NASA Lewis Research Center's Program on Icing Research

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NASA Lewis Research Center

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Program on Icin Research*

14078 ab3- NASA LEWIS RESEARCH (NASA-TM-83031)

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CENTER'S PROGF.AM ON ICING FESEARCE (NASA) ".

CSCL 01C ' It, 17 p HC A02 /hF A01 Unclas G3/Oj U1131 tv J. J. Reinmann, R. J. Shaw, and W. A. Olsen, Jr.

Lewis Research Center.

Cleveland, Ohio, •

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^.i ,^ ^ ^y 1. O l 7 7' .i x ^ 1p ode X, Nio Prepared for the Twenty-First Aerospace Sciences Conference4 { sponsored by the American Institute of Aeronautics and Astronautics Reno, Nevada, January 0-13, 1983 Y •« i -

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NASA LEWIS RESEARCH CENTER'S PROGRAM ON ICING RESEARCH* J. J. Reinmann, R. J. Shaw, and W. A. Olsen, Jr.

National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio Thus, the helicopter, general aviation, light Abstract transport, and commercial transport aircraft now NASA is again actively involved in aircraft share common icing requirements: highly effective, lightweight, low-power consuming deicing systems, icing research. This paper briefly describes the and detailed knowledge of the aeropenalties due to new research activity in ice protection systems, ice on aircraft surfaces.

icing instrumentation, experimental methods, analy- NA'-" has organized a new aircraft icing re- tical modeling for the above, and in-flight re- rn search. The renewed interest in aircraft icing lias search prograw at the Lewis Research Center to help solve the icing problems for modern aircraft. This come about mainly because of the new need for

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new program is concentrating on (1) new ice pro- all-weather helicopters and general aviation air- tection systems, (2) new icing instrumentation, (3) craft. Because of increased fuel costs, tomorrow's commercial transports also will require new types improved icing test facilities and testing tech- niques (cspecially for helicopters), and (4) wide- of ice protection systems compatible with the more spread use of large, high speed computers to lower efficient high L_ -pass and turboprop engines. And development and certification time and cost. Our all types of aircraft require better estimates of long-range plan is based on recommendations made in the aeropenalties caused by ice on unprotected several s>j dies of the icing needs for modern air- surfaces.

craft. ( 3 -) This report gives an overview of Introduction NASA's current efforts :n this new icing research program.

If an aircraft is to fly safely through icing NASA Aircraft Icing Program clouds, it requires protection on those surfaces that suffer unacceptable aerodegradation from ice Figure 1 shows on the left the main elements accretion. During the 1940's and 1^'50's, both the of NASA's current aircraft icing research program, NACA and industry helped solve the icing problems and on the ri g ht the detailed efforts include% in for those aircraft that flew IFR (instrument flight each element. - We shall briefly describe the rules), which included mainly the commercial and search efforts in each element.

military transports, a few qe9 rdl aviation air-

craft, but no helicopters.(II+-

Ice Protection Systems Today, due to technologicdl advances in avion- ics and fliqht controls, nearly all helico p ters and Pneumatic Deicers for Helicopters. Currently, general aviation aircraft can be equipped to fly helicopter rotor blades use electrothermal de- IFR. .et only a few military helicopters have ic- icers. An alternative is the pneumatic boot de- ing clearances, and no civil helicopter has yet icer, which offers ;:he potential of lower weight, been certified by the FAA for flight into fore- lower power consumption, simpler operating con- casted icing. Many of today's general aviation trols, and lower costs. In a joint research pro- aircraft are certified for icing, but they rtly on gram, NASA Lewis and B. F. Goodrich Co. developed ice protection technology that is over 20 years pneumat deicer roots for UH-1H helicopter rotor old. The relatively small payload fraction and low blades ) The best deicer boots tested in the power margins of these smaller aircraft mean that '-ewis Icing Research Tunnei (IRT) ;Fig. 2) were their ice protection systems must be light in installed on a U.S. Army UH-1H helicopter at the weight and low in power consumption. Since small Army Aviation Engineering Flight Activity at objects accrete ice faster than large objects, all Edwards AFB, Califorr`d. These boots will be test- the deleterious effects of icing happen faster and ed on the UH-1H in icing this winter under a joint are more serious on small, unprotected aircraft: program between the Army, NASA Ames, and B. F.

drag rise, torque rise, power loss, lift deteriora- Goodri-h Co.

tion, stall angle decrease, and stall speed Electrothermal Deicers. Lewis is developing increase.

one- an(Ttwo-dimensiona ransient heat conduction Because of high fuel costs, today's large com- alyze electrothermal deicer codes to mercial transports need lighter and more efficient systems. ( / To obtain validation data for the ice protection systems. Tomorrow's transport air- codes, B. F. Goodrich Co. will install an electro- craft will need alternatives to the hot-air ice thermal heater blanket on a UH-1H rotor blade sec- protection system because bleed air will be scarce tion and Lewis will instrument it with thermo- on the more efficient high-by-pass-ratio engines or couples between the various layers of the heater high speed turboprop engines.

blanket. The UH-1H blade section will be tested or an oscillating blade rig in the IRT. These tests Parts of this report were previously presented and the heat conduction codes may help determine at the First Ir.ternationl Workshop on Atmo- proper heater power levels and on/off times as a spheric Icing of Structures sponsored by the function of outside air temperature and cloud Electric Power Research Institute and the U.S.

liquid water content.

Army Cold Regions Research and Engineeringy Laboratory, Hanover New Hampshire, June 1-3, 1982 (NASA TM-82919

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old style icing cloud instruments were compared ;n Glycol Fluid Systems. There is considerable interest in freezing-point-depressant systems. The the IRT sp° I cloud to determine their relative University of Kansas, under a grant from Lewis, has accuracy a d their limitations over a broad range l0 i to:tedl ! the glycol system on two modern gener- of IRT ope • ,`ing conditions. The instruments test- al aviation airfoils in the IRT (Fig. 3). The sys- ed were primarily those used to determine drop size tems used the modern fluid distributor made of and liquid water content (LWC). Each instrument stainless steel mesh by TKS, Ltd., of Great was installed and checked out by its user (owner) or manufacturer to insure that it was operating Britain. We have also tested a fluid distributor properly. The IRT spray cloud proved to have ade- made of a porous composite material that offers the potential advantages of lighter weight and lower quate repeatablity and spatial uniformity for the needs of the program. costs than the stainless steel mesh. Further de- velopment of the composite dis`ributor is needed The LWC indicated by all of the instruments tested was compared with the standard IRT LWC cali- before it can replace the stainless steel distribu- tor. Another application for the leading edge bration. Figure 5 shows that most instruments agreed with each other and the IRT calibration fluid distributor is to keep bugs off laminar flow wings. In a joint program between NASA Langley within about *20 percent; the laser spectrometers, and Lewis, a fluid distributor will be installed on however, generally exhibited a larger scatter in e laminar flow wing and tested for bug and ice pro- their LWC indications. The data were taken at a tection. Lewis is using all test data on the very low temperature to avoid any thermal error due glycol system to develop a data base and desiin to water run-off.

procedure for the modern porous leading edge fluid Eight ASSP (Axial Scattering Spectrometer Probe) and three FSSP (Forward Scattering Spectrom- distributors, which are more efficient than the eter Probe) laser spectrometers for measuring drop- distributors tested in the 1940's and 19501s.

let size were compared in the IRT spray cloud.

Electromagnetic Impulse Deicers. The electro- Data from six of the spectrometers were obtained; magnetic impulse system offers a potential alter- the others failed for various reasons. The ASSP nativetg 5 t 6 hT conventional hot-gas anti-icing data showed a scatter of about *4 um over the systems.11 The heart of this system consists range of 10 to 25 um. The FSSP data were about 4 of a flat, spirally wound coil of wire installed um higher than the ASSP data. Figure 6 shows what inside the leading edge of the airfoil. When a a *4 um variation in droplet size caused in ice capacitor is discharged through the coil, the mag- shape and drag on a NACA 0012 airfoil (21-in.

netic field of the coil induces eddy currents in chord). The ice s.,ape changed significantly and the airfoil skin, causing it to deflect rapidly.

the resulting drag coefficient changed by a facto An electromagnetic impulse deicer system for of five.

comme-vial transports was recently tested in the Ice Det rs. Lewis has funded Ideal Re- IRT in a joint Lewis/industry program (see Fig.

to develop an instrument to de- search, nc. % 1,11 4). Data from the tests are being analyzed. Lewis tect ice on the surface of an aircraft component has also assembled a NASA/university/industry team and to measure the ice thickness and growth rate.

to develop the impulse system for both general avi- The MIAMI (Microwave Ice Accretion Measurement In- ation and transp ort aircraft. Wichita State strument) consists of a resonant surface waveguide University, under a grant from Lewis, has set up an w4th related electronics and a microprocessor. The interdisciplinary team composed of aeronautical, wave guide, which mounts flush with the surface, is electrical, and structural engineers who are work- 0.2 in. wide by 1.41 in. long by 0.393 in. deep.

ing with several airframers and an aircraft elec- It has a re c—a nt frequency of 6.27 GHz without any trical components manufacturer. The companies are ice. As ice buir?s up, the resonant frequency of contributing equipment and design/analysis ex- the waveguide shifts. A plot of the experimental pertise. The impulse system will be applied to resonant frequency snift versus ice th i ckness is both metal and composite wings and engine inlets.

shown and compared to an empirical curve fit in Tests will be :onducted in the Lewis IRT, and later Fig. 7. This curve-fit is programmed into the in flight if the results warrant it.

microprocessor to calculate ice thickness and ice Icephobics. Icephobics is the generic name growth rate.

given to any material that, wren applied to a Ideal Research, Inc., has demonstrated that surface, reduces the adhesive bond between the ice the MIAMI works in principle. But further develop- and the surface. Besides reducing the adhesive ment is required to demonstrate that it can dis- bond of ice, an icephobic suitable for aircraft tinguish between water and ice, because under glaze must also resist erosion by rain and sand, must not icing conditions both water and ice are present on be carried away with the shed ice, and must with- the surface. This problem seems to be solvable. stand exposure to weather including the sun's heat and ultraviolet rays.

Experimental Methods As part of a joint program between NASA, the Air Force, and the Army, several icephobic coatings Icing Research Tunnel. The Lewis Icing Re- were tested in the IRT. No coating, however, met search Tunnel IRT is the largest icing wind tun- all of the above criteria. Lewis currently has a grant with Clarkson College of Technology to devel- nel in North America (Fig. 8). The IRT has a 6-ft op an icephobic coating. Dr. H. ,lellinek, the high by 9 ft wide by 20 ft long test section; a top airspeed of 300 mp'i; a refrigeration plant which principal investigator for this grant, successfully developed an icephobic coating for the St. Lawrence pr:Auces total air temperatures down to -30 * F and which provides for year-round operation; and 77 air Seaway locks while he was working for the Army Cold atomizing water nozzles which produce a simulated Regions Research and Engineering Laboratory.

icing clou4 with liquid water contents from 0.5 to over 2 g/mrJ The IRT test section operates from Icing Instrumentation sea level (at 0 mph) to 3000 ft altitude (at 300 Cloud Instrument Evaluation. In a joint pro- mph). The IRT was built in 1944; today it is in gram between Lewis and the Air Force Flight Test continual use and constantly has a 2-year backlog Center (Edwards AFB, Calif.) a number of modern and of test requests. The IRT :an test selected

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full-st-ale components such as airfoils A engine ing test facilities for helicopters and their com- inlets, and it has ever; tested propelle and air- ponents. Flight testing in natural icing clouds is 1pn craft engines in the diffuser H^wns eam of the expensive because experience indicates that it main test section. would take several years of winter flying in is a uni- Airfoil Performance in Icin . The natural icing conditions to prove that the helicop- versal need for ata on t e aerodynamic gradation ter meets icing certification criteria, and even J two-dimensional airfoils in icing. F )m tests longer to get research type of icing data.

's and 1950's ipirical in the IRT during the 1 Two icing simulators exist for testing com- that predict ' lift plete helicopters: The Icing Spray Rig, a ground formulas were developed kl) drag increments while accounting for hord and an y to , -t Facility at Ottawa, Canada; and the HISS thickness of the airfoil, liquid water a tent and (Helicopter Icing Spray System), the U.S. Army's temperature of the cloud, airspeed, and ,,ration of inflight icing simulator. The Ottawa Spray Rig the icing encounter. We recently tested in the IRT tests helicopters in hover or low-speea tran- currently used on general aviation two airf oils sition. The HISS tests helicopters in forward aircraft. One of these airfoils has a blunt flight. Both operate only in the winter season and leading edge that gives higher maximum lift coeffi- are subject to the whims of the weather.

cients and "softer" stall characteristics than the The Lewis IRT has tested full-scale engine older airfoils that were tested to obtain the em- inlets for nearly all U.S. helicopters that fly pirical formulas. Figure 9 shows the drag predict- IFR. What the helicopter industry lacks is an ic- ed from the empirical formula versus the measured ing tunnel that can test main rotor blades under drag for the two airfoils over a wide range of ic- simulated flight conditions. In an attempt to tee ^ng conditions. Most of the data for the modern if the IRT can be useful in testing rotor blades, airfoils fall within the rather wide spread of re- we are building two rotorcraft test rigs (Fig.

sults for the older airfoils. But Fig. 9 shows 11): an oscillating blade rig and a rotating blade that the empirical formula seriously overestimates rig. The oscillating blaae rig will simulate var- the drag for the high LWC tests, which were done iat : ons in pitch angle during forward flight, only for the modern airfoils. These results point t'.ereby giving more realistic ice shape data on up the need for better analytical methods for pre- full-scale rotor blades. This aerodynamic data may dicting airfoil performance in icing.

oe useful in p.edicting performance degradation of Other modern airfoils, such as laminar flow helicopters without ice protection. The oscill,t- control wings and supercritical wings will be test- ing rotor blade in the IRT may also prove useful ed in the IRT to determine how ice affects the for initial testing of deicer systems even though aerodynamic performance of these newer airfoils.

the oscillating rig does not simulate centrifugal has also contracted wit. Sikorksy Air- NASA Lewi s forces and the air speed is less than Mach 0.4 in craft to test five modern rotor blade sections in the IRT.

the Canadian National Research Council's high speed The rotating blade test rig will be used to icing tunnel. The rotor airfoils are test an OH-58 tail rotor (about 5 ft in diameter`.

two-uimensional, six-incn chord, scale models.

Rotating blade test results will be compared with Sikorsky will obtain increments in lift, drag, and oscillating blade test results to determine the pitching moments caused by ice accretion, at Mach importance of centrifugal force and Mach number on numbers up to about 0.1 with the airfoi's both fix- ice shape. The main usefulness of the rotating ed and oscillating. They will also document the blade rig will be to study the ice formations and ice shapes by making molds of the accreted ice.

to measure the aerodynamic degradation caused by This data for modern airfoils will be made avail- the ice. Model rotors could also be tested in the able to the rotorcraft industry for estimating IRT, but the icing scaling laws must be verified, rotor torque rise, and will also be used by NASA to and nozzles are required to produce water droplet guide their analytical studies in ice accretion volume median diameters less than 10 um. We are modeling and aero performance penalty predictions.

working toward these goals.

Testing with Artificial Ice. High speed com- Lewis has been advocating that their now dor- puters are now available and must be used to model mant Altitude Wind Tunnel (AWT) be rehabilitated the ice accretion process and to analyze the com- into a propulsion and icing wind tunnel (Fig. 12).

plex flow around airfoils having rough, irregular The new AWT would have two test sections: a 20-ft shaped ice caps that can cause flow separation aro diameter section with speeds up to Mach 1 and a reattachment. To determine what physics must be 45-ft diameter section with speeds up to 50 knots.

included in the aerodynamic flow model, static The high speed section would test deicers on os- pressures must be measureo on the surface of the cillating, full-scale rotor blades up to blade-tip airfoil an.; the ice

r ip. These surface pressures

Mach numbers; it would test helicopter inlets with are extremely difficult to measure under icing con- simulated rotor downwash, and it would do complete ditions, so we have replaced the actual ice on the rotor tests on typical scale model rotors. The leading edge with a wooden replica and obtained low-speed section would test complete helicopters static pressures and drag data in the IRT with the (with truncated'blades), and it would have a rotor icing cloud turned off. kIl Drag results are whirl rig for testing full-scale rotor blade deicer shown in Fig. 10 for both the real ice and the wood systems.

replica (rouqhness was simulated with grit) for Icing Scaling Laws. All icing simulation fa- both rime and glaze ice. The drag for the artifi- cilities are limited in the model size they can cial ice agrees satisfactorily with the real ice.

test and in the air speed, altitude, droplet size, Fixed-wing aircraft are often flown with artificial liquid water content, and temperature they can ice in order to determine the aeropenalties due to attain. As a consequence they cannot duplicate all ice. Artificial ice may some day be applied to of the icing conditions necessary to test an air- helicopter rotor blades to determine aeropenalties.

craft component. To get around these facility lim- Helicopter Test Rigs. As mentioned earlier, itation$ . ing scaling laws were derived in the s; no civil helicopter is yet certified by the FAA for 1950, t14 however, these relationships have flight into foreca3ted icing. A key reason for never been properly verified. Proper experimental this lag in technology is the lack of adequate ic-

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accretion modeling code (17) which will calculate verification is extremely difficult because of ser- two-dimensional ice accretion shapes on airfoils ious facility and icing irstrument limitations.

In an attempt to verify the icing scaling for rime through glaze icing conditions. The laws, Lewis and AEDC (Arnold Engineering Air approachae ends the work of Stallabra S pnd D elopment Center, Tullahoma, Tenn.) have entered Lozowksi (191 and Ackley and Templeton.^ 19J The into a joint research program. The experimental code is compatible with the water droplet trajecto- verification uses the complementary capabilities of ry code developed by FWG, and allows the airfoil the large, low-speed Lewis IRT and the small, flow field and resultant collection efficiency to high-speed AEDC free jet. Lewis is pertorming be recomputed as the ice accretion changes the air- foil contour.

research on the energy balance, the heat transfer coefficients, and the catch efficiency of airfoils Transient Hea'^ Conduction Codes. The Uni- to improve the existing icing scaling laws. AEDC versity 7o is developing one- and is testing several spray nozzles to find one that two-dimensional heat conduction codes to model electrothermal deicers. A preliminary version of produces the small droplets required for testing small-scale models and _iso to improve all icing the one-dimensional code is given in Ref. 9. The simulation facilities. Verification tests will codes include a moving water-ice interface because consist of testing a series of airfoils under flight te°. results indicate that rotor blade sur- several sets of icing tunnel conditions that are face temperatures can reach 60 * F oefore the ice p redicted by the scaling laws to give equivalent sheds.

Aerodynamic Performance Codes. The Ohio State crag and ice shape results.

Verified icing scaling laws would (1) permit University is developing a capability for predict- accurate tests at actual facility conditions, which ing aerodynamic perform Ce eegradation of airfoils duplicate the results of conditions unattainable by due to ice accretions. i They start with that facility, and (2) permit tests of small-scale existing aerodynamic analysis codes for airfoils, models of aircraft and rotors to determine the and modify them wherever needed to model the flow around airfoils with ice accretions. As a separate aeropenalties of icing.

activity, Ohio Stat y is developing a method to -)re- dict overall aircraft performance degradation that Analytical Methods uses the results of the various other The NASA aircraft icing research effort in- two-dimensional codes being developed.

cludes extensive aircraft icirc analysis. The Texas A and M University is using the fixed-wing methodology developed at Ohio State Uni- long-tenn goal is to use cempL ?rs to predict the details of an aircraft icing e , counter. versity and extending it to calculate the perfo rm- Computer ance degradation of propellers and iielicgpilr codes will be developed to predict changes in over- all aircraft performance a, , a aircraft ha, dling rotors in both hover and forward flight. llZZ characteristics due to ice accretions on unpro- As ;-ig. 13 indicates, several additional cor- tected surfaces. Other codes will be developed to puter codes remain to be developed. But first, design ice protection systems and analyze their fundamental experiments must be conducted to gain a performance.

better understanding of the physics to guije the modeling efforts. Also of critical importance is Today's large, high-speed digital computers accurate verification data to determine computer were not available to the NAPA icing researchers in code capabilities and limitations. Unfortunately the 1940's and 1950's, and up until 1980 virtually little verification data exist and getting some of no icing analysis codes were published in the open it will require new icing simulation facilities, literature. The increasing costs of icir,g flight test rigs, and instrumentation capabilities.

tests provide strong motivation to substitute air- craft icing analysis methods for test programs

where possible. Flight Research

Currently we are developing some of the re- Lewis has started an icing research flight quired codes and verifying their accuracy with ap- propriate experiments. These codes are being de- program using NASA's . :n Otter airplane (Fig.

14). It will be flown out of Lewis during the ic- vEloped througn a combination of in-house efforts ing season from November through April. A joint and various grants and contracts. Figure 13 indi- U.S. Army/NASA helicopter flight test program is cates the large number of compu er codes required.

also discussed below. The flight programs are in- Also shown are some (but by n , . 2ans all) of the tended to insure that researchers conducting icing required interfaces. The figure also shows areas of current resean:h in NASA. tests in the IRT or developin g computer codes in support of .,J ng have first-hand knowledge of how Water Droplet Tra ectory Codes. FWG Associ- their resul'.: compare with flight test results in nc., is developing a particle trajectory ates real icing conditions.

code- 15 ) to calculate two-dimensional tr:ier,tor- Validation Dat,, for Icing Simulation ies about single- and multi-element airfoils, Facilities. There dues not seem to have been ary two-dimensional inlets, and axisymnetric inlets at systematic attempt to prove that icing simulators angle of attack (symmetry plane only). The flow do a reasonable job of duplicating the natural fields are calc.iated using appropriate Douglas icing condi t ions. Lewis plans to obtain, during Aircraft potential flow codes.

flights in natural icing conditions, ice shapes on Atmospheric Science Associates has developed a standard cylinders and airfoils that a.iy icing sim- three-dimensional particle trajectory code for cal- ulator can try to reproduce.

culatingg t ajectories about three-dimensional non- For ex,mple, the same airfoils and cylinders lifting and and lifting bodies. The code can used in flight will be installed in the IRT where calculate water droplet trajectories about the com- flight icing conditions (airspeed, LWC, drop size, plete aircraft. Again, appropriate potential flow and temperature) will be duplicated. Drag, ice codes developed by Douglas Aircraft are used to shapes, and ice growth characteristics obtained in predict the aircraft flow field.

the IRT will be compared with those from natural Ice Accretion Modeling Codes. odes. The University icing. 'ne flight and IRT data comparisons will of Dayton Research Institute is ceveloping an ice

measure the IRT's ability to simulate natural icing proved icing test facilities. Ice accretion model- conditions.

ing and aerodynamic analysis of flows around rough, Instrument Evaluation. This flight program irregular ice surfaces with separated and reattach- affords an opportunity to comp are severa'. modern ed flows represents one of the most challenging cloud instruments with one ano r her and also with problems remaining in classical fluid mechanics.

the rotating multicylinders and u'l s l ide instru- ments that were useo in the 1940's and 1950's. The References Twin Otter will be equipped with all of the modern, f1ightworthy cloud instruments. 1. Reinman, J. J.: Selected Bibliography of Icing Cloud Data. On each icing flight NASA NACA-NASA Aircraft Icing Publications. NASA will collect icinq cloud data and give it to the TM-81651, 1981.

FAA who is collecting and correlating icing cloud 2. Bowden, D.T.; Gensemer, A. E.; and Skeen, C.

data taken at lower altitudes with modem A.: Engineering Summary of Airframe Icing instrumentation.

;ethnical Data. FAA-ADS-4, F ederal Aviation

Meeteo^roloW NASA Langley has developed a

i.gency, 1963.

nunerica T-

a7 comic e k " ) to forecast the future state 3. Pete-son, A. A.; Dadone, L.; and Bevan, A.: of the atmosphere at mesoscale. The code is en- Rotorcraft Aviation Icing Research Review and titled MASS (Mesoscale Atmosphere Simulation Recommendations. (D210-11662-1, Boeing Vertol

System), MASS uses a 50 km grid spacing over North Co.; NASA Contract NAS3-22384. ) NASA

America, with 14 levels in altitude and 51 sec com- CR-165344, 1981.

putation time interval. After each icing flight, 4. Breeze, R. K.; and ClarK, G. M.: Light Trans- Lewis gives Langley the location and altitude where port and General Aviation Aircraft Icing Re- the Twin Otter encountered icing. Langley uses search Requirements. (NA-81-110, Rockwell this data to validate MASS by backcasting the con- International Corp.; NASA Contract ditions at the -)ecified location of the icing NAS3-22186.) NASA CR-165290, 1981.

encounter. 5. Koegeboehn, L. P.: Commercial Aviation Icing Airplane Performance. NASA and the Ohio State Research Requirements. NASA CR-165336, 1981.

University will con uct Tnflight icing experiments Rotorcraft Icing-Status and Prospects. AGARD 6.

AR-166, 1981.

to measure lift and drag degradation of the Twin Engineering and Development Program Otter's wings, and also overall airplane perform- 7.

ance loss. Ohio State will install a heated wake Plan--Helicopter Icing Technology Research.

FAA-E_"18-8, Federal Aviation Administration, survey probe and a static pressu-e Delt on one of 1981.

the Twin Otter's wings. Thrust iiorsepower measure- ,T.,,nt techniques will be oevelopea. Flight results 8. Blaha, B. J.; and Evanich, P. L.: Pneumatic Boot for Helicopter Rotor Deicing. NASA wil. be compared with similar results of tests in the IRT on a Twin Otter wing section. CP-2170, 1980.

Helicopter Performance. NASA (Lewis and Ames) 9. DeWitt, K. J.; and Baliga, G.: Numerical and the U.S. Army , ATL Ft. Eustis, VA and Simulation of One-Dimensional Heat Transfer in AEFA Edwards AFB, CA) have a joint helicopter Composite Bodies with Phase Change. NASA flight research program. The purpose of this pro- CR-165607, 1982.

gram is to determine if two-dimensional airfoil 10. Kc^lman, D. L.; Schweikhard, W. G.; and data can be used in existing helicopter performance Albright, A. E.: Icing Tunnel Tests of a codes to predict hover performance under icing con- Glycol-Exuding Porous Leading Edge Ice Pro- Army will fly a UH-1H helicopter in tection S y stem on a General Aviation Airfoil.

ditions. T he (KU-FRL-464-1. Kansas Univ Center for the Canadian Ottawa Spray Rig. After the UH-1H Research, Inc.; NASA Contract NAG3-71.) NASA accumnulates ice on its rotors, it will be moved CR-165444, 1981.

out of the cloud and the Army will measure its per- 11. Magenheim, B; and Rocks, J. K.: Development formance characteristics. The UH-1H will land and and Test of a Microwave Ice Accretion Measure- NASA will document the ice formed on the rotor ment Instrument (MIAMI). NASA CR-3598, 1982.

blades, using molding techniques and stereo photo- 12. Gray, V. H.: Prediction of Aerodynamic graphy. From these molds full-scale, rotor airfoil Penalties Caused by Ice Formations on Various sections will be made. Thee sections will be Airfoils. NASA TN D-2166, 1964.

tested in a dry transonic wind tunnel to obtain 13. Bragg, M. B.; Gregorek, G. M.; and Shaw, R.

lift, drag, and pitch moments. This section data J.. Wind Tunnel Investigation of Ai r foil Per- will be used in helicopter performance codes to formance Degradation Due to Icing.

predict hover perfomance degradation. The AIAA-82-0582, 1982.

predictions will be compared with the measured 14. Dodson, E. D.: Scale Model Analogy for Icing hover performance.

Tunnel Testing. D6-1976, Boeing Airplane Company, 1966.

Concluding Remarks 15. Frost, W. F.; Chang, H.; Shieh, C.; and As you can see from this review, NASA's new Kimble, K.: Two Dimensional Particle Tra- icing research program is broadbased, and cover: jectory Computer Program. NASA CR to be both basic research and engineering applications. published.

The program is well coordinated among the various 16. Norment, H. G.: Calculation of Water Drop NASA Research Centers, the FAA, the 000, univer- Trajectories to and about Arbitrary sities, industry, and some foreign governments. Three-Dimensional Bodies in Potential Air- flow. NASA Ck-3291 9 1980.

This coordination eliminates duplication of effort 17. MacArthur, C. D.; Keller, J. L.; and Liner-., and facilities, and Helps assure that we are work- J.K.: Mathematical Modeling of Ice Accretion ing on the right problem.

on Airfoils. AIAA p aper Gur planning and research reveal that the ic- 82-0284, 1982.

ing problem has four mein needs: advanced ice pro- tection concepts; improved icing instrumentation; advanced icing analysis methods; and ew or im-

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21. Korkan, K. D., Daeona, L.; and Shaw, R. J.: 18. Lozowski, E. P.; Stallabrass, J. R.; and Hearty, P. F.: The Icing of an Unheated Non Performance Degradation of Propeller/Rotor Rotating Cylinder in Liquid Water Droplet-Ice Systems Due to Rime Ice Accretion.

AIAA-82-0286, 1982.

Crystal Clouds. LTR-LT-96, National Research Council of Canada, 1979. 22. Kaplan, M. L.; et al.: A Mesoscale Eighth 19. Ackley, S. F. and Templeton, M. K.: Cow uter Orfir Numerical Modeling System and the "Red Modeling of Atmospheric Ice Accretion River" Tornado Outbreak of 1979, Parts I and CRREL-19-4, Army Cold Regions Research and II. Presented at the 12th AMS Conference on Engineering Lab., 1979. Severe Local Storms (San Antonio, Texas), Jan. 11-15, 1982.

Bragg, M. B.; Gregorek, G. M., and Shaw, 20.

R.J.: An Analytical Approach to Airfoil Icing. AIAA 81-0403, 1981.

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WATER SPRAY SYSTEM &D LOW SPEED TEST SECTION DRIVE DRIVE FAN C00_AG COILS MOTOR f STEAM SLOTS HEATED - TURNING VANES • ENGINE EXHAUST VTEST SECTION WATER SPRAY REMOVALS :OOP 29 D., MY LONG SYSTEM ` Figure 12. - Flaw circuit for proposed rehabilitation of the Lewis Altitude Wind Tunnel (AWT).

i AERODYNAMIC FLIGHT, PERFORMANCE ENVIRONMENTAL PENALTIES CONDITIONS PARTICLE ICE AIRCRAFT FLOW FIELD ACCRETION PERFORMANCE TRAJECTORY AERODYNAMIC BODY LOADS GEOMETRY ON ICE INTERNAL HEAT TRANSFER ELECTRO• MI HOT GAS THERMAL SYSTEM SYSTEM SYSTUA SHED ICE CHAR.INCLUDING TRAJECTORIES MECF'1HICAL TRO• PNEUMATIC VIBRATION SE BOOT SYSTEM \ IVOTEM SYSTEM NOTE: F7 INDICATES AREA OF CURRENT COMPUTER CODE DEVELOPMENT FREEZING P T DEPRESSANT BY NASA URC ICEPHOBICS SYSTEM CD42-13126 Figure 13. - Flow chart showing NASA's methodology for aircraft icing analysis.

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