1、REPORT No. 485THE DRAG OF AIRPLANE WHEELS, WHEEL FAIRINGS, AND LANDINGGEARS-IBY mLLTAM E HEBBNsmm, Jr. ad DAVID BIQLMANNWJMMARYTe8t8 were made in the 7- by X)-foot m“nd tumndand in the f?O-foot tunnel of the iVatM AdvisoryCom those in the 7- by 10-foot tunnel weremzde a-t air speede up to 0 miik per
2、 hour and t7w8ein the i?O-foot tunml were low-premure wheei% adtire8 maybe wed the proper wheel faihg mm.yredwce thedrag due to a landing gear me than any other re-fhlP#lt;fdtingOfand zunding g88 halving a L?lk3 supporting 8t7Wthave ks drag than my other types of nonretraetimJgears. Ao, the theaerod
3、ynamic interference between wheels and struts;the drag of a wheel with various wheel fairings; thethe drag of difkttypes of larding gears; the effect of wings and aradial air-cooled engine on landing-gear drag; the ef-f ect of changes in pitch angle on landing-gear drag;and the effect of various mod
4、ifications to landingjggarson their drag. From these data an analysis oflanding-gem drag was made and an indication of the10wA drag obtainable with a nonretracting landinggear obtained. The investigation included tests of5 pes of wheels, 6 types of wheel fairings with 8modifications, and 22 differen
5、t lanclhg gears -with atotal of 55 moditkations to these gears.All the landing gears tested were attached to anopen-cockpit fuselage and the tests were made withoutpropeller slipstream. Most of the test-swere made at0 pitch angle and without wings or an enggineattached to the fuselage. Howeverj the
6、effects ofwings, of a radial air-cooled engine with and without193Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. .194 REPORT NATIONAL ADVTSOBY (JOMMITTEE FOB AEBONAUTI(YScowling, and of pitch Me on a number of diilerentlanding gears were measured.
7、The IanO-gear program has been extended to in-clude tests on other pes of landing gears, the resultsof which will be presented in subsequentreports.APPARATUS AND METHODSTUNNELSThe 7- by 10-foot wind tunnel, in which a part ofthe lanw-gear dpg investigation was made, is fullydescribed in reference 4.
8、 The standard force-testmodel support was used. Tests were made in thistunnel to determine the drag of whids, the aerody-namic interference between wheels and struts, thedrag of the 8.50-10 wheel with various wheel fairings,the drag of half of landing gear 2a with variousmodiikationsj and the drag o
9、f the 8.50-10 wheel andhalf of landing gear 2a in yaw.The 20-foot propeller-research wind tunnel, in whichthe remainder of the tests were made, is described inreference 5. The method of supporting the test set-ups on the balance is shown in fiege L Tests weromade in this tunnel to determine the drag
10、 due to lancl-ing gears used in conjunction with a fuselage, wings,and a radial air-cooled engine.TESTMODELSAll models tested were designed for an airplane of3,000 pounds gross weight because full-scale modelscorresponding to this weight were the largest thmtcould be conveniently accommodated in the
11、 tunnelsused for the testing.Wheels.-The five different wheels and tires usedin the tests were: An 8.50-10 low-pressure wheel andtire; a 27-inch streamline wheel and tire; a 25 by11-4 extra-low-pressure wheel and tire; a 30 by 5 diskwheel with a 30 by 5 high-pressure tire; and a 30 by 6disk wheel wi
12、th a 82 by 6 high-pressure tire. (Seefig. 2) The 2 wheels vviththe high-pressure tires weretaken from service; the other 3 were wooden modelsFxciunnl.Landlng gem 3b with wheel Mr3ng A mounted on td fusohwaProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,
13、-,-,. -,1! .THE DRAG OF AlBl?IiAN33 WELS, HEEL ImmGSj AND IL.41WIWGGEAIt inolusive, with numerals addedvdlen necessary to indicata mod.il.lcationsto the basicform. (See figs. 4 to 9.) Fairings A, B, and C dif-fer only in cross section; fairing D difEers in crosssection mndhas a cut-out in the side e
14、qual to the tirediameter (8.50-10 wheel and tire) ; f airing E consistsof a short tail and a small fairing that partly coversl,he inside of the wheel; and f-o F covers only asmall portion of the inside of the wheel. All thefairings were made from sheet aluminum.Fuselage, wings, and engine.-In order
15、to conformwith the other models, the fuselage used in conjunc-tion with the landing-gear tests was constructed tothe average fuselage dimensions of an open-cockpitairplane of 3,000 pol.mdsgross weight. (See fig. 17.)Two rectanear wings of Clark Y section wereattached to the fuselage for part of the
16、tesks. A W2-by 15-foot wing was used to simulate the lower wingof Qbiplane cellule and a 6- by 18-foot wu was usedto represent the wing of a low-wing monoplane. AWasp radial air-cooled engine, cowled and uncowled,was used during some of the tests to determine itseffect on the landing-gear drag. The
17、relative loca-tion of the fuselage, the engine, the wings, and thelanding gears is shown in fiewes 17 and 40.Landing gears,-The lapding gears numbered la tollb (see figs. 18 to 34) were attached directly to thefuselage. Gears 12 to 14c (figs. 35 to 39) were at-tached to the fuselage and the 6- by 18
18、-foot wing.All landing gears were designed to comply with therequirements of the Aeronautic Branch, Departmentof Commerce. Design outside dimensions were strictlyadhered to in the fabrication of the various parts.Although information concerning the relative weightsof the landing gears would be of co
19、nsiderable interest,any attempt at weight analysis would be too involvedto come within the scope of this repofi The standarddimension chosen for the vertical travel of the wheelwas Ginches, and for the wheel tread, 6 feet 6 inches.All round struts were encased in fairings of Navy 1strut section, fin
20、eness ratio 3. In cases where stream-lined tubing was used, the tubhg was of “ standard”section, which is a modification of Navy 1 strut sec-tion. In some instances tandem struts were fairedtogether, this being done in accordance with the rc-ommendations of reference 6. A few of the landinggears inc
21、orporated wire bracing in their structures.The type of wire used was, in all cases,that commonlyreferred to as Cstreamlined) wire, although it isreally lenticular in cross section.The oleo action of all gears was strictly conven-tional with the following exceptions: Gears lb, lc,2b, 2c, ha, and llb,
22、 as tested, would have to use anoleo shock absorber in the fuselage with a suitablelinkage to give the required “wheeltravel or have oneincorporated in the. vtheel. GearalQ wod:. have theoleo shock absorber in the wheel or ihside the wheelfniring. ,Gears 3b, 3c, 13, and 14a would require asplined ol
23、eo shock absorber or its equivalent. Gear12 could have a conventional oleo strut but the wheelwould swing about a point directly in its rear.TESTSThe only measurementstaken during the tests wereair speed and drag. The maximum air speed used inthe 7- by 10-foot tunnel was 80 miles per hour, thatbeing
24、 the maximum obtainable; the maximum speedused in the 20-foot tunnel was 100 miles per hour:Wheel tests,-The drag of the wheel-and-tire unitswas measured at air speeds up to 80 miles per hour.Throughout the entire investigation the 8.50-10 wheeland tire was takwi as the standard unit because itappea
25、red to be the most commonly used in service.The selection was made solely for comparative pur-poses.Aerodynami interference beeen whes d strut,-The interference drag created by having awheel and a length of strut in close proximity was de-termined for all wheels used in the landirg-gear inves-tigati
26、on. Two ditlerent strut sections were used sep-arately for this work; one was of Navy 1 section, !+/4by W! inches, and the other was of circular sectionwith a diametm of 24 inches, Each strut was hingedat the wheel axle and the angle between the wheel andthe strut was varied in successive steps from
27、 0 to 90during the test The interference drag was obtainedby deducting the sum of the wheel drag and the strutdrag from the drag of the combination Figure 3shows the arrangement of a wheel and strukWheel-fairing tests.-l%e 8.5W1Owheel and tire wastested with wheel fairings A, B, C, D, and E at airsp
28、eeds Upto 80 miles per hour. All modifications tothese wheel fairingg as tested alone are shown in fig-urw 4 to 8, inclusive. Check tests were made on mostof these models in the 20-foot tunnel at air speeds upto 100 miles per hour.The 8,50-10 wheel in yaw.The drag of the 8.50-10wheel was measured at
29、 air speeds up to 80 miles perhour with the wheel yawed in successive .+tepsfrom15” to Mi”.Testson half of landing gear 2a with 8.50-10 wlieeL-Tests were made on a complete half of lan gear2a with the 8.5 table VII-B deals with gearsdesigned for attachment to the wing or wing and fuse-lage. An attem
30、pt was made under each classification6013+14to isolate the drag due to the wheels or wheels withwhl fairings, to struts, and to fittings plus interfer-ence. The drag due to these parts and to fittings plusinterference is also presented in percentage of the totalmeasured drag. A ratio of measured dra
31、g to com-puted drag is included for use by designers in evaluat-ing the drag of any type of ge, having given thedrag of the component parts. The entire analysis isbased on gear drag at 0 pitch angle and excludesthe effects due to the engine and the 4+2- by 15-foot-Wing. ,Reference to the tables will
32、 show th5j;: :/$/ Sfreomline sfrut“ -Round,. #G6 o L-d.=. i+ ,a t N IA .Br* e ,a w1! f4 . , .$ , -f:e - - _A IQ -. - _ _ _.-b- _ _ _$L-. -. .- - - - .- _- - RJ+4-C0 %4 N _/ / / “7” 42” +I(11. . _,/ 21“ - - . .+P :/- -42”FIGUIIE 4Drag and dlmensiona of wheel falrlng A. Fkrm 6.Dreg and dlmenelons 0 wh
33、eel fnlring B.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-THE DRAG OF AIRPLANE WEDIELS, WHEEL FAIIUNQS, AND LANDJNG GEARS-I 203,- - -,%g%80 rnPk4.61h- ,- -hle hdf foirlng A c25% aII One half c-*I foing B 428+ k: 2 I,- lo;%: f em“ :f:wWithout whee
34、l foimrig , 11.5 Iwl fcm+ngI* . .mod E. .9;8*l“”;= El8 E;,SL2 - w-1” E,8. fkwfion L, froni edge “m into -:- T- - T-TT G ,-36%11, 1 i11 1!: Clark Y IIIIII 7 !W;l: ecion- iI L- Y- _ -1 ! 1I-_ - J 3o j- -+ + -JJ r+I ?- _ - - ,tt Y ; I - -/I+ + +-locafions,oieoscollopsed._l- =-_-_-_3_7L-_-=_+3- .f_-_-_-
35、=_J-_J; Fuse/oge m ounfed in513;-k.:-_/,! inver+ed posfionFIQUBE 17.Sketch of fuselage showing Iocntions of wings, wheem and ouglnc.Norn.-AU am deaignwl for O- by lS-foot wfng have the wheel loeatlons 13 FfncheE to the rear of etandard loeatkns. The trend of gears 14n, 14b, nnd 14c s7 feet 8% inehm.
36、ME;:qw, / YOleo exiendedSx7ered / .Y.Oleo collapsedIfi”x 2”stremnllne tubeFIGm+IIlS.Dmg and dimenaIona of gem in.Dmg of gear at100 m.p.h. (oleos estended) : 8. GO-10 wheels, 42.5 unds.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-THE DRAG OF AIRPLA
37、NE WHEELS, WHEEL FAIRI.NQS, AND LANDING GEARS-I 207. ., JlYv- 3- ,T , , r.+14dl + 20fi”4 )*121%.+W, O lb,x l%” tubeY, Gear lC,“ streamline wirew-Fmmm 10.Dmg and Mreemdons of gears lb and 1s.Dreg of gears at 100 m. A.EP0und8C1I: ,-,1 1/j,F-_ 54”I.!I Y, “/,.6 61Guan22.-Drag and dimensions of gear 2d-
38、Drag of gear at 100 m.p.h. (O1OOSextended) :8.60-10 wheels, 43.0 pounds.IX, Oleo extendedx7BrQurm23.-Drag and dlmenidone of gear 3E.Drag of gear at 100 m.p.h. (oleos extended) : Pounds8.50-10 wheels. -. -_ -_- 43.5S.5O-10 whetifngs fakedT, k 2 streamline fatringU, k 3 wheel fairlng AV, Na 4 cuffs ov
39、er cylinder and fittingsW, ;eFturrmz 213.-Dmg and dimensions of gear 4. Dmg of r at 100 m.p.k (oleos estended) : 8JO-10 wheels, 30.0 pounds,v, = streamline wireW, 7 “x6M”sfrecunlineC?X, Ieo extendedFIGURE Z7.-Drag and dlmemdoaa of gear 6. Dmg of gear nt 100 m.p.h. (oleos extended) : 8.50-10 wheels,
40、88.0 pounds treomline icbe-No. 1 cuff-1/over struf,W-yl/.jI 3oy a71“ 1: IL- - -J19jf* J ,6%”_2“*1). Fk -i =:i5X”1“ :I ,37,4f” I ,I II II II ,1aurm 2fLDrng and dimensions of geo.r 7.Dmg nt 100 m.p.h. (ohms extendwl) : Pound88.60-10WhG-_-_ -_ - - 61.58.60-10 wheele, mwlltleatlon l-_-_ 56.0Provided by
41、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-212 REPORT NATIONAL ADVISORY COMKLTTEE FOR AEEONAUTI(YS!FKUJEEI30.Dmg and dimensions of gear 8.Dreg of gear at 100 m.p-h. (oleos extended) : Pounds wing leadhm,*Pod e ure foot; ct o 6. Wing data taken from ref-eren
42、ce 8.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REPORT NATIONAL ADVISOEY.P A modMfon AI -B - 630- 4.6D- 7.7 %! It;D (modlEcatIonDO- L5E- ;gnWhwl -.-.-.-.- .A-. -.- . . . . - . . . . . . . -Aiu iA modiOmtlon 1 . . . . . . . . . . . . . . . . . .
43、. . . .A mcdillcation . . . . . . . . . . . . . . . . . . . -fdcatlOn3 -B_ . _. _. _. _._ . . (Mnoh radirlsfllfets). . . . . . . . . . . . . .u. ./E !d-fnnb radius 51Ms)-E l-inoh mdlos flllet$-E l-bmh radius dllets-modlfimtionEd.E 141KJJradiusdllets-mwMkatlonsE!andEt-E(1-lnob mdrx folets-modillcatio
44、m Etand;lL 211.09.89.2Ii:13.8)Wmr.eUdrogaOm.p.hPoundsL 3Zb24i;Z616i !23:+23mDrag atIOm,p.h.Al;30by5highprmnre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4%632 by61hpressure . . . . . . . . . . . . . . . . . . . . - 46.6 -i 4LANDING GEAR llbI 1I8.5I-10 low . . . . . . . . . . . . . .
45、. . . . . . . . . - R: . . . xE27-lndI ne. - .I IProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.THE DRAG OF AIRPLANE WEZEU, WHEEL MIItLNGS, AND LANDING GEARS-1TABLEl VI.-EXWTN3T OF VARIOUS MODIFICATIONSUPON THE DRAG DUD TO LANDING 3ARS MOUNTEDON TE
46、ST lNJSELAQFl, 0 PITCHCondltfonof gearTLANDING GEAR 20T8.W1Owhmk-8JJ3-10whwlsjwheelkdrfng0-LANDING GEAR 3h -f8,W1OWheal %-;FUSELAGE WITH 6-BY 18-FOOT WfNG LANDINQ GEAR 140I8JJ3-10wh- n o -8.60-10 wheelajWhd Mrlug 0- MO =3TARLIl VII-A.-ANALYSIS OF JAND12NG-GEAR DRAGLANDING GIWRS DEYSIGN1313 FOR A!l?TACHhIIINTTOTRITOD TYPESI1* . . . . .-I Til i7iilb- 4.3 19.42B-2b-.-_-2u.-._-_-!M-
