Document
NASA Technical Memorandum 86906
AIAA-85-0468
NASA-TM-86906
/ C)f67JCJ?J CJ74CJ
..
Icing Flight Research: Aerodynamic Effects
of Ice and Ice Shape Documentation
With Stereo Photography
Kevin L. Mikkelsen, Robert C. McKnight,
and Richard J. Ranaudo
Lewis Research Center
Cleveland, Ohio
and
Porter J. Perkins, Jr.
Sverdrup Technology, Inc.
Middleburg Heights, Ohio
Prepared for the
Twenty-third Aerospace Sciences Meeting
sponsored by the American Institute of Aeronautics and Astronautics
Reno, Nevada, January 14-17, 1985
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VI.l, 111111/11111111111111111111111111111111111111 NFOOllO t r l\j , i'j ... ! II ~
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ICING FLIGHT RESEARCH: AERODYNAMIC EFFECTS OF ICE AND ICE SHAPE DOCUMENTATION WITH STEREO PHOTOGRAPHY Kev1n l. M1kke1sen, Robert C. McKn1ght, and R1chard J. Ranaudo Nat10na1 Aeronaut1cs and Space Adm1n1strat10n lew1s Research Center Cleveland, Oh10 and Porter J. Perk1ns, Jr.
Sverdrup Technology, Inc.
M1dd1eburg He1ghts, Oh10 Abstract THP thrust horsepower, hp A1rcraft 1c1ng f11ght research was performed a a1rcraft angle of attack referenced to floor 1n natural 1c1ng cond1t10ns w1th a tYP1ca1 tW1n 11ne, deg eng1ne commuter type a1rcraft. Development of a data base cons1st1ng of 1c1ng cloud parameter 6F flap def1ect10n, deg measurements, 1ce shapes, and aerodynam1c measure- ments was begun. Results from f1ve 1c1ng research Introduct10n f11ghts are presented. Dur1ng research 1c1ng encounters, 1c1ng cloud parameters such as temper- The NASA lew1s Research Center 1S conduct1ng ature, 11qu1d water content, and droplet Slze were an a1rcraft 1c1ng research program. Fl1ght test1ng measured. After the 1c1ng encounter, 1ce shapes 1S performed 1n natural 1c1ng cond1t10ns to support several maJor program e1ements. ,2 Among these were documented and aerodynam1c measurements were taken. The 1ce accret10n shape on t~e w1ng was elements are f11ght exper1ments that prov1de 1ce documented w1th a stereo photography system. The accret10n shape and attendant aerodynam1c drag data 1ncrease 1n w1ng sect10n drag was measured w1th a for the purpose of va11dat1ng the NASA lew1s IC1ng wake survey probe. The overall a1rcraft perform- Research Tunnel and computer codes. As a part l/') ance loss 1n terms of 11ft and drag coeff1c1ent of th1S program 19 1c1ng research fl1ghts were (J) changes was obta1ned by tak1ng steady level speedl flown dur1ng the 1983/1984 season. Because the M N power measurements. Se1ect1ve de1c1ng of a1rframe results of many f11ghts were slm11ar and 1n order I "-' components was performed to determ1ne the1r con- to avo1d repet1t10n and to focus 1n on key obser- tr1but10ns to the total drag 1ncrease. Eng1ne out vat10ns and results, data from only f1ve 1c1ng capab111ty was analyzed for the 1ced a1rcraft. It f11ghts are descr1bed.
was shown that the stereo photography system can be used to document 1ce shapes 1n f11ght and that Th1S paper presents results of NASA's 1c1ng the wake survey probe can measure 1ncreases 1n w1ng f11ght research 1n the fo110w1ng areas: (1) docu- sect10n drag caused by 1ce. On one f11ght, the ment1ng w1ng 1ce shape by stereo photography, (2) w1ng sect10n drag coeff1c1ent (Cd) 1ncreased measur1ng sect10n drag for the 1ced w1ng w1th a approx1mate1y 120 percent over the un1ced base11ne wake probe, and (3) cont1n~at10n of the work at an a1rcraft angle of attack of 6°. On another descr1bed 1n NASA TM-83564 Wh1Ch deals w1th f11ght, the a1rcraft drag coeff1c1ent (CD) 1n- measur1ng the overall performance loss of the a1r- creased by 75 percent over the un1ced base11ne at craft caused by 1ce and the contr1but10ns of var1- an a1rcraft 11ft coeff1c1ent (Cl) of 0.5. ous 1ced a1rframe components to the overall drag 1ncrease. In add1t10n, measurements of the corre- Nomenclature spond1ng 1C1ng enV1ronments are reported and related to the FAR Part 25, Append1x C, cert1f1ca- Cl a1rcraft 11ft coeff1C1ent tlOn cr1ter1a.
a1rcraft drag coeff1c1ent A short f11m 1S ava11ab1e Wh1Ch documents the NASA 1c1ng research fl1ght program.
C1 w1ng sect10n 11ft coeff1c1ent The A1rcraft Cd w1ng sect10n drag coeff1c1ent The 1c1ng research a1rcraft 1S a tYP1ca1 tW1n KIAS 1nd1cated a1rspeed, kn eng1ne commuter type a1rcraft. It has PT6A-20A turb1ne eng1nes (Wh1Ch generate 550 SHP each at KTAS true a1rspeed, kn sea level standard cond1t10ns) dr1v1ng three bladed propellers. MaX1mum gross we1ght 1S 11,000 1bs.
lWC 11qU1d water content, g/m3 long range crU1se speed 1S 127 KTAS at 10,000 ft, standard day, and maX1mum gross we1ght.
MED mean effect1ve droplet d1ameter, ~m The a1rcraft 1S equipped w1th electrothermal MVD ant1-1cers on the propellers, eng1ne 1n1ets, and med1an volume droplet d1ameter, ~m ", w1ndsh1e1d. Pneumat1c de1cer boots are located on RMC rotat1ng mu1t1cy11nder the w1ng outboard of the eng1ne nacelles, on both hor1zonta1 and vert1ca1 stab111zers, on the w1ng SHP shaft horsepower, hp struts, and on the rear 1and1ng gear struts (the a1rcraft has f1xed land1ng gear). The pneumat1c ss sooted s11de droplet catcher de1cers located on the vert1ca1 stab1l1zer, w1ng struts, and 1and1ng gear struts are nonstandard Copyrlghl © American Inslotute of AeronautiCs and This paper IS declared a work of the U S A.lronauIIC., Inc. 1985 All rlghl. reserved Government and therefore IS In Ihe puhhc domain The system was act1vated from a sWltch at the co- 1tems allOW1ng add1t10nal capab1lity 1n measur1ng component drag through select1ve de1c1ng. p110t's statlon. The photo lmages were pos1tlve R color exposures on Kodak Ektachrome ASA 64 f11m.
Instrumentat10n Photogrammetr1c analys1s of the 1ce accret10n IC1ng Cloud Parameters lmages was performed uSlng a K and E DSC 3/80 com- puter1zed analyt1cal comp11er system. An analysls Measurements were made of cloud llqu1d water of the lmages under h1gh magn1f1cat10n would gen- content, volume med1an d1ameter droplet Slze, drop- erate a f1nely spaced array of 1ce surface spot measurements. These measurements were made over let Slze d1str1but10n, a1r temperature, reference approx1mately a 10 1n spanw1se sect10n of the w1ng, 1ce accret10n rate, durat10n of the 1c1ng encoun- ter, and fl1ght speed. IC1ng enV1ronment data from concentratlng on lce peaks and valleys In order to electron1c sensors were recorded on a d1g1tal tape get a measure of 1ce surface roughness. Each meas- recorder. See F1g. 1 for 1nstrument 10cat10ns on urement's spac1al coordlnates were then plotted on the a1rcraft. one compos1te prof11e V1ew express1ng the repre- sentatlve shape and roughness of the lce accretlon.
Instrumentat10n 1ncluded: Wln Wake Survey Probe and Surface Pressure Belt
f Sys em
For 11qU1d water con~ent: Johnson and W1111ams (J-W) heated W1re probe, produced by Cloud Technology. The w1ng wake survey probe and surface pressure belt system was des1gned and bU11t by the OhlO For cloud droplet Slze d1str1but10n and volume State Unlverslty, Columbus, OhlO. The wake survey med1an d1ameter: rotat1ng mult1cyl1nder 7 and probe cons1sts of a geared, motor dr1ven probe, sooted sllde droplet catcher. w1th separate P1tOt and statlc probe t1PS located 1/4 chord aft of the w1ng tra111ng edge at about For a1r temper§ture plat1num res1stance total 69 percent of the sem1span. The probe can traverse temperature probe, produced by Rosemount, Inc. an arc of 180· through the w1ng wake (F1gS. 1 and 3). The probe lS dr1ven by a stepper motor In the For reference 1ce accret10n: Pressure-type w1ng. Stat1c and total pressures are measured 1n IC1ng Rate and Accret10n Meter (PIRAM), devel- the w1ng wake along w1th the correspond1ng probe oped by NACA. pos1t10n 1n the wake. Pressures are measured by transducers located 1n the cab1n. A m1n1computer It should be noted that 1c1ng cloud parameters 1S used as a controller and data logger. The com- are d1ff1cult to measure. Accuracy 1S dlfflcult puter calculates wlng sectlon drag coeff1c1ents by uSlng momentum theory (the veloclty def1c1t 1n the to determlne and absolute cal1brat10n standards are lacklng. Measurements were not, 1n general, cor- w1ng wake 1S related to the drag of the wlng sec- rected for local flow fleld effects caused by the tlon). Dur1ng 1c1ng fl1ghts, heaters ln the wake presence of the alrcraft. The phllosophy of th1S probe kept the probe free of 1ce and a n1trogen report lS to correlate avallable 1clng cloud data purge system kept pressure 11nes clear of water.
and 1ce accretlon propert1es wlth correspondlng lce shapes and aerodynamlc data. For further deta11s A pressure belt lS located at the same spanw1se about 1c1ng 1nstrument results see Ref. 2. w1ng statlon as the wake probe, but on the Opposlte w1ng (Flg. 4). The pressure belt measures wlng Stereo Photography System surface stat1c pressures dur1ng clear a1r fl1ghts and cons1sts of strlp-a-tubes wrapped around the EmploY1ng technology developed by the U.S. A1r wlng. Stat1c pressure holes are located on the Force Arnold Englneer1ng and Development Center pressure belt around the w1ng surface. Each stat1c (AEDC), 0,11,12 NASA LeW1S personnel des1gned and hole has a pressure llne feedlng lnto the cab1n.
bU11t a w1ng stereo photography system for the A ScanlvalveR 1S employed to read the pressures.
lC1ng research a1rcraft. The obJect1ve of the sys- Cutoff valves are used to lnstantaneously trap all tem was to obtaln stereo pa1r photo 1mages of the pressures In the 11nes before the pressures are wlng's lced leadlng edge that would enable measure- read. Data can be reduced "on 11ne" dur1ng a ment of the 1ce surface through photogrammetrlc fl1ght or on a post fl1ght basls. The on llne data reductlon capab111ty allows real t1me evaluat10n analys1s to generate proflles of the 1ce shape w1th a mln1mum acceptable resolut10n of +0.03 1n (+0.04 of data quallty. Raw data are processed more accu- percent chord). The system's cameras are two- rately at the Oh10 State Aeronautlcal and Astro- Hasselblad 70 mm format motor dr1ve un1ts w1th 250 naut1cal Research Laboratory on the1r Harr1s/4 computer than can be 1n fl1ght. See Refs. 13 and mm lenses mounted In the nose of the a1rcraft beh1nd opt1cal glass v1ewports (F1g. 2(a)). The 14 for a more complete dlScusslon of the wake sur- cameras' f1elds of V1ew encompassed a common por- vey and pressure belt system.
t10n of the w1ng lead1ng edge located at about 69 Alrcraft Performance Instrumentatlon percent of the sem1span. To provlde spatlal refer- ences 1n the photo-1mages needed for photogrammet- A1rcraft performance measurements were made rlC analysls, an array of control pOlnts was pa1nted on the w1ng lead1ng edge sect10n and the wlth cal1brated serVlce system 1nstruments. The wlng fence. The pOlnts' prec1se pos1tlons were only 1nstrument used that was not part of the then measured and catalogued. The control p01nt Sh1P'S serV1ce system was the heated angle of array wlth general d1menSlons lS d1agrammed 1n attack probe. Performance data was recorded F1g. 2(b). To lncrease contrast and character of manually. Instrumentatlon 1ncluded: the 1ce surface 1n the 1mage, a 2000 W/sec flash un1t WhlCh sldel1ghted the vlewf1eld was dlscharged Eng1ne torque' Edlson Torque Pressure Gauge durlng the exposure. An electron1c control system (lb/1n 2) was used to synchron1ze the shutters and flash. Propeller RPM: General Electr1c (percent) Pressure A1t1tude: Aeroson1c Encoder (ft) Stereo photographs were taken Just prlor to or Ind1cated A1rspeed. Bend1x P10neer (kn) durlng wake survey measurements and speed/power Angle of Attack. Spec1alt1es, Inc. (deg) measurements.
F11ght Test Procedures Results and 01Scuss10n The a1rcraft was flown 1n clear a1r to estab- N1neteen 1c1ng research fllghts were flown 11Sh an un1ced performance base11ne 1n terms of a durlng the 1983/84 season. To avo1d repet1tlon and 11ft curve and drag polar. Steady, level, perform- to focus In on key results, data from flve lclng ance methods (speed/power measurements) were fllghts are presented hereln. These fllghts are emp10yed. The un1ced 11ft curve and drag polar referred to by thelr numbers and were chosen for were der1ved to estab11sh a bas1s for compar1son the followlng reasons. Fllght 84-19 provlded alr- between the 1ced versus un1ced a1rcraft (see A1r- craft performance measurements WhlCh lncluded some craft Performance Loss Due to Ice sect10n). component delclng. Fllght 84-27 provlded a severe glaze lclng encounter after WhlCh both alrcraft The wake survey and pressure belt system was performance and wake survey measurements were made.
also flown 1n clear a1r to estab11sh an un1ced Fllght 84-34 provlded the most complete set of data basel1ne 1n terms of a w1ng sect10n 11ft curve and WhlCh lncluded stereo photographs, performance drag polar. Wake probe measurements were made on measurements, and wake survey measurements. 01S- the r1ght w1ng wh11e w1ng surface pressure measure- cussed In less detal1 are Fllghts 84-29 and 84-32 ments were made at the same spanw1se 10cat10n on WhlCh along wlth Fllght 84-34 provlded stereo the left W1ng. The w1ng pressure belt was never photography data show1ng a correlatl0n of lce used 1n 1c1ng COnd1t10ns.
accretlon extent on the wlng surface wlth droplet Slze.
The general procedure dur1ng 1c1ng fl1ghts was (I) accrete 1ce wh1le measur1ng the 1c1ng enV1ron- The followlng results and dlScussl0n are organ- ment, (2) eX1t the 1c1ng cloud and document the lzed by the subJects: characterlzatlon of lclng w1ng 1ce shape w1th stereo photography, (3) measure encounters, lce shape documentat10n wlth stereo the 1ncrease 1n w1ng sect10n drag w1th the wake photography, wlng sectl0n drag lncrease due to lce, survey probe, (4) measure the decrease 1n overall and alrcraft performance loss due to lce.
a1rcraft performance, and (5) se1ect1ve1y de1ce a1rframe components and obta1n drag decrements. Characterlzatlon of IClng Encounters Aerodynamlc measurements and stereo photographs A1rframe 1ce was accreted at crU1se f11ght cond1t10nS (approx. 135 KTAS). Wh11e 1n 1c1ng, a of lce shapes taken followlng an lclng encounter are referenced to those lclng cloud parameters that relat1vely constant crU1se a1rspeed was ma1nta1ned by slowly 1ncreas1ng power; however, In heavy created the lclng condltlon. IClng envlronment lclng, once maXlmum contlnuous power was reached, observatl0ns and measurements are presented In a speed decay of 10 to 15 KIAS would sometlmes Table I under two categorles: the baslc lclng occur. IClng 1nstrumentatl0n contlnuous1y measured cloud varlables and the propertles of the lce lc1ng cloud parameters. The pneumatlc delcers on accretl0ns. Measured cloud varlables lnclude 11q- the wlngs, empennage, and struts were not actlvated uld water content, droplet Slze dlstrlbutl0n, medl- durlng the 1c1ng encounter; however, propeller and an volume dlameter, temperature, and the duratlon englne lnlet heaters were always kept on. After a and extent of the lclng. Ice accretl0n propertles sufflc1ent amount of lce had been accreted on the lnclude lc1ng rate, reference amount of 1ce accreted, and the shape of the lce format10n as alrframe, the alrcraft would be flown to eX1t the 1clng area. Generally, the qUlckest means was to determ1ned by observatlon. Plots of cloud 11qUld cllmb and fly above the lclng cloud. water content versus tlme durlng the lclng encoun- ter are glven 1n Flg. 5 for Fllghts 84-19, 27, and At thlS pOlnt, level f11ght speed/power meas- 34.
urements as well as wake survey measurements were made. The flrst speed/power measurements were made The lclng encounter lS characterlzed by two w1th the a1rcraft all lced, excludlng propellers approaches. The flrst approach relates the encoun- and englne lnlets. Subsequent speed/power serles ter to Its frequency of occurrence. Lewls and were made after selectlvely de1clng alrframe com- Bergrun 6 presented charts showlng the probabl1- ponents ln order to establlsh varlOUS component lty of speclflc lclng condltlons. For jxample, the contrlbutl0ns to the overall drag. If lt was LWC measured on Fllght 84-19 (0.30 g/m ) would determlned v1sually that lce was sheddlng durlng be equalled or exceeded In only 1 out of 450 lclng the measurements, the serles would be abandoned. encounters when found In comblnatlon wlth the other Measurements were not attempted unless the alrcraft measured lclng parameters (table I). ThlS low was totally free of lce prlor to the lclng encoun- probabl11ty stems prlmarlly from the unusual dura- ter. That lS, all lce on the alrcraft was due tl0n of the lclng produced by the fllght test pro- cedure of holdlng wlthln the lclng cloud. The solely to the documented lclng encounter. All performance measurements were made wlth flaps up second approach for characterlz1ng the 1Clng (6F = 0°). encounter lnvolves the FAR Part 25 lclng parameter envelopes.
Wake survey measurements of the 1ced wlng were made alternately w1th speed/power measurements. For many years the extremltles of lclng condl- Dur1ng wake survey runs the a1rcraft was flown at tlons have been gaged by the FAR Part 25 1clng constant a1rspeed and angle of attack. It took parameter envelopes used to deslgn and certlfy alr- about 160 sec for the wake probe to traverse behlnd craft. Thus, lt lS of 1nterest to assess the the wlng whl1e taklng data. lntenslty of a glven lclng encounter In relat1Y9 to these envelopes. Flgure 6 from FAR Part 25 glves the maXlmum 11qUld water content to be found contlnuously In stratlform clouds as related to approxlmately 50 stereo palrs that were taken dur- mean effectlve drop dlameter, alr temperature, and 109 the season: 25 percent allowed measurements wlthln the acceptable resolutlon band, 50 percent horlzontal extent of the lClng encounter. ThlS FAR envelope of maXlmum condltlons lS for a standard gave results wlth unacceptable resolutlon, and 25 dlstance of 20 mlles (17.4 n ml). For lClng percent could not be analyzed. ThlS success rate encounter dlstances other than the standard dlS- lS a reflectlon of the fact that the system was tance, the maXlmum llqUld water content may be belng developed throughout the season.
lncreased or decreased dependlng on whether the encounter dlstance lS shorter or longer than the Flgures 10 and 11 show examples of stereo palr standard dlstance. Data have shown that the hlgher analysls. Each of the proflle Vlews presents the contour of the wlng leadlng edge wlth the lce the average llqUld water content of an lClng encounter, the more locallzed the encounter wlll accretlon surface represented by data pOlnts. As dlscussed prevlously, each data pOlnt represents a be. A llqUld water content correctlon factor relatlng maXlmum llqUld water content wlth horl- measured posltlon on the lce surface wlthln about zontal dlstance has been developed from preVlOUS a 10 ln spanwlse band. Thus, the proflle lS a data gathered by NACA (FlgS. 6 (a) to (c)). The composlte lce proflle representlng shape and rough- maXlmum llqUld water content lS modlfled by multl- ness. Clusterlng of the pOlnts glves a measure of plYlng values of maXlmum llqUld water content for lce surface roughness over thlS spanwlse sectlon.
the standard dlstance by the approprlate LWC Approxlmately 75 pOlnts were measured from each correctlon factor determlned for the actual dlS- stereo palr to deflne a representatlve lce surface tance flown ln lClng. proflle.
Flgure 10 presents a serles of proflles, from Data from Fllghts 84-19, 27, and 34 are refer- enced to the FAA deslgn and certlflcatlon envelopes Fllght 84-34, WhlCh show that the lce accretlon was In FlgS. 6(a) to (c) (Fllghts 84-29 and 32 are not undergolng subllmatlon and erOSlon. Subllmatlon referenced to the certlflcatlon crlterla Slnce no lS when the lce changes dlrectly from a SOlld to a performance data are presented for these fllghts.) vapor. Eroslon refers to the process where por- Shown In Flg. 6(a), for example, are the deslgn tlons of the lce, partlcularly the lce feathers, become structurally weak enough (by subllmatlon or envelopes and the lClng encounter data of Fllght 84-19. The measured values of mean effectlve drop- the sun's radlatlon) that the aerodynamlc forces let dlameter (11 um) and llquld water content break them off the lce accretlon. ThlS occurred 3) (0.3 g/m are plotted on the top graph (SOlld after the lClng encounter durlng the perlod In WhlCh aerodynamlc measurements were taken. Some symbol). The actual horlzontal dlstance glves an LWC correctlon of 0.43. The alr temperature meas- lce feathers and the small "upper horn" of the lce accretlon dlsappeared after a perlod of 37 mln.
ured In thlS lClng encounter was -6.8 °c (19.8 OF), WhlCh for a mean effectlve droplet dlameter of The temperature durlng thlS tlme was cold (_11°C statlc, 12.2 OF). The alrcraft was flYlng above 11 um, 31ves a maXlmum llqUld water content of 0.8 g/m (as shown by the lnterpolated value the clouds In the sun wlth an average true alrspeed (dotted llne) on the top graph). But thlS maXlmum and pressure altltude of 126 KTAS and 8250 ft, llqUld water content lS for the standard dlstance respectlvely. Ice subllmatlon and erOSlon affect and should be reduced b the LWC corre~tlon fac- the aerodynamlc measurements. F1Ylng ln between tor of 0.43 to 0.34 g/m (0.43 x 0.8 g/m). ThlS cloud layers, out of the sun, lS best when POSS1- lS shown by the SOlld llne on the to~ graph. Com- ble. The aerodynamlc data acqulsltlon tlme should parlng the maXlmum value ~f 0.34 g/m to the be reduced ln order to mlnlmlze the problem.
measured value of 0.3 g/m , we flnd that the measured value was 88 percent of the maXlmum Addltlonal stereo photography results, from (0.3010.34) as glven In Table I. Flgures 6(b) and Fllghts 84-29, 32, and 34, are presented ln Flg. 11 (c), Fllghts 84-27 and 84-34 respectlvely, were and show a correlatlon of lce accretlon extent llm- constructed by emploYlng the same procedure. ltS wlth droplet Slze measurements. The proflles exhlblt a deflnlte varlablllty ln the extent of the The correctlon factor relatlng maXlmum LWC lce accretlon on the upper and lower surfaces. Ice wlth dlstance lS of prlmary lnterest In determlnlng accretlon extent lS related to droplet lmplngement the amount of lce Whlch can accumulate on unpro- llmlts. At the nearly constant condltlons of alr- tected surfaces durlng an lClng encounter. How- speed and altltude that were flown, the dlfferent ever, for deslgn of most lce protectlon systems, lmplngement llmlts would prlmarlly be a functlon the maXlmum LWC (from the FAR Part 25 Appendlx C) of the cloud droplet Slzes. Flgure 11 shows that for the standard dlstance (17.4 nm) lS used. the wlde range of droplet Slzes measured durlng the encounters dld, ln fact, produce large changes In Ice accretlon shapes are documented by photo- lmplngement area. Very small droplets created a graphs for Fllghts 84-19, 27, and 34, and are pre- narrow lce accretlon (FLT 84-32) whereas much sented In FlgS. 7 to 9. The photographs show larger droplets gave a wlde lce band along the examples of lce accretlons on varlous components leadlng edge (FLT 84-29). Droplet Slzes were meas- of the alrframe lncludlng the wlng, tall, struts, ured elther by the rotatlng multlcyllnder method wheels, and antenna. (RMC) or by exposure of sooted slldes. Both meas- urements were analyzed for the volume medlan drop- Ice Shape Documentatlon Wlth Stereo Photography let Slze (or m an effectlve ln the case of the RMC measurements), dlstrlbutlon of the slzes, and maXlmum droplet Slze determlned by the dlstrlbutlon Stereo photography results from Fllghts 84-29, 32, and 34 are presented In thlS sectlon. For as deflned by Langmulr ln the RMC analysls pro- Fllghts 84-19 and 27, camera system problems pro- cedure. An E dlstrlbutlon was common to the exam- duced degraded lmage quallty that prevented accept- ples shown In Flg. 11. As a result, the maXlmum able analysls accuracy. The mlnlmum acceptable droplet Slze, WhlCh determlnes the llmlts of resolutlon band was ~0.03 In. Overall, of the lmplngement, lS the same multlple of the volume medlan for each of the three examples.
reason for the Shlft lS unknown. However, Slnce Wlng Sectlon Drag Increase Due to Ice the lnterest lles In measurlng performance dlffer- Results of the unlced basellne tests for the ences, the 1983/84 lClng data are compared to the wake survey and pressure belt system are shown In 1983/84 unlced basellne data. Next, performance data from three lclng fllghts are presented as well FlgS. 12 and 13. Flgure 12 shows a plot of wlng sectlon 11ft coefflclent versus alrcraft angle of as a dlScusslon on englne out capablllty.
attack. It should be noted that thlS lS not the local angle of attack at the wlng, rather, lt lS Fllght 84-19. Fllght 84-19 was flown In glaze lClng condltlons wlth LWC of 0.3 g/m , statlc the alrcraft angle of attack refetenced to the
temperature of -6.8 ·c, and an encounter tlme of
floor llne. The wlng lS at a 2.5 lncllnatlon to 49 mln. Flgure 7 shows phot09raphs of resultlng the floor llne and lS also subJect to an lnduced angle of attack effect. Flgure 13 shows the wlng lce accretlons on the alrcraft. The alrcraft sectlon drag coefflclent versus the wlng sectlon eXlted the lClng cloud at 5700 ft for a serles of performance measurements. SlX steady-state per- 11ft coefflclent for the unlced wlng. ThlS meas- ured drag polar exhlblts an unusual plateau at formance measurements were made taklng a total of 30 mln to complete. Results are plotted on CL sectl0n Cl's from about 0.65 to 0.9. It should be noted that the alrcraft has NACA type double- versus a and Co versus (CL)2 graphs shown slotted flaps on the full span wlth the outboard In FlgS. 16(a) and (b). Referrlng to Flg. 16(b), tralllng sectlons belng allerons (wake survey three measurements were made wlth the alrcraft all
measurements were made on the outboard reglon). lced. At CE = 0.25, the all lced alrcraft
showed a 31 percent lncrease In drag over the IClng data are presented and compared to unlced unlced basellne. The next three measurements were measurements. Iced wlng sectlon Cd measurements made wlth the wlng struts and landlng gear struts are plotted agalnst alrcraft angle of attack, delced. By farlng a lln~ through these three data rather than Cl, Slnce the pressure belt was not pOlnts and looklng at Ct = 0.25, the drag lS reduced to 18 percent over the basellne. ThlS drag used In lClng condltlons. In Flg. 14, wlng sectlon drag coefflclent versus alrcraft angle of attack reductlon appears too large Slnce lt corresponds for lClng Fllghts 84-27 and 84-34 lS plotted and to 42 percent of the total drag caused by lce. If compared to the unlced wlng drag data to lllustrate the low data pOlnt at CE = 0.4 lS 19nored, the drag lncrease caused by lce. The largest drag and another llne drawn, then the drag reductlon becomes 22 percent over the unlced basellne. Thus, measurements were recorded on Fllght 84-27, WhlCh was a severe 91aze lClng encounter. At an angle of the lce on the wlng struts and landlng gear struts attack of 3.1 , wlth an alrspeed of 121 KTAS, the contrlbuted about 29 percent of the total drag drag lncreased 56 percent over the falred base- lncrease due to lce. Ice also caused a decrease llne. At an angle of attack of 6.0', wlth an alr- In 11ft as shown on Flg. 16(a). At an angle of speed of 101 KTAS, the drag lncreased by 120 per- attack of 6' the 11ft coefflclent lS about 12 per- cent over the basellne. The other lClng fllght cent lower than the unlced basellne.
shown, Fllght 84-34, shows a much smaller drag The performance measurements quoted above took lncrease. At an angle of attack of 0.9', wlth an place over a perlod of 23 mln. Conventlonal photo- alrspeed of 148 KTAS, the drag lncreased 6 percent over the basellne. At an angle of attack of 7.2', graphs taken durlng thlS tlme lndlcate that some wlth an alrspeed of 97 KTAS, the drag lncreased 19 lce subllmatlon or erOSlon occurred. Stereo photo- percent over the basellne. The magnltude of the graphs were not avallable for thlS fllght. The drag lncrease lS a functlon of the amount of lce amount of reductlon In drag due to subllmatlon and on the wlng, the lce shape, and the lce roughness. erOSlon lS unknown. Although the general lce shape remalned, the characterlstlc roughness was reduced.
From photographs (FlgS. 8(a) and 9(a», lt can be seen that the lce on Fllght 84-27 was a great deal rougher than that on Fllght 84-34. The wake survey Fllght 84-27. Fllght 84-27 was flown In mlxed measurements from Fllght 84-34 were made durlng the (l.e., rime/glaze) lClng condltlons for 25 mln wlth tlme perlod beglnnlng 12 mln after the lClng LWC of 0.34 g/m and statlc temperature of encounter and endlng 30 mln later. The shape of -5.2 ·C. Flgure 8 shows photographs of resultlng the lce accretlon durlng thlS perlod was documented lce accretlons on the alrcraft. Ice degraded the wlth stereo photography and lS presented In alrcraft performance slgnlflcantly. Three measure- ments were made wlth the alrcraft all lced. Flg- Flg. 10.
ures 17(a) and (b) show plots of CL versus a
The efforts reported hereln represent the flrst and CD versus CE. The drag lncrease for
attempt to perform In-fllght measurements of wlng the all lced alrcraf~ was very large. Referrlng sectlon drag lncreases caused by lce accretlons. to Flg. 17(b), at Ct = 0.25, lt can be estl- The unusual form of the unlced drag polar suggests mated that the drag lncreased to 75 percent over the unlced basellne. The lce also caused a that addltlonal work should be done to more thor- oughly understand and verlfy the measurements; decrease In 11ft. Referrlng to Flg 17(a), at an nevertheless, the wake survey probe dld detect Slg- angle of attack of 6' the 11ft coefflclent lS 16 nlflcant lncreases In drag and therefore warrants percent lower than the unlced basellne. Subllma- contlnued future effort. tlon of the lce accretlon was not a problem Slnce the alrcraft was not In the sun.
Alrcraft Performance Loss Due to Ice Fllght 84-34. Fllght 84-34 was flown In mlxed The basellne 11ft curve and drag polar for the lClng condltlons (l.e., mlxture of rlme and glaze) unlced alrcraft were obtalned to establlsh a basls for 22 mln, wlth LWC of 0.58 g/m , and statlc for 11ft and drag coefflclent comparlsons between temperature of -6.5 ·C. Flgure 9 shows photographs of resultlng lce accretlons on the alrcraft. Data the lced versus unlced alrcraft (FlgS. 15(a) and (b». Basellne performance measurements from the plots are shown In FlgS. 18(a) and (b). Three 1983/84 season show a Sllght Shlft towards lower measurements were made wlth the alrcraft all lced.
drag from those reported In Ref. 4. The exact Referrlng to Flg. 18(b), at CE = 0.25 the
drag lncreased for the all lced alrcraft to 38 englne out capabl11ty only at dangerously low a1tl- percent over the unlced basellne. Two measurements tudes. Such would be the case lf an lce protectlon system falled or dld not protect a sufflclent area were made wlth the wlngs delced. Wlth the wlngs delced, at Ct = 0.25, the drag was 26 percent of the alrcraft.
over the basellne. Thus, at C~ = 0.25, the lce on the del cable portl0n of the wlngs contrlb- Conc1uslOns uted 32 percent of the total drag lncrease due to lce. One measurement was made wlth the empennage 1. It has been shown that stereo photography and wlngs delced and resulted ln a drag of 22 per- can be used as a means to measure natural lce shape profl1es ln the f11ght envlronment.
cent over the base11ne. Thus, lce on the empennage contrlbuted approxlmate1y 11 percent of the total lncrease ln drag due to lce. Ice also caused a 2. It has been shown that a wake survey probe can be used ln f11ght to measure lncreases ln wlng decrease ln 11ft. Referrlng to Flg. 18(a), at an angle of attack of 6·, the 11ft coefflclent lS sectlon drag caused by natural lce.
about 11 percent lower than the unlced base11ne.
Sub1lmatlon of the lce accretlon was documented and 3. The tlme requlred for aerodynamlc data dlscussed prevl0us1y In the Stereo Photography acqulsltlon must be reduced In order to mlnlmlze sectlon. Performance data was acqulred durlng the errors caused by lce sub11matlon and erOSlon.
tlme perlod beglnnlng 10 mln after the lClng encounter and endlng 49 mln later (refer these 4. Glaze lce affects the performance of alr- tlmes to the tlmes of the stereo profl1es shown In craft far more serl0usly than rlme or mlxed lce Flg. 10). (l.e., comblnatlon of rlme and glaze).
Englne out capabl11ty wlth lce. For F11ght 5. Glaze lce can rapld1y erode englne out capa- 84-27, thrust horsepower versus veJoclty plots were blllty lf an lce protectlon system falls or does developed to present the effect of glaze lClng on not protect a sufflclent area of the alrcraft In englne out performance. These plots were con- order to reduce enough of the drag lncrease caused by lce.
structed by comparlng the two englne f11ght derlved thrust horsepower requlred curves for the unlced and lced alrcraft agalnst a ca1cu1atl0n of one Acknowledgements englne thrust horsepower aval1ab1e. One englne THP aval1ab1e was calculated by uSlng (1) maXlmum AEDC's D1Ck Palko and Pat Cassady provlded contlnuous power settlng charts ln the pl10ts hand- gUldance enabllng Lewls to bUl1d a stereo camera book wlth 100 percent propeller rpm at sea level system for the alrcraft. They also analyzed stereo and 96 percent propeller rpm at any altltude, and palr lmages to generate the lce shape proflles.
(2) propeller efflclency charts to calculate pro- OhlO State Unlverslty deslgned and bUl1t the wake peller efflClenCles used to obtaln THP. Trlm survey and pressure belt system. Jerry Gregorek, R1Ck Frue1er, and Mlke Hoffmann put a great deal drags caused by asymmetrlc thrust were measured on of work lnto maklng the system operatlona1 and In the unlced alrcraft by featherlng one propeller and were found to be neg11g1b1e; l.e., wlthln the scat- processlng data. The B.F. Goodrlch Company of Akron, Ohl0, supp11ed pneumatlc delcer boots for ter of our base11ne measurements. Englne out capabl11ty ln thlS dlScussl0n refers to power the vertlca1 stablllzer, wlng struts, and landlng requlrements and does not address posslb1e hand11ng gear struts.
qua11tles problems caused by an englne out wlth References lced control surfaces.
1. Relnmann, J.J., Shaw, R.J., and Olsen, W.A., For the unlced alrcraft, Flg. 19(a) shows the base11ne thrust horsepower requlred versus ve10clty Jr., "NASA Lewls Research Center's Program on for standard day, standard welght, and sea level IClng Research," NASA TM-83031, 1983.
condltlonS. For lClng F11ght 84-27, Flg. 19(b) shows approxlmate englne out capabl11ty where data 2. Ide, R.F., and Rlchter, G.P., "Eva1uatlon of has been corrected to standard day, standard IClng Cloud Instruments for 1982-83 IClng Season F11ght Program," AIAA 84-0020, January welght, and sea level condltl0ns. Flgure 19(c) 1984.
shows englne out capabl11ty for F11ght 84-27 at test altltude condltl0ns and standard welght. The results show that the glaze lce accretlon of F11ght 3. Shaw, R.J., "Progress Toward the Development 84-27 lncreased the requlred thrust horsepower of an Alrcraft lclng Ana1ysls Capabl11ty," NASA enough that the englne out capabl11ty of the alr- TM-83562, 1984.
craft was serl0us1y reduced. Although further measurements were attempted after se1ectlve delclng 4. Ranaudo, R.J., Mlkke1sen, K.L., McKnlght, R.C., of the wlngs and empennage, test condltlons were and Perklns, P.J., Jr., "Performance Degrada- not conduclve to acqulrlng data. Based on our tlon of a Typlca1 TWln Englne Commuter Type 4, delclng the experlence from past measurements Alrcraft In Measured Natural IClng Condltlons," wlngs, empennage, wlng struts, and 1andlng gear NASA TM-83564, 1984.
struts would have provlded safe englne out capabl11ty. 5. "F11ght Research In Natural IClng Condltlons," NASA fl1m serla1 number C-314, 1984.
In general, lt can be seen that glaze lce con- dltlons can rapld1y erode englne out capabl11ty. 6. Nee1, C.B., Jr., and Stelnmetz, C.P., "The Undeslrab1e condltl0ns would eXlst lf an lce pro- Calculated and Measured Performance Character- tectlon system reduced the drag an lnsufflclent lStlCS of a Heated-Wlre Llquld-Water-Content amount such that lt could not provlde englne out Meter for Measurlng IClng Severlty," NACA capabl11ty at any altltude, or lf lt provlded TN-2615, 1952.
7. Brun, R.J., Lewls, W., Perklns, P.J., and 13. Gregorek, G.M., Hoffmann, M.J., Welslogel, Seraflnl, J.S., "Implngement of Cloud Droplets G.S., "Data Acqulsltlon System for In-fllght on a Cyllnder and Procedure for Measurlng Alrfoll Evaluatlon." SAE Paper No. 760462, Llquld-Water Content and Droplet Slzes ln 1976.
Supercooled Clouds by Rotatlng Multlcyllnder Method," NACA TR-1215, 1955. 14. Gregorek, G.M., Hoffmann, M.J., Welslogel, G.S., and Vo~el, G.M., "In-fllght Measurements 8. Lewls, W., "A Fllght InvestlgatlOn of the Mete- of the GA (W)-2 Aerodynamlc Characterlstlcs," orologlcal Condltlons Conduclve to the Forma- SAE Paper 770461, March 1977.
tlon of Ice on Alrplanes," NACA TN-1393, 1947.
15. Lush, K.J., and Moakes, J.K., "Performance 9. Perklns, P.J., McCullough, S., and Lewls, R.D., Reductlon Methods for Turbo-Propeller Alr- "A Slmpllfled Instrument for Recordlng and craft," pp. 5:1-20; Dommasch, D.O., "Data Indlcatlng Frequency and Intenslty of IClng Reductlon and Performance Test Methods for Condltlons Encountered In Fllght," NACA Reclprocatlng Englne Alrcraft," pp. 6:1-47, RM-E51E16, 1951. AGARD Fllaht Test Manual, 2nd revlsed ed., Vol. I, e ited by E.J. Durbln and C.D.
10. Palko, R.L., and Cassady, P.L., "Photogram- Perklns, Pergamon Press, Oxford, 1962.
metrlc Development and Appllcatlon at AEDC," AIAA Paper 82-0610, 1982. 16. Lewls, W. and Bergrun, N.R., "A Probablllty Analysls of the Meteorologlcal Factors Condu- 11. Palko, R.L., and Cassady, P.L., "Photogram- Clve to Alrcraft IClng In the Unlted States," metrlc Analysls of Ice BUlldup on a U.S. Army NACA TN-2738, 1952.
UH-IH Hellcopter Maln Rotor In Hover Fllght," AEDC-TR 83-43, October 1983. 17. "Ice Protectlon," Alrworthlness Standards: Transport Category Alrplanes, F.A.A. Regula- 12. Palko, R.L., Cassady, P.L., McKnlght, R.C., tlons Part 25, Sectlon 25.1419, and Appendlx Freedman, R.J., "Inltlal Feaslblllty Ground C, 1974.
Test of a Proposed Photogrammetrlc System for Measurlng the Shapes of Ice Accretlons on Hell- copter Rotor Blades Durlng Forward Fllght," AEDC-TR 84-10, Aug. 1984.
TABLE I. - ICING CLOUD DATA AND ACCRETION PROPERTIES FOR ICING FLIGHTSa Fllght number 84-19 84-27 84-34 Fllght date 2/3/84 3/15/84 4-18-84 Fllght data 1 Average pressure altltude, ft 5306 8526 5578 Average true alrspeed, kn 134 137 137 3 Average alrcraft angle of attack, deg 1.4· 2.2· 1.6· (referenced to alrcraft floor llne) 4 Start tlme of lclng encounter 14:16 12:39 10:40 IClng cloud data 5{a) Total temperature, ·C -5.2 -3.5 -4.8 5{b) Statlc temperature, ·C -6.8 -5.2 -6.5 6{a) Average LWC, gms/cu m 0.30 0.34 0.58 6{b~ MaXlmum LWC, gms/cu m 0.70 0.70 0.90 7{a Duratlon of encounter, mln 49 25 7{b) Extent of encounter, n ml 110 57 50 8{a) Mean effectlve droplet dlameter, m 11 15 10 E 8{b~ Droplet Slze dlstrlbutl0n E E 8{c MaXlmum droplet slze, 11m 30 41 27 Cloud type Stratus Stratus Strato-Cu Ice accretl0n propertles Type of lce (see photo) Mix Glaze M1X 11 Shape of lee (see photo) -------- -------- --------- 12 Average reference accretlon rate, In/hr 2.9 3.4 5.8 13 Reference total accretl0n, ln 2.4 1.4 2.1 14 Characterlzatlon of lclng ( a) Frequency of occurrence (number of lclng encounters to equal or exceed) 1 ln 450 1 1 n 150 1 ln 900 (b) Certlflcatlon crlterla (percent of max LWC) 88 79 104 aS ee reference 4 for complete explanatl0ns of table elements.
6.30 (20.67) WAKE 1. 45 (4.75) SURVEY
I---Jf t
PROBE, ,
, ,ROTATING
, / MIJLTICYLINDERS ,
~ r;=:::;F' ===~====i ~ 1=====::C::::=!!::;::::==1\
1. 98 (6.5) \ \
T
LWING ,/ SURFACE DROPLET CATCHER ,/,/ PRESSURE (SOOTED SLlDE)----"'/ BELT ,ROSEMOUNT TEMPERATURE I WAKE SURVEY I PROBE SWEEP, I / I / I -,/ I Figure 1. - NASA LewIs Research Center ICing research aircraft and locations of ICing Instruments, wake survey probe, and wing surface pressure belt. All dimensIOns are In m (ft).
AFT CAMERA, FLASH I ,FORWARD I HEAD, \ / CAMERA I \ I
, I
I I I WAKE SURVEY _ PROBE--- (al Stereo camera system layout 81/2-""""'- .-1
-'--~ 1.8
2 1
"'
------
(bl Reference control POints on wing surface and wing fence used In analYZing stereo pair photographs. DimenSIOns are In In.
Control pOints on wing fence positioned on lines that Intersect the wing surface at 2% chord spacing.
Figure 2. - Stereo camera system used to document Ice shape on wing ahead of wake survey probe.
Figure 3. - Wake survey probe on right wi ng.
Figure 4. - Surface pressure belt on left wing.
MAXIMUM LWC (0. 70) 7 / / RMC-r-_ (0. 80) / / ---,....-.-.4/ .8 rt'I
/
E .6 I I
- C'l
.4
,3 .2 ~ 0 10 20 30 40 50 (a) FLT 84-19 • . 8 rt'I E .6 C'l
.4
u .2 ~ (b) FLT 84-27.
,MAXIMUM 1.2 I LWC (0 90) /\ RMC I • / \ rt'I AVERAGE / \ / \ .9 E / /
- C'l
.6 u .3 ~ 0 5 10 15 20 TIME, min (c) FLT 84-34.
Figure 5. - Variation of liqu Id water content (LWC) with time for three ICing encounters. LWC measured con- tinuously by Johnson and William's liquid water content meter and Intermittently by rotating multlcyllnders.
• ACTUAL DATA FROM FLIGHT 84-19 (SEE TABLE I) --- FAR ENVELOPES AT CONSTANT TEMPERATURE FOR STANDARD HORIZONTAL EXTENT OF 17.4 n mi (20 st ml) ---- MAXIMUM LIQUID WATER CONTENT AT THE FLIGHT MEASURED STATIC TEMPERATURE OF -6.8 C AND FOR STANDARD HORI- ZONTAL EXTENT OF 17.4 n ml --- LIQUID WATER CONTENT CORRECTION FACTOR USED WHEN HORIZONTAL EXTENT IS DIFFERENT FROM 17.4 n mi --- MAXIMUM LIQUID WATER CONTENT AT -6.8 C CORRECTED FOR HORIZONTAL EXTENT OF 110 n mi 1.0 ~ .8 LLJ I- «rn ~ E c- .6 - 0> => 0""': - Z ....JLLJ :EI- .4 =>z (0.34) :Eo _u (0.30) x « • 2 :E
o (11)
10 15 20 25 30 35 40 MEAN EFFECTIVE DROPLET DIAMETER, ~m 1.5 1.3 I- Z~ LLJO 1.1 1-1- Zu 0« Uu....
.9 ~z LLJO I- - «I- .7 ~~ c~ -~ =>0 .5 Qu ....J (0.43) .3 .1 5 10 50 CLOUD HORIZONTAL EXTENT, n ml (a) flight 84-19.
Figure 6. - Icmg encounters superimposed on FAR appendix C of part 25 contmuous maximum (stratiform clouds).
• ACTUAL DATA FROM FLIGHT 84-27 (SEE TABLE n
--- FAR ENVELOPES AT CONSTANT TEMPERATURE FOR STANDARD HORIZONTAL EXTENT OF 17.4 n mi (20 st mi) ----- MAXIMUM LIQUID WATER CONTENT AT THE FLIGHT MEASURED STATIC TEMPERATURE OF -5. ~ C AND FOR STANDARD HORI- ZONTAL EXTENT OF 17.4 n mi --- LIQUID WATER CONTENT CORRECTION FACTOR USED WHEN HORIZONTAL EXTENT IS DIF- FERENT FROM 17.4 n ml __ MAXIMUM LIQUID WATER CONTENT AT -5. ~ C CORRECTED FOR HORIZONTAL EXTENT OF 57 n ml TEMPERATURE.
°c
.8
,-0
~ , "...-(-5.2) «('/"\ ',,,,x..
~ E.6 "
S -;;, '~O ""
Q ~ (0. 43) I---~ " ""
LLI ...J "" § g (0.34) ,20 ....... , ..............
::Eu ....................., g .2 ....... _.............. ....... ....... .......
~ -30 ....... _ ....... - ........ - .......
c:::; --- ....... __ --.. --- ___ .......
- -
Ow m ~ ~
m MEAN EFFECTIVE DROPLET DIAMETER. 11 1.5 1.3 t- zo::: LLlO t- t- 1.1 Zu
8i:E
O:::Z .9 LLI 0 t- - «t- ~~ .7 00::: (0.61) -0::: =>0 au .5 ::i .3 .1 5 W 50 100 500 CLOUD HORIZONTAL EXTENT. n ml (b) Flight 84-27.
Figure 6. - Continued.
• ACTUAL DATA FROM FLIGHT 84-34 (SEE TABLE I) --- FAR ENVELOPES AT CONSTANT TEMPERATURE FOR STANDARD HORIZONTAL EXTENT OF 17.4 n mi (20 st ml) ----- MAXIMUM LIQUID WATER CONTENT AT THE FLIGHT MEASURED STATIC TEMPERATURE OF -6.5° C AND FOR STANDARD HORI- ZONTAL EXTENT OF 17.4 n mi --- LIQUID WATER CONTENT CORRECTION FACTOR USED WHEN HORIZONTAL EXTENT IS DIF- FERENT FROM 17.4 n mi --- MAXIMUM LIQUID WATER CONTENT AT -6.5° C CORRECTED FOR HORIZONTAL EXTENT OF 50 n mi TEMPERATURE, 1.0
°c
(0.85) .8 " 0
"
" ".... ,(-6.5)
,,', '<
,,',./ "
(0.58) (0.56) ',,10 ",
, "
.4 -20 " ' ........
...... .................. "-
.......... ......"
.2
- ................ ........"
-30 -- -- -_ ..........
--..::::-- --
- -
30 35 40 15 20 25 m MEAN EFFECTIVE DROPLET DIAMETER, 11 1.5 1. 34 1.3 ,
"-
I- Z~ L.LJO , 1.1 I- I- Zu
"
8~ , • 9 ~z ~Q ,
" "-
«l- s: ~ (0.66) i----------l.
c~
3@5
O'u .5 ::J .3 .1~LL~~ __ ~~~~~_L~~ 5 10 50 100 CLOUD HORIZONTAL EXTENT, n ml (c) Flight 84-34.
Figure 6. - Concluded.
(a) Wing leading edge ice formation.
(b) Ice formation on wing strut.
Figure 7. - Ice accretions on aircraft at ti me of aerodynamic measurements for flight 84-19.
(a) Wing leading edge ice formation.
(b) Ice formation on wing strut.
Figure 8. - Ice accretions on aircraft at ti me of aerodynamic measurements for flight 84-27.
(c) Ice formation on empennage.
(d) I ce for mati on on wheel and landi ng gear strut.
Figure 8. - Concluded.
(a) Wing leading edge ice formation.
(b) I ce for mation on wi ng strut, Figure 9. - Ice accretions on aircraft at time of aerodynamic measurements for flight 84-34.
(c) Ice formation on empennage.
Figure 9. - Concluded.
TIME AFTER EXITING ICING CLOUD, t, min
o
riCE FEATHERS Figure 10. - Stereophotography results showing variation In composite ice profiles with time (after eXiting the ICing cloud).
FLIGHT 84-32 FLIGHT 84-34 FLIGHT 84-29 MVD (SOOT S IDE), 11m MED (RMC), 11m 10.1 14.6 E (SLIDES) E (RMC) E (RMC) LANGMUIR DISTRIBUTION 16 (SLIDES) 28 (RMC) MAXIMUM DIAMETER, 11m 40 (RMC) (5% vol. ABOVE THIS) LWC, g/m 0.23 0.58 0.15
STATIC TEMPERATURE, °c -7
-4 -6 TRUE AIRSPEED, KTAS 141 137 145 PRESSURE ALTITUDE, ft 8200 5600 7600 ICING DURATION, min 22 49 Figure 11. - Correlation of ice accretion extent on wing surface with cloud droplet size (larger drop sizes produce greater ice coverage of wing surface).
FLIGHT NUMBER (NO ICE) 84-40 1.2 0 0 84-41 b.
84-42 1.0 84-43 0 84-44 .8 .6 .4 .2~~~~~ __ ~~-L~~L-~~~~ -1 0 1 2 3 4 5 6 7 8 9 lD 11 12 AIRCRAFf ANGLE OF ATTACK (REFERENCED TO AIRCRAFf FLOOR L1NE~ WING CHORD IS AT A +2.5° INCINATION FROM FLOOR LINE, deg Figure 12. - Un iced 11ft curve for wing section. liF cOo.
FLIGHT NUMBER (NO ICE) .014 84-42 b.
84-43
o
C,!)
84-44
o
<C "C .012
g;u
Z~ OZ _LLI I- - . OlD Uu LLlU: VI u..
C,!)LLI zO _u .008 s: .2 .4 .6 ,.8 1.0 1.2 WING SECTION L1Ff COEFFICIENT, C /, Figure 13. - Unlced drag polar for wing sectIOn.
li = 0°.
F FLIGHT NUMBER
• 84-27 I
• 84-34 \ ICED ~ 84-42
o 84-43 NO ICE
o 84-44
.026 "t:> U
¥'-
.024 ~
/
z ,- LI...I .022 u u:::
i
.020 L.J...
I LI...I .018 u (,!)
I
« • 016 c::
/
z .014 i= .012 u LI...I
o
Vl .010 (,!)
z .OOB $: .006 -1
o 1 2 3 4 5 6 7 8 9 10 11 12 13
AIRCRAFT ANGLE OF ATTACK (REFERENCED TO AIRCRAFT FLOORLlNE; WING CHORD IS AT A +2.5° INCLINATION FROM FLOORLlNEl, deg Figure 14. - ComparISon of wing sectIOn drag coefficient as a functIOn of aircraft angle of attack for the Iced and un- ICed wing. OF = 0°.
1.4 FLIGHT NUMBER (NO ICE) ....J u 1.2 84-18 .....: z 84-21 ~ t:, 84-22 u 1.0 u:::: L&..
LLJ u .8 t:i: ~ t:i: .6 « c::: u ~ « .4 • 2 -2 0 2 4 6 8 10 12 AIRCRAFT ANGLE OF ATTACK (REFERENCED TO FLOOR LINE), deg (a) lift curve • • 10 .02 L-.....I-~ __ L--L-.....I __ ~-L __ L-.....I-~ __ L-~
o .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 1.1 1.2
AIRCRAFT LIFT COEFFICIENT SQUARED, C L (b) Drag polar.
Figure 15. - Lift curve and drag polar for unlced ICing research aircraft (baseline). OF ~ 0°.
ALL ICED
o
WING STRUTS AND
o
1.2 LANDING GEAR STRUTS DEICED BASELINE UNICED 1.0 .8 .6
.4
.2_2 0 2 4 6 8 10 AIRCRAFT ANGLE OF ATTACK (REFERENCED TO FLOOR LINE). deg (a) lift curve • • 12 (!) 0 .10 .0-- U <c
_-r\ooo-
~
_-_"""I....J
of-.:' .08
J"'.-:::::----
G:~ --:::-~ <cu ~-
--=.-:&:- __ --- 0
uti: .~ ~L.LI -0 <cu .04 .02 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 AIRCRAFT LIFT COEFFICIENT SQUARED. C L (b) Drag polar.
Figure 16. - Change In aircraft 11ft curve and drag polar due to Ice for flight 84-19. 6 = 0 , F 1.2
o ALL ICED
BASELINE UNICED
o
.2_2 0 2 4 6 8 10 AIRCRAFT ANGLE OF ATTACK (REFERENCED TO FLOOR LINE), deg (a) lift curve • . 12 0- ,0--
-0--
C,!) 0 .10 U <c
c::: • -
of- 08 ti: ~ .
<cu
5EE .00
e:~ <Cu .04 (b) Drag polar.
FIgure 17. - Change In aIrcraft 11ft curve and drag polar due to Ice for flIght 84-27. OF = 0°.
All ICED
o
o WINGS DEICED
WINGS AND EMPENNAGE DEICED ~ 1.2 BASELINE ...J U
1.0
....: z UJ u u:: u..
.8 UJ o u t:;: :::J .6 t:;: ~ e:::: u e:::: .4 ~ .2~--~ ____ L- __ ~ ____ ~ __ -L __ ~ -2 0 2 4 6 8 10 AIRCRAFT ANGLE OF ATTACK (REFERENCED TO FLOOR LINE), deg (a) lift curve • • 12 C..!) 0 .10 0-- ~u c::: •
--
-- -0-- -
~ ~ .08
u..!::!::! -- -0----
___ --- ...-0-: .......... -- ~u .06 ___ ~
5E
~~ ~u .04 .02~~--~--~~~~--~--~~--~~
o .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0
AIRCRAFT LlFf COEFFICIENT SQUARED, c
l (b) Drag polar.
Figure 18. - Change In aircraft 11ft curve and drag polar due to ice for flight 84-34. OF = 0°.
FLIGHT NUM3ER 0 84-18 0 84-21 ~ 84-22 0..
..c 0:: L.U :5: 0..
L.U VI 0:: :::c I- VI ::> 0:: :::c I- 200~--~--~----~--~----~--~ 50 70 90 110 130 150 170 TRUE AIRS PEED, kn (a) Thrust horsepower required as a function of velocity for the uniced aircraft. Flight test data corrected to standard day, sea level, and stan- dard weight conditIOns (ll 000 Ib) (baseline).
Figure 19. - Flight 84-27, effect of glaze ICing on thrust horsepower required relative to calculated one engine thrust horsepower available. OF = 0 • UNICED POWER REQUIRED, \ , \ \ ~ 700 c:::: l.LJ <: ~ 600 LLJ V') c:::: a :c 500 l-
V') ...---
:::l \ \ c:::: :c LONE ENGINE I- 400 POWER AVAILABLE (100% PROP rpm) 50 70 90 110 130 150 170 TRUE AIRSPEED, kn (b) Flight test data corrected to standard day, sea level, and standard weight conditIOns UNICED POWER REQUIRED , \ ALL ICED \ PON£R REQUIRED,: '
'\ p
c..
..c 'I I I
ffi 600
I :s: a 0...
LLJ I ~ 500
P
a / :c l- V') \ ~ 400 :c LONE ENGINE
----
I-
,........--
POWER
/""
300 AVAILABLE (96% PROP rpm) 200 L...-_---L.. __ ..I...-_-L __ ...L..-_-...L._-----.J 50 70 90 110 130 150 170 TRUE AIRSPEED, kn (c) Test conditIOns at 7600 ft, flight test data cor- rected to standard weight on Iy.
Figure 19. - Concluded.
3 Recipient's Catalog No 2 Government Accession No
1 Report No NASA TM-86906
AIAA-85-0468
5 Report Date 4 Title and Subtitle
IC1ng F11ght Research: Aerodynamic Effects of Ice
6 Performing Organization Code
and Ice Shape Documentatlon With Stereo Photography
505-45-54
8 Performing Organization Report No 7 Author(s)
E-2395
Kevin L. M1kke1sen, Robert C. McKnight, 10 Work Unit No Richard J. Ranaudo, and Porter J. Perkins, Jr.
9 Performing Organization Name and Address 11 Contract or Grant No
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135 13 Type of Report and Period Covered
12 Sponsoring Agency Name and Address
Technical Memorandum
National Aeronautics and Space Administrat10n
14 Sponsoring Agency Code
Washington, D.C. 20546
15 Supplementary Notes
Kevin L. Mikkelsen, Robert C. McKnight, and Richard J. Ranaudo, NASA lewis
Research Center; Porter J. Perkins, Jr., Sverdrup Technology, Inc., Middleburg
Heights, Ohio. Prepared for the Twenty-third Aerospace Sciences Meeting sponsored
by the American Institute of Aeronautics and Astronautics, Reno, Nevada, January
14-1 7, 1 985.
16 Abstract
A1rcraft 1C1ng fl1ght research was performed in natural icing conditions. A data
base consisting of icing cloud measurements, ice shapes, and aerodynamic measure-
ments is being developed. During research 1C1ng encounters the 1C1ng cloud was
continuously measured. After the encounter, the ice accretion shapes on the wing
were documented w1th a stereo camera system. The 1ncrease 1n wing section drag
was measured wlth a wake survey probe. The overall aircraft performance loss in
terms of 11ft and drag coefficient changes was obtained by steady level speed/
power measurements. Selective deicing of airframe components was performed to
determine their contributions to the total drag increase. Engine out capability
in terms of power available was analyzed for the iced aircraft. It was shown
that the stereo photography system can be used to document ice shapes in flight
and that the wake survey probe can measure increases in wing section drag caused
by ice. On one fl1ght, the wing section drag coefficient (Cd) increased
approximately 120 percent over the uniced baseline at an aircraft angle of attack
of 6 • On another flight, the aircraft drag coefficient (CD) 1ncreased by 75
percent over the uniced baseline at an aircraft lift coefficient (Cl) of 0.5.
17 Key Words (Suggested by Author(s)) 18 Distribution Statement
Aircraft lcing; F1iqht research; Unclasslfled - unlimlted
Aircraft performance
STAR Category 05
19 Security Classlf (of this report) 20 Security Classif (of this page) 21 No of pages 22 Price"
Unclassified Uncl ass if1ed
"For sale by the National Technical Information Service, Springfield, Virginia 22161