was because the attempts made to use the Johnson-Nilliasm LNC meter in the cells resulted in inaccurate data.

Duct airflow is measured utili=ing a steam heated total pressure probe and four heated _all statics. Duct air temperature is read on an electrically heated Rosemotmt probe.

Aircraft 7_nker Facilities Reference 121 contains discussions of the advantages and disadvantages (shortcomings] of aircraft tani<er testing. It is the opinion of some Air Force experts that (after observing numerous evaluations of ice sensitive co_aenent ice protection subsysteF_] tanker, natural, and wind tunnel tests conducted on similar planforms do correlate where similarity in temperature, airl_ow, average LWC and drop sizes exist. However, with tanker tests the models are ai_,_ys full scale, and the aircraft, in combination with the spray tanker, has the capability to move different sections of the aircraft in and out of the spray cone, providing a degree of safety not found under natural icing conditions.

Tanker tests are reliable but meteorological conditions day-to-day carmot be controlled. Variations in hu_nidity and ambient temperature, effects of cloud cover, and freezing level altitude are a few factors which have to be reckoned with when conducting tests with a tanker. With [)resent systems, adeqt_ite control is maintained over the flow, both in rate and voh_ae, off air and _ater to produce consistent clouds having an average LWC of any chosen vatue from 0 to 1.-5 gr_s,"cub_c meter of air. Ho_,ever, only" very limited control over droplet at--e distribution is attained. ['his is due to the fact that the spray nozzles are usually desismed to operate most effectively over a fLxed distribution having a mean droplet size or a fixed flow rata. Also, the clotM behind any tanker ks turbulent, as opposed to the stable conditions in ;uitural _eather. ,q;ere i_ a definite distance from the tanker Ln which to 7roperlF conduct m-flight icing tests. F!Tmg too close to the non--los produces liquid _,ater instead of ice, and too far from the no::tes produces equally tmtu_able _ce cF,'stafs. Rime ice through clear ice fe,'-'_tions :_l', _a_,ii', l'e gelid in that 7a;-t o_ thu _!utid }et:_een the _*o e xt re?los.

In recent years, the Air Force ]_as attempted to g,nprove the spray system (reference 61). Limited calibration of a modified icing nozzle configuration was jointly performed by the A_VL:Land the 4950 test wing, IqP.a_B, Ohio. The basic modification consisted of blocking 50 of the i00 nozzle elements in the icing manifold. The resulting calibration of the nozzle configuration showed that the system provided droplet diameters in the range of 26 to 212 microns; an iamprovement in the 18 to 944 micron range of the ur_odified manifold configuration. Since natural environment droplets are from 20 to 50 microns, the problem remains.

FacihLies Rankin_s Table ._X is an assessment of the icing facilities by relative ranking.

The "Facilities" column also contains some subdivision by including methods with the facilities. The various factors are ranked with each facility in an order from 1 to 6 beginning _ith the top '_mdisputed Best" rank of 1 to a "Fair" ranking, n_rnber 6. In the places where nc rankings are given, the assessment factor is not applicable to that particular method or facility.

Therefore, no overall ranking of one facility against another is given or is it thought to be necessarily appropriate.

ASSESS%ffL\T OF N-EZVICE PP&)TECTIC'N ,qETHODS (TASK 6) The majority of modern light transoort aircraft and some general aviation aircraft will fly in icing conditions, •either in the course of regular routes or during inadvertent/unavoidable encounters. Conventional ice protection systems [electrical, hot -_- _hemical, and pneumatic) have been developed to the ertent that technical Lmprovements seem to come only in small expensive steps. Consequently, there exists a requirement for ne_' innovative, low power, and inexpensive ice protection syste,._. The major technical need (reference 29) is a system characterized by a small required specific power.

By this, is meant the smallest amount of po_er per square inch of the projected surface. Such s stems are discussed :n detail in the succeeding paragraphs.

EI_CTRCI3ff_ULSE [(T PRt_EsCTION STSTEN Electroi.mpulse deicing is based upon the tec.hnology of exerting an impactless mechanical shock to the a_rcraft skin in such a way that the elastic de fo,_..ations of the skin result in a mechanical shedding of the ice.

Accordin_ to reference 132 in a mere discrete definition, it is said that a hi;gh acceleration is vv, parted to the skin by a high pulse of energy, in such a Why that the ice is shed or nrecipitated m an inertial _ - '- • ,ash!on.

7h,,e 1 ........... _ . _,_,-_ec_l,_n i< a 2CCnCLqic:d S"SIeV charauter:_ed h'¢ io_ _o_e .... "..... ,,[.n therr_al-e!ectric • - - e • _e,,Ul,[,;,en_m as CoTp_ared """ systems worth consideration as a ne_, concept for ice protection. _te i h v N

_J

N [

J

X _..f .

X '_['L'--'d_ ¸ _ "0 Z, i -_r ...i i I -.3 electroimpulse system is based on the principle t.hat an impulse, coming in a precise time sequence, causes deformation in the skin and ice laver. The resultant mechanical stresses in the skin are of smaller values _han the fatigue limit or the limit of cyclic strenKth , while those stresses arising in the ice layer are sufficient to effectively destroy the bond, resulting in ice shedding.

[n order to avoid large deformations, the electroimpulse method uses a nonccntact remote action such as electronic induction. To decrease power required, the system uses short power impulses followed by prolonged time intervals to recharge electric capacitors. Optimizing the shape of the impulse also decreases the power consum_ption. For optimum efficiency the capacitor discharge time is controlled as a funczion of the natural' frequency of the skin and is usually set to be less than one-fourth of the natural time period. By establishing a sharp wave-front pulse of ener_F, in the electromagnetic (inductor) cot1, the skin is rapidly displaced and caused to vibrate at its own frequency. }_x_dm_n displacement occurs at one- fourth of the period; also, the ice must be shed while the skin is accelera- tulg to its ma-xinmm rate during this period• The power requirement for the electroLT_ulse _'stem is about i/i0 of that required for conventional ice protection _v -_ • _ s_ms, and is discussed in this section under "Ice Protection System Penal _es.

T],_e electroimpulse delcin_ system it, an aircraft COrLSiStS of one or several standard sets of units; the actual m_ber depending on the size of the aircraft area to he protected against icing. A standard set comprises an electrlc unit, a programm]mg switch, several dozen inductors, and the correspondJJ_g number of semiconductor switches - thwriscors. The electrzc nnit conslsts of a vo[ta_e transformer, a rectifier] and capacitors. The _lectric Lulits may be 3tandardized, and therefore used on practically anv t?_e of aircraft. Figure I_ shc_s a tYPical electrical schematic and leading edge arrangement. "" The desi_n and location of the inductor_ is extremely Lmportant. The nt_.ber of inductors should be kegt to a minimum and the}- should be used with .,na.XiT_, efficiencY-. Efficzency is governed by the gap between the shn _nd wire turns in the inductor. 7he Lnductor itself is ,_oumted to a nonmetallic ,or insulated] ri{id bracket such that the bracket deformation is much T_ch -<fuller them the skin defoL-n.ation. ]q',esrea of skin protected (vibrated] by the _ _" - -- • _nou/d ,.a__ be _are_::l_ determ.Jned and there -' be some over[a[_ or" [nduct$rs can be r._de in various shapes and sizes, a!thou_h :<ost are ro'_m.[for de<ign convenience. ?he nu-rber cf xire turns i_ a ._uncticn of the skin rigidity _nd rill/it), of the st._cture, so several t'._es of flnductor_ nay be re_iuired on one aircr:_ft or cor_onent therco_. Sometflne_ t'^n inductor_ in series ccmnected to one thvristor trait wLll _rc, ve to be more effective and _,ill :_ll_w _n Lncre_se in the ncnber of inductars in a stmndard set.

FfEare il, Electrot-zr:ulse <v<¢em .-_tails, Re-: : i The chordwise and span_ise spacing location of the inductors is extremely iJmportant. The inductors should be :_unted along the span of wing or stabilizer at intervals of 20 to 40 inches (500 to i000 mm). If the ribs are closer together tha_ this interval range, then an inductor should be mounted at every rib spacing. The shorter the span or the closer the ribs the more sharply the rigidity of the structare increases. As a result, the require- ments for effectiveness of the inductor increase; also, a thicker skin is required because the stresses increase accordingly. The inductors should preferably be me mted between the rib_. However, it is convenient to use the ribs for mounting the inductor bracket. A loss in efficiency, occurs when the ribs absorb a portion of the induced vibration amplitude _i_ich is measured in fractions of a millimeter.

The electroimpulse deicing system concept ;s still in the research and development stages in this countr}/ with very. little information to form a data base.

Laboratory tests have been conducted (see reference 55) to check the efficiency, _rsatility, and possibility of future application of the electro- L_ulse deicing system, in tXis test prcgrar_., a c_tilever (horizontal] beam was set up, part of _hich was covered by ice or a specific mixture of mortar whose properties _L_alated those of ice. Subsequently d_,mnuc loadings were applied at variotm distances from the be:_n end and the pattern in which the ice or mortar failed was observed. Parameters affecting the ice or mortar failure, such as beam length, distance from impact (knductor_, layer thick- mess, .md temperature of ice were measured and recorded. A szmple theory for static beam loading _s developed.

_e tests performed were principally concerned with the mechaJLic5 of crack formation amd failure of ice or mortar deposit. Since the principal concern was not the operation of the impttlsive deicing system, impact Id\_amic) loadir_g ',,ase,._ioyed _or deicing instead of inductor devices. A miler'areof mortar was used rather than ice in most cases, becaase it was a more convenient .,_aterial to ase during the tests, not retluiring refrigeration with propertie_ _,hich do not depend trpon a_mbient ter@erature.

!he naLn purpose of the L._pulsive loading of the bem_ ior on an aircraft outer skin_ is to induce a t_oxn_ral wave which wi\i transmit some sort of ener_' capable of removtng or breal, in_ the ice on the surface. The flexutal wave is believed to be made up of two other _ave t)pes: .i) a shear _,ave transmitted by shear deformations, _d i21 a dilatation wave prepogated by me,ms of rotation of cross-section about the bemm' neutral :txis. _he sheaf and dilatation waves are purelv transient phenomena and at [east 1!) reflec- tion_ of the two ?roi_agated _,aves occur before the first aode of ;'ibrat:on i:- estabi:s).ed. _ce :,ill ',L'<L_I].L', b:eak ,hl::ng the trL_-,sient pe:isd nn_ is of:- ;,her, v:bratio,_ on tr,e bear'_ are _et _,, so that the vib:'atiens are ro, t involved in _he initial fakir:re of the ice, a/thou_h the inert:a[ effect3 "an inasten the ,_ltimate :'e_ova[ of the Lee.

The tests indicates that where there were cracks in the mortar caused by static loading, significantly higher L._pulses were required for initial removal of the mortar (Joel. The mortar _ould absorb some of the wave energy, by not letting it _ally transmit through the empty spaces of the cracks. [t must be rememb_ered, then, that the type of ice accumulated on a wing at higher speed, particularly a highly swept wing, also has highly' irregular shapes (lobster tail effect) ,with gaps which can absorb a signifi- cant proportion of the wave propogated through the skins.

The principles of the electroimpulse system are basically sound, and they are not new _ince some sheet-metal-forming processes have used the same principles for ,man,-years ireference 102). Howe_r, the main attraction is that the electrounpulse system affords an electromechanical method of shedding ice. which means the skin surface does not have to be heated above freezing - as is the case for electrical or bleed air systems. As a result, the electroL,_pulse system operates almost independently" of outside air temperature LC&T] and Lh'C. However, there is some purpose (in different U_'C conditions] in changing the cycle tiane so as to allow some ice mass to form on the surface before it is shed. [t is implicit in this ty_pe of system that they do not have the mmback or insufficient heat problems which plague many present deicing systems.

Becatuse of the potential merit of the etec=rei,._pulse type system and the interest sheba by" various organizatibms, it is recommended that further research and development activity, be conducted to explore, in _.Dre detail, the tee!melee" of this system. Practical test models representing current and pKmned airfoil conflfaration_ and fabricated with the proper m_ter[als and desism tecba%ques shot_ld be tested Ln an icing tunnel to validate the ?erfomance of the system. These research and development test_ shottld be desi_med to concurrently provide par_etric &_ta as a fot_dation fo_ an organized &lta base which will st_pporr the recB_irements of the general avzaticn indtmt.m" in the design of such an ice protection system for existing z_Id ftlttlre _iFcraft.

\_ICR¢;_A\I: ICE PRLrFECF'.tzN &"NCEPT 7h,e basic convept _-t:_di_*[ tn the feasib ;litv .malvsis of refe,'ence 113 ,_ the :_e of a surface waveg_',ide, cor,'posed of a thin laver of a stable dielectric T_teria! that has apprexi_._telv the sane dielectric constant a:_ ice, for deleing the surf:tee to _bich it is aFplied ;fivR_re 15_.

in the tce_tr<e condit:on, microwave pc_,er !n._ected into the surface _ave<uide _,_Ii propagate dc_t :he dielectric slab, _ith relatively !;etle ie_s )f Fe_,er, b_ ,uccess:ve ref!ect'ens _ff xts bo_mdaries :n :_hat !:a: been te::::c,! _ "t: _Fped -x'de." U_.is :cquires that the anc!e ef ip,cidcnce ef t!:c :2_C1"0_,.1\'05 ,'II %!_e ,ti:'-z;_IO_ovtglc I:itort'Ace exceed the c:'!t_c:i. *II_*.0, aC, (or :eta[ :ef'ectlcn. .\., lavc:>: of !co bec_n to fern on the licl,_'ctric sLtrface, they :,i'i have the el:oct o: thicken:n< the 3urtlce :,uv,,.2:i?.e ;o that Holdout _r _,ce Adhesi on 8_d c_ A_r c I O_.Iec., tc _

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_2 lce-2ie!ectric _L;T_Ce ;vave_zJe. R_,f tl3 microwave energy will be able to penetrate the ice layer and be totally reflected at the ice-air interface (figure iS). The ice layers containing the microwave ener_" will be subject to dielectric heating by dissipation of the microwave energy and will experience a temperature rise. Only the ice will experience appreciable heating, the ice itself providing the mechanism for converting microwave energy to heat. In the conventional therm_l deicing system, electrical energy is converted to heat in resistive heater pads that l'ine the entire leading edge of the airfoil; sometimes the entire leading edge of the airfoil is heated, including portions where there may not be an.%" ice.

The high efficiency of the microwave deicer depends upon the following considerations : I. The microwave technique provides a means of efficiently directing ener_" only to the existing ice. The airfoil itself is not heated.

[f there is no ice, there _ill be only minor heating of the airfoil leading edge.

2. _.e use of hard, smooth, erosion-resistant dielectric coatings, such as aRunina, significantly reduces the strength of the ice adhesion _ond, resliting in lower _icrowave power requirements.

5. Hicrowa_ heating is very rapid and is localized to the vicL-ity of the adhesion layer. The rate a_ which the ice is heated can be controlled by ,nulsin_. The loss of heat conduction is a relatively slow process so that there i_ a very rapid net gain in heat.

.-%,e major benefits required of a microwa_ deicin_ system that are believed to be feasible are as follows: i. Low Po_er Consumption _'. Low We i ght 3. Low Cost _. [-!i£h>hi:,.ta!na_ilitv .ks sno_,n tn t_<ure 16, a _.t,._al micrn_wave d_clng system 7reiL,_na_ desicn - _-; *, _, ,." _/iv CO[LSiSt Of the follcwin_ corn_ments: _on• . :.J .... fJn ' Hicrowav'? -'''"_'" 3ol)t q • _ 3LK_ [er /fOWl2 S?L|TTER _AV| GUIOZ F_|I||L| JQINT-......_ _OTATIHG C]R(Ut,J, R h q •

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WA_E CHOX!

|0102 SLkD[ STATIONA _'f CIRCUL_ WAV_ GUIO£_ ,, $_RfAC_ #A_! GUln_ S1ECTtON A-A Fi_m_e 10. _licrowavc _eLcer l_otor Bla_e Eoncept 3. Distributor/Power Divider 4. Feeder 5. _licrowave Tube 6. Power Supply 7. Pilot's Control Panel 8. Ice Detectors 9. Temperature Probe (OAT) The estimate of prime power requiremen_ to shed ice on an airfoil Jeading edge is an order of magnitude less than that required by an equiva- lent electrcther, nal deicing system.

The micre_nve deicec system requires that the deicer boot be fabricated from highly erosion resistant dielectric materials to protect the surface from sand, dust, and raLn. Some of the materials which ha_ received the _rea_est attention so far are alumLna, lennite, polyurethane, and nickel.

The most Fopular combination of mmterials is alun6na and pol>_rethane, which provides erosion shields equivalent to or better than nickel at considerably lower _ei_ht penalt}'.

The feasibility of a micre_nve deicer depends upon the dielectric constant and the loss tangent 0:7 the ice appearing on the airfoil (or ice sensitive cormponent_. A literanure search :,_zdedurLng the feasibility studies of reference ILS revealed that this sFecifio information was not presently directly available.

The less t_._ent of the ice _hich acc_lates on the leading edges of an airfoil is differ_Lt than that of st_'tically .Crop,n,pure, single crystal ice !reed for scient[fi_ FuG_ses. Some of the si_n_ificant differences are the fo i low/'_g: i. ihfrozen Water <iontcnt Juper-ceoled Water Content" 2. Air Content _. _Ite of Jro;,t!', The most signific_t parmneter affecting the loss tangent of the ice is the percent of unfrozen water content. The loss tangent is defined as follows for any dielectric material: E r' tan 6 = ¢, -- Loss Tangent of _terial Heated e" = Imaginary part of dielectric constant c' = Real part of dielectric constant The dielectric cor_stant is made up of the imagina_, and real parts.

Depending upon the t>]_e of ice and the frequency considered, the loss tangent can vary several orders of magnitude. Since the power required to heat any dielectric material [usJ_lly expressed in watts per unit voltme) is directly proportional to the loss tangent, it is extremely important to k-now the less tangent associated with the characteristics of ice accumulated on a protected component, Loss tangent tests have been conducted in the laboratory (reference 87] with various t>-pes of composition o£ ice which were supposed to represent natural Icing and cover the full r_nge of tan _ e.rpeeted. Although these ice compositions :_I>'represent some of the expected types for helicopter blade icing, the}" are probably not the t>Tes best suited to represent the type(s) of ice collected by ice sensitive components on light tr:msport and general aviation aircraft, _a_ticu/arl? - those not in close proximity to large bodies of salt _._ater. Salt was used in the high-loss ice samples of the tests cited un r_','orence _7. l]_e ice collected on fixed wing C/A t}_e aircraft would be nero :>_ified by the so called low-loss sl._ples which take longer and require .-_re power to shed. '_e possibility of improving the she4 time and power requirements for low-loss ice, is through tile use of a third layer in the dielectric composite which is called a "[ossier" layer. The third layer i5 a thin, low loss erosion strip used for controlling the surface _,ave b_uide attenuation constant,

ICEPHOB IC _tATERIALS

[cephobic coatings have been a subject of investigation for the past 20 years. ._ny attempts have been made to fLnd a lightweight, inexpensive substance that can easily be applied to aerodynamic surfaces which would either prevent the formation of ice or reduce the surface adhesion force to the extent that aerodynamic and/or dynamic forces would remove the ice (reference 60). A fundamental requirement in any research program to find an opt_ icephobic coating material, is the knowledge of what causes ice adhesion and how to minimize it. Factors that play a part "in the adhesion of ice to a surface are as follows: i. Van Der Waals Forces 2. Hydlogen Bonding 3. Netting 4. Rouglmes s 5. Contamina_.ts Including Air) 6, interface _hemistF:" ". Contact Angle _educing the adhesion of ice requires reducing substrate wettability makhlg it more hydrophobic, his is accomplished by reducing its reactivity and surface forces, making it mere inert mld mere incompatible with water.

Also, the resulting higher contact angle makes it m, ore hkely to occlude air at the Lnterface. Air at the interface reduces the bending and produces stress concentration_ which reduce adhesion.

Water i_ prone to hydrogen bonding, which is the basis of the Ice str_icture, and thus, _ater and ice are attracted to a substrate [surface] }mvin_ H-bondabie _anFcnents , i.e., o_ygen atoms. A low ice a_eslon surface should then be tree of oxD'gen atom._.

_]_emca! bending strength cr ener<%" varies with different atom i-_ir._and _nL,,.t,__> _o _:te relative activity or inertness ct a _ubstrate. \ high energy surface, exhibiting high interracial ener_/, has high attraction for a contacting fluid m_,d a low energy surface the opposite, A low ener_." surface t._en ts desir;_ble. Pel)'_cric fluorocarbons and hvdrocarbons have low ener_" 5tiFf3_es. ._.'lev ]<a',el,]:_ ,l,'-r3ct!ov. (_r ;,ater m- i'u tee a_leSIOR.

.a/though fluorocarbons have low ice adhesion (much lower than metals), teflon (PTFE) for example, under repeated freezing v.wcles or high droplet impact velocities, produces stronger ice adhesion than expected. Ibis occurs because: C1) high impact of droplet penetrates into the material pores to anchor ice, (2) the soaking changes the contact angle, and (3) during repeated Ereeaings, the micro air bubbles are removed, thu5 adding bonding strength.

.another difficulty u-ith low ice adhesion materials like polyethylene, teflon, or silicones is their softness or creep. Poor abrasion resistance may preclude their use on aircraft _ere there is high u_pact and wear e.vposure.

In order to obtain low ice adhesion and induce ice release, certain conditions must exist which include the followung: i. Low energy surfaces of solid substrate (or applied coatings).

2. ._,osence of high energy., contamination of the surface.

3. Presence of low energT cont_tien to impair bonding.

4. "cclusion of air to impair bonding and promote stress concentrations.

5. (_tirnt_.. deKree _f surface roughness to encourage alr entrapment.

O. Substrate construction or properties that promote generation of stress and subsequent adhesive failure of the ice.

-. Appropriate stresses.

The appropriate stresses for initiating and propagating adhesive failure ,as given in reference oO'l include the followung: I. Single shocks from direct mechanical impact.

2. Flexing of the member/coma?onent in normal use.

5. 5_nic or ultrasonic vibration at optL.-a_n frequenQ" iqgcsed electronech:mical!v.

I. Heating (or cooling) intermittently to create te.nperature gradient< n.nd differential therm_, e.,rpar, s_on to stress unterface.

P:'cvLie alterp, ati:_< _trips .": high and low ceetftcient-of-exgmsicn _ateria!s in or beneath _urface to develop sire>: _Tcn to:met'art:re c!;m_e.

6, Utiii:e bLmetallic elements to magnify displacement upon thermal change. ;_hen heated by radiation, electrical resistance, or hot tquid, thes_ bimetallic elements would induce local stresses in a flexible skin.

The implication is that some external stress is needed to initiate cracking, etc., for ice shedding to occur. This requires that the ice sensitive member or component be designed for natural tqexing or be provided with an ice protection system which is a combination of an icephcbi¢ material and a mechanical, electrical, or thenml system. The best use of icephobic materials in combination with other ice protection systems is a subject £er an icing research pro[ram.

Icephobic mmterials should be investigated to determine which candidate _teria!s exhibit the characteristics _:_st desirable for application to fLxed wing light transport and general aviation aircraft, such as: I. Low cost.

I. Ease o£ installation Ln nm_ aircraft or retrofit in older aircraft.

3. Permanent or semipeTmanent coatings.

- 4. Compatibility with other aircraft _z_rials.

3. Ease o{ _r_l_,IterloJlCe.

6. Reliability.

_. Combined use w_th other ice protection/s'ress rnduclng systems.

[cephobic _.naterlals possess the potential advantages of low cost and light ;,ei<ht. According to reference 98, a savings of over 10@ pounds _ay be reailzed Ln the use of icephobics over an electrothe._l equivalent system for large aircraft. _e u__e of icephobics, as _th the microwave _nd electroL_pulse s>'3tens, does not involve the problem of nmback ice _^hich is often a characteristic of the thenmal systems.

_h.e majari_- o£ the documents obtained during tile l_t-rature search and listed in the co.r,_mter file cn icephobics concern research and development testin< o:" : eFhebic materials for ice protection of helicopter rotor blades.

The obvious ad_anta.<e of the helicopter rotor blade over the fixed airfoil is the d>nanic force of the rotatin_ blade for sheddin_ the ice, even through thi_ force is vat=able eve _ the length of the blade. The fixed w_n_ _rcraft r_u_t atta.:: cor_iderable \elocitT. or _ i_ht 5need to approach t?e aercd_-namic fcr_e_ ava:la}'le to the rotor kl order t_' induce shedding.

Fig_ures17 and 18 showthe results of sometests conductedby the U. S.

ArmyCold RegionsResearchand Engineering Laboratory, Hanover, New

Hampshire. In figure 17, the averageshear force required to dislodge the

ice from the tesz sampleis plotted against successive or repeated ablative

tests. The results are very erratic. Twocoatings showedvery low adhesion

force repeatedly until the test sampleswere subjected to simulated rain

tests, after which the adhesion forces increased to the baseline value.

Figure 18 showsthe life of a DowChemicalCompany substanceunder the flight

test conditions.

The NASA research programmust investigate the following factors

considered Ln the use of icephobics for ice protection systemsfor fixed

wing aircraft: .

The candidate materials which ,must exhibit the optim_Jm low energy characteris=ioq, utilized with or without a soft (i.e., sponge) substrate.

2.

The aerodynamic forces required to remove fractured ice - minimum required with the candidate materials for various sl=es and shapes of ice accretions.

3. 2_e meti_ods bywhich the required initiating cracks or fractures will be made in the ice accumulation.

.K Ai] of the first three considerations aboce for both straight and swept airfoils.

_DUCED iCmf _R_,_C_ .ON _.QUIK_,I=NT .h\_ ICING D_STRb?._-FATION ASSESS_E.\T TASK "_ GF_\'ER&L A comparison of a t_pical general aviation aircraft t_ight profile to a modern jet transport profile shows that in many ways the light aircraft is faced with a more difficult ice protection design problem (reference i].

Statistical data cm_i!ed by the F.C\ over an eleven year period ifi_:res 29 through IL_ show that the most ccrmmnlv L_si_ed cruisin< altitude for _enera! avi_tiJn i_ around 5,01]0 feet :,here the larzest number of icln_ encounters occur. Therefore, £eneral aviation and light transport aircraft ,operating :_ to i@,000 feet _ have a more demanding enroute Lee protect:on r_quirement than Jet transports flying at t'_ical altitudes of 30,000-4_,I]0 _ feet, .,ell abo,,e 2cs_ of the icin_ conditions. Also, the ;et transports climb to altitude ve O' luizklv, thus minLmi=ing their ex?osure.

8_ .U_¢OJTID • _IIICON[ _R_AS[ $_S I t I / I I I 11 I z/ - I /1 I / • _[P( Oid I / / I I \,_-(I_.LOGLIS$ \ = I // I I x \ I II I I " \ \ Ill j l / IWAI[II SP_b.Y *EST_ / (_,_7i_ i?_*iT _|ST] _ ,-_-*---r _- --r--- -'-I .... n _----r:--- - T>---_ 3 _0 4O _O tO 100 110 140 "IISEO O_ A S4_PLI OF _lY| P£_ _IL_TICH 1|$T _i_ure i_. .kver_e Shear Fcr=e Fer 99lation " " _e: _'_- mii_Mmu_m_ AVRADC0,,I i t I¢£ PHOBI( CO_TI:IG _LIGXT TESTS ii I- -Two t,lat_-fiats _.... d ;Jan-F.% '" : -HISS,,_H-IH Tests -BOW E-2,!_O P,t_st E..... _ >79 min:_tts .__°( ; 0._ ]jm _ >_O m ;n,.,t_s 4"C ; 0.50 t/.¢s >77 mbut*s .IO+C ; 0._ _/'m _ 40 minut_ _m;l_ s_e_) .|O°C ; Q..SO g,'_ :3 mi"utes (1:_4'Je hm_q -;_°C ; 03.5 _/'u_ -[.ff._cts _f _,3:n, q_,',t,4, a:d _u._t, _t: ",_qc,';3 8" .w,.i

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,J .L i Sd31_D,-_i 3 iO _'bIF',,_i _J , , , ,__ t Data on the characteristics of icing clouds with regard to icing severity _have been outained from a %_riety of locations _round the _rld, mostly in the northern hemisphere. They cower diverse time periods, flight conditions, and sensing equipment. A very. excellent surmnary of the icing severity data from various sources including the .NASA Perkins Report, the 1972 Briggs and Crawford British Data, and the V. S. Savin, et al Russian data, is contained in reference 102, a study of ice protection for advanced helicopter designs.

No new" icing severity measurements have been reported in the United States since 1952 (reference 102). However, foreign icing severi_, data collected more recentlF (1972) confirmed the %_didity of the older U. S.

data, as sho_n in figure 21. The figure is an overlay of a liquid water content probability curve derived by Lewis in 1952 from 1940's data super- imposed on the probability curves from V. S. Savin's data, which was based on five times more data gathered over a twenty }'ear period.

REDOt_J0 iCE PRCTECTION R_QUIRD_N'[ In setting up a h>_othetical ice protection system requirement that is tess than the se%_rest icing condition required by FAR 25 (Appendi__ C], one must consider the following: I. ',_hatare the actual cloud icing severity data measured woriJa_ide from all sources': 2. t_hat is the accura_, of the measured data (i.e., do the data from various sources verify each other)?

5. ;_hat are the present design requirements for full ice protection as established b?" the F._47 Considering the given flight envelope or profile for light trmnsport and general aviation aircraft, how can the design requlrements [F_ FAR 25 icing envelopes) be logically or plausibly reduced without compromising physical realities Ln a ha:ardous manner; 5. i_hat other factors may be addressed tc redt_e the ice protection requirer_nt from the _everest icing condition?

Pae operational implications of limited, i.e,, less thin1 full F.b\ FiR 25 ice protect:on certification, reqinres that the' felto_ing areas _e studied for possible h'_rovcment<: i. Dispatch _les -_. klrc%_ N lt IO[IS _9 FiTare .... ,_ .

.... _a_er _ontent as a Fur, orion ,Dr ._'_ient Temverature _t _n..n_ ..'l_mtities q, .....

I]0 3. Airborne Instrtmmntation Requirements 4. Forecasting I_provements 5. Air Traffic Control Restraints 6, T._" ,..mg I_tensity Definitions Levels of Icing Severity Atapropriate for the various G/A aircraft in terms of: (a} altitude, (b7 temperature limits, Lc_ icing intensity, and ld] geographical limats.

#ulso to be considered for less than the fui1 FAR 25 certification requirements, _edd be the consideration of matching limited protection svstenm to limited icing ¢onditiomg. IT_is _uld require definition of allow- able ice accretion rates and know, ledge of the penalties associated with the ice accretions for each individual aircraft. The decision as to _hat components shotlld be protected in the desismated limited icing condition, _uld necessarily Be based on as much analysis and testing of the aircraft and its protective svster_ as presently" rcxluiredfer the fu.ll FAR 2S cert i f [cat i_n.

An alternate _tv of showirg icing severity probabilLtv is sho_m in figures 23 .rod 2a as calculated during the study for rete,.-,mce h 2 Tt"_ese ctnT"es _l',o_ independent probabil itv of icing tenrcerature m;d liquid water content belo_ /0,00t] feet.

The present stmqdard icing conditions used for the design of all ice protection svste'as are t_e icing envelopes of F,\-\ F,_ Part 25, :_ppendLx C.

_aese envelope,_ of conditions are she_,n in fig_.res 23 and 2_ and are the basis for ce,.'ttficatio,: for all aircrnft ice protection svste,_s if the ai,"pLme [5 to t_v in '._o_,n icing conditkoils. Ilmse envelopes do ,,tot represent physical retatlonships between the variables, but represent co_bin- at ions of the pa=auneters COils[doted to have surf to tent probability of occurrence to :Itlke tt approp:'[ate that [Falls_or{ category aircraft be ,te-ismcd to cope with them ;reference l -_.

Since the F_ebabilit_ of encc,,mter:ng natural ic:ng conditions beh_, _I- qo_7 _ar:_. _ . _ ,,tmc remote ,re?'erence I0'_ i:ldica_ed ,,as _eetl s}lo1_n _,_ be _\'"" ,Iv that J,ma,[ian expe:+I:nCnters ,_,i,;. not find ,me enc,2t_lter belo_ -[I°C ,,I2.-'"F _ .... ,. .,.+4,,+, the "-;"++ estL_ :','l reduced if:he CO[2_I*. lons *.'O1" I i<]lt tr,lnS_'ot'{ .l_,,[ gellera_ AVl.lt ion .lirfr_l:-_ _!'< F:lt i:1( }'el _1_ l'_,,l_*_ ! to,.,; ,llttt:;de ;,t_uld be the <u:!e as the COl/rill ivy[Is [-I-cpo_ed t I _ _ l " !le[1c_D[er5 , :!_',l_,c5 "" an_ _ "_ , _,_,t) Jtll-%eS are the _;u.",_' a. _ _.!le existHlg :-.\,R .a c',[I_.es except that the 1,_, ,'e:'!pcr:ll',Ire ii:n[: '_ -I- _"" _,,l"!:', c_l:_, _._. ,.-I_ ...< !l.t','e .-OllSl_[eF_'d _ .,_e;- ao_.. ,t__a,,,,_, _ , ,h: the _o_er 112ai _. _,e_,l[is< _ ,_f the L ........... • I00 90- 80- a_ -J _0- © 50- 40- 3G- _q 20- _a I0- -10 12 -14 -10 -18 o> 2 -4 -6 -_ v?t TStt _[ air T[_pC<aTURE - "C FL_re 23. ,kltsfde :kit Temperature Txceeda_ce ProbabL1ktv Below' t_,OOO Ft. Ret- 102 _gI_ilX"LI' PA¢:'" ;..

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ASSES_MF.\T OF \IRCKkFT iCING INSTRL_GNTATiON - F_XISTING AN_D UNDF_R DF%_LOP_fl=?cr Mrcraft structural icing is one of the major weather related hazards to general aviation. This lm:ard can be greatly reduced if the aircraft are provided with devices that will do the following: i. Warn the pilot of icing conditions or give _m indication of initial icing before the pilot wo,.id otherwise be able to detect it.

2. Give the pilot an accurate indication of the icing rate or intensity, if he chooses to remain in the iclng conditions.

Another requirement is for the quantitative measurement of the various icing parameters which stems f_om the F.aA certification requirement for demonstration of the aircraft to operate safely in icing conditions. To fulfill thls requirement, it is necessary to obtain quantitative data on flight parmueters such as airspeed, altitude, CAT, etc., and on icing conditions such as liquid water content, droplet size and distribution, and ice acctm_,lation (size and-shape). .klso, qualitative data on aircraft hand- ling, such as stability and control are required.

An assessment of the icing instrumentation presently used or under development by various industries and Government agencies, both _, home and abroad, has been accomplished through a review of the literature. The doct_ents containing icing instrt_.entation information were selozted by interrogatio_t of the colorer file for such data (see Appendix C - Comments Table on [nstr"_._ments). The extracted Lnformation has been stm_arized in table _'XI. The table contains a list of icing instr'_entation by name, agency source, and/or inventor. The type of principle of operation is sho_'n for each instrl_ent as data have been found in the literature. The instru- ment utilization, the measured iclng parameter(s], _md the problem areas associated with the instp_nent which may limit its accuracy or its utilita- tion are given where .known. The lack of a check re:irkin the problem area coltman does not necessarily mean there are no problems with an instrt_nent, it can mean no &tta _,ere available.

There are two basic methods of detecting and assessing icing in fli._ht and all icing instr_nents fall into these two categories <reference 33_.

The _irst method is to allow ice to acc_n_late cn a s_fitable probe _md then detect its presence ,ice accretion instruments_. ,-he second method _s to sense the atmospheric ¢onditlons conducive to icing and then to continuotLsly e\,-aIt,.lte _ts likely severity i Lnferential or thermal detectors;.

TABLE .XXI ASSES_T OF ICING INSTRb%_'qTATION ; ! i

- ii

I _otlt _n_ 'lJ_ L_ _ Lnd_ra • Ix x ix Ice accretion instr_nents include rotating cylinders s.nd discs, stationary and vibrating _ds, pressure orifices, beta radiation probes, etc.

The accretion method is the simplest but it does have the limitation that at high LWC and high subzero temperatures the latent heat that is released as the ,_ater freezes raises the temperature sufficiently to prevent all the water from freezing. If the instrunent operates above this "Ludlam Limit" (freezing fraction less than one), it will underestimate the LWC. The accretion probe must be deiced, usually thermally when a predetermined amount of ice has formed. This is followed by a "dead time" for the deice and subsequent cooldown periods before the next reading can be taken.

At first glance, it would appear that the accretion meter is the _st direct detection and _rning device, but there is a wide _ange of icing conditinns where there is no simple correlation between the impingement rate and the potential accretion rate and the form of the ice. Considering all of the variables of catch efficiency, a_._ient temperature, L_E, and airspeed, etc., the accretion t_e _nstrument will give fairly acc arate readings in low water content air at re: ratures below -it_,°C(14=F).

The thermal or inferential ice detection and LWC instruments utilize a heated probe or wire, exposed to the alrlqow, that is either maintained at constant ter_perature or has a constant heating power applied. The power required or the temperature _ittained can be used to determine the L%_C, whoa the convection cooling is accolmted for. inferential instrt_ents have the advantage, in that they depend solely on the evaporation of water and temperature measurement and do not suffer from the limitations bnposed on accretion instruments due to acc_nulatien of stray deposits. However, instruments such as the Jo_cn-Wiili_T5 instrJment, used widely over the years, _Iderestimate LWC when droplets _ch lar_er than I00 microns are present. Inaccuracies occur in turbulent -.'lowin ascertatnin_ the _unt of convective cooling.

A third method of detectu_g _nd a_zessing icing in flight and in icin_ WlIld ttmnels fvr airframe stw,_cture or engine tests, uses c]olld particle sizing instrt_nents such as the Knollenberg system. These instruments measure the ilg_L _cattered by a [..article as it passes through :i laser be:_n.

The resultant si_T, al is a f_mction of the particle diamete_ and is used to generate a cotmt in one of the fifteen 3 micron-_i.Je size c_5annel_ in the a_xially scattering spectrorLeter prube. L-his instnzment measures droplets in the 3 to 15 micron range. FartieLes in the iC to 300 mzcro:_ JK_meter r.an_2_ are neasured by one of the Particle Measuring Syste,_, Inc. optical array probes _ref_rence 56_. 7his in_t_ent uses fifteen 1_2 _cTon-_,ide _ize channels for co_ting the particles. By electronically inteKrating the :r_er of particles and the _i-es of particles, an e_tima_e of the i.hC cr_ be _nade _,ith the Knollenberg t>l_e ef instr_ner_tation.

The majority of the ice detector and particle me_suring/counting

instruments that fall into this third category are used in icing wind tunnels

or engine icing test cells. However,som_of the laser (ASP)systera_such

as used by Meterorology Research, Inc. (_I) are small enoughto he adapted

to aircraft for use in certification or in meteorology research data

gathering. Thesesystemsare connectedto a complete systemwhich may

include altitude and te_perature measuringinstrtm_.ntation as well as the

data recording system. While this Kind of instrumentation is excellent for

aircraft certification progr_ to qualify them for flight into knownicing

conditions, it is muchtoo large and expensive for standard aircraft

equipmentfor ice detection and intensity determfu_tion for pilot warning

pin-poses.

.Assessment of icing instrumentation is complicated by the fact that different groups or different researchers cite such different opinions on effectively the same kind of lnstr_nentatlon. In reference 157, experience with oil slide data for measuring droplet sizes in the 10-S0 micron r_nge resulted in data too large by a factor of 1.8. Errors were due to evaporation of small drops, coalescence of drops [small ones into big ones), and Impact or flattening errors. In reference 33, oil slide droplet sampling gave repeatable, stable samples such that there was no reason to doubt the accarac'/ of the oil slide system. It was $'_ated that the reason that none of the normal problem5 attached to oil slide m, easurements were encountered, was due to the choice of oil and the method of operation. The oil used was a Shell DenU__ 250 or a straight _tineral oil <_zj_ 250. The procedure was to e._tend the slide for only 20 seconds, expose it for i/I0 to 1/20 of a second and then retain the slide in the conditioned cabin of the airplane.

Considerable research remains to be done with respect to icing instru- mentation technology.. This research includes the follo_,ing: i, For exlstin_ instrumentation, determine the practical or optimum range of conditions for the instrt_ent, its percentage of uncertainity, and the proper operational procedures.

Develop new icing parameter instrumentation such as the laser hologram _ and three dimensional systems with the associated electronics t,hat may be used in icing ,_ind tunnels. For this use, slze and co_plexzty are not [Lmating factors and the intent is the development of equipment that can be used as a standard for calibration of s,-vailerand tess ex-pensi_ instrumentation. There is no s_m_dard at present.

_?evelop small accretion _.d Lnfe_ential icing instruments that c;in be calibrated in Lcin_ t_me!s a_;aunst the sta_dard equipment with the desired hi_b level of confidence. The Lnev?ensive small instP_nents can be the sultable Inst7Jment5 needed by _eneral avlat ion aircraft.

10t

The instrumentation required for airborne utilization should include

instrtm_nts for measuringliquid water content, outside air

temperature andpossibly meanwater droplet size. kbwever, in the

case of the latter parameter, it is not necessary to know the droplet distribution for aircraft icing effects evaluation. A/so required for the airborne instrumentation which will be used for supplying data for foreCasting, is the recording and transmitting equipment. Development of this equipment is required right along with the sensing equipment if weather stations are to be provided with the required data base for current up-to-the-minute quantitative foreCasts.

ASSESg_Vr .%'_q) REC0_N_DATIONS FOR ICING FACILITIES (TASK 8) NASA recently completed a survey of aircraft icing simulation facilities in North .America, providing for each faciiicy its operational parmmeter ranges and size restrict.ons. [The results of this survey and a similar skm_nary from reference 150 for the European facilities are provided in Appendix E.) Each North ._nerican facility was classified by NASA as one of four possible types: (a) wind tunnel, L'b) engine test facility, (c) low velocity facility, or (d) tanker facility. The advantages and disadvantages of each" of these categories were previously discussed in the section on "=_rperimental Prediction _thods."

The wind tunnel capabilities presented in the above su7%'ey indicate that test chamber slzes va_" from 0 inches to only 4.3 feet, when ._%5A tacilities are excluded: These size restrictions limit testing ip these tunnels to instru- nents, small components, or _cale mode[_ of larger air, raft components. Larger co_onenzs and full scale aircraft will have to be tested in the K-kSA Icing Research Tunnel [[KT% or the rehabilitated .Altitude Wind Tunnel IAI_T3. Only six wind tunn_'l_ other than the IRT and A%_[ are listed, ind of these, only three tlLockheed, Boeing, and N]TC-Canada% appear appropriate for testung of small co_:onents or scale models of aircraft. :is a result, in addition to size restrictions, availability of these t_mels to indtLst_." becomes a problem.

It becomes increasingly appar=.'t that in order to obtain the wind ttmnel data base required to solve general a_iation aircraft problems, the _\SA icing '_Ind tunnels will ,have to be util ted to a Ereater degree, and improve- merits will have to be made to e.rpand the applicabklity of these tunnels, _ncrease :he accuracy of test measurenents, and reduce the turnarotmd time ber_een tests. These facilities are discussed in *mre detail below, :ncluding ::eeded instrumentation, and recomm, endations for usage.

:_eta_l< of the existin< );q<..% he:.i5 :\ltitt_de :_ind Ttmnei u'e ,,:o_,n in ficu:'e .'9. P:e,,osed rehabilitation _difi_atkons indicate that the \;¢: '.,ill have ::,e !arfe _!;_:['er_ :'or testi:'_ cor_lete or larae secri_n_ _f [02 u <D # / I03 aircraft. One test chmnber is 43 feet in diameter and the other is 20 feet in diameter. The altitude versus velocity envelopes of the _ different test sections are sho_n in figure 30. The altitude capabilities of the facility are sea level to 55,000 feet. This capabili?/ is applicable to both test sections since they are in the same loop. The velocity of the 20 ft diameter section is roach 0.8 mm_inun and the velocity of the 45 ft diameter section approaches 60 knots maxi;m_n. An overlay of the general aviation operational envelope on the Ahq characteristics en%_lope is shown in figure 31. The characteristics of the Z0 ft diameter section completely contain the _eneral aviation envelope. The 45 ft diameter section characteristics are shown to be outside of the flight envelope of general aviation, but are applicable to ground operation and certain aspects of landing and takeoff oper._.t ions.

A future option to the rehabilitation desig_n of the AWT is to provid_ a 90,000 horsepower drive meter unit for the 26 ft diameter fan which Ln effect triples the power of the smaller drive motor. The "hack leg" of the tunnel wil] have a sinDple rotor whirl rig for testing large scale rotors at speeds of appro×imateiy 60 knots. An overlay of these characteristics on the genera/ a_iation envelope ;'figure 33] shows that most of the envelope below- LO,000 feet is included in the envelope if the previsions of this option are added.

[t is understood from a recent conversation with ._ASA Lewis Icing Research Center staff members, that the q0,000 horsepower drive motor unit will be a future proposed modiflcation _o the facility. _e velocity in the !0 ft dianeter section will be sonic for the ma.xunum power condition.

In an effort to realize maxLmum efficiency with regard to the ener_" requirements of the AI_T operation, it is recermnended that simultaneous testing in the 43 ft section and in the 20 ft test section b _ considered whenever [t is posslble and practical to schedule them in that way. Thi_ will requlre considerable planning and coordination under the direction of ._ki& personnel, -_o that tunnei conditions will be suitable to the require- ments of both icing test programs.

The A',_T 10 ft di&T.eter test section with it broad range of altitude and velocity condltions will have the capabilities required for icin¢ tests or: a variety of _<oncral aviation aircraft ice sensitive structure and cov4_onents and assoclated Kenera/ research. 7he followin_ are representatlve of the t_pes of test3 envisioned for the t_.o test -<ections.

i. ._ing ice and tail ice interactions.

_. Wing :rod fuselage j_z_ct:ire_.

\

\

"C _E_ m k-- L.J > I b r i')3

20'D TEST SECTION

TEST SECTION

PERFORMANCE

ENVELOPE

_J

COOLING

F-- N F-- -.J

ICING

<STUDY)

__/___//j-ALT LIMIT

.J

I

I T F : ! '

100 200 500 -4LU 500 6C0

VELOCITY,K>_OTS

[ l

I I T I I , r l I

.2 ,4 ,6 .8 1,C

_",ACt I II '_D[_.,, : F i _a r,_ 31.

Comparison of a T)_ical c_nera! .\viation -htrcraft I]_eration_tl F-nveloFe ;_i r h the .-_T C,Ipahii ities

/

©

20'D TEST SECTION

_45'D TEST SECTION

LOW PERFORMANCE

A/C

COOLING

HIGH

PRESSURE

A/C

ICING

_ALT LIMIT

-- (STUDY)

200 300 4UU

VELOCITY, K,,OTo

T i I

I i T _ I

,8 ],o

0 ,2 ,4 ,6

MACII_'': _ F1

,_'erl.lv or" C, enet-_lI -\vt.tt[on L_erati,on r_q_elo!'e LLI£ t.

3. Wing and engine combinations.

4. Propeller, engine, fuselage combLnations.

5. Empennage pod-mounted engines and fuselage (ice shedding problem).

6. Large wing sectiorm.

7. E_pennage sections (con_plete vertical and horizontal stabilizers; T-tails or V tails; fuselage interaction).

8. Nacelle inlets.

9. Full sca±e verification tests of scale model test techniques used in sma_l icing wind t_nels such as the IRT or smaller industD'/ university icing tunnels, to verifF accuracy of mathematical scaling factors used for scale model testing.

I0. Research and initial calibration of water spray systems designed for use on icing tanker aircraft.

_SA ICING RESKZR_ _J_I£L (IRT) The .NASA Lewis Ic_ng Research Tunnel, which is the largest icing tunnel (6 feet by 9 feel) in the United States, has been used for testing sections of f'_Lll scale aircraft st_acture, full scale small components, sad scale models of many ice sensitive components such as the following: i. Straight and Swept Wing Sections I. Engine Inlets 5- L_dome s a. _lissile Co_qponents 5. Tail Surfaces, Horizontal and Vertical _. Fuel Vents ". Helicopter Rotor Blades $. ..l.,ator f'orn-- a Engine _._tu _u Xoses I0. ,._l...c_t_, z.hS ,Particle 5e,?arator_

ii. PneumaticBoots

12. Engine Cowlings

13. Inlet Screens

14. Antennas

15. Slatted Wing Sections

16. Slotted WingSections

In addition to the ice sensitive components that have been tested by

various aircraft companiesin conjuction with .NASA, manyother basic research

programson icephobics, ichng instrumentation, ice protection systems, and

other aspects of general icing technology,have been conducted by ,NASA over

the past years in the IRT.

The IRT is a closed-return atmospheric ty_e t_mnel with rectangular cross-sections except at the 20 ft diameter drive fan in the return leg. ]he four corners have turning vanes and the contraction section has a 14 to 1 area ratio. The test section is 6 feet high, 9 feet wide, and 20 feet long.

_tax_num speed for the en_pty test section is 300 miles per hour, creating a test section pressure equivalent to about 3,000 feet altitude. The floor of the tunnel contains a _ountlng plate located on a turn-table which is nearly 9 feet in diameter. The tunnel airflow may be refrigerated to -15°F or lower, if necessary. Calibrated icing clouds nay be generated with liquid water contents from about i/2 to 2 grams/c_bi¢ meter with volu_ne mean droplet diam, eters from roughly i0 to 20 microns. The drop size distribution is approximately a Langmuir "D" t_e. The iclng cloud is Lmiform in inten__ity un the center of the test sectlon over a region about 3 feet high by 5 feet wide.

_le IRT is operated by K_A personnel, but the company testing in the facility" must build the model and supply a test crew to install it, r-_n the tests, record the chta, and remove the test equipment at the conclusion of the tests. The company must provide its own data recordung and data process ulg systems.

An L._rcvement in these conditions wou/d be to have N_KSA provide the data recording and processing equipment. This _,ould inch_ie stanchrdi:ed temperature recording equipment for the standard thernocet©le materials ne.,-c..all >- used in the temperature range of icing and ice protection systems.

Pressure measur:ng equipment .md the data recording equipment for reasonable ranges a_nd nu-abers of _arameters could be provided _,hid_ '_uld simplify the loglst,_cs probier_ and help the preplanni_g of many of the test prograc,s.

Any special:zeal tnstn=entation should still be supplied by the company" doing the test, the s_me as before. _" providing data recording and automated data llO

reauction systems, test efficient" would be greatly improved. The result

_uld be to simplify test plannLng, reduce setup time, and increase

conveniencein operation during the actual testing periods.

The liquid water content and droplet size of the atmospheric icing

clouds provided in the IRT are controlled by the w_ter and air pressures in the spray nozzles and the air velocity in the wind tunnel. The tunnel and spray rig Fmve been calibrated for combinations of LWC, mean dropl_t diametenand airspeed, and _raphs have been drawn so nbat other conditions can be determined. Wheneeer a test is conducted, the required pressures and water flow rates of the spray system are calculated from equations and graphs based on the desired icing parm_eters and the calibration of the tLmnel.

Individual measurement of the icing parameters using any of the commonly accepted instrumentation, for evoke test run, is generally considered urmecessary for these facilities.

Improvements to the .NASA IRT was one of the subjects addressed by the industry/Government questionnaire. .&n evaluation of the suggested modifications and needs of the IRT to improve its utilization and efficiency are specifically ms follows: [. A large test section appro×£_ately 15 ft x 15 ft is required.

(lT, is could be the 20 ft diameter A_fF section.)

2. Increased range of liquid 'water content (at least the complete range of continuous icing as defined in FAR 2S, Appendix C).

3. Improved instrunentation (see Discn_ssions).

¢. Hi_her speed _pability (400 k_ots has been suggested].

5. Altitudes up to 20,000 feet.

6. l_roved accuraL_.- in _ethod of setting air and _nter pressure in spray system.

" A uniform cloud at the test section.

3. Lower temperature range _-2_°F).

9. An automated control system which would assist in faster stabiliza- tion of tunnel condition to save ti_e and ener_'.

i0.

Cor_iete recalibration of liquid _ater content ind droplet size versus rotometer, air _uld _,_ter pressure [after other improvements • in 3pra\" system, etc. ale ,%ldde _ .

Iii 11. Refurbish vanes, blades, etc.

12. Improved wake drag system.

13. Blowing/falling snow and ground fog capability.

14. _re ttm_nels (facilities) to reduce lead times (improve availability).

15. Provide IRT force balance system.

INSTRU_N_fATION REQUIRemeNTS FOR ICING P_S_kRCH The kind_ of test techniques and instrt_entation that should be avail- able for icing research are the kinds that are oriented towards gathering the information necessary to resolve problems. _ne ici_,g tunnels should have the condition control, instrumentation, test sample capacity. ,and other sophisti- cation to meet this purpose. Sufficient variation in instrumentation should be utilized such tAat the complete required range of para_eter values will be covered. Since no instrumentation exists today which can be considered as an industry, standard to measure all ranges of liquid water content and droplet size/distribution more ths_n one t>me of instrument for measuring these parameters _ii be required in an icing tunnel to increase its efficien O- and flexibility.

Conventional instrt_nentaticn is required to measure temperatures, pressures, and drag and hft forces. Specialized instrumentation is required to measure total pressure and temperature in _he icing environment. Heated calibrated probes are required for measuring total temperature and pressure° Different methods of photog_raphy should be provided for good visual coverage of the test model in the icing turanel test section. _Dtion pictures, television, and still photog_raphy provisions are required to record all ice deposits of interest on model _unted in position in the tunnel.

Special portholes should be provided for photographic coverage of inaccessi- ble areas. Telephoto lens and wide angle lens should be available for those photos and situations requiring such equipment.

Along with conventional equipment such as m_11tiple ©'finders and droplet o_i slides, _m inline laser holo_raphy system shotlld be available for measuring liquid water content m_d droplet size for both calibration purF_oses and act_ml icing tests.

A large m_etmt of test data will result from all the measurements dis_ed above. [n nrder to assinliate the data successfully, it is L_port_It that data reduction be accomplished quickly :rod efficientiF, to serve as a tool for test direction during tke course of any given test serles.

..%n aut_m._lted &ata reduction s','stcn, should be considered for this purpose.

TESTING TPO_NIQU_.S

Testing techniques _ an icing wind tunnel should ensure that the air and water supplies be automatically controlled so as to provide the desired icing conditions (i.¢., mm_In_m conthluoUS or m_ximum intermittent) while keeping the droplet diameters nearly cons;ant (droplet size distribution) for warying periods of time. Techniques should also ensure that the main flow of the tunnel is saturated so that evaporation will not modify, the droplet diameters which could in turn cause ice a¢Ctmm/ations not representative of the set conditions. Continuous monitoring of the tunnel air humidity, during icing tests may be accomplished through the use of automatic dew point hv%_ometers in the test section. This .has been accomplished in the SI-5_ \bd_ e Wind Tunnel (reference 23). Humidity affects the heat and mass transfer from droplets in the spray as well as the heat and mass trznsfer from the surfaces subjected to ice acc_xilation.

KECC_DED USAGE OF .NASA ICING _I.N_ TUN_]_L F_ILITIES The .NASA icing research tunnels should be used to provide whatever test data are needed to solve the problems of general aviation and light transport aircraft. High priority problems should be attacked first, but imy have to be postponed ,until the A_T is rehabilitated (about 1987_ if large scale testing i_ required.

The literature search _nd review, and the ,government/industry survey identified about eleven areas of needed research which _irectly require testing in the icin_ wind t_nnei_. Additional testing would also be required to support other research areas for verification of newly developed ice protection svste_ and anal}_tical prediction _ethods. Powerplant icing tests _'ould be pursued at the engine test facilities.

Some of the high pr.iority items identified include generation of icing data for the newer airfoils in existence today, and the aircraft penalties which accnle from this ice buildup. Yhe N,_SA LeRC facilities can be used to provide such _asured ice buildup and the resulting performance degradations- Alternatively testing at _iA LeRC could be used to define the ice accretion and shape. ?hen si_milated ice, based cn the icing tunnel resuits, could be .... . _ "_ - _ in any one of a variety of the dry" used to test alrtoll pertormmt_e et_eut_ , " air wind tunnels throughout the country, this might be a preferable approach, since the _str_,ents for measurement ot aerod>-namic drag, lift, pitching moments, etc., are readily available at the latter facilities.

._other approach _,_uld be tc use the NASA LeRC facilities to obtain measured eerfor-_nnce data on airdoils with real or simulated ice addretlon5.

FiiKht tests of aircr:_ft utilizin_ the sm_ airfoil and simulated ice _ accretion ;,ill _rovide qtmlitative performance data from pilot results for cor_arison and i_'erification of overall effects of ice accretion. These co_par[_,cns will _rovide the desirable levels ot confidence _o aircr,_:t Ferform,._,c e characteristics and certification Furp oses.

To study the effects of airframe and nacelle ice shedding on engine

performing.co, a combineduse of _kSALeRC and existing large englne te_t

facilities might be appropriate. The large engine test facilities in the

U. S. (mainly the AEDC test facilities in Tennessee)have not oniy increased

in size but ]_ve modernizedtheir state of operation, including instrumenta-

tion for measuringLWC anddroplet size/distribution. Thesefacilities are

used primarily for engine icing tests for full scale engines. NASA LeRC%

AI_Tfacilities would be used to define the nscelle inlet ice accretion

characteristics and the amountof ice shed from the airframe which would be

ingested by the engines. The AEDC test cells would be used to define engine ingestion characteristics, inJet anti-icing/deicing system operation, etc. Integration of icing test programs with more than one facility could '_tim_tel}- lead to more standardized icing instrtm_ntation for measuring the si1_ulated cloud icing parameters.

As part of any program to develop ice accretion analysis models, it would be necessary to provide actual icLqg data for support and verification of the models, it would be advantageous to use the _kSA icing wind tunnels for thls purpose due to the capabilities and controllability of wind tulmel conditions. Controlled testing of subscale and full scale components in conjunction with model development will assure consistency and accuracy, of the restdt_.

Scaling effects shouid also be addressed in the NASA icing tunnels, especially after rehabilitation of the ,%%_q. Scale model testing in the IRT would be verified by full scale tests in the ANat. The data _Duld then be used to determine appropriate scaling parameters to improve icing predictions based on scale-model testing or anal}_tical models.

Horizontal tail stall, wing-tail interaction, and ice shedding from full scale structural components are research areas for which a large, rehabilitated AI_T would be ideal. Due to safety considerations, it _Duld be [mwise to test for these effects in natural ice. It would also be uneconomical, for reasons previously discussed, and control of the degree of icing _uld be up to nature.

These and a number of other icing wind t_-Lnel test programs are discussed in more detail in the subsequent section. It is important that KASA utilize its facilities to provide ice accretion data for new airfoils, to verify the development of new or improved prediction models, and " assess the aero- dynamic and safety penalties due to icing on wing, empennage, combinations, or due to ice shedding into engine inlets.

i14

Section V

RECO_f,_ED .NASA ICINGRESL_R(]I PROGRAM (TASK 9)

GENEP_&L

Discussedin this section of the report are stmmariesof the payoi fs md

potentlal benefits of research into nex or advancedice protection syste_[s, required advancements in icing forecasthlg and icing definitions, requirements, for i_proved accarate new instrumentation, and new and/or improved anal>-tical ice prediction methods. This sunmmry is a prelude to the specific research prog_ram listed in detail later in this section.

Figur_ 3& is a flow chart of integrated icing research tecbmical areas.

The prh_,arv elements of each are listed, and the integra[ion and/or relation- ship of each area is shown by the connecting lines and arrows to aircraft design and certification. The design and certification tasks are shown with _m_ny of the other elements to be directly connected with the main goal of safe operation of general aviation aircraft in the icing environment.

This goal of safe operation and i_roved utilization of present and future llght transport and general aviation aircraft can only be achieved by new and continuin_ research pro kn-mns directed towards i_prevenent of the technology, data base.

iCE 'PR_CT_ON 5'YSTE2..IS In order to surm_arize the areas of m_xmmJm payoff and potential benefits of new research progrmms on ice protection systems, many factors which have been addressed in the earlier sections must be considered. One of these factors has to do with the deslrable .qoals of any new or improved ice protection system dest_on. Listed in rank order with the most [:N>ortant _oal first. :_re the fallowing: I. Provide the Required Protc_ction.

3. Low _iunufaczurung, Installation, and _hintenance Costs 3. Low ;_e i_ht _. low Po_er Req4irement -<. Hich Neliabi!ity o. SL_Di[Cltv Ot veration -. !.!ini..m.m Effect on _ercdvnm._ic Perfc_.-rmnce / r.. ............ -- ........

i 7 aa _'2__ : - _ L- :2 { .c, ::< 7- _" 2 2 : 8. Goals of equal inpertance include: a. Ease of _intenance b. Quick Response c. _ti_imal Effect on Pilot hbrk Load d. Ease of 5_thematical Analysis for Aid in Certification The results of the literature search and survey questionnaire indicated that the t)._es of ice protection s)ster_ considered'the most promising for future development are the folla_ing: i.

Icephobics Electroi_pulse 3.

._[icrowave 4.

Acoustic S.

Combination _thods lone is primarily iceDhobic material._ • . y O.

Lngine lVaste Heat (.E._haustgases, cooling systems and hot oii systems,l Antifreeze Fluids Ligh_veight Pnec_tatic Boots 9.

_t.._ent Electrical Syste_m Heatin_ zads, surface coatinKs, etc.) " " • i0. _bre Efficient _pplication of Hot Bleed Air _:e first five systems are new systems which have been investigated to some ,legatee by variotL_ organizations in ho'h Governanent and indu_tr? but as vet have not bet-n develope_t to a prototype level m this ccuntr%-. _e last five basic _vstems have been used with _anv variations. _le'." have met wLth considerable success o_er _._nv years, but :t is the considered opinion of re;my extorts in the field that _ch c:m still be done to ir_rove the desl_m :md aFpi:catien o:: these t)pe_ of <>_rems. ._fh,.erefore. the resea:'dh reouirenen_.

Fl_m contains suegested research rotated to i_rovements of what would he censtdervd cl,l or proven s/stem_s as _,oLI as the ne_; concepts.

11- The promising lower weight _md lower power features of new ice protection system concepts (such as the electroi_mpulse or microwave svstems) _ly be attained only after a considerable dollar investment into the feasibility studies and developmental tests required to produce protct}Te systems. This investment should be compared with the investment required to reduce weight and power of conventional/proven systems or to reduce their installation, reliability, and maintenance costs. However, this comparison cannot be made with confidence until enough research work hss been accomplished on the new concepts, and on old system improvements, to obtain the data necessary to make the required trade studies. To this end, research effort is suzgested in the research program plan for conducting tradeoff studies to evaluate the ice protection systems best suited to light transport and general a_iation _pe aircraft.

It should be noted that in some cases, considerable savings could be produced by demonstrating that an ice protection system is not required, For oxalic, if research on the aerodynamic penalties associated with ice accretion on the unprotected leading edges of the wing and empennage of an aircraft, coupled with the operational characteristics of the aircr,_t, showed that the need for ice protection of these components is not required, then considerable savings could be realized.

ICING FCR_GLST[N(; A.\© ICING DEFINITIONS Research in icing cli_tolo._U', meteorology, and cloud physics to increase the data b_e for developin_ L_p_ved statistical desigm icin_ envelopes, icin_ intensity definitions, _nnd timely forecasting, will lead to more accurately defined rcquirement_ tot ice p_tection systems. This research will also provlde for better utilization of the general aviation aircraft wlthln their defused [h,_its of operation.

ICING IXX_XSI_" DEFINITIONS Current definitions of icing intensities were established by the Naticna! deordinating Cor.ruttee for Aviation Ln Feb_:arv 19o4 and adopted by ti_e Subcommittee on _eteorolo_ica] Services in i9o8 for reciprocating engine, straight wing aircraft. These qual_tative intensity definitions of "trace, Ii_ht..._derate. and severe" have been interpreted differently for different lir_raft. \ qt_'hntitative definition of i¢in_ intensity is rc_{uired '_hich _,L_uld ilion, the pilot to evaluate the effects of icin_l with respect to the LEticular aircraft he is _q','in_.

?;[St ,U]d cut're[_.t efforts have ]-een directed tc_<_rd _t;ch qu_tit:c;',-e e',aluaticn>, [.'r _.x,_lc, ,it_i_tative do:init_,ms relatu_g the Lch_,c mte,,',_[tv ,ic:'init_,3_ts tc ::quid ;,ater _cr, tcnt :,ere ;'ut Ln the lPo9 Air :',eatke:' 3e_,ice "_|:',t:,t[ _" u_e,[ ):It h) ;,Ot'k )f [.e_,t> 1 _,l- t'ro, _, )_\S,\.in 19-'. '(e_,t,_; :',f. l- <;;<go-;to< th.%t ,ieti;liti.)P,_ :-ei.{lia< the ,_'t_te )f ,JCI[CCTiOn of [-0 l._ "_l' ['I[[c'-_ per hour on a O'linder 3 inches in diameter may satisfactorily be u_ed for quantitative measurements. FurthermOre, efforts to correlate ice collection rates on a four inch diameter sphere have been used to suggest new ways o£ estimating ice accretion for forecasting purposes (reference 5). This technique is intended to be an i_rovement on the Air Force Skew T-Log P Therm_d)_amic DiagT_un ,_thod for existence of icing conditions and their intens it)'.

Both the literature search and the survey questionnaire r_sults indicated that there is much dissatisfaction with the current definitions of icing intensity. It is felt that further efforts such as discussed above are warranted, and a research item ha_ been included in the prOgram plan which addresses the problem. It is the desire of o,11 ¢oncern£-d that new definitions will be useful in tr_z_sitioning the currently qualitative icing intensity definitions to qumntitative values ;_'hichapply to individual aircraft.

FORHC:STING ,-k%'D ICING E,\%-IN3_LX,'T _DELS Icing foreCasts have been pl:ovided by the National Weather Service (.N%¢S] and the U. S. Air Weather Service (A;_) for about l_ years without significant changes in the basic techniques to provide these forecasts (references 22 and 9-'1.

W]:en the .hltomntion of Field Operations and Se._'ices. (:_OS) system is insta!ied by the k%_ at Weather Set-cite Forecast Offices 0_FO's), weather • * forecast ot_:ces, a.na air traffic control centers, it will do away with the present system. _e _F_S _iil elL,ninate all the telet_7 _e_Titers and facsimile r:_c,hines and the enormous quantities of paper they generate and substitute :m all-electronic system in _hich weather mfo:_-atien will be displayed on ,% screens. A weather map will arrive 40 times faster than it weald on paper, ,as_er.

and messages about 30 thnes _" * • _. x Currently, forec:ksts /including those for icing condl.ton.-_ are issued three tunes a day. :hey are trpdated as new data mdicate t,hat cb_n_es are ;,arr:mted. ;;[th the advent of .a&cOS, the N_',S will be in a position to Frovide forecasts e','e_" two hours for four-hour periods. SinGe 95 percent of flights have a dur:_tlon of four hours or less, forecast of t,-4 hours is an iwortant step to meet pilot der_mds for i._proved forecast__ :F..kk-_SA Aircraft :cm_ , -," "- v [9"3 _.

;_orkshop .at .e,,, , : \lthough i::.rcvene::ts have been ::ade _n forecasting:, particuL_rl?" :n the of _" r_tior areas for area of timkn_, .a, • i; _t:ll :'_ch .,) be done. _'ne ,._t collection ,of ,:tmnti:ative ich:_ &ira :or forecasting.

IF_,rovor_e_lt i5 :n *_ " P:ese _l.ata ',,o1:1,: ilso '_e 'ised to .md:!te "r validate current ,._-.n._._n. o.

,n_Ln. _. - :_ _ .?,e4l,onGents tO t!lt _ St_IWC V c_tle>tlonnalFe I[ :,_C:tt_-I _.cin_. ; -, :-,-.ond,.,_n_.

- . " - i i " liLt. SO e _ for i_rover,.ent in --_,s ..... :uld aF_at_ ic:n_ envelope_, :1 ,'le. _ -h,-, a:'eas :l,Ive _ee:: cL't_si-:eI'_-_ Ill _,!le [,I'c_o _ev[ re_ear,Jh :_I:ul.

At pr_ent, one of the major hurdles to overcome in changing to quantita- tive forecasting will be in convincing the federal agenQ" _cordinating and controlling meteorological sea-ices that this is the desirable course to take.

New programs in icing instrumentation research to obtain instruments for me_surLng the t_Te of data which aid5 quantitative forecasting is a step in the right direction.

INSTRU_._R_ATION Although significant _dvances in instrumentation tec]miques and design have already tmken place, accepted methods of measurement still differ by more thaJ_ plus or minus Z5 percent in the determination of basic parameters such as liquid water content and dr_p size in ground test facilities. Yhe problem is much more difficult in aircraft t-light installations due to the limited space available and the usual cost restraints. There is no standard instrt_nentation of such proven accuracy that it may be used to calibrate other instrumentation in all r_.nges of par,_neter values.

_rom the assessment of the literature concerning both the current instrumentation available _nd that which is under development, there is still a requirement for much research to be accom{31ished in this field. There is a need for the develep_nt o_ accurate, continuous operation instrumentation for ,-e, asurin_ LWC and droplet si:e and dlstribution in icing wind tunnels for all rxnges of air velocity, altitude, and temperature conditions, l]_e development of this t_e of instrumentation will not only allow for the calibration of _he icin_ t_mnel spray equipment, but will allow the tu, anel to be used for cali- bration of oliver t)q_es of instrm_entation measuring the store parameters, detect st_tie changes in spray system conditions net normally found _ithout instrm:_entatien, :rod provide the capability of testing _pray systems for use with -_'artker aircraft or other icxn._ ttmnels, etc. The development of instmm_entatien ,._itha h[,<h confidence level for use in icinK wind ttmnels will lead to the development of smaller, less extensive instm_nentation for airborne u-_e, _is will restilt from the capability to calibrate the less e\pensive equipment with confidence and increased kmowled.<e, Development of hi_hl>" accurate and,'or calibrated airborne icing fnstn_- mentation will facll!tate the establishment of qtmmtitative iciA_ intensity data considered extremely desirable, [f not ,._mdatory, for h_rovin_ fcin_ forecasts, revifln< re_ul.ltions for flvin:_ in kr, o_n ici::_ by _eneral aviation l,.rcraft. _md _:_?rovin_ b]fo::nation for :qi;ht decisions by fnd_vldual ?ilots -LN.._] >,'7 : C-\I. 11!D_X_S F_oth the l=terature search ._nd the results of the su:-_'ev _uest[om_aire indicated that the m.k_orft Y of the femoral ,_viatlcn hldust,_" utii_c the ,;k\ 311S-I doct_.,cnt a:; one of thc'r most [,,-pertunt references '_,_th respect to ]din< te¢hr.elc<v, j:'ec:f:cailv, it is one of their _)st i_,o:'t.mt reference_ ',_tt!: iJO respect to ice accretion prediction and ice protection system design.

However, questionnaire responses indicated that .A.DS-_ technology needs updating and i_provement in many areas including fluid systems ice shape predictions, new airfoil shapes, etc. Beyond ADS-4, a small number of specific doct_ents were mentioned by number or author in the survey answers.

These are listed in the su_na_ of the survey/questionnaires in Appendix D.

The majority of those surveyed possess or desire co_puter codes for ice accretion and/or ice protection analysis. In _eneral, these codes are considered proprietary by the company who developed them. The indication is that the codes developed for ice accretion prediction and for heat transfer analysis are all very sL_lilar in nature and essentially contain the following elements: I. T_D-dimensional potential f.ow field analysis.

I. Two-dimensional droplet trajectory analysis based on 15-20u droplet for ice accretion (or h_ngmuir distribution), 1O-50u droplet for impingement length, etc.

3. Co_puter code to calculate local cmd overall catch efficiencies rand the _dified inertia parameter Ko- 4. Trsnslent 3r, d steady-state heat transter code that calculates heat require- _ents, with various refinements for convection losses, evaporation rates, _nback ice _£_ur.ts. te._eratures, and areas of the heated surface that are dry or vJruning wet.

[n reference I:I, a computer code is described £or calculating ice shedding characteristics of airfoils and other bed_,"shapes. This code includes ice shedding times _md simplified shed ice trajectories. A few com_anies have tec.kniques develooed for predicting ice shapes. Genera-ally, tittle or no detail on these tecJmiques have been indicated except that at [east one company nentioned that their tec,hnicue applied only to .<la=e <uushroom or double horn] t_e ice. in other "areas of concern, indust,_. ,"has developed com_uter code_< for" engine nacelle inlet_< for calculating ice accretion and heatLng requirements- .\[1 of the malvtical tec,hniques currently kme_n that pertaU', to design _md eerfor_.,_u_ceof ice _rotection _<y-stem_s are for conventio_lal systems _,e., elec_rothe_l, hot-air', nech_mical, and free:ing ter_erature depressant flulds?. [a addition, there are not analytical tecN_iques in the l,_terature vet ,_vailable .:or tb'-' desi_ _n or _erforr_nce inalvsis of the suggested new s',-stev_ _uch as electroL.-?ul-<e, _icro_,ave, _cephebics, and acoustical. _I__ only re_orted ',,orkenco_.mtered h_ this study pro_rm_ !u%,,'e been sere _e:i_iSil- it'." 5t'idie_, :_stlv related to helicopter rotor blades.

l-'l [n li_:ht of the proprietary nature of the existing codes and the expressed desire of the industry, for access to such codes, research efforts should be undertaken by .NASA to improve the availability of existing and new codes for industry use. This may be done by .NASA acting as a clearing house for currently available codes and/or developing new codes in-house or through contracted efforts.

ICING WIND TUN%_L TESTING It is the concensus of opLnion of many experts in the field that icing wind ttmnel testing has been and still is the best method for determining ice accretion rates and ice shapes. The icing parameters can be carefully controlled within the tunnel and testing can generally be conducted conveni- ently without too ..manyrestrictions on weight, power, inst_mmentation used, etc., except for the size limits of the facility itself. Therefore, much of the research program is directed towards the use of the .NASA IRT and a refurbished .%I_T to obtaining the icing data that meets the needs of the general aviation and light transport industry.

Scale _odels have alwa>'s presented a problem with regard to scaling factors to be used for all of the icing parmmeters. If scale model test results could be effectively applied :o full-scale components, large savings in tbr, e and cost _otdd result by eliJ_nating the need for expensive full-scale testing or flight testing in natural ice. Tests using new and current air- f_ils are therefore Lncluded in the program pl_ to research this area.

Tests are also proposed to evaluate the effects of ice accretion cn aLLxil_a_" inlets and cuz_'ed engine inlets. Other proposed icing wind tunnel tests include tqight centre[ surface flutter, wnng tail interaction, horizontal tail stall, and ice shedding c,haracteristics. Associated with the wind tunnel tests, .are investigations of the methods for ice simulation to be used in dr>" air testing.

K_l!4 StaRT .%,\0 LONG 1-d._M ICING RESLkRC2/ P[.CN RESF_-\Ru'N [7±xF ,_iring the course of this stud?', a c_mprehensive search was r_de of the recent 'iterature concerning aircraft icb,,g. In addition, k_verndwnt agencies :rod mdL_tl_, • _ere surveyed to o_,tain £arrent aircra/t icixlg data and vie_,- _oints on icLn_ prebtom_. As the t,_rk progressed. _amv areas where the _cin_ tec,_ano[o_ was ;_eak or lacking were tmcovered. Also, new ice protection svsterk_ '*h:ch promise reductions in weizht, cost, oI Fewer usage '_ere ;.dent:fie&

Theseefforts cul_J_nated in the formulation of a list of research item_

that are resnonsive to the needsof the general aviation and light transport

indust_'. Because of their nature, manyof these items are responsive to the

needs of large aircraft and helicopter industrles as well. In table ._XII is

the list of the items which resulted, including short descriptions of the _,_pe

of research programsuggestedfor each one. They are groupedwithin the table

by the general area of study, and together, they form the basis for the short

and long term _$SAresearch programsuggestedherein. The eight general areas

of study are listed below.

i. instrtm_ntation 2. _Nteo_logical Efforts for Determining Icing Criteria 5. [oephobics and )_ntifreeze Fluids 4. Icing Wind Tunnel Testing 5. Ice Protection Systems Development and Evaluation 6. _nalylical Tec.hniques for Prediction/Certification -. Pro uuls Lon 8. L_hers K_.NKING AND _TZ _±Nb _le list of research item_s in table M_XI[ reflects the desires expressed by the general aviation and light transport !ndust_" in the literature and through the survey. However, there was no ciear-cut concensus expressed _ to which area should be addressed first, other than the general a_reement in the sup.-ev that a t:'aining film for t'light in icing conditions would be beneficial.

._ a ,'esult of these vaD'Lng opinions and deslres, it is difficult to rank and schedule the [isted research items in order of L_ortance. In addition, an}' atte._t to do _o r_L_t include ether considerations, such as availability of test facilities, ft_nd_, progr_n balance, and the need for complementary or preLininam." efforts. For ex._ple, the development of standardized, accurate _ind tt=u_el inst_:entation is an effort that would affect all subsequent _,ind tt_mel test work. Also, :malvtical methods for prediction :rod certification mtL_t be verLfhblc b)" te_t results, and so sheull follo_, or be concurrent wlth related test efforts.

.-\ t_,nt,lti\'e < -_',_' ' ;" " o_ the TosoaFJq LTCYP_ _ L. . _d in .... t_.a_._ ' " _'_;"_ " table '(XII is ..... :e, _._ lS SRO_,P,, _,ith "" _ * ' " _nCOe'_Ll_<i.q_ the .... _t f;.','e \'ears, :iil_ "_,_[I_ _Pl-q the last _ Z l%'e, .%_.

Tl'nned .a_:es 'cn're,,e::.e:lt3 :or the ,_.n< Resea,_h T:u_.nel [RT' Lqd the TABLE XXII SUC_STED RESEAR(}{ PROGP_ INS_U_ENTATION I. ICING I.NSTRL_NTATION Joint .XASA/industry/Air Force program to develop highly accurate instn_en- tation for measuring icing parameters in icing wind tunnels and in airborne operations behind a tanker or in natural ice.

a. Wind Tunnel Instrumentation to be used as a Standard for Calibration of Other Smaller Less Krpensive Instrtm_entation Joint NA&%/industry program to develop highly acL_ira_ instrumentation for measuring the complete range of icing parameters (drop size, distribu- tion, LWC, etc.) th3t we deslred to meet all design m_d certification needs• This instr_nentaticn _ill be used for calibrating smaller, less expensive airborne t>?e instI_entation and for the development and/or improvement of icing facilities spray equipment for artificial icing.

b. .kirbome T)_e Icing Parameter 3_a_surin_ lnstr_=nentation Joint K_%/industm., pre_ram to develop inexpensive, durable, and accarate inst._nentation for airborne measurement of icing parameters.

Literature search of all _-urrent data on instrt_entation and contacts with _._mnufacturers _nd inventors. ¢6tain information on principle of operatio_ reliability, ac_rac%', parmmeter :neasured, Y[I_F,*maintenance records, etc.

Test existing and new concepts for icing rate, LWC, drop slze/distribution, and OAT; all inst.._zmentation required for icing definition, forecasting, and pilot reports. Instn_nentation _111 be tested/calibrated against standard mstr_m, entation developed in (a].

_TECROL£<IIC_ EFFORTS FOR ICING CRf_RIA i. ICTNC IN_NS[_" DEFTNITIONS Combined interagenu_" study bet_een K_CA :rod F:\A to develc_ _ulmtitat:ve loin< intense.t\ - .lefinitiens that can _e i--_ediate[v interpreted'by a trained ?ilet and ap_,iied to his s_ecif_c aircraft. Study should inch:de use and non- . use of s::mdardi:ed and calibrated Lnex?ensive instrumentation Isee item 1 in tend<motion '.,ithicing definitions. Ln ebTectivc of the study :,ould be to establish !t:antitat_ve icin Z zntens_tv definitions that zou[d be _ro_o__ed is a_n addition to the F_R's which do not presently contain _mv <uch [lef'initJons.

'_!,k':m 7!:no Between F:_t:_re It: TABLE .M'XII (continued) . COLLECTION OF ICING CLOUD DATA FOR USE IN CORRELATING [CIXG P.aRA_ZTERS FOR FORECASTING, ICING CLIb_TOLOGY, AND ICING EN_¢'I RDN_£\_ ,_DDELING The Air Force (.aJeFDL)has plans (Ref. 125) to instrument a C-130E aircraft extensively for obtaining icing cloud data, both standard meteorological measurements amd measurements on LWC, droplet size/distribution and tempera- ture will be made for correlation and relationship to standard weather analysis.

A joint XASMAir Force effort is suggested here, since the Air Force pimps include commercial aircraft in their icing cloud measurements progr-_m. One of ._ASA's functions would be to correlate the measured data for comparison and updating of the early X_CA data. Program modifications as required, could be ,,madeso that sufficient data at the l_wer "altitudes, which apply to both helicopters and general aviation, would be taken to improve statistical models in this range.

', 4. \_RIFICATTON OF ICING F-\%]RC,_/F-NT_DDELS "_ Various models of the icing environment exist presently or are foreseen i for the future. Research to expand the data base in order to verify new models to be used for design and certification is required. Efforts should be coordinated with the .air Weather Se_ice Organization for ,measured meteorolog- ical data pertaining to the standard icing parameters. Correlation of statistical data will be requlred to support theoretical models and identify where more data are required. The research will also help to identify where i.._provements in forecasting are required.

I 5. MI_C£D [CIN(; CONDITIONS (ICE 2.<RTICI_S & St,rPERCCOLED WATER DROPLETS] Stud*," of producing and cantrollLng mixed conditions in an icing wind ttmnet __nd controlling particles form.,edfrom droplet freezeout and snow from ccolin_ coil_. Determh_e effects on accreted ice for shape and _ize, density :me a&hesion. _sess relationship to natural envtronment.

v. 'OIPHOBIC J£.\7[N<5 5¢1.[D b,D FLUTD: PER)_\\tL\-7 OR SEIIF['Z_:C\_/\q ' ?nvesti_ate the .=.mdmmental mechanisT_ o{ ice a_zes;on. ;.ce :'racture, ,rod ice <heidi:u: .u:2 their relatlonsh_2 t<th :ce..heblc -aterta!s for a:rcraft ice nrotecti-n. :::v.-st-.'ate [ceehebic r=lte:i_is :7,_r :via<s, 9r,rpei;ers. e:mem_:_ge, en<ine cm.i. eng::_e inlets, .me eneule co_.nponents. Test for chemical de,.'.rada- : ticn af _rcyerties. duration, retiabilitv, Linit ef Loin< conditions. :rod dd_b.eslatl :n combination with ether protection svste:: or methods, investigate the -" ; ................ _ _: beth fluid "oe:m<" t'_--e .rod _e'- " .......

e,c>..v.,, ........... . . ,,J.Lei,,a:,_Ft_ IceP]IO[_I.C5 md the[:"-cT_ati),t-lt'" :,ith 2ther :::_teria_.<.

TABLE LXII (continued) 7. :_\TIFREE2E FLUID SYSTDIS Investigate alcohols, glycols, etc. for compatibility with various air- craft materials. Determine limits of their use, etc. IrNestigate fuel additives for jet-fuels rand for carburetor ice prote:tion. Test the same additives for JP-4 and for gasoline and their limits of use.

ICING WIND TUN_]_L TESTING 8. ICING RESEARCq TUNN]IL TESTING OF .AIRFOILS Program to test full size models, full size sections, or scale models of new airfoils, with or without slat and/or flap configurations, rest new 23026X, 00.'CX,6-series, new LS, 31S, Eppler, supercritical airfoils, and other new airfoils for ice collectiorts rates, collection efficiency., ice shapes, etc. _asure C t and CD and detemine Ko in a range from .001 to 1.0 for all the airfoils. Tests should obtain data at angles of attack and ranging from -0 ° to +16 _ in la--4-5 ° increments. The [co shapes should be determJmed for tenperatures ranging from -22°F to +32°F. Data from tunnel tests should be compared with computer codes to verify.'the codes, and should also be verified by flight tests in natural ice to expan d a reliable data base.

9. ._IE,,'r_O. DS FOR ICE SDtIL%TIDN I MOULDING, CASTING TEL'iNIQUES DEX.]fLOP_ENT WITH WAX]iS, PLASTICS, A\_D ICE DIELECLRIC SIMULATION) Research study to develop techniques for making simuaated ice shapes for dry air tests. Investigate moulding techniques, accuracy requirements necessarT for sLmulation for s_ept/_answept models, aa:d materials to use.

Dielectric and other properties for simulated ice accretion on radomes and aaltennus will be investigated. Investigate methods of attachment to aircraft St rocture.

tO, ..IEROD_,._41IC EFFECFS ON AIRFOILS USING SI3UIATED [LT FOR CERTIFIC_,TION Petermine aerodsmamic effects on airfoils with si_mlated ice shapes, based on certification requlrements. .Data wt[l i,.._Vrove safety when flight testing aircraft with ice shapes. Coordinated program of wind ttn'mel tests will be proposed for reducing flight test grogram scope as well.

i!. F&I'E DF BLCC,_kcGE OF ALDtlLIARY AiR INLETS $,\IL\'fS IN ICING _velop _.ethods of estimating or predicting rate of blockage of atL\iliarv air inlets _md cr vents by ice bull&re.. Test various sites and shapes of atLxiliar," i'_lets in varieus [cLqg conditions to verify .nechod of prediction and tc a,;ce.,-ta:n the e_r,,nr of the blockage.

1"_ TABLE ._XII (continued) 12. CL]IVhD ENGIN_ INLETS INCLUDING TURBOPROP LNGI_ LNIZTS Combined .NASA and industry, research program to determune ice protection requirements and methods for S-shaped turbOprop and other engine air inlets.

Flow distortion caused by icing and ice shedding in the S-shaped inlet can cause _.ngine stall. Explore and evaluate effects of ice accretion and ice shedding.

--13. FLIGHT CONTROL SURFACE FLUFI_R Research program to determine vibration and flutter caused by icing on control surface. 5_termine limit for icing nf umprotected surfaces of typical G/A aircraft. This program could be combined with items IS and 18 and possibly item 14. Program would be intended to provide additional data base to verify ana!_-¢ical ice accretion prediction methods developed in other, but associated, research programs.

14. h_NC-TAIL INq_RACTI@N iN ICING Test for the interaction between the _/ng and tail as ice accretes on the leadin_ edge surfaces of both co).Donents. _asure aero effects of chan_ing an_le of attack of wing and tail requirements due to ice accretions. Requires full size _oomDlete'_ aircraft in large wind tunnel facility. How the LWC and droplets are affected by :qow field and if the LWC get centrifuged out before it hits the tail, are questions to be addressed.

15. HCR220N_FAL TAIL STALL A.N_D ICING Tests of T-tail, V-tail, and conventional tails for aero (stall and pitchin_ moments_ characteristics with ice accretions or simulated ice accretions. LLmits for allowable ice accretions will be determined by characteristics measured for incremental buildup ot accreted ice.

16. SGkLE _DEL :C5 _STING Research study to develop tec_hniques for applying scale model test re;uits to full scale components. Ice tests on both scale cmd full size models ',,[IIbe accomplished to develop the necessary correlation equations.

Large _md >nail 'aind tunnel facilities will be utilized tn testing. Results be cove.areal with test: data from fli:ht to<is in natural tee. Verification I fl[lht tests in na'_ura[ icing shot:l/ be coordinated with the test prob_mv_ of items $, 21, and 25.

i_ _- TABLE .'C<II (continued) 17. ICE SHEDDING INCLUDING brNSY_ETRICAL SHEDDING OF ICE FROM wINGS ._ND HORIZONTAL STABILIZER Investigate the mechanism(s) of ice shedding including natural shedding characteristics of wedge shapes. Study the aerodynamic effects of uatsvmmetri- cal shedding of ice from the wing and/or tail of an aircraft (G/A typical).

In partio_lar, the roll characteristics (wing shedding) and stability problems (horizontal stabilizer shedding) should be investigated for various sizes and shapes of real or simulated ice. Tests can be accomplished in the large AI_T (full size aircraft) and on scale models in the IRT.

18. BALANCE HORN DESI_ FOR WING/TAIL ICING Test various designs of balance horns on the movable sections of the horizontal and vertical stabilizers (rudder and elevators) for me.thcds to prevent ice accreticn from interferring with stability and control. Gaps between fixed and moving parts, ice shields (heated and unheated) , and heated leading edges, etc. will be tested. Rubber tab on fixed portion to help remove ice on movable portion.

19. PNEI2,D, TIC BCOT FUND.&%ENT_ALS Investigate new" lightweight pnetm_tic bout systems in conjunction with industry for wings, tail, etc. for conventional locations. Determine conmatibilitv with other systems. Determine optLmum cycle ti_resl etc.

Penalties for residual ice accumulation and Lnvestigatio:_ of principles of ice fracturLng.

tO. ENGINE }-_4T FOR ICE PROTECTICN Dete_.mmine best method of application of bleed air for anti-deicing; c¢clic, intermittent, etc. Investigate piccolo tube, sungle skin vs double skin tecbniques. Evaluate the internal heat transfer coefficients. Conduct i researc_h to determLne best use of limited hot air available from small jet engines. Explore other methods of extracting engine heat for ice protection, ' i.e., hot engLne oil, exhaust gases. %p_lication of waste beat for ice protect ion.

:I. XI_" ICE PROTE_LTION bq'STEM STb©Y Posszble )olnt venture be?,ceen \&SA and indust_ T.

1:8 TABLE _II (continued) 21. N]_N ICE PROTECTION _'ST_ SI_JDY (continued) a. Electroi_pulse Evaluate the feasibility of candidate electroimpulse deicing systems on airfoil models (wing, tail, and propeller). Determine the design criteria and major installation problems. Evaluate the system performance for various icing conditions. Assess typical weight and power requirements, system complexities.

b. Microwave Evaluate feasibility of candidate microwave deicing systems on air- foil models (wing, tail leading edges and propellers). .Assess the microwave system requirements and system cot_plexities and the installa- tion problems and environmental sensitivities. Evaluate system performance under various icing conditions; power requirements, etc.

.Assess llmitations of its use; i.e., what ice sensitive components can the system be used with.

22. ICE PROTECTION TRADH©_ STInDIES Develop the methodolog%" required to evaluate systems for weight power, reliability, availability, cost, maintenance. Evaluate combinations of systems best suited for typical G/A and light transport t_pe of aircraft.

include instr_nentation in total integrated systems.

._3. .<N'[I-ICING CONSIDEZATICNS OF CC_[oOSITE_-S Research prcgrmn to evaluate _ethods of ice protection of airframe and engine components .made of composite materials. Systems should consider electrical and pneumatic boots, electroimpulse, microwave, and hot air systems.

Initial investigation should determine where co._posites will be ,used on leadin_ edges, etc_ Study should include the use of carbon fibre leading edges, the long tern fatigue characteristics _hen pulse or vibrati<n systems are considered. Tests shcu/d be cenducted to find the thinnest skhns practical and the thermal characteristics of the materials. The effects of antifreeze fluids on composite ._aterials should be investigated.

.'i. CtT_Uq'KR CCDE FCR AIP_nOIL{ S_ iC! ACCP_TI©N Develop co.r_._u_er codes for predicting ice collection and collection efficiem<." on airfoils to compare :,ith ichlg tunnel tests ind natural ice flicht tests ?e'.-elo_ nre_rln for calcu!atinq A/[ s'.-_tem:',erfor_mce which can al_o or'edict -"e;sin£ characteristics of :_a:'zinal k/7 sFsten.

TABLE KXII (continued)

25. C0_UTER PROGRAq (CODE) DE_LOPE_T FOR U_fl_ATED

AIRFOrLS ICE S_LpEs Develop method of predicting ice accretion based on dyTlamic situation with increasing ice buildup. Reqtlires changing geometry, efficiency of catch flow field, etc., and effect on local catch efficiency. Develop program to predict ice shape (configuration). Co-pare and verify by test data.

20. TH_-DLMENSTON_L CUNPUTHR CODES FOR ICE ACCRETION (SWEPT I_XNCS, ETC. ) Three-dimensional computer programs are applicable to ice accretion on _-wept leading edge mOdels and engine inlets. E%_luation of the requirements of such a model should precede its development to assess the ex-tent of ' rmproved accurac; of the tec,hnique Over tw_-dL_ensional techniques. The use I . .

of the code is to support the initial d_cision as to the need of an anti/ ideaclng system and also to predict the performance of the system in meeting the certification requirements. Justification of program may be through reduced _-ind tvrme! and/or flight test tune required to verify ice accretion Prediction and ice protection system Performance.

2". FROST ACCII,[II.ATION DUPJXG (;ROUND OPERAT]'C',," " PROTECTION _Z_tODS AND PRkZ=--XT[ON Research study of the form, ation of frost on parked aircraft and limita- tions for takeoff. [nvestigate dangers of melting and refree:e prevention and/'or protective measures. .assessment of lift and drag penalties. [nvesti- .gate &aalytical smulation models and ';e:ification testing, 28, CONPUTER CCDE FOR [L_ SHEDDING _kRAC,'TERISTrCS Develop a coquuter code I'malvt-- ._ .

of time for all -_*_,,, .... "_ , ical mode<, tor toe sheddim, _< _ c, • _u_e_ and tenperatures assoc;_A ,._,-L . 7-,_ -o _t -t_qctlon Cc_uter model with '-' ,' • lcLn_'Mtltude wind ttmne/ for _ _*_" lckng, _erify the shapes. - airfoils and other body IQ i" T " " -@-StT-,E,CR " "_'" * c .... R£SiMRG{ Research prc,_ran to further e.'cplore the use of Teflon for coat!m< carkuretor cn ,"_Pone,-,t5 such ;Is the throttle riate and shaft to prevent the _%osl_.,_n or ice. Test combined _v_,.< . __e,, '.:Sl,q_ let[on c_Hted CO . _ • _.

• 1 . • _. . .PlrL:F_.{I _,,_ £Lrld it;el additive to prevent _ce _epo_-t_tens and _ce c,'_'stais which form b D-_ckages.

] 7-_ _

TABLE _Ir (continued)

3C. JET ENGINE ORFTvN-JET ENGINE SPINNERS

Possible X_SA/industry joint program to investigate the effect of spbmer shape on ice buildup. Several engines are unheated becauae of shedding characteristics of the configuration (conical) of the spinners. Along with this study _muld be a study of the droplet trajectories in the inlet and the areas of ice accretion on the rotating components. Research could lead to reduced penalties associatd with engine ice protection systems. Research should be directed toward the development of a methodolog%" for predicting the ice shedding characteristics of spinners with and without the addition of ice'_hobic _terials.

trr_, _,RS 51. COB_UTERI2ED DATA FILE ON ICING NASA :rod ind_tr3," combined effort to continue adding ai1 literature on , icLng to the computeri_ed data file. Add ,_ii old and recent doc_aents from DDC, .VfIS, .KkSA, etc. Add bibliographies on general aviation, large transport.', al_d .%iiitarv including helicopters G'STOL) to the file. IIaprove "lookn_p" tables )f dat:1 coding told tec!miques for reviewing and storiang information.

Result :tg file wetdd provide u _er with i,rmediate accessibility to any or all icing tecb_nolo_" data.

32. TR41N[Ng FIK\_ FCR [_N_K.kL A\q.,\TTON PIICTS Program to produce training fiI_ for C/', pilots. 3b_ie films will contain latest tp to date information on forecastLng techniques, _cing defini- tions, metro data, safety" procedures in icing encotmters, importance of ',ksing _L'I svsterm_ provided, etc.

33. [C,'Xd T,k\Mi_ FI\CILITY Combined k_<..\,\Jr Force, :rod indust1_' research program directed toward the i:z_rovement in the desi<n 2f the tanker spray system5 to provide droplet sizes _'<30u_ a.,'proxi:natmg naturak _ce conditions, tnch_dfng distribttton.

_si,:,u spray ri< for mLnlTaan induced tu:!,ulence by the :'i£ itself. I,atest :'eForts indlcate artefacts to abt:nn ,imp si:es in ",roper r:mge have been _u>ucces>ful te &lie. iustn_nentatior, to measure icimt p:u-m-eters in f!i_ht accurately. _q required. ,iombine efforts with item 1. '<.kS..\ icing :,ind t:mne l facil[tzes ;,il'_ be used to test desi<ns of aezzle elements md mstt_,ancnts to ' ::¢asure :'ar:_eter_ And r,Lu_es o:" colltro[ of _!:eso :_aF:E2OtOFS. ,'_OS:I[_:_ ',,ill !'C cc,nT..'ared ;,ith t,u:ker flight test data.

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I I , i i ";, i t I ..... 4 ..... -t ...... i ' I I : i I ...... I ' i ; ' i : i J i i i ..... .i i I I..... -t I 3_lance horn .ne_z_'n 3oot F_nd,_nen: al _ Trade _ t-_d_e_ _Dph_a=_n ;o _dv_c_ Co_o5z_5 _e_ _::l- _e _ _L_e'_ Altitude Wind Tunnel (AWl") are shown first, since such of the subsequent effort is predicated on their availability.. ,Note that .AWr rehabilitation will not be completed until the 1987 fiscal year, and as a result, several full or large.scale model test progra_ are scheduled after that date.

The two areas listed first in the program plan concern instrtm*_ntation and meteorology. Both of these areas have already been discussed above, and their importance can be summarized thusly: (i) development of high/y accurate and/or calibrated instrumentation is required to establish quantitative icing intensity data for immediate use in forecasting, m_d to accurately quantify the results of the wind tunnel and flight testing outlined later in the program, and (2) meteorological effort3 are required in order to improve the accaracy and efficiency, of forecasting mad to utilize the i_proved instrumen- tation in gathering data which will update icing environment models which could allow increased aircraft utilization.

In the ne,rt area of research, icephobics develop_nt is shown as an ongoing effort. It i5 recommended.that icephobics research should be carried on at a moderate level umtil a promising icephobic _,aterial family is identified. At this point, research should be intensified to develop an ice- phobic that can be applied to wings, propellers, e_pennage, engine cowls, engine inlets, etc. l_hat is most attractive about an icephobic is that it co,_prises a '_passive" system which can easily be applied to existing aircraft, is low in weight, and hopefully, will be of low cost. [f a highly effective icephobic could be quickly developed, then the goal of increased aircraft utilization in icing environments would be more easily attainable.

,%s far as icing wind tunnel testing is concerned, the plan is laid out in order of the items which industry, felt are needed first, except that full- scale aircraft or large-3cale model testing is deferred until the ANT rehabil- itation is complete. The short term aeed__ are to provide icing data on the newer airfoils - both accL-ecion and pena/ty data. Wing-tail interactions, horizontal tail stall, and ice shedding research should utili:e the large wind ttmneh Scale model testing will require the use of both the [RT and the AWT, and if this research study is successful, it would allow future scale model test results to be applied to full-scale components with confidence, reducing the need for expensive and time conslm/ng full-scale testin_ or t-light testin_ in natural ice. Wind tunnel test results will _-Iso be used to validate anal}_tical .,_odelsdeveloped concurrently or after testing is completed.

Included umder ice protection syst._'r.-s is an effort to develop new systems such as those utili:ing microwave and electromagnetic impulse principles.

These t>_pes of systems are not read)" for application right now and will probably not be in universal lme for a good many )'ears. It has been estimated that it would take up to eight )'ears to fully develop a system such as the microwave s,:stem (reference 131%. However, because of the potentialb,' substantial payoffs to the class of ai_raft under study, _t _uld appear wise

to begin studying these systemsimmediately, carrying on their study into the

long term phase of the research plan. Results of initial developmentefforts

for these system would be availaDle for use in the systemstrade study effort

proposedlater in the program.

Short term researnh studies should be carried out in the areas of balance

horn design, boot fundamentals, improved waste engine heat utilization, etc.

There has been an indication that trade studies of the various systems would be of use to the industry, and these have been scheduled to follow the previously mentioned system studies. Advanced composites are being utilized more and _ore by military and large aircraft manufacturers. However, for the general aviation and light transport sector, system_ com_patible with advanced composites do not currently pose a pressing urgency., and have been deferred in the program to cross over from the short to the long term.

.Analytical techniques involve prediction models for ice accretion, ice shapes, and penalties. In the program plan, it was decided that model development of ice accretion and ice shape prediction for the new and future generation airfoils should not be undertaken until verification data are generated in the wind tunnel. L-]_ree-dimensional ice-accretion models would follow after development of the two-dimensional ice accretion codes.

Analytical studies and ,model development of the aerodynamic effects of ground fros; acc_m_alation, as-well as ice shedding characteristic studies, require correlation with data taken in the A%_T, and so are scheduled as long term research items.

In the area of propulsion, the carburetor icing study is of great i_uportance to the general aviation class of aircraft, and has been scheduled for the short term. _le use of passive spinners on engines to shed ice and the fact that some engine shedding characteristics are not fully understood, coz_rise a resea_h study area to follow into the long term.

.-he remaining efforts ("Cthers"_ are sho_n in the plan schedule to occur in the short term. A computerized icing data file would contain biblio_aph- ies and data on icing from .NASA, DDC, NTIS, and the general literature. This file '^ould he available for interrogation by all interested parties when addressin_ their problems concerninK icin_ or during the course of the subse_uent efforts detailed in the plan. A t._aining film on aircraft icing was urliversalL'; acce_ted as a sound idea, and earl)" production of that fihn _,ouLd be in order for training of general aviation and light transport pilots.

A ion_er term effort would entail a joint effort of X&5A and others, to 1_pro_'e tanker sprnv sU,'ste_-s for _se in :-light testin_ for development or ceFtlfication. D.'_is effort _md several others :_ny require the use of large tacil_t:es, .e_d thus L< forced Lute the longer term.

[3a FUNDrNG ,REQUI RE_VTS The funding requirements for each of the listed research items are difficult to define. They are highly variable since so much depends on the specific statement of work that is finally developed for each item. For example, a statement of work for the development of a computer model could include the following tasks: i. Develop equations which define the problem.

2. Write the computer program a. using a specified computer language.

b. for use with specific computing system (e.g., IBM, CI)C, etc.).

c. interfaceable with other existing codes.

3. "Debug" and perform, specified test ca_es.

a. Verify accura¢%" using existing anal)-tic,_l or test data.

5. Document and prepare a "User's _Xtanual."

6. Costs for "cor_puter time."

[n addition to the above, tasks ,vclstbe added for administrative purposes, such as : i. T.nterim and final reporting (technical and financial).

3. cqTal presentatierts with attendant travel requirements.

3. Final report publication and reproduction.

The complexity of the phenomenon bein_ modeled will be a ,,_njor factor for determinln< the scope and cost of the effort, but all the above factors will also be contributors ar_t can sometimes :_t_mifv this cost, _.e sponsoring agency c;m thus affect scope by controilin_ requirements for what the program :mist accomplish, by establishing reason:ible accuracy constraint<, providir, Z HI reduced form the data to be used for verification, m_d ,_ini_d:in_ administra- tive requirements, where feasible.

For the ?ur?cses of the pro<rmn Fimn, each analytical effort was .isst.'ned to ,ierctnd _,ne to t;,_-:,_neffo_t. ,It a cost of about _O_.O!_t]_er :n;m-.-ear. .ks noted :ibove, this f[$1re is valiable, ,ie!_endin Z on the tecb.ntcal :_d ad._inistrat i've :_,',.'.:irement_.

Wind tunnel testing is another research area where costs can be highly variable. In addition to the admlnistrative tasks discussed above, a t?_ical test program_ould also include _he follo_ing technical tasks: I. Detailed test plans (run schedule and test conditions)- 2. Design of test mndel to specified scale.

3. Fabr:cation (including material costs).

4. Wind tLEulel tests.

a. Coordination and facility scheduling.

b. _Ddel installation.

c. [nstr_nentation and recording eq_lipment.

d. TLLnnel operating costs.

e. Travel md accon_odation of test teazn personnel.

_. Data reduction and analysis.

o. Final report preFaration.

_,¢o of the najor cost contributors to such an effort are the model desL_m aad f_:brication :rod the testing aczivity itself. The scope of the effort ,,ill be affected by the scale and ce_)!cxitv of the ._odei, the instrca:entation rc_uirements i.e. , nt_mber and t>]_es of measurements] , and the mm_er of test conditions and data _oints requir_i. Test costs can be as rmch as several thotk_and dollars per" hour of actual test time, ar, d while much of the testing _,_uld occur in the _-k_ icin_ wind tL_nels, this cost _Lst be accounted for in dete._n_ ining the ftanding requirements for an?" prolonKed test activity. .ks ex_Lmpte of these costs, a .,_>Jerately sized 120 hour d_" air _ind ttanneL test progrtEn on a 0. l-scale complex nacelle inlet was recently priced at about i4@0,00£, inclading wind t,or_el costs.

Estimated fLmd:n£ rtxmirements for the pro<r.!Jn are presented in fz:<ure 30. be:he of the research itenL_ .ire neither test Fro_r_ or r_del :evelcF nents _md are :'ere diffic'_;it to cost out. :]:eir actual costs _ill al_o depend _n the final ;,crk :.acka_es, but estimaltes are present_ki an,}-,a>', has,x: on the f'._:di::__ act iv!iv :,i:ic!: \s felt :r:":'rotgr_ate relative to the other ?ro_r:I?__.

Note that the ,um':mts ::-e_i'.-en ::: :.:S," doll:iT:. :n 7ust five vo:ir,;'^]I:1 h _, "_ :'e:'cc::t L:::'l.:ti,m r4te. 1,'_'.2:,: :::S:' ,:ellar: :,i![ translate te ::_o,:_37- [3(' Incidentally, in Appendix A of K.KSA-CP-2086 (KaS.4/F.-_A Workshop on Aircraft Icing, reference 83), the SAE Icing Research panel concluded that she cost of work packages required to meet research requirements could wa_ _ from 1/2 million to 2 million in 1975 dollar_. These costs are not unlike what are est£_ated here. Further, in FAA+ED-0¢ -2 (reference 122), '_qelicopter Operations Research and Development Plan," costs are est£mated for various efforts in icing research during a five year span. .As it turns out, the FAa.yearly totals are in the same ball park, although rationales are not presented to back up their estimates. The F._ feels that peak icing research funding of about $2,700,000 per year is required during 1982 and 1985. This compares to the $2,430.000 and $2,760,000 presented in figure 36.

These cost figures are to be regarded as relative numbers to compare one program, with another and are in no way absolute values. Changes in the inflation rate, more e,rplicit detailed information on individual progrmms, scientific breakthroughs, etc., could all change these estimates in a dramatic wa}'.

15- i CD _ i F--- --I i _0 I I Lr_ t_ P e"

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Section _] CONCLUDING RE,_RKS This research study has identified the requirements for a research and development program to meet the needs of th_ light transport and general aviation industry. During the course of the study, the present icing technoloB2/ data base including a_Lal?-tical tec_hniques and facilities generally available to the indust_ has been assessed. >_my areas where the data base is weak or nonexistent have been revealed and it is these areas which have been addressed in the research programs suggested herein. Along with the suggested research prcgrm_s, there are a number of general and specific conclusions that can be reached as a result of this stud}, as follows: l° It is the consensus of opinion of the majoriD, of icing e_rperts that there is a need for a great deal of work with respect to the light transport and general aviation aircraft categories icing operations and certifications, specifically in the areas of: a. Icing intensi_" definitions.

b.

Improvement and updating of FAR 25 envelopes to include specific flight operational characteristics of general aviation as well as those of transport category aircraft.

c. Icing weather forecasting, including real time reporting.

,J.

Certification of aircraft cn a basis other than"_dl or noth_ig," i.e., partial certification for t]ight under ILmited icing conditions.

e. Standardization of icing certification requirements for specific t)?es of aircraft.

_nv effort to expand the utilization of light trmnspert and general aviation aircraft (where this cml be interpreted to me<m an increased nL_nber of imadvertent or deliberate penetrations of icing conditions% rakes zandatoP,- the requirement for i_roving _he sk111s ;_nd knowied_$ of the pi!oL'crew wlth regard to the nature and hazard_ of aircraft icing. .±iso requtred is a thorough Lmderst:mding of the l_mitations of his 7articular aircraft md ice protection sT.'ster_provi,led, in the icLn< conditions forecasted and 'or enco_mrered.

!39 .

_le sho_-t term and long term research plan list of specific research requirements will provide ,NASA LeRC with a basis for an overall icing research program to meet national needs. It is recommended that the X&SA LeRC incorporate the suggested research pre[_am for light transport and general aviation into their overall icing research program.

Mm_y of the research requirements outlined in the program contribute to the need for the rehabilitation of the ,k_SA LeRC ANT with icing research capabilities. As a result, rehabilitation of the .NASA LeRC IRT and A_T facilities is recommended. Fhe improvements and additions suggested in section _V are to be considered in this recommendation.

There is a general consenstm of opinion that the ,k_tSALeRC should be the center of aircraft icing expertise for basic research and consultation and should act as a clearing house for exchange of information for industry, involvement. However, it is also recommended that XASA LeRC have an input to the Air Force (._FDL) :;:ing programs to achieve ._tt_al benefits and savings to both agencies. It is recommended that these joint efforts be in such technology areas where .41 = facilities and experimental _Drk will augment the .NASA progrmms, particularly in low altitude climatologT and instrumentation.

The _rk IV oo,_puterized data management file was successful in that it provided a means to effectively retrieve reference materials as required to accomplish the program tasks, as well as providin_ for a bibliography of icing tecGnolo_- information. Further development of the }_rk IV or sL_'tilarcomputer management file is recommended in order to realaze more full)- the total capability of the system in providing a means of storing and retrieving icing tecb_olo_ data at all levels of detail.

Particularly, the file should be structured so that specific hnformaticn found in the literature may be retrieved through file interrogation in output formats acceptable for direct use in reporting.

The results of the study indicated that from a purely technical stand- point (involving ice protection system methods, ice sensitive components, ice accretion, etc.) there is very little difference between the research requirements for light transport and general aviation aircraft, and any other type of fixed wing aircraft except in _'o major areas of difference: a. Ph)'sical differences.

,-_.erational characteristics includhng altitude, scheduled/non- scheduled routes, crew training, aircraft size, and icing exposure.

_2"_ _ner_- or power _e,el_ available for aircraft Lee protection subsFs tens.

14c_

b. Nonphysical, re_nilatoo" (see }[o. I, Conclusion).

(i) F.kA la_les and regulations on certification, including FAR 25,

Appendix C envelopes are not tailored to meet operational

characteristics of general aviation type (i.e., no allowances

for partial certification, etc.)

(2) Low altitude climatology and statistical models, real time

forecasting, and quantitative icing definitions need more

specific direction towsrds general aviation.

The program that has been presented includes research specifically

oriented towards general aviation aircraft as well as research which is

applicable to all classes of aircraft.

The assessment of new and/or potential concepts for ice protection

.

systems revealed she existence of such concepts as microwave and electro-

impulse deicing systems which in theory, will provide great savings in

cost, weight, and power for ice protection. It is reco_ended that

further research is warranted and should be conducted On these concepts

to determine their feasibility for application to light transport and

general a-iation aircraft.

. 7he study revealed the need for considerable new research to be conducted

in the general area of icing inst_entation for both airborne and icing

wind turmel application. Specifically, it is recommended that research

be directed towarcLs the development of highly accurate instrumentation

for measuring icing parameters, i.e., LWC, droplet size/distribution, etc. for all ranges of values, to serve as an j_dustrf, standard.

10. It is recommended that in_provements to the N-_,CALeRC IRT Facility Lnclude

modern standardi:ed inst!namentation recording and data reducing

(processing) equipment.

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L3 tJu.- >- I _LD_ L_ Z i C 6-- o;; _" _" r _ .\.41 Z_ ZZZ G_ _Z_ _t_Z _ e APPE'¢D[X t3 LOOKUP TABLES OF CODES USED IN ICING RESEARCH DA'FA FILE B-I SENSITIVE COMPONENTS TABLE OF ICE TABLCL OOO TABLCL DO1 COMMENTS, MAJOR PROBLEM COMPONENT NAME OR TABLCL 00Z sIMPLE DESCRIPTION TABLCL 003 A _HERE, HOW DOES ICE FORH TABLCL 004 B WHE_I DOES ICE FORM TABLCL 005 C I$ IT A PROBLEMs NHY TABLCL 006 NONE LISTED TABLCL 00T AIRCRAFT ENGINESt GENERAL TABLCL 008 rABLCL O09 TABLCL 010 JET ENGINES TABLCL IO0 A MAIN INLET TABLCL IlO A PRIMARILY MUSHROOM ON INLET LIP.

TABLCL _11 IF NO NODULES ALONG LENGTH RUNBACK TABLCL 112 HEATED. HEAVY FORMATIONS ON PRO TABLCL 113 TUB ERANCES- TABLCL I14 B _ROUND SUBCOOLED CONDITIONS TABLCL 115 I NFLIGHT SUBCOOLED CONDITIONS TABLCL llb C ICE SHEDDING IS MAIN PROBLEM TABLCL II7 SOME LOSS IN POWER T&BLCL ll_ TABLCL 119 B BLOW IN DOORS TABLCL IZO A LE_DING EDGE wHEN OPEN TABLCL 121 SLUSH ICE COULD BE HEAVY [ABLCL _ZZ ICE ON EDGE, SEALS TABLCL 122 B GROUND ONLY TAXI SLUSH TABLCL 12_ OTHERWISE LIGHT IN SUBCOOLED COND, TABLCL 125 C BLOr..K_GE FROM SLUSH CANNOT TABLCL [2b CLOSE DOORS TABLCL 12T TABLCL 128 TABLCL 129 C INLET NOISE SUPPRESSION TABLCL 13O A NO FORMATION OF ICE FROM DIRECT IABLCL 13[ IMPINGEMENT. NOISE SUPPRESSION TABLCL 132 IS ACCOMPLISHED BY COATING DUCTS TABLCL 133 B GROUND RUNUP FREEZING RAIN E FROST TABLCL 134 C ICE SMEDDING INTO ENGINE TABLCL 115 TABLCL 136 TABLCL 137 TABLCL 138 TAELCL [3q O NOSE CAPS TABLCL I_0 A PRIMARILY MUSHROOM AT NOSE TABLCL 141 B SAVE AS MAIN INLET TABLCL 14Z C SAME AS MAIN INLET TABLCL 143 TABLCL 14_ TA8LCL 145 TABLCL 146 TABLCL 147 TABLCL 148 TABLCL 149 E SCREENS TABLCL 150 A ALL FORMS AT EACH WIRE TABLCL 15l B GRQUN0 RUNUP, TAXI, FLIGHT, ETC.

TABLCL 15Z C ALMOST IMMEDIATE BLOCKAGE DUE TO TABLCL 153 CLOSE SPACING. EXTREHE THREAT TO TABLCL 154 AIRCRAFT SINCE ALL ENGINES FAIL TABLCL 155 SIMULTANEOUSLY TABLCL 156 TA@LCL 157 TABLCL 158 TABLCL 15g F INLET GUIOE VANES TABLCL _bO A PRIMARILY MUSHROOM ON LEADING TABLCL 161 EDGES, BRIDGING =OSSIBLE TABLCL L62 B GROUND RUNUPt TAXI* FLIGHT, ETC.

TABLCL 163 C CAN HAVE BLOCKAGE IN SHORT PERIODS TABLCL I64 sHEDDING, JAMMING CAN CAUSE COMP TABLCL 165 STALL, INTERFERENCE WITH ROTOR TABLCL 166 BLADES, TABLCL 167 TABLCL l_B TABLCL 169 TABLCL ITO G ROTOR BLADES A SAG AS 160F TA_LCL 171 B SANE AS 160F TABLCL 17Z C SA_E AS 16OF TABLCL 173 TABLCL IT_ TABLCL 175 TABLCL 176 TABLCL 177 TABLCL 178 TABLCL 179 H FRAME STRUTS TABLCL tOO A PRIMARILY MUSHROOM ICE ON THE TABLCL 181 sTRUT LEADING EOGES TABLCL 192 S GENERALLY IN FLIGHT TABLCL 1B3 B-3 L ___ -- TABLCL C DA_GE FRDM SHEDDING, DECREASING TABLCL 185 ENGINE TDRGUEp INCREASED FUEL TABLCL 1e6 FLDw TABLCL I87 TABLCL 188 TABLCL TABLCL 2O0 FANJET ENGINESt HIGH BYPASS TABLCL 210 A APP_ ITEMS FROM 100 TABLCL Zll A API_ FOR ITEMS FROM 100 TABLCL 212 B Av By Ct Ot F, G TABLCL 213 C TABLCL 219 TABLCL 220 B FAN TABLCL 2ZL A PRIMARILY MUSHROOM LE OF FAN BLADE TABLCL 222 AERO HEATING AT TIPS TABLCL B GROUND WITH ADIABATIC EXPANSION, TABLCL 22_, E SUBCDOLED CLOUDS DURING GROUND TABLCL 225 TAXI _ FLIGHT CONDITIONS.

TASLCL 226 C SHEDDING, STALLv ASYMMETRIC LOADING TABLCL 227 AND ENGINE ROUGHNESS.

TABLCL 228 TABLCL 229 TABLCL 230 C BYPASS TABLCL Z3L A LIGHT ICING AT TURNS, SPLITTERS, TABLCL 23Z ETC, TABLC.L 233 B SAG AS FAN EXCEPT THAT FAN PRESS* TABLCL Z34 RATIO PROVIDES SOME ADIABATIC TABLCL 23S HEATING.

TABLCL 236 C NONE IDENTIFIED TO OATF.

TABLCL 237 TABLCL 23B TABLCL TABLCL 30O TURBOPROP ENGINES TABLCL 310 A APPR ITEMS FROM IGO TABLCL 31!

A Ai, D_ _, G_ H TABLCL 312 B TABLCL C TABLCL 3L'_ TABLCL 315 TABLCL TABLCL TABLCL 31B TABLCL 319

TABLCL

320 B PARTICLE SEPARATORS

TABLCL 321

A ICE FORMATION DEPENDS UPON TYPE OF TABLCL 322 SEPARATOR. MULTIPLE INLET5 COLLECT TABLCL ICE AT INLETS AND CENTER DIVIDER TABLCL IN THE FLOW CHAIN TABLCL 325 B GROUND RUNUP, FREEZING RAIN AND TABLCL 326 FROST GENERALLY IN FLIGHT.

TABLCL C BLrrKAGE OF THE AIRFLOW PATHS TABLCL 32S WOULD OCCUR RAPIDLY FOR SOME TABLCL 329 DESIGNS.

TABLCL 330 C SCREENS TABLCL 331 A ICE FORMS AT EACH WIRE TASLCL B GROUND RUNUP, TAXI, FLIGHT, ETC.

TABLCL 333 C ALMOST IMMEDIATE BLOCKAGE DUE TO TABLCL 33_, CLOSE SPACING, EXTREME THREXT TO TABLCL AC SINCE ALL ENGINES CAN FAIL TABLCL 336 SIMULTANEOUSLY.

TABLCL 337 TABLCL 338 TABLCL ,_39 TABLCL A PULL PROPELLERS TA6LCL A ICE FOR_S NEAR HUB ON LE OF BLADES TABLCL 3_2 AERO HEATING AT TIPS.

TABLCL 3_3 B GROUND RUNUPt TAXI, INFLIGHT.

TABLCL C RAY CAUSE UNDUE VZBRATTON.

TAELCL 3L,5 SHEDDING CA_ CAUSE DAMAGE TO AC TABLCL 3_6 TABLCL 3c.7 TABLCL TABLCL 349 [ABLCL 350 B PUSH PROPELLERS TABLCL A SAME AS PULL PROPELLERS EXCEPT TABLCL 352 THAT BLADES CAN _E DAMAGED BY TABLCL 353 UPSTREAW ICE SHEDDING.

TABLCL 354 B SAME AS PULL PROPELLERS TABLCL 35_ C SAME AS PULL PROPELLERS TABLCL 356 TABLCL TABLCL 358 35<) TAELCL TAflLCL 360 C ENGINE COWLING TABLCL 361 A MOSTLY MUSHROOM ICE _OR_S ON LE OF TABLCL 3_2 COWL WITH RUNBACK IF HEATED TABLCL 363 B SAME AS WITH JET ENGINE TABLCL 366 C ICE SHEDDING IS MAIN PROBLEP TABLCL 365 TABLCL 366 TABLCL 367 TABLCL _3E tABLCL 369 TABLCL _0 PISTON ENGINES TAELCL _10 A ENGINE COWLING TABLCL 411 A HOST LY MUSHROOM ICE FORMS ON TA8LCL 412 COWL LE TABLCL ;13 B GENERALLY INFLIGHT TABLCL 414 C ICE SHEDDING AND STRIKING OTHER TAELCL 415 CCMPONENTS, BLOCKAGES TABLCL 41& TABLCL 417 TABLCL 418 TABLCL _19 TABLCL 420 B CARBURETOR TABLCL 421 A HOST LY CONDENSATION OF WATER FROM TABLCL 422 AIR INTAKE TABLCL 423 8 ON GROUNO IN FROST CONDITIONS IN TABLCL 424 PLIGHT OURING DESCENT TO LAND TABLCL 425 C FREEZE IN JETS CAUSING ENGINE rABLCL _26 STALL. ICE CAN FORM AT ABOVE FREEZ TABLCL 427 ING AMBIENT CONDITIONS TABLCL 428 TABLCL 629 TABLCL 6_0 C PULL PROPELLERS TAELCL 431 A SAME AS WITH TURBOPROP ENGINES rABLCL 432 B SAME AS WITH TURBOPROP ENGINES TABLCL _33 C SAME AS WITH TURBOPROP ENGINES TABLCL 634 TABLCL 635 TABLCL 636 TABLCL 637 TABLCL _3B TABLCL 639 TABLCL _0 O PUSH PROPELLERS TABLCL 44| A SAME AS wITH TURBOPROP ENGINES TABLCL 442 B SAME AS WITH TURBOPROP ENGINES TABLCL 6_3 C SAME AS WITH TURBOPEOP ENGINES TAELCL _4 TABLCL teat.5 TABLCL 6.4.6 TABLCL 447 TABLCL _8 TABLCL _9 AC INST NOT ICING TABLCL 500 A PITOT STATIC TUBE TABLCL 510 A ICE FORMS ON PITOT HEAD OR MAST OR TABLCL 511 INSIDE SENSING LINES TABLCL 512 B ON GROUND FROM FREEZING RAINt COND TABLCL 513 IMPACT ICE IN FLIGHT_ FREEZING IN TABLCL 516 LINES DURING CLIMB TO ALTITUDE TABLCL 5L5 C CAUSES ERRONEOUS READINGS IN INSI TABLCL 516 USING P!TOT STATIC PRESSURES TABLCL 517 TABLCL 519 B ALT & ROC ORIFICES TABLCL 520 A ICE FORMS AT ORIFICE INLET OR TABLCL 521 I_IDE SENSING LINES TABLCL 522 B ON GROUND FROM FREEZING RAINt COND TABLCL 523 INF!.IGHT FROM IMPACT OR RUNBACK TABLCL 5Z6 ICE T&BLCL 5Z5 C CAUSES ERRONEOUS INDICATIONS OF TABLCL 526 ALT _ ROC TABLCL 527 TABLCL 528 TABLCL 529 C YAw VANES TABLCL 530 A MOSTLY MUSHROOM ICE FORMS ON LE OF TABLCL 531 VlCCE & VANE ARM TABLCL 532 B GENERALLY IN FLIGHT TABLCL 533 C CAN CAUSE ERRORS IN INST SENSINGtIEtPROB TABLCL 534 -LB4S WITH STALL WARNING SYSTEMS TABLCL _35 TIBLCL 536 TABLCL 537 TABLCL 538 TABLCL 539 O TOTAL HEAD PROBE TABLCL _._O A SAME AS PITOT STATIC TUBE TABLCL 541 B SAME AS PITOT STATIC TUBE TABLCL r>42 C SA_ AS PITOT STATIC TUBE TABLEL 543 TABLCL 54_ TABLCL 5_5 TABLCL rr_6 rABLCL 5_7 (" f"%II!L _-lK;p h, ' Ot,t,,lir_i" TABLCL 548 TABLCL 549 E TOTAL TEMP PROBE TABLCL 550 A MOSTLY MUSHROOM ICE FORMS ON TOTAL TABLCL 551 TB_P PROBE TABLCL 552 B GENERALLY INFLIGHT TABLCL 553 C ICE ON SENSOR WILL CAUSE ERROR IN TABLCL 55& AIR I"GTAL TEMP MEASUREMENT TASLCL 555 TABLCL 558 TABLCL 557 TABLCL SSB TABLCL 559 FUSELAGE TABLCL &_ A WINDSHIELD TABLCL 610 A ANY TYPE OF ICE MAY COVER SURFACE TABLCL 611 OF WINDSHIELD TABLCL 612 B ON GROUND, FREEZING RAIN, FROST, TABLCL 613 ET_.TAXI,INFLIGHT FROM IMPACT ICE TABLCL 51_ C OBSCURES VISION OF THE CREW TABLCL b15 TABLCL 616 TABLCL 617 TABLCL 618 TABLCL 819 B WINGJFUSE JUNCTURES TABLCL 6* A SAME AS k WING EXCEPT AT THE FUSE TABLCL 621 WHICH NAY BE CLEAR wHEN BLENDED TABLCL 62Z BODIES ARE USED.

TABLCL 823 B SAHE AS WING TABLCL 6Z_ C ICE SHEDDING T0 HORIZ STAB OR TABLCL 625 ENGINE INLETS WHEN SIDE INLETS TABLCL _b ARE USED.

TABLCL 6Z7 TABLCL 828 T4BLCL 829 C STATIC VENTS & BREATHER TUBES TABLCL 630 A NO FORMATION UNLESS FACING FORWARD TABLCL 631 EXCEPT FOR FREEZING RAIN. RUNNING TABLCL 83Z wATER CGULD ENTER VENTS, FREEZE TABLCL 633 B ON GROUN0t LOW AIRSPEEDS TABLCL 634 C OE_NDS ON VENT FUNCTION TAgLCL 635 TABLCL b36 TABLCL 637 TABLCL 838 TASLCL _39 O SCOOPS TAELCL 640 A ICE FORMATION ON LIP LE OF SCOOP, TABLCL 641 INTERNALLY IN DUCT BENDS TABLCL 66Z B GROUND RUNUP_ TAXIt PRIMARILY IN TABLCL 643 FLIGHT TABLCL 64._ C REDUCE OR CLOSE OFF AIRFLOW TABLCL 645 1ABLCL _6 TABLCL 64T TABLCL 648 TABLCL 649 TABLCL 650 E DRA INS A ICE FORMATION AT DRAIN OUTLET AND TABLCL 65I DRAIN LINE TA_LCL 6_2 g FREEZING RAIN, FOG, OR COND ON TA_LCL 653 GF_UNO, IMPACT ICE RUNBACK TABLCL 654 INFLIGHT TABLCL 655 C CLOSE OFF OF DRAIN OR CLOGGING OF TABLCL 656 LINES TABLCL bST TA_LCL 6_8 TABLCL 659 TABLCL 660 F OTHER JUNCTURES A ICE FORMATION DEPENDS ON CONFIGUR TABLCL 661 -ATION OF JUNCTURE. SAME AS wING TABLCL 662 FUSE IN SOME OASES TABLCL 663 @ SMwE AS WING FUSE TABLCL 664 C ICE SHEDDING DAMAGEtINCREASED DRAG TABLCL 6_>5 TABLCL 866 TABLCL 667 TABLCL 66B TABLCL _69 TABLCL 670 G ANTENNAS A PR_ARILY MUSHROOM ICE ON LE OF TABLCL 671 ANTENNA AND MAST TABLCL _TZ B GENERALLY INFLIGHT TABLCL 673 C SHEDDING DAMAGING OTHER AC COMPO TABLCL 676 -_NTS. DEGRADATION OF ELECTRONIC TABLCL 675 E(_JIPMENT PERFORMANCE TABLCL 676 TA_LCL 677 TABLCL 67B TA3LCL 679 H RADOMES TABLCL &80 A MU_ROOM ICE ON NOSE/SIOES OF TABLCL 581 TABLCL 682 R ADOME, FREEZING RAIN B-9 B GENERALLY INFLIGHT TABLCL 683 C SHEDDING AND DAMAGING ENGINE/AC TABLCL be4 CO4PON_NTS, DEGRADATION OF RADAR TABLCL 685 PERFORMANCE TABLCL &86 TABLCL 687 TABLCL 688 TABLCL 689 TABLCL 690 I EO WINDOWS A SAME AS WINDSHIELD TABLCL b9I B SAME AS WINDSHIELD TABLCL &92 OF ELECTRO C DEGRADES PERFORMANCE rABLCL 693 OPTICAL EQUIPMENT TABLCL 694 TABLCL 695 TABLCL 696 TABLCL 69T TABLCL 698 TABLCL 699 TAIL SURFACES TABLCL TO0 A HORIZONTAL TABLC L 710 A PRIMARILY MUSHROOM ICE ON LE TABLCL 711 B FREEZING RAIN, FROST ON GROUND TABLCL 712 GENERALLY INFLIGHT TABLCL T13 C INCREASES DRAG_ REDUCES CONTROL TABLCL 71_ AN) STABILITY TABLCL 715 TABLCL 716 TABLCL 71T TA_LCL T1B TABLCL 719 ELEVATOR TABLCL 720 A ICE ON SURFACE, PRIMARILY IN HINGE TABLCL 721 OR MORN AREAS TABLCL 722 B FREEZING RAIN, FROST ON GROUND TA_LCL 723 INFLIGHT TABLCL 7Z_ C INCREASE ORAG, BLOCK MOVEMENT OF TABLCL 725 ELEVATORS REDUCING CONTROL OF AC TABLCL 726 TABLCL 727 TABLCL 728 TABLCL 729 C VERTICAL TABLCL 730 A PR _ ARILY MUSHROOM ICE ON LE TABLCL 731 B GENERALLY INFLIGHT TABLCL 732 C INCREASES DRAG AND STALL SPEEE_ TABLCL 733 MAY REDUCE CONTROL AN0 STABILIT_ TIBLCL 734 B_IO TABLCL 735 TABLCL 736 TABLGL 73T TABLCL "/'_8 TABLCL 739 O RUDDER TABLCL 740 A NO IMPACT FORMATION, MAY GET ICE TABLCL T_l IN HINGES FROM RUNBACK WATER TABLCL 7_Z B ON GROUND FROM FREEZING RAIN OR TABLCL 7&3 FRI3ST GENERALLY NOT INFLIGHT TABLCL T&& C REDUCES CONTROL AND STABILITY TABLCL 745 MAY BLOCK RUDDER MOVEMENT TABLCL 746 TABLCL 7_T TABLCL 7_8 TABLCL 749 E T - TAlL SURFACES TJBLCL 750 A PRIMARILY MUSHROOM ICE ON LE TABLCL 751 1CE MAY FORM IN HINGE AREA TABLCL 752 B GENERALLY INFLIGHT, ON GROUND TASLCL 753 FROM FREEZING RAIN AND FROST TABLCL 75_ C INCREASED DRAG "TABLCL T55 TABLCL TS& TAPLCL 757 TABLCL 7_8 TABLCL 759 F V - TAIL SURFACES T&BLCL TbO A SAME AS VERTICAL STAB ILIZEr T_BLCL T61 B GENERALLY IN FLIGHTt FREEZING RAIN T&BLCL 762 FR_)ST ON GROUND TABLCL 7b3 C INCREASED DRAG, CONTROL AND TABLCL T&4 STABILITY. PROBLEM IF 1CE FREEZES T&BLCL 789 IN HINGED CONTROL sURFACES TABLCL 788 TA_LCL 787 TABLCL T_8 TABLCL 769 WINGS TABLCL 800 A SWEPT & STRAIGHT TASLCL 810 A ALL FORMS OF ICE ON LE, PRIMARILY TABLCL 811 UPPER HORN OF _USHROOM, IC_ RUNBAC_ TABLCL 812 ICE BEHIND LEADING EDGE TABLCL _13 B ON GROUND FROM FREEZING RAIN AND TASLCL 814 FROST, TAXI, INFLIGHT TABLCL 8[5 C INCREASED DRAG AND STALL SPEED, TABLCL 81& B-f1 C_TROL,STABILITY, ANO SHEDOING TABLCL 817 PROBLEMS TABLCL 818 TABLCL 8!9 TABLCL 820 B AILERONS A NO IMPACT FORMATION, ICE MAY FORM TABLCL 821 IN HINGED AREA TABLCL 8Z2 B ON GROUND FROM FREEZING RAIN AND TABLCL 823 FROST TABLCL 8Z_ C BIND OR JAMMING OF AILERON TkBLCL 82S MOVEMENT TABLCL SZ6 TABLCL B27 TABLCL 828 TABLCL 829 TABLCL 830 C FLAPS A PR_ARILY MUSHROOM ICE ON LE OF TA_LCL 831 OPEN (ExTENOED) FLAP TABLCL 83Z B GENERALLY INFLIGHT TABLCL 833 C PREVENTS OR DISTURBS AIRFLOW OVER TABLCL 834 FLAP. REDUCES EFFICIENCY OF FLAP.

TABLCL 835 INCREASES DRAGt SHEDDING TASLCL 836 TABLCL 837 TABLCL 83_ TABLCL 839 T_BLCL 8_0 O SLATS A PRIMAKILY MUSHROOM ICE ON LE OF TABLCL 9_!

S_T AND WIN(; wITH SLAT OPEN. ICE TABLCL 8_2 ON SLAT TRACK TABLCL 8_3 B GENERALLY [NFLIGHT TABLCL 9_4 C INCREASED DRAG, REDUCED LIFT AND TABLCL 845 FLAP EFFICIENCY TABLCL e46 TABLCL 847 TABLCL E_8 TABLCL B49 TABLCL 850 E SLOTS A FORM OF ICE DEPENDS ON SLOT CONFIG TABLCL 851 UP-_TIDN AND LOCATION TABLCL 852 B FREEZING RIIN/FROST ON GROUND.

TABLCL 853 INFLIGHT IMPACT ICE TABLCL 854 C REDUCED EFFICIENCY OF SLOT BY TA_LCL 855 REDUCING OR DISTURBING A]RFLOW T_BLCL 856 TABLCL 857 TkBLCL 858 TABLCL 859 B-12 E FENCES AND V/G TABLCL BBO A PRIMARILY MUSHROOM ICE ON LE TABLCL 861 B GENERALLY INFLIGHT TABLGL B62 C PRIMARY PROBLEM CAN COME FROM TABLCL 863, SHEDDING SINCE SOME FORMS OF ICE TABLCL I_ROVE FUNCTION OF V/G SOME TABLCL B65 INCREASED DRAG TABLCL 866 TABLCL 867 TABLCL 86,B TABLCL 86'9 G CANARD TABLCL 870 A SAME AS WING TABLCL 871 B SAGE AS kING TA_LCL B72 C SAME AS WING TABLCL 873 TABLCL 874 TABLCL 875 TABLCL 876 TA_LCL 877 TABLCL 878 TABLCL 879 H GENERALt MANY COMPONENTSv ENTIRE AIRCRAFT TABLCL 880 AIRFOILS_ COMBINATIONS TABLCL 381 ICING INSIRUMENT$ TABLCL BB2 (ABLCL bg3 TA BLCI- 88_ TABLCL 885 TABLCI. 88b TABLCL 887 TABLCL 885 TABLCL 889 CLASSICAL COMPONENTS TAELCL 900 A CYLINDERS T ABLCI, 910 B SPHERES TABLCL 920 C FLAT PLATES TABLCL 950 O RIBBONS TABLCL 940 E HE_I SPHERES TkBLCL 950 = ELIPSOID$ TABLCL 960 G CONES TABLCL 970 RECTANGULAR hALF-BODIE_ TABL_L 980 I WEDGES TABLCL _0 ABBREVIATIDN$/MNEH_IC_ TABLCL 060 SUP_R=SUPPRESSIC_ TABLCL 06,1 LE=LEADING EDGE TABLCL 06,2 B-13 063 AC=AIRCRAFT TABLCL 064 ROC2RATE OF CLIMB TABLCL 065 ALTtALTITUDE TA_LCL 066 INST=INSIRUMENTATION TABLCL 067 CCND=CONDENSATION T_BLCL 058 FUSE-FUSELAGE TABLCL 069 STAB=STAB%LIZER TABLCL 070 EC_EL ECTRO-OPT I CA L TAfLCL 071 V/G JVORTEX GENE_A TCR$ TABLCL 072 AP_R_APPROPR lATE TABLCL 090 GUIDE TO REVIEWEA TASLCL END OATE/TI_C Ib JUN 19BG / G8;44:13 PST TABLCL

TAELIPM 00 TABLE 0F ICE PROTECTION/PREVENTION METHOD

TABLIPM 01

TABLIPM 02 THE METHOD IS DEFINED BY THE TRANSPORT MEDIA AT THE

ANTI DE--ICING INTERFACE(SUCH AS M0T AIR) G THE FLOW

TABLZPM 03

04 CONFIGURATION (DOUBLE SKIN)

IABLIPM

TABLIPM 05 NOT APPLICABLE

TABLIPM 06 NOT DISCUSSED OR MINIMAL DI_USSION TABLIPM 07 PREVENIION VIA OPERA./IONAL PROCEDURES TABLIPM 0S HOT AIR CONT--TUBE OR SINGLE SKIN-INT T_BLIRM 09 HOT AIR CONT--TUBE OR SINGLE SKIN-PICCOLO TUBE CHORDWISE TABLIPM 10 HOT AIR CONT-TUBE OR SINGLE SKIN-PICCOLO TUBE SPANWISE TABLIPM 11 HOT AIR CONT-DOUBLE SKIN--INT TABLIPM 12 HOT AIE CDNT-PDROUS FLOW TABLIPw 13 HOT AIR CONT--SLOT/EXTERNAL TABLIPM 14 HOT AIR CYCLIC-TUBE DR SINL_LE SKIN-INT TABLIPM 15 HOT AIR CYCLIC-TUBE OR SINGLE SKIN-INT-PICCOLD TUBE CHORDwISE TABLIRM le, MOT AIR CYCLIC-TUBE OR SINGLE SKIN-INT-PICCOL0 TUBE SPANWISE TABLIPW 17 HOT AIR ONE SHOT-TUBE OR SINGLE SKIN-PICCOLO TUBE CHQRDWISE TABLIPM 19 MOT AIR ONE SHOT-TUBE OR SINGLE SKIN-PICCOLO TUBE SBANWISE TABLIPM _'0 GENERAL, MANY METHODS TABLIPM Zl HOT AIR CYCLIC - SLOT/EXTERNAL TABLIPM 22 HOT AIR CONT. _ CYCLIC - SLOT/EXTERNAL TABLIPM 23 TABLIPW Z4 ELECTRICAL-INTERNAL_WOVEN WIRE PADS TABLIPM ELECTRICAL-INTERNALt COATINGS TABLIP_ 26 TABLIPM 27 ELECTRICAL-EXTERNALt WOVEN wIRE PADS TABLlPM ELECTRICAL-EXTERNAL, COATINGS TABLIPM TABLIP _ 30 PNEUMATIC-_HORDWISE TUBES TABLIP_ 31 _NEUMATIC-SPANWISE TUBES TABLIPM 32 TABLImW 33 FLUID SYSTEMS IPOROUSD-GLYCCL BASED TABLIPM 34 ¢k'IIO SYSTEMS ;POROUS)-ALCOHOL BASED TABLIPM 35 FLUID SYSTEWS (POROUS)-CTHER TABLIPM 36 TABLIPM 3"/ ACOUSTIC - TYPE I TABLIPM 38 ACOUSTIC - TYPE IT TABLI_ 39 TABLIPM _,O MICROWAVE - TYPE I TABLIPW MICROWAVE - TYPE II TABLIRW ;2 TABLIPW ;3 ELECTRO-IMPULSE - TYPE i B'I5 ELECTRO-IMPULSE - TYPE II TABLIPM 4.5 TABLXPM 4& ICE PHOBIC -FREEZING DEPRESSANT TABLIDM ICE PrW}BIC -I. IQUIO FILM, LOW VISCOSITYt LOW ADHESION TABLIPM ICE Pt-_BIC -SOLID COATING OR TAPEr LOW ADHESION TABLIPW 4B rABLIP_ ¢9 ICE SHIELDS -- UNHEATED TASLIPM ICE SHIELDS -- HEATED ELEVATZIR OR RUDDER HORNS TABLIPW 52 LOW REFLECTIVE PAINT TABLIP_ GROUNO APPLIED (ETHYLENE GLYCOL g WATER) TABLIPH 53 54 FUEL AD01TIVES TABLIP _ 5fl TABLIPM ABBREVIATIONS/MNEh_NICS TABLIPM 80 INT-INTERNAL TABLIPM CONT=CONTINUOUS TABLIPM TABLIPM St., TABLIR_ TABLIPq TABLIPM 8b TABLIP _ 8T TABLIPM 88 TABLIP_ 90 GUIDE TO REVIEWER TABLIPN IF THE DATA SOURCE DISCUSSES ; SINGULAR SPECIFIC ICE TkBLIPM PROTECTION METHODt USE ONLY ONE AS INDICATED IN THE LIST TABLIDM IF SEVERAL ARE OISCLGSED, USE THE GENERAL CALLC_JTS TABLIPM 93 INDICATED IN THE LIST, 9,:,.

TABLI_M TABLIP _ TABLIPM TABLIP_ TABLIPM TABLIPW DATE/TIME 16 JUN 1980 / 08:44:13 PST END TABLIP W B-I_ TABLE OF STATE OF ART CATAGORIES TABLSOA O0 TABLSOA 01 TABLSOA 02 TABLSOA 03 OPERATIONAL USE-IN COMMON USE OFF THE sHELF TABLSOA O_ OPERATIONAL USE-0FF THE ,SHELF NOT IN COMMON USE TAELSDA 05 OPERATIONAL USE-OES CONCEPT OEV-POTENTIAL USE/GOOD IDEA TABLSOA 06 OPERATIONAL USE-DES CONCEPT OEV-IDEA NOT TOO GOOD TABLSOA 07 OPERATIONAL uSE-NEW IDEAS TABLSDA 08 OPERATIONAL USE-I_PROVEM6NTS TABLSOA 09 RES LAB USE-OFF THE SMELF_ IN COMMON USE TA8LSOA 10 RES LAB USE-OFF THE SHELF_ NOT IN COMMON USE TABLSOA 11 RES LAB USE-NEW CONCEPT-SINGLE PURPOSE ONE TIME DEV ARTC TaBLSOA 12 R_S LAB USE-NEW CONCEPT-NOT DEVELOPED TABLSOA 13 RES LAB USE-NEW IOEAS TASLSOA 14 TABLSOA 15 TABLSOA 16 TABLSOA 17 TABLSOA TABLSOA ZO IMPROVEMENT S T_BLSOA TA_LSOa 21 TABLSOA ZZ Z3 TA6LSOA Z_.

TABLS_A r_BLSOA ABBREVIATIONS B0 T&BLSOA RES=RESEARCH DES=DESIGN OEV=OEVELCPMENT BI TABLSOA LAB=LABORATORY ARTC=_TICLE _2 TJBLSOA GUIDE TO USERS TABLSOA 90 END DATE/TIME 3.6 JUN 1980 / 08;_#_:13 TA6LSOA ' • t , : , •. "j B-I- TABLE OF DATA AVAILABILITY TABLDA CO THIS CATEGORY IS FOR INFORMATION ONLY TABLDA OI NOT A SORT CATbGORY TABLOA 02 rABLDA G3 PUBLIC LITERATURE, JOURNALS, ETC TABLDA 04 GOVERNMENT LITERATURE - uNRESTRICTED T A BL,-_A 05 GOVERNMENT LITERATukE - _ESTRICTEO (ALL) LEVELS TABLDA 06 CONTRACTOR LITERATURE - AVAILABLE TABLDA 07 CONTRACTOR LITERATUkE - p{._OPRIETARY T ABLL_A OB CONTRACTOR LITERATURE - _TRICTION TABLDA _'9 TABLDA 10 TABLDA 11 TABLDA I2 TABLDA L3 TABLDA 1 L, TABLDA l_ TABLDA 16 TABLOA 1'7 TABLDA 19 T &BL_& l?.

T A_LD_. 20 ABBRE v IAT IONS TABLDA 80 GUIDE TO uSERS TABLOA DATE/TIME 16 3UN I*@80 / OB;'_4 ='13 T t,.B L D A END TABLE OF SOURCE DATA CATEGORIES -DATA BASE/FACILITY TYPE TABLSOI TABLSOL P_OBLEM IDENTIFICATION, SOLVING 0Z TABLSDI REPORTING, BASLE CATAGORIES TABLSDI TABLSDI O5 TABLS01 COMMENTARY ONLY TABLSOI STATISTICAL STUDY OR SURVEY 0T TABLSOI OPEKATIONAL EXPERIENCE REPORTING rABLS01 EMPIRICAL EQUATIONS TABLS01 TEST FACILITY USED AS BACKGROUND TABLSOl TUNNEL TEST CONVENTIONALt ICING tl TABLS01 TUNNEL TEST FREE JET, ICING 1Z TABLSDL TUNNEL TEST DIRECT CONNECT, ICING-ENGINE TABLSOl TUNNEL TEST CONV_TIONAL, DRY AIR TABLSDI TUNNEL TEST FREE JET, DRY AIR TABLSOl 15 TUNNEL TEST oIRECT CONNECT, DRY AIR tO TABLSO1 FLIGHT TEST, TANKER TABLSD1 17 F_.IGHT TEST, NAT LRAL ICE TABLSD1 18 FLIGHT TEST, DRY A1R TA6LSD1 SPRAY RI_, FAN BLOWN TABLSD1 SPRAY RIG, WINO BLOWN TABLSDI ICING TEST CELL T&BLSD1 ZZ NATURAL ICE _ TANKER FLIGHT TESTS TABLSDI TUNNEL IESlS G FLIGHT TESTS (DRY AIR) TABLSDI TUNNEL TESTS & FLIGHT TESTS (ICING) TABLSOl 25 COMPUTER PROGRAM & F_ILITY TABLS01 2_ LABORATORY TEST SETUP (APPROPRIATE EQUIPMT) TABLSD1 TABLSOl 28 TABLS01 APPLIC_T] ON ANALYSIS 3O TABLSD1 TABLSD[ 3Z T&BLSOI TABLSOL TABLSDI TABLSDI ABBREVlATIUNS T_BLSDI 80 GUIDE TO REVIEWER T,_BLSOI OATE/TI_E lb JUN 19BG / 06:_*:L3 PST E4D TABLSDI B-17 TABLE OF SOURCE 0ATA t SUBCATEGORY - METHOD OF EXPRESSION O0 TABLSD3 TABLSO3 METHOD OF EXPRESSION - WHAT IS THE GENERAL OR HIGHEST TABLSD3 OZ (MOST ACCURATE OR MOST SOPHISTICATED) METHOD OF TABLSD3 EXPRESSION OF THE UOOJMENT.

TABLSO3 O_ TABLSD3 05 0ESCRIPTIVE QUALIIATIVE TABLSD3 DESCRIPTIVE QuANTIIATIVEiORA_IINGS, ETC.)

TABLS03 07 MATHEMATICAL EQUATION_ AND PROCEDURES {GENERAL) TABLSD3 C;8 04 COWPUIER PRDGRAMS/OATA TABLSD3 10 EXPERIMENTAL OBSERVATIONS TABLSD3 EXPERIMENTAL MEASuKEMENTS TABLS03 11 INTERPOLw EXI_,APOL/PREOICTION METHODSICORRELATION FUNCTIONS TABLSO3 12 SCALE MODELING TA_LSD3 SPECIFIC EQUATIONS - 8REGUET TABLS03 14 SPECIFIC EQUATIONS - wETTED SURFACE, TOTAL TEMPERATURE TABLSD3 15 SPECIFIC EQUATIONS/METHOD - ICE ACCRETION PREDICTION METHOD TABLSD3 SPECIFIC EQUATIONS/METnGD - PENALTIES TABLSD3 TABLSD3 T_BLSD3 TABLSO3 2O TABL$03 2L TABL503 22 TABLSD3 TABLSO3 2; Z5 TABLSD3 TABLS03 80 ABB_EVIATIONS TABLSO3 81 I_TERPOL=INTERPOLATION EXTR APOL=EXTRAPOLA_ON TABLSD3 9_ GUIDE TO KEVIEWER TABLSO3 DATE/TIME _6 JUN 1980 / 0B:4J*:13 PST TABLSO3 END B-.7_ TABLSO", OJ TABLE OF SUu_CE OATA,SUBC_TEC, CRY- pRoG. R _ D PHASES.

T ABLSD'_. 0)` TA_LSD'_. 0Z ICING PROG R_'_ PHASE - ',,,HAl PHASE CF THE RESEAKCH TABL$O_ 03 OR _C, QUISITION CYCLE L]SES THE REPORT DEAL wITH TABLSD_ 04 T _LS04 05 _ T ASL. SD'k' 06 GENER AL TABLSD(.,. 07 E_PLORATORY - SEARCH FCR PROBLEMS, [OEAS, ETC.

TABLSD4 08 BASIC RESEARCH 08 STUOYIPHENOMENA, MATER[ALS, NEW TECHN(ILOGYI TABLSI]'W" gO ARPLIEg RESEARCH (EVALL".TE, APPLY, EXTEND- TECHNOL{]GY} TAELSD_ LJ STATISTICAL _ . _ T ABLSO.W LI _ - -- -...........

TABLSO_ LZ CONCEPTUAL DESIGN T AB_-SD_- L3 DESIGN T ABLSg/., L_, OEVELOP_ENT TABLSO'k' L5 COMBINATIONS OF )`2 THRU L_ I ABL S D_" [b TA_LSO t, 17 VERIF)`CAI')`ON -- - - - - " T ABL S 0._ I8 T ABL S_'_" L9 CERTIFICATION IABLSD_ 20 COMBINATIONS CF )`7 THRU 20 TA_LSO_ 2), T ABLS D_' 22 F ABLSO_" 25 .... - T AE)LS CIr. 2_.

T ,_ 8L S C,_, 25 T ABLSO_ 20 T ABLSD_. 21' T AE_LS34 2B T A_L SO_ 2o - " T A_L S C'_, 30 I ABL_ O._. 80 ABBREV IAT IONS T ABL_,J4 _[ T _-bL S 04 8Z TAbLSO& _3 T " B L S D I_' _'_" IABLSD'W' 93 GUIDE TO REVIEWER TABLSD_ ENO D:'-TE/T)`ME L6 JUN LgBO / 0_.;'_4|3g ,').

TABLE OF SOURCE DATA, SUBCATEGORY - PHENOMENA TABLSDZ 00 THIS TABLE OEFZNES THE SCIENTIFIC/ENGINEERING TABLSD2 0£ DISCIPLINE OR PHENOMENA INVOLVED IN THE OATA SUCH AS= TABLSDZ 02 PHYSICALt THERMOOYNAMICt ACOUSTIC* ELECTRODYNAMIC, TABLSO2 03 CHEMICALt ETC.

TABLSDZ 04 TABLSDZ 05 NOT DISCUSSED TABLSDZ 06 MEAT TRANSFER(DRY AIR) EXTERNAL TABLSD2 _7 HEAT AND MASS TRANSFER(WET AIR) EXTERNAL TABLS02 08 HEAT 1RANSFER INTERNAL TABLSO_ 09 TOTAL HEAT-MASS TRANSFER TASLSDZ 10 HEAT BALANCE I NTERNAL/EXIERNAL TABLSD2 11 COMBINATIONS OF Q6 THRU 12 T_BLS02 IZ TOTAL SYS HEAT & MASS xFER ANALYSISIWING OR AIRCRAFT) TABLSD2 13 FLCW FIELDS TASLSO2 I_ T_LSDZ 15 WATER DROP TRAJ/COLLE4_TION EFFICIENCIES (CLEAN AIRFOIL) TASLSDZ lb wATER DROP T RAJ/COLLECTION EFFICIENCIES (ICED SURFACE) TA6LSDZ i7 ICE ACCRETION CONDITIONS G/OR DATA (UNSWEPT) TABLSO2 18 ICE ACCRETION CONDITIONS E/OR DATA (SWEPT) TABLSDZ lq ICE SHEOOINGt CONDITIONS _/OR DATA TABLSDZ ZO AERO EFFECTS OF ICE ACCRETION - LOCALIZED TABLSDZ 21 TOTAL AIRCRAFT EFFECTS ANALYSIS/DATA ETC.

TABLSD2 Z2 CONDENSATION ICE (CARBURETORS/FET ENGINE INLETS) TASLSD2 Z3 METEOROLOGICAL TABLSOZ Z_ ICE ADHESION TABLSD2 2S 1ASLS32 2b TABLS02 Z7 TABLSD2 2_ TABLSD2 Zfl TABLSD2 30 TABL$02 31 TASLSD2 33 ABBREVIATIONS TABLSO2 80 XFER=TRANS FE R TABLSCZ 81 EXT=EXTERNAL TASLSD2 8Z GUIDE TO REVIEWERS TaBLSOZ qO PST DATEITI_E 16 JUN 108O / 08:4J*:13 TABLSD2 END O0 TABLE OF ICING CONDITIONS TABLIG TABLIC 01 TABLIC 02 1ABLIC 03 TABLIC O4 NO ICTNG CONDITIONS TABLIC C5 LIQUID WATER CONTENT (LWC) TABLIC DROPLET SIZE, MEDIAN DIAMETER TABLIC O? DROPLET SIZE, MEAN EFFECTIVE DIAMETER TABLIC 08 0ROPLET SIZE, AVERAGE DIAMETER TABLIC O_ AIR VELOCITY TABLIC 10 AMBIENT TEHPERATURE TABLIC 11 ALTITUDE 1Z TABLIC DROPLET SIZE DISTRIBUTION TABLIC 13 LWC, TEMPERATURE TABLIC DROP SIZF, LEC TABLIC 15 DROP SIZE, rEMPERATUREt LwC TABLIC 16 _IND TUNNEk, ICING CONO TABLIC 17 WIN0 TUNNELt DRY AIR CDND TABLIC 1B FLIGHT TEST, ICING COND TABLIC _9 PLIGHT TEST, DRY AIR CONO TABLIC 20 rANXER TEST, ICING COND TABLIC ZI SPRAY RIG ICING COND TABLIC 22 CERTIFICATION DEFINITION (O5, 06, 11) TABLIC 23 OTHER COMBINATIONS TABLIC 2_ HORIZONTAL EXTENT TABLIC VERTICAL EXTENT TABLIC Z6 LOCALE TABLIC ZT SEASON TABLIC ZB COMMUTER PROFILE TABLIC GENERAL AVIATION PROFILE TABLIC 30 TRANSPORT PROFILE TABLIC 31 HELICOPTER PROFILE TABLIC STRATOS PROFILE tCONTINUOUD) TABLIC 33 CUMULUS PROFILE TABLIC 34 MAX CONTINUOUS - CERTIFICATION DATA TABLIC 35 INTERMITTENT MAX - CERTIFICATION DATA TABLIC OTHER _MAX° CCNT, _ INTERMITTENT MAX,) TA&LIC 37 WATER DROPLET/ICECRYSTAL COMBINATION TABLIC SNOW, FROST TABLIC 39 FRE=ZING RAIN ;O TABLIC WATER IN FUEL IFREEZING CONDITIONS) TABLIC ICE PROPERTIES TABLIC ;2 TABLIC ;3 TABLIC TABLIC _5 SO TABLIC ABBREVIATIONS TABLIC S] LWC=L[_UID WATER CONTENT TAELIC _2 COND=CONOIIION TABLIC _3 MAX=_&X|MUM TABLIC B_ CONT.=CONTINUOUS TABLIC _UI_E TU USERS TABLIC END DATE/TIME L5 JUN LqBC / ¢8:_:13 PST B-Z3 TABLE OF PENALTIES ASSOCIATED wITH ICING/ANTI-ICING TABLPN1 Ol TABLPN1 PENALTIES ARE RELATED PRIMARILY TO THE PARENT AIRCRAFT TASLPN1 02 PENALTIES ARE GENERALLY DIVIDED INTO CATAGORIES SUCH TABLPNI AS PERFORMANCE RELATED, SAFETY RELATE0, RELIABILITY TABLPN1 RELATEDt COST RELATED OR USAGE RESTRICTION RELATED.

TABLPN1 05 TABLPNI 06 07 NODATA TAELPNI NOT _PPLICABLE TABLPN1 0B GENERAL TA_LPN1 09 COMPONENT PENALTIES TABLPN1 tO E/OR DELTA FUEL _NGIN3 BLEED PENALTY LCOM PRESSOR LOSSES) TAELPNI hEIGHT TA_LPNL 12 POWER IELECTRICAL) TA_LPN_ 13 cost TABLPN1 RELIAfiILITY TABLPNI 15 AIRCRAFT ASSOCIATED PENALTIES TABLPN1 WEIGHT (FUELI _ABLPN1 17 ETC, _EIGHT tTOT_L STRUCTURE _ FUEL TABLPNL POWER TA_LPNL ],9 20 DRAG TABLPNI CANOE EFFECT (BERGUET EQUATION) TABLPN1 21 22 PAYLOAD EFFECT TA_LPN1 LANDING PERFORMANCE TABLPNI 23 TAKE--GF_ PER FDRMANCE TABLPNI 24 Z5 STALL EFFECT TABLPN1 TABLPN1 26 CRUISE SPEED MAXIMUM SPEED TABLPNJ 27 2B RELIABILITY TA_LPNI 29 SAFETY TABLPN1 COST TABLPN1 30 31 OPERATIONAL COST TABLPN1 OPERATIONAL FLIGHT RESIRICTIONS TASLPNI 3Z TABL_NI 3_ TABLPN1 TAELPN1 TA_LPNI 80 ABBREVIATIONS ETC.

TABLPN1 PWR=POWER 8L TABLPNI ASSOC±ASSOCIATED rABLPNI B2 WAX=MAXIMUM TABLPN1 83 TABLPN1 TABLPNI B-24 TABL3 OF PENALTIES RATING TABLPR O0 WOOIFIES THE PENALT'f DATA BY A JUDGEMENT RANKING TABLPR Ol TABLPR OZ TABLPK 03 NOT APPLICABLE OR NO 0ATA TA_LPR 04 NO SIGNIFICANT EFFECT TABLPR Q5 SRALL EFFECT TABLPR _6 TABLPR 07 rlODERATE EFFECT rABLPR _8 TABLP_ 0'9 SEVERE EFFECT TABLPR XO SEVERE - SAFETY EFFECT TABLP_ 11 CATASTROPHIC EFFECT TABLPR lZ TABLPR _3 TIELPR 1_ TABLPR 15 Zb TABLPR TABLPR _7 TAELPR Ig TA6LPR T&6LPR ABBREVIATIONS TABLP_ TABLPR / 08"-44-" 13 X6 _UN 1980 END DATE/TImE TABLPR B-25 s • TABLE OF TYPES OF INSTRUMENTATION (ICING) TABLTI GO TABLTI Ol TAOLTI OZ TABLTI OB TABLTI O_ TABLTI 05 TABLTI 06 TABLTI 07 TABLTI OB DYE TRACER-IMPINGEMENT CHARACTERISTICS TABLTI 09 ROTATING SINGLE CYLINDER TABLTI lO KEILY PROBE-DROP SIZE DISTRIBUTION IN CLOUDS(GND BAS) TABLTI II GSFC LASER NEPHELOMETER - LWC - WATER DROP COUNTER rAbLTI 12 ROTATING MULTICYLINOERS - DROPSIZE & LIQUIO wATER CONT TAELTI " I3 FIXEO LARGE DIAMETER CYLINDER - DROPLET SIZE TABLTI 14 NASA ICING METER - LIQUID WATER CONTENT • TABLTI _5 HEATED WIRE ME TER-JOFNSON WILLIAMS-LIQUID WATER CONTENT TABLTI 16 OIL SLIDE DROP SNATCHER - DROPLET SIZE TABLTI 17 LASER BEAM [ASP) - MRI - KNOLLENBERG TABLTI 18 FORWARD SCATTERING SPECTROMETER PROBE-PMS-KNOLLENBERG TAELTI 19 ICING SPHERE TABLTI 20 NGL "HOT ROD'I-ACCRETIO_ ROD - LIQUID WATER CONTENT TABLTI 21 VERNIER ACCRETION MEIERIVAM)-ICE ACCRETION - LWC TABLTI ZZ EVAPORATIVE TOTAL WATER PROBE LHC METER - RUSKIN TAdLTI 23 DYNAMIC ICE DETECTQR/ICE SEVERITY-STALLABRASSIRINGER TABLTI 2_ ICING ONSET CETECTOR - RDSEMOUNT - VIBRATING ROD TABLTI 25 ICE DETECTOR - RESISTANCE TYPE TABLTI 26 ICE DETECTOR - PRESSURE TYPE TABLTI 27 ICE DETECTOR - MECMANICAL SCRAPER IABLTI 28 ICE DETECTOR - INFERENTIAL (HEATED wIRE { CYLINDER} TABLTI 2g ICE DETECTOR - SOVIET CO-_A TABLTI 30 ICING PRE;ICTOR - RADAR TABLTI 31 ICING PREDICTOR - oTHER TA_LTI 32 MICROWAVE ICE DEIECTCR TABLTI 33 NUCLEAR ICE ACCRETN MTR-ATTENUATION&RADIOACTIVE SOURCE} TABLTI 34 ICING RATE METEK - TEDDINGTDN INFERENTIAL METER TABLTI 35 TABLTI 3b ICING RATE METER - TV RASTER ACCRETION METER ICING RATE METER - RO.SEMOUNT TABLTI 37 TEMPERATURE PROBE - AIR TEMPERATURE T_BLTI 38 PILOT - STATIC PROBE - ALTITUDE, AIR VELOCITY TABLTI 3q BETA RADIATION ICE DETECTOR TAOLTI _0 TABLTI _I PHOTOGRAPHY - ICE SH_ E 6 SIZE TA_LTI _2 B+26 WEIGHING ISCALES| - ICE SIZE, DENSITY _3 TABLTI TABLTI ICE C_YSTAL SIZING - FORMVAR REPLICATOR _5 TABLT!

ICE CRYSTAL SIZING - ICE PARTICLE COUNTER,MEE INDUSTRIES TABLT!

ICE PARTICLE COUNTER (UW - IPC)TURNER & RADKE t,T TABLTI FIBER-OPTICS PARTICLE-SIZING SYSTE_ (FOPSS) TABLTI PARTICLE-SIZING INTERFERDMETER (PSl) TABLTI BACK SCATTERING PARTICLE SIZING SYSTEM (BSPSS} TABLTI HOLOGRAM SYSTI_M TABLTI TABLTI MORE THAN ONE TYPE TASLTI TABLTI TABLTI TABLTI ST TABLTI TABLTI TABLTI TABLTI ABBREVIATIONS ETC.

TABLT!

ACC_ETN=ACCRETION TABLTI &ET=0ETECTION TABLTI GND BAS=GRO_J N0 BASED TABLTI IPC=ICE PARTICLE COUNTER 8_ TABLTI LWC-LIQUIO wATER C_'_TENT TABLTI MRI=METEORDLGGY RE.ARCH, INC.

TABLTI MTR=METER 8T TASLTI NRC=NATIQNAL RESEARCH COUNCIL 8B TABLTI UW=UNIVERSITY OF WASHINGTON TABLTI GUIDE TO REVIEWER TABLTI 90 [5 JUN [980 1 G8:_4:I3 PST ENO DATE/TIME [ABLTI TABLIP O0 TABLE OF INSTRUMENT PHENOMENOLOGY TABLIP O1 PRINCIPLE OF OPERATION OF INSTRUMENT TABLIP 02 TABLIP O3 TABLIP C4 TEMPERATURE TABLIP 05 PRESSURE TABLIP O6 DIFFERENTIAL PRESSURE TABLIP OT VIBRATION -- NATURAL FREQUENCY BASED ON MASS TABLIP 08 ELECTRICAL RESISTANCE TABLIP O9 PROXIMITY TABLIP IO OPTICAL TABLIP 11 MICROwAvE TABLIP ELECTROMAGNETIC TABLIP 13 ACOUSTIC TABLIP 14 MECHANICAL TABLIP 15 OTHER TABLIP 16 MORE THAN ONE 1T TABLIP INFRARED SYSTEM TABLIP INDUCED AIR FLO_ _ OPTICAL SENSOR TABLIP 19 TABLIP 20 TABLIP 21 TABLIP TABLIe 23 TABLIP 24 TABLIP 25 TABLIP BO ABBREVIATIONS TABLIP 90 GUIDE TO USERS TABLIP END DATE/TIME l& JUN 198G / 68:44:13 B-2_ TABLIU O0 TABLE OF INSTRUMENT UTILIZATION _ CONTROL TABLIU Ol TABLIU 02 TABLIU 03 FORECASTING TABLIU 04 TABLIU 05 STATISTICAL RESEARCH {NATURAL CONDITIONS) TABLIU 06 FLIGHT OATA ACCUMULATION iNON-UTILIZATION IN FLIGHT) TABLZU 07 wEATHER BALLOONS WEATHER STATIO_ TABLIU 08 AIRBORNE PILOT UTILIZED - COMMUTER AIRCRAFT TABLIU 09 AIRBORNE PILOT UTILIZED - GENERAL AVIATION TABLIU I0 AIRBORNE PILOT UTILIZED - HELICOPTER TABLIU IT TABLIU 12 AIRBORNE PILOT NON-UTILIZED -- TELEMETERED TABLIU 13 AIRSORNE PILOT NON-UTILIZED OPERATIONAL A/C DATA BASE RESEARCH - WIND TUNNEL TABLIU 1_ TABLIU 15 RESEARCH - TANKER JUTOWATIC -- PILOT NON-CONIROLLEO SENSING E PROTECTION TABLIU 16 TABLIU 1T AUTOMATIC - PILOT NON-CONTROLLED (NO LITES OR DISPLAYS) TABLIU 18 PILOT INTERACTIVE - AUTO SENSING - INTERACTS NITH DISPLAY TABLIU 19 PILOT INTERACTIVE - OBSERVATION OTHER TABLIU 20 TABLIU 21 NORE THAN ONE TABLIU 22 TABLIU 23 TA_LIU 24 TABLIU 2_ TABLI_ 26 TABLIU 27 TTABLIU Z8 TABLIU 29 TABLIU 30 TABLIU 80 ABBREVIATIONS TABLIU 90 GUIDE TO U_ERS TABLIU END DATE/TI_E 16 JUN 1980 / G8:_:13 TABLE OF RESEARCH _ SERVICE INDEXES O0 TABLRSI TABLRSI TABLRSI TABLRSI 03 TA8LRSI TABLRSI 05 TASLRSI O7 _ABLRSI NOT APPLICABLE FOR NASA RESEARCH OR SERVICE TO INDUSTRY IABLRSI ITEM OF INTEREST, BUT SUFFICIENT RESEARCH ACCOMPLISHED.

TA=LRSI Oe PAST RESEARCH OF QUESTIONABLE QUALITY BUT LOW IMPACT TABLRSI PAST RESEARCH OF QUESTIONABLE QUALITY _ HAS HIGH IMPACT.

TABLRSI 11 NEW RESEARCH NEEDED - LOW IMPACT, MEDIUM PRIORITY TABLRSI NEW RESEARCH NEEDED - HIGH IMPACT, HIGI "= PRIORITY.

T_@LRSI 13 RESEARCH METHOD E DATA OF VALUE TO LIGHT AIRCRAFT TABLRSI TABLRSI 15 TABLRSI TABLRSI SERVICE ITEM OF INTEREST - PRESENT KNONLEDGE TABLRSI 1B TABLRSI 19 TABLRSI 20 TABLR$I 21 TABLRSI 22 TABLRSI 2; TABLRSI Z_ TABLRSI ABBREVIATIONS/_NEMONICS SO TABLRSI RES=RES_ARCH TABLRSI GUIDE TO REVIEWER TABLRSI 9O Qq TABLRSI 16 JUN 1980 / 08:_,:i3 PSI TABLRSI END DATE/TIME TABLE OF SCALE RATINGS FOR LITERATURE TABLRR 000 EXCELLENT TABLRR Ol VERY GOOD TABLRR 02 GOOD TABLRR 03 -EDIUM TABLRR O_ FAIR TABLRR 05 O_ NO USE TO THE ICING RESEARCM PROGRA_ TABLRR O& DATE/TIME I6 JUN IqSO / _8:_:13 PSI END T&BLRR

.APPENDIX C

ICING RESEARCH D_.a FII_ IN_RROG_TIONS :]_e lal references in Appendix A were reviewed from the standpoint of the objectives of tills study. The resulting codes, data and cor_aents _,_re input "rot,; a c_mputerized data file for subsequent _nipulation lnd klterro._ation. In this appendix are a number of such interrogations which provided infor_tion abou_ the literature m_d were used Lu arriving at the conclusions and reeo_endat!ons of this report. Note that the first interrogation pres-_nted provide7 the .-eference co_ents for every one of the doc'_,ents reviewed, lhses cerements are in essence, mLni abstracts for each re_ere_ce.

The ot.he_ mnterro_ations :;ere made from the srcmdpoint of the variotks task requirements, and deal with a_nMytical methods, new ice protection _ethods, h_tF._entation, penalty data, etc.

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Z 3: .+ ._ , i ICING }LESE&RC_q FILE SE.ARt24. FOR REFERE_\CES .aDDRESSING CERTIF iC_'TION REQUIRG_'IE\'TS oUTPUT: a_ Ref No., icin_ Condition, Reference Co,_aent b'l Ref Ne., Co_r_ents Re Ice ghenomena :" .T. : *- i _ J .it Z _ .. _-= ;-_== i.. = ;-;

_ •

:( Z_ _a _4 IL Z L -<'_ _ - z _Z _ X _ ..... =_ ....

_- _ -_ _z I _._' .T Z z _ ---- Jj I + h._il _ --Z N _i _,( _ _=_ ,._ _ ,-_ _ :I '4 i_ zz =- ,+,_ =-: z _Z q Z -: + ._ - Z_ ZZ _[_._ _,JZ Z_ .( :[ _ T r = z m =g _Z _w _ Jd . < z ,.- v_ *.*Z =£ ,:a i 11,_ m_J X T_ z _ z_ _ _ --" • _- t I I .<PP E\]} IX D _r [X]DUSTRY/GO_]£_h_-\_ SU_RY _ St@_'EY QL_£STIOX%[&I RE BACKGROUND .kND RECC_I_-\E]ATICNS A survey/auestionnaire was sent to 60 members of industry, C_vernment, and universities who are involved in icing related activity in the field of general a_iation and light tramsport aircraft. Only 23 responses were returned. I%,_isresponse rate appears t)_ical, based on corments found in the literature regarding similar surveys.

A nmnber of those on the _,_i!ing list were contacted almost eight weeks after tr_smittal of the ques:ionnaire to inform them that we would still accept submittals if they had any. This ;_s done because the original transmittal letters had requested that the questionnaire be returned ,within _o weeks after receipt. Several phone calls had been received requesting exter_slons to this two week period, so it _,as asscmed that there might be others who were ,tunable to meet the two week turnaretmd and so did not subp/t a reply.

l-he fol!o_np telephone call_ verified this suspicion. It _ns quite difficult to _ke contact with most of the individuals, since ,.na_,y were out sf te_n on business, in conference at the time of the call, etc. Obviously, these are vet%- bus'," people, m_d if the two week deadline were to e.vpire, the," ;,ou!d mos= likely not be cole to take the time to pursue the question- naire, e.:_eciallv if the?" felt that it wouldn't be used in the sur_'e'/. [t is rec_m_ended tbd{t in future su_-,'e?-s, a tL-.,eiL_.it be suggested, but encouragement should be gwen for submittal within a reasenab!e period to acco_odate :he work schedules of the respondents.

Some toP, males o: ,]overnme,]t _gencies were represented b F .-mre thmn one individual one had -_', t£sually at different divi__ions af the sar.¢ :o._-p, any.

!n one inst:u_ce, a me,Set of one division had lad'.cared to us that he we<lid be returnin_ a cuest_onnaire. ;_hen contacted about ei£h[ weeks later, he noted :hat s:dDsequentl:,"he had fotmd out that a member of a sister divis_:cn had __ireadv submitted a top!v, s_nd since ne thought ;_e needed cnlv :he reFlv ?e - cc:]:m<'., he did net bother to subP.it his. in the future, :,hen ?oil in< -_iittFie <e<bers of the <<he cc_p_any or a_enc',-, i::strt:cticns shoul! be expiiclt as ta '.,bother [ndi,,-iiual :r coorie_ated reFiies are .iesired.

:l ,_as ........... ] :'.',_.ber 3_ ":''" ' I; I Y.Ot ,'_,"-o_': _--_ " t:<&t "_'" na,i ne::'::n< ,:f '.a_de tc _n ...... to ::'.e -,e'.era_ ,TOte _,_ u:d :il .u; . _,_ ,_hu ' '"_ lontacte<[ [,iter. [t '' " _ _e _- ,.,5 .... _. as ii- *-_ Dt}ter__ '"- ,u.. ,c_.i. _. _r<at ,..ai.le '-.,, " .... _._ _:.:I-.'¢'.S ID :el ]R !:72e_ille _ee_a£k ,211 :_nat K.:_ _" -e-=''[l. ;0 2:L:1 }'e "-e'''-_'.X, ._-. :_"'';L_"->_*. _ ,1 _o;t:tlr.l' 5:Ioti;4 2e enci?se4 "_ .,.,e_.4_-;-_' ;_" _, _'et it-, • 1 , - z which '_,oald i_dicate whether or not a response will be forthcomir.g. Ibis step _,ott!d aid tremendously m planning the coll_ilaticn of the survey results and kn estabtfshh_g a cutoff date _cr i-co_orating the results in the mah_ effort.

l]_is appendix is divided _nto two parts. Part 1 presents the survey/ questiomnalre, including the cover letter, as it was nailed out to the various individu,zl s • in part 2 _s the stmmm_" of the questiormaire responses received from industr." and C_vernment. _e replies are stm_nar_zed qtL_ntitatively, whe"e t'o_-s[ble, and all comments of interest have been included. The results in cart i have been used _o >t_pport the assessments, conch_ions, and ":-ecorrm.endationspresented irt the body of this report.

_aPPE\'E'4X D- t L_:_ _ :R F'fiA.\S,_!: :'F_. 2X'8 51rR_,2_" Qtt!STION,X-\IRE

ASA

. ] A 1 ..... . : • \÷'_'" r" " • £ "= b: Dear NASA has recently started a new program in aircraft icing re- search at the Lewi_ Research Center, Cleveland, Ohio. The program will include in-house research, university grants, and industry contracts. Since you are a member of the general aviation or small t=ansport aircraft indust_" {manufacturer or operator_, >'our reco_mendatio_ for our icing program are i_porta_t.

Therefore, we have rnciuded with this letter a ,_UESTICNNAIRE cn aircraft izin@. Your responses to th=s QUESTIONNAIRE will help NASA Jetermime what advances in aircraft ice protection technology will most benefit your !ndusto'. We hope you wiil conslder this an opportunity to voice your concerns about air- craft icina, _n] to influence future NASA research.

Rather than send this _UESTIDNNAIRE directly to the person responsible far ice protection in your orq_nization, we are sendin; it to you to insure that the responses represent corporate technical policy. S=nce the _UZSTIONNAI_E is rather long, please respond only to those cuestions that }'our orglni- zation rosario as important, Please uniersta- J that the enc'.esed OUESTIONNAIRE is i_:tended _o aid you _n ....... _ - _'" _ _.._ :.....s NASA. It shoul. _.

be cons:.lerel as a 7uiJe. Please feel free to omit answers to 1 .... u 5 _,,..< erns ....... _c, • -.

__ :____e _ - LI_=A =s :-_,_'_ in ":cur i_eas, sot toe .[_:-t in .._ , C _ " - be "_- _ "_ _ ''" tunder nc • . S _,m ..... are :i're_ Ca-_e.= '_.. _..<,iJer]ti?n.---- 2.

If you choose to respond, please de so within two weeks of the date of this letter. Please send your replies and address an Z inquiries to: Mr. Robert Breeze, MA-14 Rockwell International North American A_.rcraft Eivision 815 Laph_m Street E _ Sugun.do, CA 90009 Telephone: (213) 647-3995 Sincerely Allan R. Tobiascn Manager, Aviation Safety Technology Enclosure ,_iROu_, ION The ':ASA Lewis Research Center, Cleveland, Ohio, has contracted with the North American Aircraft Division of Rockwell International to conduct a study for smal] transport and aeneral _viation aircraft icing research requirementS. The objectives of the _tudy are to define for NAS_ both a Ionq-term and a short-term icing research and technolagy program that is resmonsive to the needs and desires of members of the small transport and general aviation industry.

=or tne pu_oaes ot ;he study and this survey, small transport Is de?ined as fixed w'ng aircraft of uP %e 30 passengers, having an annual utilization of _zaut _0 hours in scheduled o_rations, and operating primarily at altitudes at or below I@,000 feet. _eneral aviation re_ers lc fixed wing a!rcra:t utiiized in r_on-mi]itary and unschedule_ airline operations.

_ircraft 4!in the following t>mes of engines are being consigered: jet and fan engines, turbaprees, and piston engines.

..B ...... E5 '3_ THE '_ R -_c eb'ect_,es s# this survey a,'e to solicit from selectee gene, al a_:_i:_n an,! shall tr_ns:ort manufacture _s and government agencies technic2] datA, wher_ a,/ail_ble, but _cr'e im_ortantl}, t_e ir views, ---_en:s. a_4 r_cc_r-e_da:iens concerning iclnq research subjects.

Z[, s_ouTc be considered by _he respondents aS an e:portunit: tc .e'_e t"e _¢ Ctnce_ns _e!atin_ to it!no and ici_ oroteeti_n, and ..... _lJe_ce t_e d;rection cf _utu,'e >;_SA re_earch. Your inputs .''" _ :'*e -ef_ecLi:n ;f the broacer vie_ of the general 3_'_-'_rq 'ndus:": !_ the rec_-endations given to NASA for snort- 3no icng-te,-_ resea_c_ _lans.

_$ta_l_n@d ice Protection S>s%@'% include {!! not ai _ Frc_,_ com- i, ;resso," Diee:, {2! electrotne_':_'a!, (3) pneumatic boots, (4) engine waste neat, and 15} anti-freeze Fluids, The JSS_ has deveiomed an electroma_ne:ic-i'r_ulse ice protection system for wnic_ the?

are offering liceqsing agreements. What additiona: develoD_ent, research data, design data, or performance data are required fDr tne systems mentioned above?

, IcephQbics (ma_erials that reduce ice adhesimn) development is a high risk, high mayoff ve_ture. What priority should NASA place on developing an ice phobic?

_Vat are the mo_t important features tha_ any new ice protection , System should provide?

If new ice _rotecti_n Syste_'J could be developed or existlng ones improved, wn:cn ones _oald _rovide the greatest payoff?

"_n"er"a.,or_ "_ is needeJ an penal'_ies to 1:ne _ircraft or to individual -- _-- _ n ..... Jtt ___ _c r,- is requested t_a[ Tab!_ 2e t':l_,; O_t _ar the _a"_cus a:rcra#t or .-3mponent.3 "qa ,u:zc_e,l or :esteC 2, =:_ CC•i_arl, f_r- _n_C_ icing eer:a!t:es a_e a_il_.,.. 'Iota t"zt :'e_a!t_es ma_ _e cl,,_m 3s _L_a _aiues, :f known, cr relative rar•,kiq_'S _; *n _ _, . e pen31t_es ',n_c.l',ed.

"q ace',tic ,, :eqalt!es .'r, ._'rcr_ft Cue t_ t_e use ,z; i'=.. .,.,.__.._*_-'_-r .<,s:e's _,'e als'_ _'o'_._...... "" is re,zuested tqJt "3_]e ,''. _ ;_i':eCi _'_,t "or t'_e ','a"_e',,s 31r,Z_'aft, engines, :_ COmPonents -am_e_ctjred - " ' _e - -, ..... _!_,er! a_ 3CZLJ3 CI" ".este_ _, ,.L,Y _, .3., . -,G_ q ;'era ties ",_ ,4,.e3 3r "," are t.r- -" re" "i',e ran&!n:s. _*- tqe _e'_3_aes 2_n ,am;e'.

",,--._,.., b'ST£V ''" " _3 "_ L_re [ J t'<; _.>, "".:4 " ,," ,, e,,_r_es " ! '• _ .! .l F ." .tat'" " _ .... "_ _'"_ .... _"_"_ __'e _ Z._'_!'_ _ _'_-_' _' _ 4_ J_ m J _ R_ i m _ i m -- b -- _z 4_ m m_ i_I -- _ w_ v _ ml t_ -I m _p m _r <<U _2 J ,it z -- ,_. -- - = _.

--7 --- == 7q=i=- _D,." _ -- L Io %

_- 77

Z T-_ .< ZZ _- T_ • TL _ _ T'_L, _" _C,;_ Ai,-fo_i lift, drag, pitch moment, and stall s_eed increments cue l , tO ice accretion nave beer, obtained in the past in the NASA Lew_s Icing Eesearcn Tunnel (iRT). Do you want such icing sensitivity data from the IRT for the following: YES NO Airfoils on your current aircraft Your future airfoils 14ew computer Gesigned air_oils (Low Speec, Laminar rlo_ Supercritica I_ 2. Do yoJ want N_S# IKT data en ai_foii ice sna_es fl-om which artificial ice shapes could be made for use in dry wind tunnel and flight testing?

3. are tqere ant aircraft C2m_onents. es_e:iaily v_!nerablt to icing, fc,- wn_c_ tne airframer needs soecial design gui_e- lines. (e._.tail balance horns)?

_, Nnat research ree_s to be done to ma_e ice 2rotection s_stems compatible _Ttn air_rame CCmmonents mace of cemccsite materials?

5, in Ta_le : please iment::_ the _ce sensitive com_one,_ts _nich recuire additional research, and list, in order of i_portance, the re_uirec research "n the areas 2 ? (i) ice accretion or _a:er :z!iect!:< e_ficie"cz, ,2) _ce shecding, (3) ice zrotection systen. (_) perf2rmance ;eqalties, ,:.-_T.P,L_ _,..j'_ :._bE-< Ti_e cetnods listed eelJw are Jses fi]r determining (l) the natare and e\tent of ;cing of a comoer',eq:, L2' i_e pretecticn S,stem 7erferm-,ance, arc ,,S', aircra-: performance :enalLies cue to eitner ice accretion or 1co protectirr; Syster'; ccerat]on. _ases on >cur e,,2er_eqce, :?lease c3[m:eRt cn S_cn "_actcrs as _."e a,.cur&c/, _rac- flea;heSS, aval_a2,i!It.,, anG casts of tne:e :;etnc,.:s.

F.il-scale ic_n__ _ird t._nr,e] tests #.2-sca'e ;-l",c ,,,_r_c, S_r,':e', tests :n--l:.;nt tan_.er" sofa, Sic.,,:. t.e_t.s ]r'c_rl_ S2e_y C_dd tests F' _"t _O_'atS i'l q3'_,ar},_ ,7._,,Jbd - ar'a_:t;,:a: :e _e:.:_es ._r "d .:c"L..,%er c.c:ea ether _nat improver;eqts snou!d NASA make te their icing facilities?

_]ease aiscuss such ]morovements as test section size, air speed, range of icing parameters, instrumentaticn (e.g., force balance.

cloua parameters).

3.

Should the NASA Lewis Altitude Wind Tunnel be rehabiii%ated to provide expanded icing facilities which include a 20-ft diameter high speed test section (up to M=I) and a low speed 45-ft diameter test section with speeds to 200 knots?

YES. _ould be willing to use on a cost basi_.

YES. But do not foresee any immediate application for us.

_0. Our facilities or test procedures are adequate.

LO. No need.

OTHER: ShoJ]d smra/ s/stems be standardlzed ;or the existing _cing spray tar'kers, and snou]d instruments fcr measarirg the spray cloud ;_o_erties ce standardized?

,:. :A_CULLT:ChAL T_SH_i'_UES T_e_e are a number cf handbooks a,ai]ab]e wnicn prc_ide tecnnical icing _ata. W_ich of t_e fo_;o_ing do you use?

F_: _u_-4 Enqineer_ng Summary of Airframe icing Tecnnical _ata r._ _-,,-,6, Engineering bummar, af Pcwerplant [clng TeCh- nical _ata OT=E_: _cT'_e: _L- i'7:3 ¸ ECr_:,J'._r ECCeS " '" gr'e_ ir_linar, ¸ Jesi_T7 traJe-J_ _ St_g_S _r71 _,:r- 7r_'.s tc mission arld_/ses?

A':3: ne;_ i_ jr::e£_i:!, S_:er_ areas cc voJ feel need tc me a::_'essec _. these or qe._ ".ecmRi23_ r_Sr_d, ccoks?

4.

,_:C_ _',1_,_:" ; a'_JS C2,e"ec ::, :rleSe "_ndCCC:_,S OSt rlee3 7;"g. rL;,_ 7e r, -_ Please list and briefly explain a l), computer codes you use to design ice protection systems and to determine icing penalties.

Indicate whether they are proprietary or a_ai!able in the open literature.

, Listed below are several computer codes that NASA is either procuring or planning to procure.

0 Water drop]or trajectories for _ater catch rates and impinge- ment limits on: 2-D lifting bodies (wings, tails) 3-_ lifting bodies (wings, tails, fuselage) 3-D non-lifting bodies (fuselages) #_isymmetric engine inlets at angle of attack o Steady-state heat transfer for anti-icing analysis.

o ice accretion modeling on wings, inlets, and rotors.

o PreJic:ion of aerodynamic penaltles due tc ice accretion.

O Transient neat transfer codes for de-icer ana]ysis.

o Predict:on of shed ice trajectories.

Will _nese c_m_uter codes be of _se to you in addressing your icing requirements?

*_ES. Would s_ooie_ent or replace co_es currently used *YES. Current]) dc not use coi_puter codes NO. _oulG nee use any CO:_cuLer coGe_ OTkER: _hat ao_itlona] codes cr S_OCI_I CezLJres wcu]3 zgu _a'eL it" _nes_ cad_] 7. 2lll_ t!lem_ _2C_6 _l]] reqblre e_te,_s:_e in-hOuSe e_verCise ir_ crcg_'ai_:ilrlg s_d a_iai.,sia, SCr'e c_:'_ie_ _la, pro;or to bu ! suc'_ ar :ze ::'.:teLL'c a:-al, _- Je':t=,,- _;':la," t. ire _i_foil Ze:]::_ 4r:a;:5_ Lore- :reatec : ',:2_ at On_c _tate _lllwers'L_?

D ii I , Are you setisfied _ith the FAR 25, Apoendix C icing envelopes /or certifying genera] aviation and small transports? Please explain.

.

What changes woulc you like to see in the operational consLraints (certification requirements) relative to icing, in order to improve utilization of the existing and growing body of general aviation and sm_ll transport aircraft? now would you justify the change?

_hat advancements are needed to help justify the desired cnanges of question 2 ke.g., instrumentaticn, ice protection capanilities, and _eatner forecasting)?

4. _hat improvements in weather forecasting would most Cirectly heip _cing forecasts7 Are '/ou satisfied with the present method cf categorizing Lne Icing condicion ie.g., trace, light, moderate, severe],? Please exoiain.

[e ,/eu _ant an on-ccarJ instrument that measures cloud oraDert_es an_ that ce,uld _e used to evaluate the aircraft's capabiiity to ooerate in that kocal o]eua environment?

[c _c_ tni_k a pilot training movie Sqoui_ _e made tidal actresses t-e crcc]ems cf flight into icing conoltions_no_ to avoid it, ho_ _t affecLs aircrzft cerfonuance, FIOW tO cope With it, a'Id now :o gel out of it?

ahat asDect._" ct t']e iclng 3roblem most reed a_.e'__"_ on? in the snort Le_m? in t:'e !ong term?

'" ,,hal _re3_ of t.t'e - 3r'cDlem "_ _" ' "" _ • " 1,_in .... _ greatest.

.....r1_u.:cr7 :n trle snort te_? in tne long te_'=?

SU_,Rk " OFQUI=STI£'N_&IRH RESPCNSZS

Section I

ICEPROTECTION Sh'S_S

I.I ADDITICINAI DE_TELOP_N_, RESEARCH, DESIGN, OR PERFOrmanCE DATA

N_FDED FOR ICE PROTECTION SYSTE_ i. Updating of icing information in _]S-_ and NACA reports for new airfoil series.

Z. Regeneration of FAR 25 envelopes.

3. Carburetor anti-icing techniques, including icephoblcs/fuel additives.

4. Trade studies of cost, weight, and effectiveness of al] systems.

5. Sta.ndardi:ed design methods tc reduce engineering and certification costs.

6. Generalized computer proKrams to determine heat requirements.

". Electromagnet ic i_putl se : -- Would like to see further development.

-- Need relative effectiveness, power requirements, fatigue, desi,zn L_Ip act.

-- Testing would be 3dvantageeus to prove the performance of the system stud to provide enough information to accurately assess system ad,;antazes.

D-13

I. 2 ',_klTPRIORIZ7 SHOULD .NASA PLACE ON D5%-£-LCPING .AN ICEPHOBIC?

<

i i i _RY LOW MED HIGH \ERY HIGH LOW "PRO" CC_ ENTS I. Ideal to develop one which _muld also shed bugs and maintain laminar flow.

2. Aim [owards objeczive o£ being easily applied, noneroding, and highly ef._[cient.

3. Breakthrough is very close - further ._&D is not high risk.

I. I,'therent low cost, low weight, and Jail safe simplicity are extres_ly attragtive.

5. _%LZA should continue to investigate the }cephobic properties of new .naterials and coatings. Also, some testing may be done in conjunction _ith other deicing systems, such as m/crowave, electroinrpulse, etc.

"CON" CC5_,E\q'S L. Not much _o:ential in pursuing.

2. _,'e_-low unless one could el ininate a system cr protect difficalt to de_ce areas that might she6 _ce.

3. Low to middle _r=oritv 'anti! a prcmisin_ material flnilv is /iscovered.

i. Risk 7a>'o(£ _ee_s too high.

D-II I. 7 _P.kT ARE ,_- bk_ST IFIPORTA.",'I_ FE\!L_ES CF ._\'Y b_h' ILT PROTECTION SySTEXI?

No. of LLme Cited Fe&tur_ Low Cost Low Weight 8 Low Power Loss ._equirement 8 High Reliabili_" o 6unplicity of Operation _,linh_num Effect on Perfm_,-nm_¢e 3 Good Capab_llty 3 Low l_ra_ Lo_¢ _klinten_ulce l l \\lick Nes_onse H_n_ni:e_ ?t!ot ",fork Load i Predictable so as to 5Ln_pi:fv Certification i 1.4 I ,_HICH .NTa" OR I_.[PROVED ICE PRO_I'EL'TIONSYSTEXZ I_DUI.DPROVIDE GReaTEST P.\_,OFF?

Svs tern Ne. Times Cited _cephobics Engine Waste Heat .Xlicro_ave .antifreeze Fluids Leadln Z Edge ._ti-icing Acoustic Ice Detector Windshield Ant i-icln_ i Passive, I.o_, Weight and Power 1 ,,,,pro_ ._. _elvLng i .7lies e : -_ a._ -" Supercooled Proptet Transfor_.er 1 ElectroL.-pulse i [_ io

Section [l i I.1 .ADDITI0_L%L CCB__\-FS REGARDING ICE PROTECTION PENALTIES I* l_'e have been in_mlved with three aircraft icing programs where free:eup of the movable surface to the fixed surface occurred due to the configuration of the balance horn. One aircraft experienced iosq of rudder control. T_n aircraft configurations involved loss of elevator control. In all cases, design changes _ere neoessar v. One aircraft configuration encountered strut buffet during our natural icing flight rests. The buffet was subsequently reproduced with ice shapes attached to the struts mud the buffet traced to _rte× shedding from the glaze ice horns. Redesign was necessam-. The above deficiencies all involve tqight safety, structural loss ofa wing strut would have been cata_trophi:. Loss of pitc_h control cou/d be overcome by pilot skill if the situation were properly assessed by the crew. Singly, loss of yaw-- control on a nultiengined aircraft is a small n_K_er.

_,e largest Fenalty which could be ameliorated through K_5A sponsored R,SD efforts is the desigm time _md development _rogram cost associated with assuring safe and reliable anti icing sh'stSa_. The weight, performance, and cost penalties to the overall aircraft can best be qum::ified by the airframe comp_mv since, in virtually all cases for the class of applications se.'wed by .-\iResearch engines ,.4PU'_, business aircraft, _ud flight transports_, ;,'e are able to design our engines so that they do not require active anti-icing in the _'ngme, and our requirement i> on'_v to suppi 7 a Source of bleed air to the airframe for inlet :mr _-. zc ing.

Section III

PROPLISION SYSTT!_I ICING

[II.l ICING RESF_,kR_{ N'EEDED [N SUPPORT OF FOLLOWING PROPULSION CC_c'tgN'LN"TS &_RBL_ETORS Needs further research.

No need. [_'7 Needs more stud}- - u_ing advar.ced ice detect,OrSo icephobics, fuel additives.

Research on icephob[cs ,_otfldbe of benefit.

Tests of fuel _dditives to prevent carburetor icing.

Tests of throttle plate coatmg to prevent ice formation.

C,£!;L iyGS Needs further research.

_OIIC ,qee_ed . _ _ t- \Iter77ate air fnlet5.

_bre - < ...... ; " _' " " " [_ok !t tuqe o_ _ engine oil for it:., protection.

Reseai_ch on icetq_,obics. _,euh! be of _._.it._'_ Desi_m " ' ; --, to_ decrea._ed ._ 3cct_t_lat_o;_ on le:idin< ed<es ot ce_,l[n_.

FRI?_._/.LI: ,L< .,.l. _,l_. Fese_IFch.

"_eed :e'hfiqe ,_''_.,.rn.,l_,_ t_, •":.__..'" ......._.t. m_''., c'"'. :,.

>:Cn_" "" : " 00_ ,It _:;t" _: ¢h" i'.? _', : ..... '_ PF_t'"''' ' I i [.i (cent inued] INLET CdIDE V:W,RS .None needed. LI_ Need ice particle trajectoQ' analysis, icing H.T., standardized tech., etc.

Look at jmming tendency after delayed actuation.

Conslde, m_e of engine oil for ice protection Research on icept,obics _ould be of interest.

CORE INLETS Neec',s further research.

>(one needed. _i] .Need ice particle trajecto_" aria!., icing heat transfer, etc.

Look at '_e of engine oil for ice protection.

Research on icephob_cs woL_d be of interest.

Cowl :rod Ifp shaFe ceklectien efficient) as 6motion (inlet vel., :mg!e- of-:_ttack, droplet si.:e'_.

_sire performance ,und effect of rtunback ice due to shorter heated surface" ler,_ths with acot_stic,l[ treatment aft of inlet lip.

Need ice 7article trajec_orF ._nalFsls, icing heat trm_>fer, etc.

Rese_.rch on icephobics _ouid be of benefit.

Nene needed. _I -, -_ ; -_ , -_- ; •-- _ ,mnal'c_is, ' " he:it "'_ U1st'er, ¢tc

I[I.2 AXALkZICAL :VID EXPER_,E.\TAL RESE, kR_I P, ECIJIRED ON SHED ICE CONTROL

.-L\'D E\GI.NT DEICE HE.-_T TR._,,NSFER I. Doubtful trajecto_" analysis could be applied with confidence. Look at deicing radomes to control mass and form factor of shed ice.

_. Would like to see flight or wind tunnel ice shedding tests.

3. Look at inertial separator used for typical turboprops - low weight, low drag, simple, and low momemt_ losses.

4. No additional research needed from airframe ,nm_nufacturer's vle_point.

3. ;Vat_r catch research on rotating spinner shapes needed.

6. improvement in methodolo_" o_ shedding ice required.

-. Need research in _hat cerises shedding.

8. Desi_m _'ui/es for inertial separators needed.

9, Look at use ot e:¢hau__theat to deice engine inlet lips_ I,_. _Lm for _e_, cost engine deice system - no research needed for shed tee control.

p-:!'

III.3 P_SL_RQ]_ REQU:PHD TO _L_KI£ICE PROTECTION SYSTemS .COMPATIBLE _[TH 5NGIN]ffC(I_O,N_\'rS ,_!4DEC'F COMPOSITE ._._TERIAL5 I. >:one, but need basic data on aircraft components of composite materials, 2. Impact properties on engine composite materials.

3. Thermal characteristics of composite rraterials for inlets and nacelles.

4. Testing to develop thinnest possible skins and verify heat transfer to surface.

D-21 Sect lon I¥ AIRFP_%\_E ICING I%'.1 1g3ULDYOU LIk32.NASA IRT DATA ON AIRFOIL LIFT, DRAG, PITCH ._Q_NT ,_.\_ DELTA STALL SPEED?

YOUR FLFFJRE AIRFCILS?

AIRFOILS ON YOUR CURRENT A/C?

i L_ , , I i ! ; ! i L _ZS XO NO AXS NEW CO_IPU'TER-DffSIQNFD 4[RFOILS?

YES NO NO ._NS D-ll !V.2 ;f_brLD Y©U k::_ K-_.a. IF DATA ON ICE SK-kPES FRt_..I I%tlICH .A_RTIFICI:_L ICE SE-_PES COULD BE >tADE FOR DRY t_':._D II._,'NEL TESTS?

__i

--4

J

YES NO NC .a.NS P-25 IV.3 AIRCRAFT COp{PONT-StS \3JL\ZR_BLE *0 LI.NG .N_EDING SPECIAL DESI(_N CUIDELIN]_S CO,_IPONT_\'f NO, OF TI)ES CITED Balance Horns S a_ntennas S Stru_s 2 Control Surfaces 2 Nose Shapes l Exte_mal Inlet Scoops 1 _.ng ine [_iets !

Props l Stall Warning Devi_es i Windshields 1 _x_osed ;q_eelwells 1 None Needed - No ' - - ,,_n>x_e: i0 D- 2_

,_tbT RESELRC._ fS X_LDLD TO Y._J_ 1_ PROTECTI@N SYSYDIS [\%1

CObfP%VIBLE ;.IIH dC_POSITES?

i. Applicability of therm.,M devices - other syste._?

i. Investigate p_.culiar problems associated with variou_ systecs.

Study ice protection systems for carbon fiber co_poslte leading edges.

5. .aa_aly"ticalinvestigations should be made to determine t)_e of system most c_mpatible, followed by icing wind t_v-nel testing to verify its adequacy and establish design parmT,eters.

I. Heat tolerance of com4),osites.

5, Long term _atig_ae of cz,mposites when _m_ing pulse or who'_tory methods.

.Also, effects of a_ntifreeze fluids on _:orq:osites.

6. Testing., to d_velop thinnest possible skJa_s rand verify" heat transfer to surface.

D-25

Section V TESTING TEC}_NIQL]2S V.I RATING OF METHODS FOR ,%5SESSING ICING PRI_BLI_S RATING AS TO 5_.THOD OF %CL_'RAL_Y Full Scale Wind Turmel Tests Flight Tests in Natural Clotm, s In-flight Tanker Spray Cloud Tests Analytical Techniques Subscale _cing Wind Tunnel Tests Ground Spray Cloud Tests ._DST-TO LE-\ST PRAt_IGkL ._ETHODS In-flight Tam_ker Spr.%" Cloud Tests .-Mm Iytical Tec,hniques Full Scale ]find Tunnel Tests Flight tests hn :;aturai Clouds .]round SFr: b" Cloud Tests Subsca'_e Icing Wind i_mnel Tests In-flight 7_mker Spray Cloud Tests Subsca[e Icing ;_ind Ttume[ Tests Full Scale IcLn_ Wind gtmne! Tests Fiigi_t Tests in Natural Clou_ tna i,,'t icai Tec!m iques ,_rotmd SF,,-av C_oud :ests V, 1 (continued) IEAST-TO-SDST COSTLY ._ETHODS .knalyt ical Techniques SJbscale Icing Wind Tunnel Ground Spray Cloud Tests In-flight Tanker >pray Cloud Tests Full Scale Icing Wind Tunr, el Tests Flight Tests in b:atural Clouds IdlPRO_-_Zx_\'TS .'i&SA SHOULD }t:d,]_ TO HEIR ICING FACILITIES V. 2 Increased range of liquid water content (LI_C).

1.

Improved force balance systems to obtain lift, drag, pitching moment data.

3. Imoroved inst_Jrnent s.

¢. Higher speed capability (to 400 mph).

5. Lower temperature.

6. improved wake drag system.

7. p.egurhish vanes, blades, etc.

8. Droplet size and LWC calibration.

9. Blowing/falling snow and ground fog capability for engine inlet tests.

13. _Dre tum_els to reduce lead times.

11. instru_,.ent tz_r_ek for "frost" testing, 12. Altitudes to 20,00[) feet.

13, &utc_ated control system to assist in faster stabilization of tunnel conditions to save tLTe and ener_'.

1_. Uniform cloud at test section, [5. >teasure_r.ent of droplet size and U,_C during testing.

Io. Cor,_uter-I inked ,!ata recording and processing.

V.3 SHOD%D K&SA-LRC ALTI_DE WI.N-D IFJ_N'EL BE REHABIL!TATE&B TO PROVIDE

_XP..<'<DED ICINg FACILITIES?

=c

I ' 1 ¢ I L I z I ?

I i

21!5 YES NO NO ;_£_{ER ?,;0 .1NS 5 &',_,'$_\'T S Increase _m2ge of Lc_',g parameters.

i.

Do not associate ![ -- i requirement with icing as a problem.

2{30 ._mots adequate.

. First priority shoLild be ciL_t[c research.

1. Need £Io_ provisions to _est cngLne inlets.

Also, alternate rain spray tics.

D- _J V._ SHCL_-D SPK-\I SYSTE_t_ BE ST.K\_I_kRDI'-ED FOR THE EXISTD;G ICING SPK_Y __bTR_IKN, S T.-K.N]v_RS, .-%N'D SHOULD SPK&Y tTLO[_ PROPER'DJ _,_-_SB?__'3_Nq" '"" BE ST._\_M_E'IZED?

YES ._NS I I i

- I

I *'Hne "No's" ;,ere ,_nfferred from the foilowln.< cor_aents: h_ubtfuI standardized _,'ste:r. could bc developed. _,ea'_ need for real tzne, a..or,.abl=, water drogiet di:_meter system.

No need to standari_ze, '>L_t desi<n guidelines x_c.uld be useful. Eeed deveto rcent of inexpensive, reliable, imnedlate readout of LWC :rod droplet size instruments.

7refer z,,t to fly beh'md a ta,'fi<er due to proble,_ with controlling droplet _-'e in !C-aO_ r_mge _md difficult)" in controliing .H_rav pa_tern.

_,ve_op ne_, equipment.'tec._niques to control :rod measure D,C and droplet s _ 2e mr<" LICCLIF_ItO _}", >:tal;d&r._igation second in L'_2ort;Elce to aCcLlrate -eoasure:nent ;trld prediction of droplet size :rod distribut[on. 5t_mdardizat_on _,q', prove too _imit!ng beca_L_e ccnd:tions differ ,.,Lth a:rcraft t\_,e, Mt,_tude, Oper:lt I.OES , OEC.

co;;[d :" " .o-._I .., i:1 c._c_P_!c_t:,?r! l_]d o_'oI_.5_ ' ;_[t}:ot;t ;::p: )vc:%':lt i;l :e_,;_a." ''-

Section VI

CALCbKAT IONAL TE_IQUES

VI.1 THERE ARE A NI_IBER OF F_\]3BOOKS AVAIL_I-E _HI(_ PRO_ffDE TEOGICAL ICING DATA. _HICH O_ THE _OLLOWING DO YOU USE?

,--]

i F)A F.<-\ <_2_,iR NO CTcT_RS NOIZ_D: W.___C I_ 34 313, A Pesi_m _b.nual for Thenn,.,al A/I Systems.

I.

2. "Anal',.: ical Invest _;at_on of Aircraft W_n,JL_hield -_nti-ive G-stera-s."

3. 5AE ;_plied Cnerne&,-n&mlcs _.'_ual.

F-\\ kdvisop, d:rc:_lar 20--3, ".\ircraft Ice Protection."

4.

3.

F.'d< 25 .kp?endlx ,7. Not a h:mdbook a_< such, h_thor.

7cu;_as k:rcraft 7_t. _'_'x!--'F9-S, 'm_muai fer Aircraft _ce Prctectfon."

P-3l K ..... • VI.I .L_,E _ DESIt_ PRCCI!_/RES .%_,_D ICING DATA IN .LDS-¢ SUFFICIENT EN'OUQi TO BE ',_'t'_RK_D UP INTO C_I_trI'ER CODES FOR PRELI_II.XLMtYDES[Q'N TR4DEOFF STUDIES .Z'_-DFCR IN'PUTS IN'FO ,XlISSIC,N .<NM.YSES?

NO ._S _hst be a_,are of i:]accuracv o( data due to measurement techniques of the day.

• ".bzited appiicat fen.

it ma)- '_,e better to tkqe it nn the 7_mner it is presented _md t!_en _rite a sz,.._ple co_uter code te ha_ndle a specf£ic prob_e:n. Ln all eric. ",assb_g preg_-am tends to not be general ene_:gh to h:mdle all _7;ec t fic proe_e_.

[}_ ;" VI .3 ',¢._AT £'E]_' TCE PROTECTION PROBL_I ARi%S DO YOU FEEl. Ne_D-_"TO BE ADDRESSED BY *_ESE OR N_fiT TECRNZCAL RA\_)BOOKS?

i.

Protection of lead_ng edge devices.

_° .411 new generation materials.

3.

Neither handbook has sufficient water catch/shape data and both lack information on rotating systems and ice surface adhesion. Additional information is also needed on convection and evaporation for the _rious shapes of interest.

Rotors. No good system exists yet.

S.

Reevaluate icing criteria parameters, airfoil icing shapes data.

Parasite ice on surfaces parallel to airstre&m.

Shadow-zone and high concentration zone of droplets in the near vicinity of a fuselage. Also, effect of engine m_s flow on _'ose cowl ice collection, and L,mp_mgement &nd aerod_mamic effects data ¢n new type airfoil>, such as s_&ereriticai, both _ith and without high lift devices.

S. icing of non-airfoil surfaces.

n-3 7 Vi .-t l_]4IC-! K\IST[XG ARE.&S COVERED BY T_SE t%_.\'DBOOKS NEED k_OST [MPRC\_EN'F?

i. ,_bre accurate methods to predict ice shapes which could he sLmulated in dry" air tests.

2. A good primer for certif'f_mg to FAR 25.1093 and 25.1_19 would be helpful. AC-20-'3 is ve<_' incomplete.

3. Design methodology, design parameters for optimization.

_. )Dre exact ice shape prediction '_uld be beneficial. :Llso, the thermal a-nal>'sis given Ln the &-ZE manual should be expaalded to cover the exact alrfoil bemg analyzed.

S. Use of antifreeze fluids.

o. Reevahmte icLng criteria parameter, airfoil ice shape data.

_. Preclse methods for determination of ice shapes. Ice shapes on a 1O cn ball could be precisely determined under vario_Ls nest conditions mld used as an uapmgenent shape.

VI.5 PL_SE LIS'_ .g\© BRIEFLY EXPLAIN ,k\Y COHPUFER CODES YOU USE TO DESIGN

ICE PROTECTION SYSTDIS ._D TO DETEP2,[I>_ ICING pKNALTIES. INdICaTE _,_I-[ETb_j[R TIa_" ARE PROPRIET.ZRY OR AVAILABLE IN THE OPEN LITERATURE.

*Windshield and engine inlet anti-icing - co,any programs published in FAA certification reports.

"POT" - potential flow program - two-dimensional or axisvn_etric bow 2a.

field. Can accept models with one or more surfaces, such as an engine inlet with centerbody. Can account for engine air appetite. Includes subroutine to rotate the model to any desired angle of attack.

Accepted by F.aA.

Uses pitt to compute model Zb. "DROP" = droplet trajectory" program.

Imposes Langmuir A or D droplet i_pingement limits and water loading.

distributions as coded by FAA.

2c. 'qqO, T" = thermal program. We have developed a handbook of methods and techniques for steady state and transient. Unpublished.

2d. _Handbook for glaze ice s,h,_peprediction using analytical/graphical :nethods, using output of DROP. Water loadings within the stated population form the basis for shape prediction. 5Dthod accepted by FAA.

Computer progrm,_s based on handboo}s of \Z,I.

_. Icing collection analysis prcgTar_.

5. *AEROI,_, described in ._=FDL-_I-,9-91q_, and _ _ available on request if approved by higher headquarters.

6. *Compa_ny ther,nal analyzer program, impingement and heat requirements proton.

Several heat _ "*_ and droplet traiectoD" programs, 8.

Ice shape progran.

Aerod)mmmic flo_ f[eld definition code.

9a.

Code for calculation or: water droplet trajectories to compute _ce 9b.

collection efficiency and [Lvits of L._ngingement.

Eeat trmnsfer a.nai'.'_is code to !ete:gn.,i:_,e evaporat:.on :-_te::a_nd :-,_:back 9c.

;.de _t,-,o_ i1_t s.

' _-L.£ as _roor_etarT.

.kll '_ * tlnese ,._ere tdent _ .....

P-35

VI.6 I,_HICH OF THE FOLLOWING CC_ff_UTER CODES Z'{AT .NASA IS EITHER PROCURING

OR PL%\NING TO PRC_ WOULD BE OF USE 113 _©U IN ADDRESSING YOUR ICING REqUIREY[h';S ?

.No. Times Code Cited Water Droplet Trajectories for Water Catch Rates and Impingement Limits on: :-D Lifting Bodies i0 3-D Lifting Bofiies 12 3-D Non-lifuing Bodies ii ._.xis)_etric 5ngine Inlets 9 at Angle of Attack Steady-State Heat Transfer for Anti-ice ._nmlysis ii Ice Accretion 5_odeling on Wings, Inlets, and Rotors ii Prediction of AerodyTm_uc Penalties Due to Icing 13 Transient Heat Transfer Codes for Deicing Analysis i0 Prediction of Shed Ice Trajectories ii No Answer 8 ;*,FAT _]DDIT!C?£_I CODES OR SPECLai Fr--_.Tb%LES WOOID YOU ;<aN T IN IPdE,..SE CODES'7 i. Liquid water content and droplet size.

2. rce collection efficiency, upper and lo_er surface i_)ingement limits, etc.

3 Ice shed trajectories from wings to rear mounted engines.

Prediction of ice adherence characterlstics toward outboard sections (5-D effects).

5 Nona.\is)_netric engine inlet applications.

D-3O VI - 3iXCE ]_ZSE CODES WILL tt_QUIRE E.'CTENSI\_ IN-HOUSE EXPERTISE IN PROGK<,_,IIXC .<VD .<KALYSIS, SOME CO_PA'qIES 5[4Y _REFER -'0 BUY SUCH SERVICES. 'allEN TI-_SE CODES BECOME 0PEP&TIOK4/., SHOULD X%SA CRG\TE ._KXICE ?RGTECFION ANALYSIS CE,,TER SIMILAR TO THE AIRFOIL DESIGN ,a.'GkLYSIS CE\TER CRE_IED BY NASA AT OHIO STATE UNI_]_RISTY?

NO ANS i i OTHfR _'£S PROBABLY __ NO NO CO_[?_\TS FROM "XC" OR "PRCBABLY XO" KESPCNOE\'FS i, Would r.m ourselves.

Would prefer Ln-house _:alyses. Ho_,ever, wou/d consider outside source if Vdrnaround tire were attractive. Only _ater loading and surface pressure coefficients would be required from the outside source. Thermal analysis _Duld occur in-house.

;re do no: see the necessit," in estabiishlng an ice protection analysis center. It is difficult to see how such a center would be cost effective.

In addition, considerable product liability difficulties cot_Id be developed.

Net ._ure. %- firs: i/_ression is that the codes coL]It"be used by the co_mnies them_ae!ves. I've heard that the Ohio State facil[t\" 1< rlot being well " _'-, it '_ ._ ....

_,t_±l_ud. b too early to m{ke a _m,_, ,en_.

;. Not recor_nendod. '¢,e would rather have the codes available for our ox,n ic _.qI.l __E YOU S&T!FIED WITH THE FAR ,:_, APPE\q]IX C ICING ENZ]_LOEES __FOR CERTIFYING GEN_[<%L ._qATION ,<N_ _,[ALL TRANSPORTS? PLEASE EXTL_IN.

c ----<---_ i I

I i

r q

i

w, i i I _ZS N0 XO ANS F.A]] 13 envelcpes were _exe_oped t_m< questlom_bIe instRm_entation but i.

h_\'e been applied with good results. Indications are that envelopes are velw conse_'atlve but hard to ars_:e ,-e_,=< sagety. D_ubt RAA would wsn.t tc change criteria.

i. Have been used satis{actorily Lm past. Need t mdatLng with _re cloud &q_a on khC _-undprobabilkies to ilcilitate more me,_mingful mission an:tlyses.

"NO" C¢3f•ff:hTS _e_in ....n]r low :altitudes.

" _nte, .,it _<.

" "_-;_., _ c[oud extent is in error tor T_XL"_ *-_ _-',It([oo 5borg].

[<& Reckon would not allow time dist.,co f{ctoring specig[ed in Apscndix '" for aForov_l.. <h_e -,o_d<_n"__ _st ch_u<e_ - either Rb\ or RkR -n _ ,',., ' : ...... _ '_ kim, enco_mters StlpDort5 [[le [_R P[irt -_3 .b_pend!_ C. reouirements for £ce :_rotection at low _[titudes when the ' + ..... " .... _. , cOntlr.L_OtlS T/INS!ILL _] [c[n£ COROL_kCll> _liS .IVPlCI][ _< ,[_. _.Itdr_ iS - _'°r_ " '" " " ' _,)rT',e_ ,?_ 7110 _ ..... " : . :: r;: -.., .... '_- "" {3r ,t!i¢]-7,_l! ice "_''" • "- • <,-q .... 5bre energ F [< reumired _,hich resuk, in [nefficlcnc'. :pr ". tOP. ...... u..

_11[ cPer:_tlOIl ;" k_i_l_ ,£C[_diiiO[IS. ]%e su_/gest l]l_%t the M]' ;*" _"" 'ncnt:='.,hic.h eiininaze ice protection beio_, :_ lUp through 8, <'_ :'t ,l[[[Zlkk TM ,I[ -_'_:._ . ,{]kl S¢[l [eve[ C[: ion Arc .._ l'e ,.,i,__-._. "" " _" • ' h A.

_.._ .....n 1 kmlt:Ir _io>er to resct%rch is neede.: for better _,'_,_ ",,' Cf "'< "

4. Altitude limit - too low, validity of low te,'_perature icing point -

questionable.

The -22°F at sea level is unrealistic. Should emphasize the operational +i0 to +32°F at sea level to iS,000 ft. Design philosophy behind Appendix C is to have an envelope that will include 99.9 percent of all icing encounters and allow the aircraft to remain in these condltions for an indefinite period of time. This not needed for G/A aircraft or helicopters used in non-air carrier operations. .%]so, FAR 25 envelope appears to be inaccurate at lower altitudes <5,000 ft. ,_y also be too representative of maritime climates.

, Current icing design envelopes are based on ex-tensive NACA multica, linder data. This data should be confirmed with the more accurate scattering spectrometer instruments currently available. If confirmation cannot be obtained, new design envelope maps should be defined.

Large drop sizes are ve T, difficnalt to obtain in a natural environment - not representative of actual conditions. Also, the high liquid water content specified for the 15 _icron drops in intermittent r_xhi_mt conditions is dif*icul_ to obtain in natural icing conditions and probably not very representative of actual condition_.

D-39 VII.2 hFAT CKAXGES [_CL]_D YOU LIKE TO SEE IN _ DPERATIOK%L CONSTP.AIN'TS (CERTIFIC._TION KEQU!RE_ENTS) KE.L%TI\]Z TO ICINC, IN ORDER TO I._ROVE UTILIZ%TION OF TKE EXISTING .-LND GROWING BODY OF GENERAL AVIATION A.\-D_:ALL TRANSPORT AIRCR._n_r? HOW WOULD YOU JUSTIFY TH_ CHANGE?

i.

No changes until the validity of current data are verified.

Criteria for rotorer_ft are lacking and FAA is taking steps to t_r_J_late appropriate requirements. This need emerged as the next logical step after helicopter IFR approvals. Also, a definition of "failing and blowing snow" per FAR 25.i093 is needed.

o Raise temperature from -22°F to +i0°F, delete requirement for analysis so certification could be obtained by test only, delete ability to certify by mnalysis only. With inappropriate FAR 25 envelope, present operational m_les are intolerable. A forecast of "occasional light icing" would completely ban all nonequipped aircraft certificated in last few years, even though such exposure would probably be without si_nificant hazard.

Limitation of flight into known icing conditions should not be required when length of time in and degree of icing is known by the pilot to be very small, e.g., climg to on-top through shallow cloud laver. This could be justified by pilot jud'_ent.

[clng certification should consist of selection of the most severe points for a given application and subsequent test cf these points or their equivalent. Fixed certification points shotKd not be employed. The fixed _round fog certification point needs to be confirmed with test data or modified to retqect proper exposure to ground fe Z.

We wolJd like to .have the opt ion to certi_" by tests for not more than three f!i_hts into [cin_ conditions and analysis to co_r the remainder of the envelope. [n some cases, simulated ice shapes would be used to cover unprotected areas. We are not confident that flying behind a t:mker fives representative results. _erefore, the mnnber of fli_hss required to cover the ic!ng envelcpe _,euld be astroncmical _nd totally t_acceptable, ki=i=cd "" _ ;* .... " .....

a ....a_ :c_n< _e,.:rlcat:on for i imiled _c_n,< _ond-" "_;-"l_ci_>.

] :_e wculi izke to see m_ifo:m !nte_mre[atlcn of F.'Cq'shy all F.k4 re<i,gn'_;.

_ome " "," < veT." ,, .nulr .n_,_._a_.an and t,-" to apply _es._n. aye arbitr:iF." i_ - • i ";','Fn"_" " :' F_R _ar" ,t< ..... _a.._n_ to ".-,.- • :_:_ -o regulation .rod ""_- l; Pa._tLduiarlv l_le O_ uertorT_q/z, ce .... "_'_e_Ll._; VII.5 ',_%\T ADVAXC_VfS .ARE N]=EIIEDTO HELP JUSTIFY THE DESIRED C_<NCHS OF <U_STION i (E.G., [NSTRL_[E\TATION, ICE PRCTECTION C_PABILITIES, .<\_O ;_E_T._R FOREC4S7 ING) ?

1.

Instrumentation for real-time determination of water droplet diameter is perhaps the biggest need.

Of course, part of the problem is a lack of adequate forecasting tech- niques in the civil arena. It is worth noting that the milita_" allows partial icing operations (i.e., in light icing), provides better operational forecasts, and does not appear to have airplmnes falling out of the sk%- Ln _he winter.

A slight digression. Carburetor icc forecasts are now well within the state-of-the-art. With forecast relative h_id_ty and temperature at altitude, the forecaster could use the .NASA or Camadimn derived charts and predi¢: the severity cf carburetor ice.

3.

ActLmllv,. the desired changes of _ue>_on..... " can be justified with present capabilities. It is the pilot's judgement that is the key.

Howcvcr, any increase in ti_¢ ability to forecast icing conditions accurately would help the pilot make his decision.

L_esirable to develop new equipment or tecm_icues which could be used to control and measure liquid water content and droplet size ._ore accur_tel F.

Better forecasting - particularly at specific altitudes.

D.

FA<'Indust_* !.E07 neetin.< on lee re<ulations.

F_miliari:ation of Part 2S F:b\ people w_th FSA Part 2S alrcraft and thelr operating characteristics.

P-:l

VII.; _P_-\T I._IPRO%_3IEN_fS IN hIL&TH_R FCREC._STING WOULD .MOST DIEECrLY

H_LP ICING FOREG-LSTS7 I. "bre use of satellite photos. Improved ice forecasting rel:_tive to probability and severity.

2. Some needed. Carburetor icing forecasts are now well within the state- of-the-art. With forecast relative humidity and temperature at altitude, forecaster could use _LEA or Canadian derived charts and predict the severity of carburetor ice.

3. Icing forecasts _ould be helped r_st directly by better forecasting of te_erature changes wlth altitude and cloud tops.

4. Liquid water content real-time &_ta are the weak part of forecastlng ici_ig. Create a liquid ;,_ter content data base and most of the forecast problem would be solved.

Aircraft feedback to central forecasting unit.

2_ ...... L_a_on of drop si:e presently in cloud.

:k, term.LnatLon of liquid water content in clouds.

[]. I _ i_ VII.3 APd_ YOU SATISFIED WITH T_ PRESENT )_,TH.CD OF C4TEGORIIING _ ICING CONDITION ,'E.G., TK%t'E, LI[TIT, _DDER4T!I, S[_[Pj{)? P[E<'_F EXPb_IN.

EXPL_K,\T IONS : l° I am not satisfied with the present categories of icing severities. They are quite ambiguous and require knowledge of the airplane that the forecaster had _n, mind. As a pilot reporting scheme, they are marginally acceptable. [ would prefer a m'merical scale (one to ten or one to one hundred] listing the icin Z severities with _n airplane specific calibration [i.e., eight on airplane _'X is moderate).

7he categorizing of the icin_ condition (e.g., trace, light, moderate, severe should be tied somehow to the size air5rnme and the potential effect on _ _ Fer _0 l-lla_,_e.

$. _¢ present methods of cate_orizLn_ ice acctm_Kations !trace, li_ht, ._, derate, _evere, rime, glaze, ere. I, are inadequate and mean different things to different people. A quantitative definition scheme is needed such as might be obtained wlth an ice detector. .In, onboard ice detector _*muld be usef_il if it _ere retiable and inexpensive.

:. _e characterization of the severity of icin_ should be addressed in relation to specific aircraft.

Jlas_i-_!cation of icLng severity in tim _eteorolo_- rer_ort_ ul mere <pec:fi_ term. s, e._., inches of run_, lee per minute af'exposure.

_. Net, definition ,rod tet_ino!o<)- are needed, ihe current definitions arc n_t :'.e:mincful ta a pilot faced '.< h an or_erational preblem. Fer exm._F, le, the definition of _evere icing /[_scribe_ t.ht_ _ondition is 'h r:_te of icc.um'alati."[! ... that de:c:nK,:tnti-_cin < equiT.ment fa:i_ tc reduce 9:" centre', the ha:at/." .\t the time t}'.ts c;m be reco<ni=e/, it 'm_v ie tee [ate. )_ew definlt:,Tns md te_,,inolo<v in weather t-et,o,.tn< to ?[l_ts :',ecds t,? _e _cre q',:;mtitative _w,d related to ,,hat the :,i/,)t Jam ¢i'>er'.'e md 'zse f-r )Feraticna[ leci:_ion_, Y'_'r ex;_,Fle, I scale cmfld "'e P- 1"_ VII, 5 tcontinued] t,.sed based on the de_ree of hazard associated with atmospheric icing conditions. Specific airplanes could be certificated to tip" up to a given scale. Weather conditions could be classified according to this scale in weather reports. A pilot could be guided in his operational decision on how his airplane capability compared to the reported weather.

b. it is a _ubjective method and not objective.

", Aii a_encies mt_t use compatible tenr_, F:\-\ vs, Neather Service, etc.

8. Conditions need to be more specific as to icing parmneters. FDL Staff \_teoro[o_" is _';" _ report tentatively titled Cate<orization of Aircraft icing Response, which will use icing selsitivit> ,_mta.

9. F.Ik doesn't permit ii'_ited icing flight approvals as Ln the case with several forei_rn a_enc:es. Perhaps accepted definitions of light and , _ .... " ' counled with _e,_;ic e experience _md i_proved _'orecast[n_ .... -,- F,<\ t_osition of full approval or no apt_roval.

, - _ucm,,q_olom" for ich_g conditions.

VII .o

__IDYOU ',fa.\T _\ O>Tf_.aRD ISSTR[%__\-f T},{4T 3_LSLPRES CLObD PROPERTIES ._\D THAT COULD BE l" - .SLD TO EX:kLUATE 'ITr_ AIRL'EkFI'S CkPABILITY TO OPERATF rN F&',T LtXIIL CLOBD L\X'IRO,N,_[E_,T?

_S NO NO .&NS l, Yes, but look-ahead capability, would be required.

- _nl_ec icing _llght were permitted, a system such as the Rosemot_,t toe SeVerity Indicator would be nandator_- to appraise +he crew of acttLll conditions• " _' 5. he certainly do _unt onboard unstr._entation to _easure cloud Dro_ertics f.cr testing• _t ;,'otKd also be desirable to have equipment _,hich tepid detect within, say. ten railes,;_here actual icing conditions exist.

.=met ._e_- an all, lane flying at one altitude experiences no icing _..here another airphm, e t-lying 1,9_;0 feet above does have _m icing encounter.

_'. Yes, if cost'relia_tlltv fitter is good.

_. >,'t_d.q like a good i,!ea +_" it could be developed :_ith _,', cleat I,_t,.

.Hid ace urat-,-. " - "NO" CO>Bf&\TS _..L,..,. :lot >e requited O1l !)OaF<t.

" NO, unless the cent ',,as ,.'e_, - [o_, er ---- "' "" it: -''_vIt t*,It _I_ ,I[",* ;\ " ..... k• e?( [ 5 t :rl,._ _t,[i...,t,l_ [ lae ' " t_ ,..

'_ , _7" ..... ,,C,lt,,¢, y;tdar.

VII. 6 (cont inued] 4. Additional required instrumentation on aircraEt would constitute a safety hazard due to (a] increased pilot work load in an already ha:ardous environment, 5] additional electrical power requirements at a time when it could not be tolerated, and (c) such a device _uld requlre a probe in the airstream, creating additional drag, and malfunctions (e.g., not deice] it could create extremely ha:ardous situation in an icin_ @nvlroru-nent.

Section VIf[ GE\]ffRAL \qlI,l ]20 YOU THINK A PILOT TI%%INING _}qE SHOULD BE ,"lADE THAT ADDRESSES THE PROBLEMS OF FLIQ{I INTO ICING CONDITIONS - HO;_ TO A_DID IT, HOW IT AFFEL_TS AIRCP_AFT PERFOZ_CE, HOW TO COPE WITH IT_ .%N_ HOW TO GET LXJT OF iT?

tTS NO NO ._S dO.M_ _TS i. [n a_a_tlen to b:_sl< film, pilots should be schooled rn the =ec,il!ar!tles ._..c.l[ _ t}pe, Yes. [ think that plier trab_ing is i_2orr:mt. _bst G/A pilots are afraid of ice at first. _len with their fzrst couple of exposures _usually trace or light icing_ they become brave, i"heir bravem" continues until the first serlous encetmtcr. .%IL toe often the forecasting philosophy of overforecast,.n< ice Li.e., call for severe _,hen it's really moderate_ heLys continue the bravado un, tll the final, often fatal, serlous icin_ c:lcot_nter. _le in_tnL_'nt ratin< exmm should have realistt ! questions concernin< Lee.

.. : _,_t _,.1,n,nN nov!e on icln_: '_,otld be valuable as _ul edz_c:tt£ona] :lid.

_h.:bi :catRms ,u]i ¢;._.,u_'_- _hic5 :'rer<-te ,m ,arene_ or" loin< Di'ob[evls ',could !'e q>of/:[ .

.\ ?ilot traxain< <erie _hkh nddresses i'll<hi into k_ewn tcinK condit:on_< '.,r,u[d !'e very _orth_,h!le. [t i- not _s'_ml_ , tc buhld :I :_ene:':ll :Iti.lth)n .<t']'iane t!:,_ is caF;IbL¢ ;f h_m,:.'tn< o: _,Fin< _,ith :Ill Fc<stble Loin< c,'t;,itti'ns. Filet:; -fast continue t," be i::'_':-esscJ that _kil l, trttnin<.

md Test ef ,i',[, 'udczent ._:st ['e used HI copi;',< :¢ith loin< ,ondi: ton',.

VIII.I <continued _

6. In some way the message needs to be disseminated to aircraft o_mers on the value of anti-icing and deicLng systems and how to recognize their need.

Section IX

• INAL REC_I_E,\,'DAT:'ONS IX.1 _}IAT ._SPECTS OF _EE ICING PROBL_I _3ST NT.ED ATI_N'FION?

IN THE SHORT FEKM?

i. Ice accretion and shapes for a combination of _ter droplets and ice crystals.

2. Develop,_nt of fluid anti-icing/deicLng systems.

3. Development of airfrmne _id engine ice detectors.

4. _bdification of operating _:les.

5. Pi [ot/o_ner education on icing, 6. Pilot trainimg movie pltLs the F.:_ safety clinic subjects.

". Icing forecasting.

IN THE- LCNC 7ERH?

I. Refimement of _urrent FAR 25 envelopes and establishment of limited _Cln_ _. iMnt requirements.

1, ClimatoD<ical stud;_es of the icing probabilities in the lower airspace ,_e[ow 5,00O ft _ and in the LnLmd sections of the cotmtry.

3. _weio!):_nt of £ooi flight test sFray rigs _md inst:n_nentatien.

I. Feve!opnent of ,m fee phobic.

_. Research in a ._cnre aomm'ehensive :uld accurate definition of cli,-_Itic _ond_t ._P,s icing " " ' _ .

_. [ N ....... \S _IR'ET ,_1_ LOXd r:_, 3. Researching alternatives to pnem_atic bcots.

4. Uniform interpretation of FAR's by all FAA reizons, and standardization of certification procedures.

Training of pilots on how to avoid _ce, cope with it, etc.

Generation of experhnental impingement data for latest airfoils.

6.

Development of efficient anti-icLng for composites.

5.

Improved methods to deterr/ne ice accretion shapes on unheated surfaces.

9.

Definition of uvdated ick1_ envelopes.

i0. Reduction in engineering and certifica[ion costs to m_nufacturers.

" -_ [cin_ terms, icing reports, and certifica- li. Standsrdi:atien of Ln __oht tion p_ocedures and re_q_lat ons.

i_ _ " i_velopnent ef new, Io_" cost ice protection systems such as electro- i_ulse, micro_ve, etc.

13. [n fo_it_iatin< the XASA Icing ProgTmm, hi<h priority shorld be placed on the _eneric _Lnd basic research aspects of aircraft icing- For exmmplc, to :o_rehend ;he basic 7heno_nen of ice a_hesion _md to '_ndcrstmd the complete physical process which causes ice to adhere to other materials _,culd _epresent a major :idvancem, ent in the atte,_pts to defLne ice phobic rmteria[s :_'_dsystems wi_ich ,_ut1£ate .1£ainst or it,bibLe the accretion of ice. lhe achievement ot such a _oal would not only '.'lave far rear.henS L._xyacton aircraft safety but also _,ould be significant benefk to _rcund-based svste._ :.for exm."iple, m_tep_as for navigation aid-P, .

11.

Another ma_or program _rea for _£.\&.\ emphasis is icim,< environmental definition and forecas:ing. It [s common L_o_,led_e _men£ tile pilot PoPul:iticn _ _ "_ _ iJ RO_ encotLrltoFed dad • . _._at all tee often t_orecast _,n_ icin_ encountered is not forecast. ._lso, forecasters tend to be ,.onset- a_r_,a,_ _,ithout ice protectkn \ votive which irJ'.ibits ¢:-erat:ens in _ "" ;_ !'_sic ' : .... _ _;'_' of the ic_n_ envlre_Lment ]nd how it ch_ul<es :,ith ,,c_,.._ no_ or][,," .i_.o.._:,,-ore icc\:l'a_e _id reliable _@recast5 &lid hence u'eate:" _ _'L'iO"'{l , .,r_,;_' ' ' p_ ........ _a, _,_:v but :Ns,] :Nmvidc .qlow[e._ce _h[cb • _ _ be " _,hile ._irbo_me to minini_-e tJ_e cf£ects st: ice by :_ _C\I... hLqea • l.e'. • ,0_1 .... __ COt'.l,! dOMe .,..< <.<, - c::.Lt<o " a[Ttlude er !" '_ _;< be ' ";,,--,,-:" <ul:]ivs'- or _i:-o_rk' ,_e:Kxc:- _¢rlsor_ oa _,,c llrcr:l:t Or [y. _..,,_..,-_.-,_i _.- .tara ".F':q a ,1 - • 15.

The aspects of the icing problem which need the most attention are the design envelopes, water catch characteristics as a function of shape, improved spectrometers, drop supercooling characteristics and icephobic coatings. KISA could make significant contributions in all of these _re&s.

IX. 2 IN _LA'F .kRE_S OF T_IE ICING PROJhLE_I COULD N.4SA )[_k_ T_£ GREATEST CO_TRi BUTZ ON?

IN THE SHORT TED!?

Additional ice collection efficiencies and imp_mgement studies on l, current airfoils.

Correlate studies by a number of companies in cloud physics to validate current icim.g en_elopes, 5. Stan_ardize ici_._ tests, facilities, tnnd hlst_-u_entation.

IN Tl_'_ LONG _K\I?

Xone E©T IDL\TiFIED .kS SHORT OR LONG TE;_I <_n going progrmns in ice phobics, instrumentation, m_g analysis tec]_niques, All areas _uld Lnvolve industr)" with K%_ acting as clearlng house for exchange of h_fo_ation and the test facility for correlation or provLng tests.

Data collection from O/A operators (not "FAR" 121 oeeratlens] to .<_:bst.m, tlate chor.ges to I::__R 15 _pendix C requirement. Firmly belie,,'e that FAR 15 Appendix C is worst case for FAR 111 operations rather :h_m practical C A operations with their ability to delay flights, c._mcel flights, de_'iate to other ai._ports, use alternate R-X.kV routes, etc.

K_A cotild _,_ake the greatest contribution in the long tern in deve[o_- mep, t of an ice phobic or a s)'stcm which disturbs the supercooled r_isture bl front of the ai._piane causung it to freeze before it contacts the s'arface of the aii3)l_me.

q 4+ >ug_.e_ and described i_l this questionnaire _euld prob:fl_lv involve several different research a%encies, _ncluding the F=\-\, _he \ationai Weather be_-_tce and ?(ASA. K%bA -- best role wot_ld be as ": " L:_it iat ing ,rod coordLqat u_g a<enc)" as ;,ell as the responsible a<enc)" for .,i, _. o_ ueseaIch needed.

[ .... _ "" the • "_-_,.'". theoretl_a_- ' .ulai.,'sis cf the st_bicct, testin< of :ill available sv_ torts, then publ, < _,'. ._ ,, un.• /es iT:. <u _,.le_; for -,;_,t_.",_ ...... • _,rc. _ ",_,.

.,,>_ .... lvlet_l_ile _lesldIl5 iof l..,,_ : , _ .IOK.

._et)_-akhltO a -; ...... m_._ < ,©..t, , ,¢.,I< ,ar,_,t..c. .is :elated to ikxe,l _,'.n< and ......... ,,in< t_..,a.,. \Iso, hi'tier ,uld more tc_n< *_'÷ _:1C!11_10£.

7-_2 .m -. The ._SA contribution Should be on L_roving the tecSnolo_' base for icing prediction, measurement, and correlation with flight ex_perience.

Applications of the analysis and techniques si_ould be the responsibility of the user l_e.g., the Air Force).

8. Standardization of testing and computer techniques to allow reduced certification costs. Coordinate the information and direction with the regulatory agencies such a_ F,&$, DOT, etc.

Airfoil or component shape - desi_ to reduce ice collection )<_SA could form a bank of computer progr _5 for all shapes of hard_are and facilitate industry use of this infomation Q. Sponsor icing tur_el tests of new ice protection s)stems to deterge/he performance and feasiblity.

D-__5

AppK\_D IX E

SUR_' OFAIRCRAFT ICINGSI_I[LATION

FAC_LI _S IN NDRTH .<MERIC& ._,-D EUROFE

SURVEY OF AIEC.RAFT ICING sIMULATION FACILITIES _N NORTH AMERICA W'ZLLIAM oLSEN ICING RESEARCH SECT_O_ NASA 12WIS PESEARCH CEdaR NASA was requested to survey the capabilities of the facilities in North America that can do aircraft icing simulation tests. The survey yes requested by the Standing Committee on Icing, which is Jointly sponsored ty NASA, FAA and NOAA; the military services have also expressed a need for this survey'. European l_Ing facilities have already been surveyed and reported in AGAP_D Advisory Report 127.

TLo reasons • .r the survey are t_. (i) Inform the icing research c ............ _ty of the cspabillties of existing icing fecilitles, (2) make it easier for a _..en._al facility user tn select and contact the icln_ facility" thsz is spproprist_ for his t_st requirements, and (3) help IsclLhtv' " =answers evaluate end ._p._ve_ -_ their _ac_y._ _ The survey deter aimed the location and size of each facility, its airspeed an! temperature range, icing cloud parameter ranges, and the .aci, ..les and capa- technlcsl person to contact. The _ ":'" surveyed their tiLitles are listed in ta_ies A :o D, one for each of the four t_rpes ...... a_.o_. _a___i.__ that are described on figures A %_ D, The cs_a_.._-s __ each facility were estimated by the engineers working w ..... s_ .... j, The nu=bers in the tables are single point s:_..x.-a_- "_ ...... --_ by them of the czmplex operating curves of their .a.__._j ¢ -'';'". _an'¢, ..-"the f_cllit:es have cspabillties beyond thzt required f_r ic/n_ _gsttn 6 and these excess cs_abilitles were net inzlude_ in the tabL_,

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TYPES OF ICING SIMULATION FACILITIES

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