The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears: I

~RO. & ASTRO. LIBRARY

..4~ j!I!.- -?- /' ~~ ~-G2-e-~ ~

NATIONAL ADVISORY COMMITTEE

FOR AERONAUTICS

REPO RT N o. 4 85

( .t •

THE DRAG OF AIRPLANE WHEELS, WHEEL FAIRINGS

AND LANDING GEARS-I

By WI LLIAM H . H E RR NSTEIN, JR., a nd DAVID BIERMA NN

1 934

For sa le by t he Sn per i nt e nd e n t of Doc um en t s, Was hin gt on , D .C.· • • • • • • • • • • P rice 10 ce nt s " AERONAUTIC SYMBOLS 1. FUNDAMENTAL AND DERIVED UNITS English M etric Sy mb ol A bb revi a- Abbr evia- U nit Unit ti on t i on L en gt h _______ met er _____________ : ____ foot (or mil e) __ ____ ___ l m f t. (or mt. ) seco nd ______________ _ __ Ti me _________ (or ho ur ) __ _ ____ t s second sec. (or hr .)

F orce _________ weig ht of 1 kilogr am _____ weight of 1 p o und __ ___ F kg lb.

P ower ________ ho rsep ower __ __ ___ ____ horse p ower (me tri c) ______ P h p .

--- -- ---- -

miles pe r ho ur ____ _ ___ {kil om et ers per hO uL _____ k.p.h. m. p .h.

Spee d _________ V m ete rs pe r seco nd _______ feet pe r second ____ ____ m.p.s. f. p .s.

I 2. GENE RAL SYMBOLS

w, Weight=mg P, Kinematic viscosity

p, Density (mass per unit volume)

g, Standard acceleration of gravi ty = 9.80665

2 2 Standard density of dry air, 0.12497 kg-m-~_s2 at m/s or 32.1740 ft ./sec.

15° C. a nd 760 rom ; or 0.002378 Ib. -ft .- 4 sec.

Mass = W

m, g Specific weight of " standard" air, 1.2255 kg/m or Z 0. 07 651 lb./cu.ft.

I, Moment of inertia = mk • (Indicate axis of

radius of gyration k by proper subsc ript .)

Coefficient of viscosity 3. AERODYNAMIC SYMBOLS 1, .. , Angle of set ting of wmgs (relative to thrust

s, Area

line)

S., Area of wing

Angle of stabilizer setting (relative to thrust G, Gap Span line) b,

Q, Res ultant moment

c, Chord Z il, Resul tant angular velocity b Aspect ratio

S·

Vl p- , R ey nolds Number, where l is a linear dimension jJ.

V, True air speed (e.g., for a model airfoil 3 in, chord, 100 m.p.h. normal pressure at 15° C., the cor- q, Dynamic pressure = ~p v: responding number is 234,000; or for a model

L, Lilt, absolute coefficient C = :s of 10 cm chord, 40 m.p .s. the corresponding

L number is 274,000) .

D,

Drag, absolute coefficient CD - ~ Center-of-pressure coefficient (ratio of distance

of c.p. from leading edge to chord length)

Profile drag, absolute coefficient CD. - ~S Angle of attack

Angle of downwash

Induced drag, absolute coefficient CD, - ~S

D" Angle of attack, infinite aspect ratio

Angle of attack, induced

D." Parasite drag, absolute coefficient CD - DS"

Angle of attack, absolute (measured from zero- • q lift position) C,

Cross-wind fo:Ce, absolute coefficient C - q~

a Flight-path angle

H, Resultant force

/

REP O RT No. 485

THE DRAG OF AIRPLANE WHEELS, WHEEL FAIRINGS

AND LANDING GEARS- I

By WILLIAM H. HERRNSTEIN, JR., and DAVID BIERMANN I .. angley Memorial Aeronautical Laboratory 604 -3 4 -- 1

NATIONAL ADVISORY COMMITTEE FOR AERONAUTIC S

HEADQUARTER, NAVY BUlLDI G, WASHI GTO ,D.C.

LABO R ATORIES, LANGLEY FIELD, VA.

Created by act of Congress approved March 3, 1915, for the supervis ion and direction of the scientific study of the problems of flight. Its membership was incr eased to 15 by act approv ed March 2, 1929. The member s are appointed by the Pre s ident, and serve as such without com pen ation.

JOSEPH S. AME S, Ph.D., Chairman, CHARLES A. LINDBERGH, LL.D., Pr esident, Johns Hopkins University, Baltimore, Md. New York City.

WILLIAM P. MACCRACKEN, Jr ., Ph .B., DAVID W. TAYLOR, D.Eng., Vice Chairman, Washington, D.C. Washington, D.C.

CHARLES F. MARVIN, Sc.D., CHARLES G. ABBOT, Sc.D., Secretary, Smithsonian Institution. United States Weather Bureau.

LYM AN J. BmGGs, Ph .D., HENRY C. PRATT, Brigadi er General, United States Army, Director, Bureau of Standards. Chief, Materi el Divi ion, Air Corps, Wright Field, Dayton, ARTH UR B. COOK, Captain, United States Navy, Ohio.

Assistant Chief, Bureau of Ae ronautic s, Navy Department . EUGENE L. VIDAL, C.E., BENJAMIN D. FOULOIS, Major Gencral, nit ed States Army, Director of Aeronautics, Department of Commerce.

Chief of Air Corps, War Department. E DW ARD P . WARNER, M. , ., HARRY F. GUGGENHEIM, M.A., Editor of Aviation, New York City.

ORVILLE WRlGllT, Sc.D., P ort Wa hington, Long Island, N.Y.

ERNEST J. I(ING, Rear Admiral, United States Navy, Dayton, Ohio.

Chief, Bureau of Aeronautics, Navy Department.

GEORGE W. LEWIS, Director of Aeronautical Research JOHN F . VICTORY, Secretary HENRY J. E. REID, Engineer in Charge, Langley Memorial Ae ronautical Laboratory, Langley Field, Va.

J OHN J. IDE, Technical Assistant in Europe, Paris, France TECHNICAL COMM ITTE ES AERODYNAMICS PROBLEMS OF AIR NAVIGATION POWER PLA TS FOR AIRCRAFT A IR CRAFT ACCIDENTS MATERIAL S FOR AIRCRAFT INVENTIONS A D DESIGNS Coordination of Research Needs of Military and Civil Aviation Preparation of Re$earch Programs Allocation of Problems Prevention of Duplication Consideration of Inventions OFFICE OF AERONAUTICAL INTELLIGENCE LANGLEY MEMO RI AL AERONAUTICAL LABORATORY W ASHINGTO ,D.C.

LANGLEY FIELD, VA.

Collection, classification, compilat ion, Unified conduct for all agencies of and dissemination of scient ifi c and scientific research on the fundamental technical information on aeronautics.

problems of flight.

REPORT No. 485

THE DRAG OF AIRPLANE WHEELS, WHEEL FAIRINGS, AND LANDING

GEAR S-I

By \\ ' ILLlAM II. Ih ~ IlIlNsn : IN , .II'" and DAnD BTERMANN SUMMARY (It th e same sp ee d, tlw low-d,'a,r; yeaI' flN ' om}17isliill!7 Ii lrll'ge p 1' ce nt(tge of th e gaill obtaill({I)/r' frolll I he li se Tests ?I' e }' e mad e in th e 7- by IO-foot willd tun}/ (' I of th" l 'e tl'Ct('table ge al', fwd in tl w fJ O-foot tww el of th e National Advis()I' !I ( 'oJ)unittee fol' A e T01w~btics to dete rmin e th e drag of a I NTRODUCTION 11~t1nb e 1 ' of airplan e 'whee l, 'wh ee l fail 'ings, and land- Although the lrag of the la nding O'eal' ha been ing geMS de sign ed or sf' l e(' ted f01 ' an airplane. of 3,000 known to con titllte a l arge portion of the total dl',lg powuls gl' O,'S 'weight, All te 8f8 lI' e l' e mad e 01/, fll ll- of all <ll rpl ane in Hight (see references 1. 2, and i3), siz ed ?nod l8/ those in tl w ' 7- by 10-foot tun ne l 'I.veJ' e practi 'ally no ,' ystelllatic resea rch has been done for lII({de at ail' sp ee d8 1.tp to 80 mil es jleI' hmt1' and thos (' tile exp re purpo .. e of improving the ael'oclymullil' in tile '2 0-foot t~lIw e l w ere mad e at ah' p ee ds v,p to l'ha ra 'teri ,-tics of lancling gea, l' s, In rece nt year ' d - 700 ?ni les p e 1' hour . Alt.hough ?nost of th e landing- !:iicr n ers have 'ucces sf ully atta c ked the problem and in gea/' te st w e 1' e mad e in c onjunction with a fus e la,r; e some ca 'es have designed landin g gear s that can be (l/1(l at 0 ° pitch angl e, some of th e tests 'I.V e1 'e mad e ill partly or fully retracted in fli ght. Little informa- conjwnction with th e fus elage plus 1cing and a 1yulial tion, however, i available concerning the compan l- ai1'-cooled engin e and at pit ch angl es fl'om - 5° to (j 0 liTe drags of nonretra tinO' landing gear,; and their to obtain an indi.c ation of th e q en ?Ytl effect of th e e component part, the aerodynamic interference be- 1 J a1'io1.b8 it e ms on lan di11 ,q-g e w' dmg, All t es ts w e l' e l ween the parts, or the degr e to which attempted I'efin ment of such gears may be successfully carried mad e in th e abs n ce of prop ellel' slip s tr e am , out.

Th e 1 'e S1tlts of th e in ve stiqation 'how that th e lowe st The present inve tiO'ation was made to obtai n data d1 'ag recorded for any landing q eal' test ed t as 13 concerni ng the following: The drag of wheels; th e pounds, at 100 mil es per hmtr and 0° pitch, a nd that aE ro lynamic interference between wheels and struts; it might be possible to 1 'e du c thi s d1'ag app1'od'imate ly the drag of a wheel · with various ,vhee1 fairings; the C pound by totally encasing th e 'I.vh eeZ of th1 's .c; al' drag of wheel and gea r s in yaw; the drag of different in fai1'ings. Th e lziqhe st landing-q e w' drag 1' ec 01 'ded types of landing O'ear ; the effect of wings and a U'a8 9 pounds . Oth er point of int e l' e t bl ' ought out ra dial air-cooled engine on landing-gear drag; the ef- we1 'e : Fitting-plus-1'nte rf eren ce d1'ag of o1'dinary fect of change in p it ch angle on landing-gear drag;

typ e of landing gears a ve 1'ag e about 44 pe1 'ce nt of

a nd the effect of variou modifications to landing: the d1'aq du e to th ese qe a1's,. low-p1'essure wh ee l8 and gea rs on their drag. From these data an ana lys i ,' of ti?' es may be us ed with littl 0" no inC1' ease in landillg- landin g-gear drag wa made a nd an indication of the g w' d1 ' aq/ th e 1J1 'oper wh e l fai1-inq may re du ce th e [invest drag ob tain able with a nonretracting: landing d1'aq du e to a landing qe ar 11101' e than any oth e ?' 1' e- gear obtained . The investigation included te 't of fi;n em e nt/ fairinq of all s tnd, is of gr e at i111p01 'tance/ :) type of wheel , 6 type s of wheel fairinO's with 3 and landinq qe a1' havinq (t ingl e suppo1'ting t'!"Wt modifications. and 22 Efferent lan ding gea r ,yith a l hav e less d1 'ag than any oth e 1' typ e of nOllre t1 ' (l c ting total of 55 modifications to the e gears.

ge a1's. Also, the substitution of low-d1'aq 01' 1' e tra c- 11 the landin g gea rs te ted were attached to an tabl e landing qea/' fo1' conve ntional typ es on high- open-cock pit fu elage and the tests were made without d1'aq airplan es 1' esults in a n e gliqibl e inC1' ea e in high p rope ll er slip t ream, Most of the te ts were made fit 8p ee d, LOlO-d?'ag 0/ ' re tm c tabl e ge a:1' us ed in pLa ce of ° pitch angle and without wing or an engine c onventional ge an on low-drag ai1 'planes 1' e sult in a a tta ched to the fnselage. However, the effect, of , ubstantial inC1' e as e in hiqh sp ee d 01 ' savinq in pow er \.'ing , of a radial air-cooled engin e with and witho ll t

4 REPORT NATIONAL ADVISORY COMMITTEE FOR AEIWNAU'l'lCS

cow lin g, and of pitch angle on a number of differcnt r eference 5. The metholl of suppo rtin g the tc t set- lan ding gear wcre measl1l'ed.

ups on the balance is hown in figure 1. Te ts were The lan ding-gear program has been extended to in- made in thi tunnel to determine the drag due to land - clude tests on other type of lan ding gear, the results ing gear used in conj unction with a fu elage, wing, of whi ch will be prese nt ed in subsequent repo rt . and a radial air-cool ed engine.

TEST MODELS APPARATUS A D METHODS TUNNELS All model tested wcre designed for an airplane of 3,000 pounds gr os weiO'ht becan c full- cale models The 7- by 10-foot wind tunnel, in which a part of corresponding to this weight were the larO'e t that th e landin g-creal' Llrag inve t i gation was made, is fully cou ld be conveniently ac ommodated ill the tunnels de cribed in reference :1:. The standard force-test u ed for the te ting.

model upport was u ed. Tests were made in this Wheds. -The five differ ent wheeb and tires u ed tunnel to dete rmin e the drag of wheel., the aerody- in the test were: An .50-10 low-p ress ure wh ee l and namic interference betwee:l wheel and st rut s, the tir e; a 27-inch st ream line wheel anLl tire; a 25 by drag of the .50-10 wheel with variou wheel fairing, ll---:l: extra-low-pr ess ur e wheel an i tire; a 30 by 5 di 'k the drag of half of landing o'ea r 2a with various wheel with a 30 by 5 high-pre SU re tire; and a 30 by 5 lliouifications, an 1 the (irac )' of the .50-10 wheel and Llisle wheel with a 3~ by () high-pre 'sure ti re. ('ee half of landing gear 2a in yaw.

fig . 2) The 2 wheels with the high-pressure tires were Th 20-foot propeller-res arch wind tnnnel, in which tuken f rom sc nl ce; the othe r 3 \\'ere wooden moclels the remainder of the tests worc m aLle, .is uesc l'.io cll j 11 l~IOUHEl l.-Landlng gear 3b witb wheel fairing A mounted on te t fu clage, THE DRAG OF AIRPLA ~E W HEEL, W HEEL FA I RI NGS , AN D LA DI G GEARS- I mad e to a tole ran ce of ± 1/ 32 in c h. All tir e: had :J b, 2c, 11 a, and lIb , a t es ted , would ha ve to use an mooth tr e ad.

ol eo sh oc k ab orber in th e f uselage with a uitabl e Wheel fairings.- Th e wh ee l fairin gs were d es ignat e cl linka ge to give th e re quir ed wh ee l tr avel or ha ve one by letter s A to F, inclu ive, with mun er al ad Ie I inc: o rporat ed in the wh ee l. Ge ar 10 would ha ve th e wh n nece s ar y to indi c at e modifi cations to lh e bas ic ol eo h oc k absorber in th e wheel or in side th e wh eel form. ( ee figs. 4 to 9.) Fairin gs A, B , and C lif - fa irin g. Ge ar s 3b, 3c, 13, a nd 14a wo uld r eq uire a fer only in cro section ; £ai}"ino- U differs in cr o s s plin ed ol eo h oc k ab or be r or it s equivalent. Gea r section and has a cut-o ut in th e side equal to th e tir e 12 could have a co nve nti onel ol eo str ut b ut th e wh ee l diam eter ( . -0- 10 wh eel and tir ) ; f airing E co n. ist would swing abo ut a poin t di r ec tl y in its r ea l'.

of a s hort tail an d a s mall f airin o- th at pa rtl y cover TESTS th e insid of th e wh ee l; and fairin g F co vers only a Th e only mea Llr eme nt s taken d uring th e te t were ,'mall portion of th e in id e of th e wh ee l. All th e air sp ee d a nd dra o· . Th e maximum a 'r sp ee d u ed in fairing s wer e ma Ie fr om h ee t aluminum .

Lh e 7- by l O -f oot tunn el wa 0 mi l es pe l' ho ur , that Fuselage, wings, and engine.- In ord er Lo co nform be in g th e maximum obta ina bl e; th e maximum peed with th e oth er models, th e fn elage used in conjun c- 1I b el in th e 20-f oo t tunn el \V a 1 00 mil es pe l' h O llr.

tion with th e landing -ge ar teots ,ya co n tru ted to Wheel tests.- Th e dra g of th e wh ee l- uncI - tir e unit the aY el'age fu selage dimension: of an open-cockpi t was mea ' ur e cl at air sp ee ds up to 0 mil es per h O lll· .

ai r plan e of 3,000 pound. g ro s weig ht. ( Sec fi g. 17 .)

Thr o ugh out th e e ntir e inv es t ig ati on th e . 50- 10 wh ee l

Two r ec tangul ar wing of C lark Y section were

a nd tir e ,,-a tak en a ' the s tandard unit beca n e it

atta ched to the fu sela o-e f or pa rt of th e t es t. A 4 Yz-

app ea re 1 to be th e m os t co mmo nl y lI sed in er vi ce .

by 15 -f o ot wing was u cd to s im.u l at e the lower win g Th e sel ec tion \\'a. made so lely f or co mp a ra t ive p ur- of a biplan e ce llule and a 6- by 1 - foot wing wa used po e'.

La re pr es ent th e wing of a low -"ing mono plan e.

Aer od ynamic interference between wheels and a " T asp r adial air- coo led e no-in o, co wl ed and uncowled , strut.- Th e int e rf eren ce dra g cre at ed by hav ing a was u ed durin g orn e of th e te · t. to dete rmine it s wh ee l and a leng th of . trut in close proximit y was cl e- e ffe ct on th e landin g-ge ar drag. Th e re lativ e l oc a- ter mined f or all wh ee ls u se d in th e lanclin o- -gear inves- lion of th e f1.l elage, th e engin e, th e wings, and the ti ga tion. Tw o differe nt tru t sec ti ons wer e ll se d sep- l andin g ge ar i hown in fi g ur es 17 and 4 0.

a rat ely f or thi wo rk ; one was of J: avy 1 ,ed ion , 2% Landing gears.- Th c landing geal\ numbered ] a t o by 6% in ch es , and the o th er \\'a of r ir cula r ection lIb (see fi o-B . 1 to 34) wer e atta ched dir ec tl y to thr wi th a di ameter of 21 4 in che . E ach s trut wa hin ged fu e lag e. Gear ] 2 to 14c (fi 0- . . 35 t o 39) wer e at - at th e ,vh ee l axl e an d th e an gle be tw ee n th e wh ee l and ta ched to th e fu se lage and the G- by 1 -f o ot win g.

th e s trut was vari ed in S tl es ive teps fr om 0° to 90 ° Alliandillg ge ar s were d es ign ed to comply with the durino- th e te t. Th e int e rf eren ce drag wa s obtain ed r equireme nt of th e A e ronauti cs Bran ch, D e partm ent by Ie lu c ting the um of th e wh ee l dra g a nd th e trllt of Commerce. D es ign oub ide dim ensions were tri ct ly cIrag fr om th e lra g of th e combination. Figur e 3 adh er ed to in th e fabri c ati on of the variou part.

hows th e arrang eme nt of a wh eel a nd "h·ut.

Althou gh informati on con ce rning th e r e lativ e we ight s Wheel-fairing' tests.- Th e . 50- 10 wheel and tir e was of the landing ge ar would be of co n ide rabl e i nt ere t.

tested with wh ee l f airing s A , B , C. D , and E at air nn y att e mpt at weio-ht analy i wo uld be too im ' oh 'ed sp ee d up to 0 mil es per h ou r. All modific ati on to Lo come within th e sco pe of thi r epo rt . Th e tandard th e e wh ee l fairil1 g~ as te ted alone are ho,,'n in fi g- (limen ion chosen f or th e ve rti cal tray el of the wh ee l ur e 4 to , in cl u ive. Ch ec k te ts were ma de on mo t was 5 in che , and for th e wh ee l tr ead , 6 f eet G in ch es .

of th e e models in the 20 -foot t unn el at a ir p ee d up All rounel trut s were enca e 1 in fairin gs of N ayy ] s trut section, fineness r atio 3. In cases where s tr e am - to 1 00 mil es per hour.

lined tubing wa . u se d , he tubin g was of "s tandard " The 8.50-10 w he el in yaw.- Th e dr ag of the 8.50- 10 ectioll , which i a modificati on of Nav y 1 s trut sec- wh ee l wa s meas ur ed at air speed up to 80 mi le per tion. In ome ins tan es tand em s trut s wer e fair ed hour wi th th e wh ee l ya we '[ in succe ive step fr om toge th er , thi s bein g done in a cco rdan ce with the r ~c 15° t o - 15°.

omme nd a ti ons of ref er en ce 6. A few of th e la ndin o- Tests on ha lf of landing gear 2a with 8.50-10 whee l. - ge ar in c or po rat ed wir e bra c ing in th ei r tru c tur es. Test were made on a co mpl ete h alf of la ndin o- o-e ar Th e type of wire u. ed ,v a , in all case, th at co mmonly 2a \I ' ith th e .50-10 wh ee l and wh ee l fa ir ings A, B , l' fe lT ed to a "s tr eamlined " wir e, alth ough it i.

C, D, E, and F wi th vari O ll s modifi c ati ons. De tail ' really le nti ular in cr oss secti o n. of all modific at ions ar e shown in fi g ur es 11 t o 16, Th e oleo action of all gears was s tri c tl y co n ve n- in cl usive. M os t of th ese tests wer e ma de in th e 7- tional with the followino- ex ce ption Gears 1b, l c,

by 1 0- foot tunn el at air sp ee ds up to 80 mil es pel'

REPORT NATIONAL ADVISORY COMMITTEE FOIt AERONAUTICS PRECISIO , hour, but a f ew te sts " ere c he cked in th e 20-foot tun- lIel at all' speeds lip to la D mil es per hour.

It i ~ estimat ed that the drag of wh eels alone , wheel

Half of landing gear 2a in ya w. -One-half of landing fairings, and on e-half of gea r 2a with it:- various ge ar 2a, equipped with th e 8. 50-10 " ' heel, ,,,as t ested 1Il 0di fi c ation ', wa m eas ur ed with a precision of ±O .l for dr-au at variou anIYle of yaw at air spee d. up to pound, Landing-o' ear tests mad e in co nj unction wit" tlO mile s per hour. Th e half gear wa s yawec1 in th e fu se lag e a lone a re es timat ed to be precise ,yithin succe 'si Ye s tep from 15° to - 15° .

± 0.5 pound, whil e te ts made in con juncti on with th l' Tests at 0° pitch of landing gears mounted on fuselage fuselage, wing, and engi ne at va r ious anO" le of pit ch or fuselage and wing. -Gea r 1a to llb, inclusi I'e, with ar e es tima ted to be pr eci e within ± 1.0 p o und.

yariou s modifi c ation , wer e te -t ed for drag in con - jun c tion with the fu se la ge alon e. Gears 14a, Bb, anc1 RESULTS AND DISCUSSION 14c wer e t es ted in co nj unc tion with the fu e lag e and All drag ",du l' s pr ese nt ed in thi s r e l ~ ort were take ll 6- by 1 -foot wing, All th e'e te ts wer e mad e at ail' from fa ired c urv es of drag plotted again't d y nami (; spee d ' up to 100 mile s per hour. Th e gea r s were pressure , In cases wh er e ch eck te ts wer e mad e in lIlounted in th e inverted pos ition (fig. 1) to fa c ilitat e th e 20-foot tunnel on the re s ult s obtained in th e 7- by tes tinO" and to r e mOI 'e th e gea rs as far as possib le from 10-foot tunn el, drag valu es are g iv en for both 0 mile s th e influ ence of th e !ll odel-s upp or ting trllctur e.

p er hour and 100 mil es per hOUL In all ot he r cases 'Vh enever wing s werc used du ri ng th e tes t , th ey " 'ere the values ar e given for o nl y one a ir sp eed, For co n- set at 0° in cid en ce . Th e d rag of the fuse lage, 0 I' venience) all th e drag data pr esen ted in tabu lar forlll fu se la ge and w ing, was nl e asur ed with and without arc included on th e fio' me il lu t r atil1g th e co rr es pon l- the landing gea r atta ched . The diff e r enc~ bebyeen ing test mod els. R esu lt of intederence t est , ya w thc r e ult s wa s th e drag due to th e landin g gellr under tests, and landing-g e ar tests made in co njun c tion with tc st.

wing s and e ngin e at va ri ous pitch ang l e, a re pr e- Tests at 0° pitch on several landing gears equipped se nt ed in c urv e form for ea .. e of co mpari son.

with various types of wheels.- Th e drag du e to lan ding

Th e r es ult s of tes t. s ma Ie in th e 7- by 10- foot tun-

gea rs 1b, 3a, 8, and llb, eac h eq uipped Iyith vario us nel wer e co rr ected f or horizonta l p r ess ur e gradie nt ill types of wh eel -and-ti re units , " 'as m eas ured at air th e U Llal manner. It was n ot n ecessar y to app ly any sp eed s up to 100 mil e per hour. Th ese landing gea rs co rr ec tion s to 1' e ult s obtained in the 20-foot tunn el '- :e re c ho sen be ca u e th ey had a wid e dinr s it y of s trut Lecause the pres ' ur e g r adient " 'as n eg ligibl e. An "rrang t m e nt. pa rti c ularly HrOlln 1 Lh e wheel hub . It ag reeme nt of ± 0 .1 pound dra g at 0 mil es per h ou r I\"a s hOlJ ed that the r es ult · would s hOll ' mOl' e ge ll el"- wa s obtained betwe en the r es ult s of check te ts made <I lly th e e ff ect on landill g-gear drag of subs titllting in the tw o win 1 tunn els aft er th e horizontal pr es llre- tliffer e nt whee ls of eq ual we ight- c arr y ing ca pa c ity.

grad ie nt orre tion had been applied.

Tests at various angles of p itc h of landing gears Wheel tests.- Tabl e I and figur e 2 s how the comparH - mounted on fuselage with and without the 4V2- by 15-foot Liv e d r ags of a ll th e wh eel tested alon e, It is of in- wing' and engine. -Landing <Y e ar s 1a and lla were L er est to not e that th e 27-inch treamlin e wh eel and tested for drag at I"ariou pit ch angl es from (j 0 to fre ha s app r ec iably less drag than an y other typ e - 5°, on the fu sel age alone, on th e fu se la ge with th e te ted, an d that th e 25 by 11-:1: e xtra-low-pres nr e 4 Y~- by 15 -foot winO" , on th e fu sel age with th e eng in e whe el and tire l1a th e highe st drag re co rded. Th e (coII'le([ and un co wl e d) , and on th e fu e lag e with the eire t of a ll th ese wh eels upon th e drag due to se veral wing and the en o·ine. Th epe t es t. · wer e mad e to as- (liife re nt la nding gear ' will be s hown lat er in the cr rtalJl th e e ff ects of the different combinatio n s on th e r epo rt .

(ll'a g , dll e to (h e l anding gea r s, at air sp ee( ls up to Aerodynamic interference between a wheel and strut.- 100 mil e per h Oll r.

Tests at various angles of pitch of landi ng gears Figur e 3 s how s the variation of int e rf er en ce drag be- mounted on fuselage and 6- by IS-foot wing.- Gear 12, tween th e differ e nt wh ee l ' and a si ngl e s trut (s tream- 13, 14a, 14b, and 14c, whi ch ,yere de, ignecl for use on lin e and r ou nd) along s id e th e wh eel , as th e angl e be- hr een th e two is va ri ed fr om 0° to 90°. The inter- ]ow- \I"in g monoplan es, " 'ere tested for d r ag in co n- ference drag genera ll y in cr ease ' a, the whee l and jun ct ion with th e fu sela ge a nd th e 6- by 18 -foot willg at I'ariou .· pit ch angle s f r om (3 0 to -5 ° at air speeds s trut ar e br ou ght toge th er. Th e 27-ineh tr ea mlln e lI"h ee l and tire is affected th e mo t by th e p ro ximity up to 100 miles p er hour.

of t he st rll t.

Gear 14c wa s lat e l' te"te c1 in co njun ctio n with the fll se lag e, the (3- II )' 1 -foot lI ' illg, alld tIl(' en gin (' Wheel -fairing tests.- Th c drags of the 8,:30-10 low- (c(lId ed Hnd III1C'o l\"l ecl) to get the added effect of the prc , su re whed and tir e wi th YariOIl ' typ e, of ,, ·h ee l c no ' ine UpOIl th e drag due to t hi s gea r, fairing s ar e o' iven in tahl e II and figures 4 to 9. FrOll1

THE DRAG OF AIRPLA E WHEEL, WHEEL FAIRINGS, AND LA DING GEAR , -I 7

a tta ck other than 0° accounts for very littl e of the th e!"e re 'ults it app ears that a wheel fai rino' uch as A, whi ch covers both siele of the wheel and ha a mini- increa se in drag.

Measureme nt of drag due to vari ous ty pes of landing mum of c ro ss- 'ec tiona l area, is the best ba ic typ e.

I t is also appa re nt from tests of modific ation s of thi gears with 8. 50-10 wheels, 0° pitch .-Table IV and l'a iri ng (A I and A ) that the portion of th e wheel figures 18 to 31, 34, and 37 to 39 co ntain the r es ult of or tire th at pr otru l es from the bottom of th e fairing te sts of variou landing-O'ear type, all of which were i 1'e pon sible for most of the drag . A mu ch as 72 Illn, Ie in co njun ction with th e fu e lag e. R ef er en ce to per ce nt of the drag of the .50 - 10 wh eel and tire may th e figures will how th e differcnce. in trut arrange- be sa ved by totally enca ing it in a fairing such a !:i ment . It hould be })ointed out that although all modifica tion A 2 of wheel fai r ing A. It i al 0 int e r- trut s were of s tr eam lin e ection the fitting were e · ting to not e f rom th e t es ts of wh eel fai r ing D, whi ch it-it exposed. ' Vhen ,yir e wer e u 'ed th e fitting s were ha a cut-out in the ide a large as the tire diam eter , also le ft exposed. It i int ere tin g t o n ote that the th at no aving in drao ' will be effected unle the · id e ub titution of s tr e amline wire for s tr e amline tL'ut · of the c ut - out n ear est the tai l of the fairing is tUl'lle c1 in th e ca es of gears 1 band lc (fig. 19) an d O'ea rs in so as to pre sc nt no op en edge to the ai l' -t rcam 2b and 2c (fiO'. 21) had Ittle e ff ect on th e drag.

(modi fi ca tion D l )' I n fact, the drag of th e wheel Th e re sults obtained with gcal's 3b and 3c (figs. 24 wa .· in c l' ea !"cd by th e usc of the unmodi fi ecl fai r ing nnd 25) indicate that littl e. i sa ved ,,,,h en trut s jn D. No test. werc mad on ordinary mud g u ard s b t' - tand em, close to th sidc of a ,, -heel, arc faired c aU!:i e previou ' te t made in Great Britain 'howc (l toge th er. Th e re lativ ely hi g h d rag due to landing thaL they haye high elraO' (r eferen ce 7). gl::ar 7 (fig. 29) 'how that it is not good practi ce to The 8.50-10 wheel in yaw .-FiO'lIr e 10 how how th e [l lace a lelHrth of st rut clo e to the ide of a fu e lag .

Th e r e nlt for landing gear 11b (flO'. 34) indicate that drag of th e .50-10 wh ee l c hang es ,yith va riation in ang les of yaw. Th e d r ag of thi wh ee l i ' al mo st chi. typ e ha s mall interference c hag. Th e drag of doubled wh en it is ya wed 15 °. uch daLa ar (\ of p ra c- tile wh eels alon e j approxinJately 19 .5 pound s at 100 ti cal i nterest because many ordinary type ' of non r e- I lti le pe l' hour, whi ch leaves but 4 ponnds interference tracting landino' gea rs hav e the " 'h ee ls in yaw when illld trut drag .

Effe ct of various wheels of eq ual load-carrying capaci ty the ol eo st r ut i e xtenclec1 . Al so, th ere are 'ome tYI s of pa r tia ll y r e tracting gear that ha ye th e wh ee l on th e drag due to la nd in g gears.- Th e results of thes yawed, wh en in the r etracte I po ition, and a mll ch as wh ee l te ts are gi ," en in table V and th e figure' illu . - llalf of it ex po se d to th e ail' t ream. tratinO' gear 1b ,3 a, ,a n 1 lIb. Gear Ib ,3a, , and Tes ts of one-half landing gear 2a with 8.50-10 wh ee l lIb (fig . 19,23,30 , and 34:) ,yore cho en for thi . pal't and various wheel fairings .- Th c r e ;nIts of th e t(' ~ t · of the iny est igation becau e th ey cover ed a repr _ enta- tive ranO'e of gear .-t ructur e on which th e e ff ect of thc of half of l anding gear 2a are given in tab l III \'a l' ious typ e of wh ee l ' co uld be gene rall y shown. It lind on the figu re 11 to 16, inclu ive. Th e puq o'C is important to not e that low-pr e sllre 01' e xtra- Iow- (-f thi ' pa r t of the inves tigation was to determ in e [J re ' ur e wh ec ls and tir e may be llsed on ordinary wheth er the rel ative mer it s of Lhe fairing s as tested typ es of landing ge ar s with littl c 01' no in crea e in alone were affected by the combina tion of th e fa i r ing s draO'. , Iso, the 27 -inch tr e amlin e wheel and ti I' e, with l anding-gear trut . For the e tests all th e fair- which had the lowest elraO' when tested alone, gave inD's except A (modific ation s A , and A ), whi ch were high er landinO'-gear drag va lu e than th e . 50- 10 llot believed to be p r acti ca bI e, ,ye re use 1. R eferen ce to th e tab l and fiO'ure " 'i ll s 11o" ,- that fai r ing A , which wheel and tire, except in th e case of gear lIb. Th e 27- had lower drag than fair i nO' C when te ted alone, had in (' h s tr e amlin whecl and tir e i distinctly superIor to be modified con iderab ly a r ou nd the trut inte r 'ec- on thi latter typ e of gear. The r es ult s indicate that tion to giv e a low d r ag a fai riJ 1O' C when both were the 27-inch wh ee l and tire will not decrease l anding- combined with the lan ding-gear s trut s. It is also gear drag unl es th e aerodynamic interference between intel'e ting to note in the ca e of f a iring E (fig. 15) it and adja ce nt member i very mall. Thi ize of that modification E l and E 2 ,yere th e mo t effective stt'eamlin e wheel and tir e wa u ed becau e, at th in redu c ing the draD'. time thi s inves tigation was tarted, th e manufacturer reco mmended it for u e on co mm ercial typ es of air- Yaw tests of one-half landing ge ar 2a w ith 8.50-10 plan e . Howey er , th e 24:-inch and th e 21-inch may whee l.-Figure 10 show how the drag of one- half gear be u ed fo r airplane of 3,000 pounds g ros weight if 2a varie with ang le of ya'Y. A co mpari 'o n of the e the in fla ti on pressure i inc rea eel ufficiently. If tests data with those for the . 50- 10 wheel alone, ,yill sho" - had be n m~c1 e with th e small er wh ee l -a nd-tir e unit s that with c hang es i n yaw most of th e drag in c l' ea e they undoubt e dly would ha\ 'e s hO'YJ1 up mor e favo r - of half gear 2a i Iu e to thc incrcase in (h ag of thc wheel. The fact that the trut ar e at an0'1e of ab ly tha ll th e 27-inch in all ca e. An exten 'ion of

8 REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

the entire landinO"-gear re earch program i contem- gear 14c was te ted with the 6- by 1 -fooL ,,,inO" and plated in which te t will be included of the 24-inch engine, the most significant difference between the test and the 21-inch st reamline wheel-and-tire units.

set-ups was in the wheel tread. It 0 happened that Effect of wings, engine, and angle of pitch on the gears 14a, 14b, and Hc were de igned with a tread drag due to landing gears .-Figure 41 show the effect of 7 feet % inches in tead of the standard tread of of the 4lh- by 15-foot wing, the engine (cowled and (j feet 6 inche u ed for all other landing gears. Thi uncowled), the combination of both, and change of divergence from the standard wa cau eel by truc- pitch angle upon the drag due to landinO" gears la tural difficulties encountered in the de ign of the te t and lla. The effect of the engine alone on both gears set-up. Ina much a the wheel of O"ear Hc ,yere 1 wa to generally in rea e the drag with increa es in foot 2% inche farther apart than tho e of gear 1a angle of pitch. The wing alone had an oppo ite ef- and11a, it is thought that perhap the air flow in thi fect. The effect of the combination of wing and en- outer region could have been influenced by the engine gine was to cancel generally the individual effect . ill uch a manner a to have higher velocity at that It made little difference whether or not the engine point than at t.he location of the wheel. of gears 1a was cowled. The engine-and-wing combination low- an lIla. If this be true, tIl<.' drag lue to any gear of ered the drag of the lligh-drag gear (gear 1a) notice- the cho en standard treacl and height would not nece - ably over the result obtained with the fuselage alone.

arily b(} increased by the presence of all engine 'fhi difference wa . negligible in the case of the low- mounted a. in this investigation. However, the l'ea- drag gear (O"ea r lla). The cuneo on figure 41 incli- on for the increase in drag due to landing gear 14c cate that no pecific conclusion may be drawn from whell the engine was pre ent shou ld be found and the the e data since no definite tr end were evidenced. ]Jroblem will receive attention in the proposed pro- The data are pre ented to show the factors that may gram for future landing-gear reo earch.

affect landing-gear dr ag but do not incll1de propcller- Effect of various modifications on the drag due to :lip tream effect. landing gears, 0° pitch.- The effect of modifyinO" each Figure 42 illu st rates h ow the drag cluc to J anding of a numbe r of Efferent landing gea rs is shown in gear 12, whi ch "-as mounted on the iu e lag o an(l the table VI nnd figure 2;~ to 25. 29, 30, and 32 to 37.

6- by 1 -foot wing, varies with angle of pitch . This In order to have a better understanding of the various type of gea r has been com monly used in recent years modification. made, it is necessary to refer to the on airplane that have the landing gear incorporated figures. Ina smuch as the table and the figures con- in the wing tru · S. The re ult how that the drag due tain all the pertinent facts and a summary of re uIts, to thi gear and it component parts docroa e with littl e need be said here in di Cll , ion of the modifica- increa es of pitch angle.

(ions. The addition of wheel fairing C to landing The effect of c hang in pitch angle on the drag gear 3a re ulted in a decrea 'e in the drag <lue to tha t clue to gear 13, with its various modifications, is hown gear of approximately 23 percent, which i a very in figure 43 . This gear was mounted on the fuselage . ubstantial saving. Attention is 'alled to landing and the 6- by 1 -foot wing. The general efrect of in- gears 3b and 3c, ,, ·hich are st ructurall y i len tical, dif- crea ing the pitch angle was to decrease the drag fering on ly in themanner in which the ide "trut . are due to the gear. Modification 2 gave a much steeper faired. Gear 3b, which had the ide member faired slope to the curve of drag against anO"le of pitch than together, had a drag of 44 pound at 100 mile pel' did modification 1.

hour in its ori O"inal condition. By ucces ive modifi- Figure 44 show the yariation of the drag lue to cation this drag was reduced to 27 pounds. The big- gears 14a, 14b. and He with c hang es in pitch angle.

gest aving wa effected by the use of whe 1 fail'ino·s.

The effect of the radial eni ne, cowled and uncowled, The · trut fairinO" on gear 3c wa tripped from each on gear 14c and of wheel fairing C on gear 14a are individual member until nothing but round struts and al so shown on this figure. Again the drag due to the the wheels were expo ed to the ail' tream. In this gears decrea ed with increase of pitch angle. Thi condition the drag due to the gear wa 98 pounds decrease was probably due to the decrease ill ail' at 100 miles I er hour. The result. of the e te ts velocity around the under su rfac e of the 6- by 1 -foot clearly show that the drag may vary from 27 pound :; wing that occurred as it s angle of attack wa increased. to 9 pounds at 100 mile pel' hour for a gear of thi The effect of the cowled and uncowled engine upon type, and indicate the importance of fairing truts gear 140 was to increa e appreciably the drag due to a weU a wheel. Modifications to landing gears it. The rea on for the increa e i not readily under- and 14a al 0 show the importance of wheel fail'ing tood, e pecially ince the engine did not have a simi- for reducing drag.

lar effect upon the drag due to gear 1a and11a. Al- Tests on gears 10 and 12 how the im portance of though the latter two gears we re te ted in conjunc- fairing the wire ter minal . By so doing, 2.5 pounds tion with the 4%- by 15-foot wing and ena-ine and drag out of 27 .0 pounds were aved on gear 10. In THE DRAG OF AIf1PL. \ NE WfLEELS, WlrEEL F , \lnI NUS, AND LAND[ (: UEAl1S-1 the ca e of gear 12, ,Th ere th e wires he lp ed form a to i so lat e the drag due to the wh eel or ",heel with t;ombi nation wing an l landing -gea r lrl1;': S, G pounds wheel fairing , , to -tru ts, and to fittings plus interfer- d rag w ere ' ayed by fairing th e wire fitting s. It ence. Th e elrag clue to these parts and to fittinO's p lus should be not ed that 0 11 til is sa me gea r th e wir es and interfer ence is also presented in percentage of the total wing-bra ce trut. · accounted for mor e than half the I m ea ' ured drag. A ratio of meas Llr ed drag to CO lll- rl rag clue to th e co mpl ete htndinly-o'eu r unit.

puted lrag i included for li se by designer ' in e valuat- T e t of gea rs lIa and lIb , ,,,hich hav e s in g le ca nt i- ing the drao' of any type of gear, hayin g giv n th lever st rut from th e fusela O'e t o th e " 'h ee l, indicate drag of the component parts. The entire analy i is t.he up ori o rit y of th e 'e type as far a drag i co n- ba:ecl on gea r drag at 0° pitch angle and excludes ce rn ed . Th ere is littl e to choose between the lo \\' e:t the effects due to the en gine an 1 the 4:%- by 15-foot tlruO' figures of th e 'o two landin g O'ears. The 1 0\Yes ~ wlng.

chaO' r eco rd ed f or gea r lIa was 1 .5 pounds at 1 00 Reference to the tables will show tha t fo r all types mile pe l' hou r , whi le the lowe t for gea r lIb wa . 17.5 of gea rs the comp uted :t l'ut drag constitu tes from 12 pou nd s at 1 00 mil es pe l' houl'. If modifications A l percent to 20 p r cent of the tota l m easured drag due ~ ll1d A 2 were applied to ,vh ee l fairing A as used on to the gea r. Th e wheels O t' wheels with ,,,h ee l fair- gea r lIb , it is probab le that th e drag due to that O'~ar ings, a tested alone, co ns titut e from 40 percent of th e co uld be reduced to appr ox imatel y 14 pound , anI 11 (lrag clue to the gear: for th e multi t r ut ty pes to about jlounds, respectively, at 100 mi l es pel' h Ollr . It i pos- TO percent for the ·in gle-st ru t type , . Fitting-plus- sible to use 'uch m od ifi cation ' to a servi ce -type land - interference drag varies from about 4:1: percent of the i ng g £11' pl'Oyided that suitable me 'hani cal arrange- tota l meas ured c1rng du to O'ea rs of the lI1ultistl'ut ment are made on the wh e 1 fairing s to g ive the t ype s to negative or fayorabIe interference drag for g rou nd clea ran ce necessary for wh ee l operation. Te sts the ingle- trut type.

made on th e e tw o gea rs with the .50-10 low-press ur e Some calculations showing the effect of 2 types of wheel and 27- in h tr e amlin wheels with o ut wh ee l landing gears on the performance of 2 classes of air- fairino 'S in dica te that th e lowest draO' was ob tain ed by planes.- A 'ompa I'i ' on is m ade in table VIII of th u in g th e latt er wheels. H oweve r, it i ' £11 0 cleal' that hi g h peed ' of 2 h ypot hetic al a irplan es, 1 of lo \\' (' r en th ough a l ow -dra g l anding gea r mi ght be had drag and the other of hi g h drag, each with a nd with- withou t wheel f ai ring s the drag may b2 fu r ther out a low-d ra g an d a hi gh-drag l and i ng gear (gear reduced by an appreciable aillount if th e propel' ",h :, el ]3, modification 1, a nd O 'ea r 14:c. The table show that f airing are used. I.'yen though la ndin g gea r He ,,'ere made to r etract

Landing gear 13 wa . attached to the u- by 1 -foot

fully into th e high-drag airplane the gain in high \\ ' inO' and had a in g le trut e xt end in g from the wing s peed would be on ly 3 mil es per hour. However, to a fork over the wheel. Th e s trut was st rea mlin ed l'rtl' acting th e ame gea r on the l ow-drag airplane and th e wh ee l encased in " 'h ee l fairing A , with no wou ld re ult in an i nc l' ea e in speed of 1 .9 miles pel' f i ll t around th e ""h ee l-fairin g and ~ trut int ersec ti on. hour , 0 1' a sa ving of 23 .4 pe rcen t of the thrust hoI' e- The re uIt show a lra g of 20 ponnd at 100 miles power at the same speed. R et ra cting O'ea r 13 (modi- pe l' hour w ith the gea r in thi c ondit ion. Modifica- fication 1) used on the l ow-drag airplane would 1'e ult ti on 1, which wa an expa ndin g fillet , wa ma de at th in an increase in 'peed of o nl y .6 miles pel' hour .

'lrut and wh ee l -fai rin g intersection, and th e drag clue "'h et hel' or not the .6 miles pel' hoUl' in crea 'e in peed to th e gea r h o pp ed to 13 pounds . M odi fi cation 2, clue to a r etractab le gea r oyer gea r 13 i wOl'th the which wa a co ntinuati on of the ,,,h ee l fairing to the de ign and tructul'al compli c ation ' in all case is a wing, wa made and the d r ag \\'a agai:1 r educed to HI que tion that ca n be f'olYed only by th e de iO'nel' of pound at 100 miles pel' hour, de pite the lar ge in- airp lan es. Attention i ca ll ed to the fact that all lan d- crease in cros - ec ti ona l area. The drag due to this ilJg-O'ear drag data used in th ese co m pariso n were gear mi g ht be furth er l' du ce 1 to appr oxi mat ely 7 01' ., ca led up from r eo u It s at 100 mil es pe l' hoUl' with no pound ' at 100 miles pel' hour if th e wheels wer allowance for th e effect of R eynolds N umbel'.

entil'e ly encased in H fa il ' in g such cH i modification A " Some calculations comparing a wire-braced wing and of wheel fairing A . landing-gear unit w it h a cantilever wing and landing- Analysis of landing-gear (hag.- Th e I' esu lt s of U 1l' gear unit.-Figul' e -t5 shows the resu lts of t hi s compa ri - a nal y is of landin g-o'ea r drag al'e pr e 'ente 1 in tablcs son. The calcul atio ns al'e based on wing data tak en from r eference , a nd on landing -gear drag data caled VII -A and VII-B, in which all the landing gears from re ult · at 100 mil es per h our with no allowance tested a re cla 'sifietl ac ·ord ing to s tru ctu ral types.

for th e ffeet of R eynold ' Number. In asmuch a the Tabl e VII - A deal. with gears desio'ned for a tta eh - wire bracing on landing ge ar 12 also cons titut es a part I1l c nt to th e fuselage; table VII-B deals with gea rs (lesigned f or attachment to th e wing 0 1' wing and fllse- of th e wing bracing, any rational co mpari so n of thi Jag(l. An c ltteillpt wu s ilIade un tle l' ('ach c la s ifi c< llion gea I' wi th an y othE'I' gNU' Illll st tak e int o <1CCOlI nt the REPOrt'!' NATIONAL AD TSORY co £MITTEE FOR AERO Au~rICS wing sy tem. It was con idered of suflicient inte re t Thi matter i ' of most importance a regard quan- titative e tim ate of the drag of l anding gears at high to compare gear 12 mounted on a cOI1\'entional Clark Y recta ngu l ar wino- with gea r 13 (modifi 'ation 1) peed, there being only a mall likelihood that the mounted on a cantilever Clark Y wing, tapered in plan order of merit of the different gears will be changed form and ection. Ithouo-h the election of the type appreciably at high peed.

of wino- a we ll a the wing ar a may affect the re-

co CL US IO

ults omewhat, it i believed that the wing ele ted will how in a general way the relative mer it of the From the data pre ented in thi report the follow- o' two units . In the fio'ure the d1'a of each wing an I ing conclu ion are made: landing gear i plotted against Yelocity, the ang le of 1. The interfe r ence drag between a ingle trut attack hein o' determined by the wino- loading. CurHs 1110ngside a wh e1 and the wheel generally increa e ~ .; a:; are al 0 given fo r the complete landing-gear and", ing the angle between them is decrea ed.

units. It hould be noted that the drao- of th wi res on 2. The in ted rence drag between a ingle strut and gear 12 wa compute 1 in tead of taken from t he te ts a l ow-drag wheel i marked ly higher than the inte r - on that gear becau e the wire tru s used on t he te t ference drag between a trut and a high-drag wheel.

tiet-up had insufficient pan for the purposes of thi 1£ l ow-drag wheel are used to reduce landing-gea r l"omparison. Brace -trut were not u ' ed on th is gear drag, it i nece ary that the aerodynamic interference and all wire fitting we re a 'sumed to be bidden. The between the wheel and adjacent members be mall, figure show the 'upe r iority of the canti lever wing an 1 otherwi e there will be no reduction in drag.

landing-gear unit over the wire-br aced unit, a IthoLlCYh 3. The drag of the combination of a wheel and the difference i not great.

Ivheel fairing i due, in a l arge mea me to that portion A general relationship applicable to landing gears, of the 'Yheel which protrudes from the fairing.

of paras it e drag on the high sp e ed of showing the effect 4. Wheel fairing with cut-out in the ide hould airplanes. -Figure 46, which is a convenient hart for have a ll free edge that face the wind tmned in.

howing the r lation ' hip between a chancre in pa ra- 5. The inc1'ea e in drag of a tripod l anding gear site drag and the re ulting chano-e in the high peed in yaw is due mo tly to the increase in drag of t he of an airplane, is included to simplify the calcul ation yawed wheels.

f the high-speed chano-e of an airplane due to a 6. The lowest-drag wheel fairing te ted aave very change in landing-gear drag. The chart i appli- little reduction in drag when used on landincy gears cable to any conventional airplane and icon idered c;£ the tripod type, unles properly mo lified to reduce to be fairly ac urate the assumption being that the aerodynamic interference.

thrust hor epower and drag coefficient of the airplane '7. Low-pre ure and extra-low-pre u1'e wh el and are con tant for. mall changes in angle of attack at tires may be used on ordinary type of landincy cyear , the high-speed con Ebon. The chart shows that land- with little or no incr a e in drag.

ing-gear drag mllst be appreciab ly re luced to re uIt . L anding-gear trut should not be p lace.d clo e to in much gain in the high speed of an airplan . f the side of a fusel aae because of the high interfer nce course, a percentag change in high speed bows 1l10 re 1rag create i.

gain in mile per hour for a high-speed a irplane 9. The drag of l anding gear of the more common than for a low- .. pced aiq lane. Furthermore. the type may be CYl'eatly reduced by careful fairing of landing o-ear of n high- peed airplane i likely to fitting, wheel , and strut intersection .

con titute a o-reatcr percentage of the total d r a~ t han 10 . I t i po sible to de ign a landincy o-ear of rea on- that of a low-speed airplane becau high-.-pcecl air- nb ly l ow d r ag without u ing wheel fairino- .

11. The a "erage fitting-plu -interference drag of planes n ces ari ly ha"e low drag. Thi. poi nt is nl. o ordinary type of l anding gears is app r oxima tely 44 illustrated in the example given in table V III .

Application to design.- In using the results presen ted percent of the dr ag due to these gears.

12. The combination of a cantilever wing and canti- in thi report for air speed greater than 100 mi le lever l anding gea r appear to have Ie drag than the per hour the que tion may ari e concerning the effect combination of a wire-braced wing and gear in which of Reynold umber on the d r ag values. ince the the landing gear i a part of the win 0- tru .

drag, in general, yaried clo ely a he ratio of the 13. The ub titution of l ow-drag 01' retractab le squares of the air peds for speed les than 100 mile landing gear for cony ntiona l gear on high-drag air- p r houl', it can only be a umed that thi re l ation hold for higher peed. Until test at higher Rey- planes wi ll re nIt in only a small increa e in high . peed. For l ow-drag airplanes, the ub titution of nolds J umber can b made the va lue of drag at 100 l ow-drag or retractab le l anding gear for conventional miles per hou r hould be used, whenever po ible, a o' gea r will result in a substantia l increa e in high speed a ba i for computin the va lues at highe r speed .

TUE DRAG OF AIRPLANE W rIEELS, WllEEL FAIRINGS, AND LANDING GEARS-I 11

;:: D eF raJ1( ;e, SIllUh J.: Th e Aerodynamic ElI ct of a R et r act - or saving in powe l' , th e low-urag gear ac c mpli hing able Landing Gear. T.N. Nu. 456, '. A. C. A., 1933.

a larg e percentage of th e gain obtainable from the usc 4. lIarri ,Thoma A.: The 7- by 10 - Foot W i nd Tunne l of the cf th e re tractabl e gear.

National Advi "O l'Y CommUtee for Aeronautic. T .R. No.

412, .A.C.A., 1~1.

5. ' Yeick Fred E., and W ood, D o nald B.: The Twenty- F oot LA ~ GLEY 1EiUORIAL ERON A UT I AL LABORA'I 'O RY, Pr opell er B e earcl1 Tunnel of the National Advi or y Com- NATIONAL Aon ORY COl\fj)IITTEE FOR AERONAUTI C mittee for Aeronautic. T. R No. 300, .A.C.A., 1928.

LA 'G LEY FIELD, VA., F eb ruaJY"!J 9, 19 3.4 _ 6. Bi er mann , Da dd , a n 'I B er rn ste in , ' Villiam B ., Jr.: T he Int e rf ere n ce between ' trut s in Various Combina tions.

RE FE RE CES T .R. No. 468, N.A.C.A., 1933.

7. Bradfi eld, F. B ., nndl\lid\Y ood, G. F: Wheel, Fa ir i ngs and 1. Weicl" Fred E .: Fu ll S ca le Drag T ests on Variou Parts of l\Iud ga rd s. R. & M. No. H7!l , Briti sh A.R.C. , 1932.

Sperry M e' engel' Airplan e. T . . No. 271, .A.O.A., 1928.

!:L And e l' on, Ra~ 'lllo nd F.: Th e AerodynamiC Characteristic .) H e rrn ste in , William B. , Jr.: Full Scale Drag Tests on Variou s Part s of Fairchild (F 2W2) Cab in Monoplan e. of Three Tat e l' d Airfoil T ested in the Variab l e- D ens i ty T . . o. 340, .A.O.A ., 1930. Wind Tunn el. T.N . No. 367, N.A.C.A., 1931.

--------------- 2 7"- ------ --------- ~ 8.50-10 l ow-p r essu "e wb eel and lire. 27 - in cll s tT' nmlillf' whee l nnd t i n; ', Drag = 6.1 lb. nt 80 m.p.h . ))l' ag=5.0 lb. at 0 m.p.h.

o 3 " 6 " 9 " 1 2" / 5 " / 8 " 21 " 2 4 " I I I I I I I I I I

~ 2 9 %" ~ 1

I ,'~ ------------ -t- ------------ ~

T,_' ~~ ) r

if-- ,, *~ -r

k---------------- 24 Y-2 " -------------- ~ 25 by 11 -4 extl'U-l ow-p r ess ur e wbeel and tire . 30 by 5 disk wbeel and high-pI' ~ me tire.

Drag = 7 .1 lb. at 0 m.p .b. ao by 5 di sk wheel an d 32 by 6 high-pressure lire .

(dotted) i)rag=5.9 lb . (30 by 5) at 0 m.p.h .

Drag = G.9 lb . (32 by 6) at 80 m.p.h .

FIGURE 2.- Drag an d dimensions of wbe Is.

REPORT 12 ATIO NAL ADV1S0T\Y COM II TTEE FOR AE 1 ~ONAUT[CS

I

o· 0,27" streomline wheel

-- - -: rr 1<- 2Jq "

b, 30"x 5 " wheel lon g /' ~ '1' ----- 21" c,32")(6" " d, 25 xl/-4 "

,/ 0 --- I!""' -- -Streamline strut

",8.50-10 " "

" f i -- - -Roun d

\ \ 90 • ..s:...:::..:.=-><....=.:- ..l~' '-. _____ --.J , , !

"- , ~ .............

.....

I W~ !.- " .....

"2- ..... Br ok e flan ge 'r-. .....

~ .....

-

..... .....

--

-

..... ~:e -

,

-

-- a

r - .....

--...

- .....

-

- ~ ,-b

- -

_:':0

--

.:;.-d .iL

- .-

--£::

- -

2 -

~ - r-.

-- .-

-- ~ - ==--

-... ..... , e.f c""

t-- -

k..

- ~- c -..........:::: c.< 6 ' '- b '-....

e .

'I -c d

~

K-

r---

I----- o ~

r--

-

10 20 30 40 50 60 70 80 90 o Angle of strut w ith wheel, 8, degrees FI Gl: uf) :l.- ln l~l'rel!ence drag betwee n "I,·ut And wl wel.

X nTE.-S I .. ~nm lin e ~I .. u t of XU' ·Y 1 secl ion anci fln~n e"s I'lltio ". Air spee d, 0 m.p.h.

Drag of whe el ond fair ing of

I

80 m.p. h., 53 lb.

/- --- t ---- '\

21" . - ---4-.-----.

, Drag of whee l \ ' / ..... _--- ---_ ....

and foiring of 80 m.p.h.

I

Originol , 3.5 lb.

--Mod. AI , 2.9 " ,------ 42 "----------~ ---21 "]) --- A" 1.7" --- 25%6 "--- ,/

---

4 .- I)I'jlg- n nd dilllcnsi()n~ of whe el fai r 'ing .\ .

li "lGl ' Il E .3.-D ,'ng nnd tlinl( ' n~ionR oj whf'(' i fnil'ill g B.

THE DRAG OF AIRPLANE WHEEL , WHEEL FAIRINGS, AND LANDING GEARS-I ----Modification EJ Modification E.

free , edge bent in Dr 09 of wheel Modification E, -.

ana fairing of gap closed 80 m.p. h,4.6fb.

Drag of wheel and fairing at 80 m.p.h., 6. 4fb.

half fairing A Modified fairing --- 25% "--- tested only in One ha l f conjunction with fa i r;ing B half gear 2a - 8}2 '- -- 24 "+----~ I / FIG HE G. - Dl'ag anti dim ensions 0[ wh ee l fairin g C.

FIti U HE S .- Dra g and c1im ens ions of wh ee l fairing E.

Open side to allow Modif i cation D, removal of wheel '1 ([ree edge bent in ~--~~----~ , --- \ Drag of wheel I and fairing at 80 m.p. h.

Tested only in .

Original , 7. 7 lb.

conjunct i on With ModifIcation Dlo5.5 " ha l f gear 2a --- 25;16 "--- -1 4%3 "- H ------- 42 " One half fairing B I I I I 2}2" -8}2 "- FI GU RE 7. - Dr ag a nd (lim e n iou s of wbe e l fairin g D. l<'W U IU J 9.- Dilll eu ,' ion s of wb ee l f a iring F.

REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 2 4 I, ~ On. ha" gw 2,

I I I

X

o 8.50-10 wheel alo ne

,,/

""-

/

~

~ /"

~

~

!-o---r-

--~

r-- /x

----

../

"- x

~ x /

~i"

......- x """-

i ~

I-- x ",,-- x _ x x x

- ~ -----

- 16 -12 -8 - 4 0 4 8 12 16 Toe in Toe out Angle of yow, degrees FI GUlUl lO.-Drag of 8.~ O - 10 ",lw ei nnrl one ha lf ,l:eal' 2a in ~ ·" w . Ai" ~pecd. 80 m.p .b .

Modif ic at ions -- --- ----- 1 ---2 - - --- 3 (Ci rc ular) Drag of ha lf of gear 2a at 80 m.p.h.

Drag of half of gear at 80 m.p .h.

Without wheel f air i ng, Without wheel foiring 1/.5 lb.

11.5 lb.

With whee l fairi ng 10.c" W it h wheel fairing . 9.7 " mod. I. 9. 0" With whee l fairing 2 . 9. I " and fillets ,9 .0 " :3, 10.6 ..

FIG UR E ll. - Drag of on e- balf gear 2a with wh ee l fair in g A. FIG URE 12 .- Drag of one·balf gear 2a with wbe el fairing B.

THE DRAG OF AIRPLANE WHEEL , WHEEL FAIRINGS, AND LANDING GEARS-I x, Mod ific ation £, gap closed Drag of half of gear Drag of holf of gear at 80 m.p.h.

2a of 80 m.p.h.

Without wheel fairing , //.5 lb.

Without wheel fairing, With wheel fairing 11.5 lb.

Jf!" Tille ts , II.c " With wheel fairing , 9.0 "

r , /1.0 "

With wheel fairing r • mod. E1 ,9.8" and fillets ,8.3 ,.

r

E1 8 E" 9.c " I" E, 6: E" 9.4" ~ .. radius fillets

{

Z I" " y , Mo d ification E" front edge run into broke cover plate FI GU RE lB. - Drag of one- half g ar 2a with whe el fairing C.

1<'IOUHlll t5. - Dra;> of one-half gear 2a with wheel fairing E.

•-- Open side Drag of half a f gear at 80 m.p.h.

Wtfhauf wheel fairing , 11.5 lb.

Drag of half of gear With wheel fairing , 14.c " 2a at 80 mp .h.

W ith wheel fairing, gop closed . , 1,] .8 " Without wheel fairing, 11.5 lb.

With , 11.7 " J<"I Gl"Im 14. Drag of one· holf gear 2a wi th wh ee l foiring D.

FIGURJ1l 16 .-Drag of one-half gear 2a with wheel fairing F .

REPORT ~ATIONAL ADVI ORY C OMl\IITTEE FOR AERONAUTICS

r- 'O ''-

r-,---;;---- r - - - - - - - - T - '--';- I I , I :: ,I ' , I I (Q I I I : Clark Y 1 - , I I <:::J sec tion --- I ~ '- 35}1;" I I I 1 I

L---Y-----l ~---- ~ ---J 1 COl

I I

L ________ _ r-3' O!'

______ ,, __ -.J----Y

.,.-- +

+ ,I

,I C\J

, l +

/'S" \ Wo~p _; 18 '0' '-' ----->1 engIne -S'6"-~ I

I Standard wheel

r

+ + <--- --Iocotions, oleos

collopsed .. - - - ....

r- - -, - - - - - - - - - "..

L __ l. __ = =. -_-_-=--_-_1- I ,

'" , Fuselage mounted in

5Ilj/- \., ' ,·nverfed postion .... - _ ....

FIGt"HB .1 T. - f...;kflt eh o f fus('lugl' ~lIowiJtg l oc 'ation s of wing:-o , wh f;'(l ):.;, alld (' lIgillP, 1\0"1"10. -. 11 1 gea r s J eH ign e!l COl· G- h .1' 18- f oot wing have the wh ~e l lo ("u liolls 1:{' .

in('h(;\~ to th e rear of !'It al uittrd lo ('u. ti ,o tlt-'. Th(' tr ('u d of ~(ltUS l4a , I-tb , and 14 C b 7 feet c'h in ch es.

28%"'-- ---- -6" W, Ole o e xte n ded )< f 'Stagg er e d Y, Oleo collapsed I I, Z, lYe" x 2'}f6" 1 : / / stre a mline t u be

I;,-l.:::i ;'

I If' I I ·~I-!---·

'l-I

- 8}Z'- \

5" --{ < ----39"-" -----'1

~~- ---------- --~-~ I FWt;I<E I S.- Dra g a nd dim c nsi ons of ge ar In.

D ,· ag of gear at ]00 m.p.h. (oleos e xtend e d): .;)0- 10 whe e l·, 42.;; pouna.

THE DRAG OF AIRPLANE WHEEL, WHEEL FAIRINGS, AND LANDING GEAR -I --- 20}2"-- ~-13.i6"-1 W, Gear Ib , %i "x I/Z " tube Y , Gear l e, ~" streaml i ne wire , I , / - "-- t- -- . I" ~ r' /

- ~ ;~ " ~ -

" ------ 39 ~ "------ ---- ~- , F I Gt:UI ; 1fl .- D,·ug and dim e nsi o n" of ge ars III II"Ii le .

IJrag or gear HI 100 m.p.h. POllllrl., Gear Ie. ..:;0 to whN ' I, ___ _ _ _____________________ 44 . 0 {: c ur lb. 8 . ~O - 10 w h ec ls __________________ ___________ ~;;. 0 Gear J b, 27 - inch st reumline wheC'ls _____________ ___ 4. . II G~ar 1b, 25 by 11-1 exira low-p"es ' ure wb e cl' _____ ______ 4(;.0 Gent' Ib, 30 b~ T :; hi gh-prl'l'lsure wbe("l~ _ __ _ ________ _____ -17 . II Gcar 1b, 32 by 6 h i gh-pressure wb ce ls ___ __ _______________ 41;.5 X, Oleo extended x-- Oleo co ll opsed lYe/' x 2 '){6 " streamline tube k- -------39" -- ---- ------ FIG!;!!>: 20.- 0rag unll dimension of gear 2u. Drag of g~ar at 100 m.p .h. (01('0 ' exll' lI d. ' d) : , .~(l-10 wheels , 4(;.0 poundK.

V, Gear 2c %"x 1J8 " streamline tube W, G ea r 2b !J{" streamline wi re k---------- 39"-------+-->1 l<'lGU!ltJ 21.- Drag and d imenSions of gears 2b and 2c.

Drag of gears at 100 m .p . h.: Pound.

Gear 2b , 8.50-10 wheels __ ______________________________ 47.0 Gear 2c , .50-10 wheels _______________________________ 45.;; 6 04 88-34--2 REPORT N ATIO TAL ADVI ORY COMMITTEE FOR AERO A UTICS 5)r X, Oleo extended Y, Ol eo collapsed Z, 1f8 " x 2%6" x streamline tube -8)2"- ~---------39 ' -----------~ ----c5%; " ----- of gea r 2(] . Drag of g ea r ttt 1 00 m.p.h. (0 1 Os rxlelld e cl) : 8 .. ;0 10 wheels. 43.0 poun ck X, 'Oleo extended --6" Y, Oleo co/lapsed Z, IYB " x 2%/' streamline tube 1%"x5}{;" __/

c

k------ 39 " ------- --+--~

5 "---1

FIGURE 23.-Drag and dJme nsions of gear 3n .

Drag of g ea r at 100 m.p.h. (oleos ext e nded) : POUlI1l 8 . 50-10 wheel s ________________________________________ 43 .5 .50-10 wh ee ls. wheel fairing C ________________ _______ :la.;; 27 - inch streamline wheels _ ____ _ __ _ __________ ____________ 45.0 25 by 11-4 extra low - pre sure wh ee ls ___ _____ ____________ 4~ . 0 30 hy 5 high - pr ess ure whe e ls ___ ___ ______________________ 4a . 0 THE DRAG OF AIRPLA E WHEELS, WH E EL FAIRINGS, A D LA DING GEARS- I 5 , No. 1 gop ftY l ed i n. fittings f a ire d

T, No. e sfreom li ne f' a iring

V , No. 3 whee l fai r in g A V. No. 4 c uffs over cy li nder and f i t t i ng s W, No. 5 w heel f ai r in g C X. Oleo exte nd ed y , coll a pse d --- 19 " -- 37 #/ " " " , :1 I.

J~

1,' LGU IUJ 24.- D l'ag a nd dim e nsion of ge ar Sb.

Dr ag of gea r a t 100 m.p.m. (oleos ext e nd ed ) : Po unu s 8 .50- 10 wh eels ___ __ ___ __ __ _ __ _______ ________________ __ 44 .0 .50- 10 wh eels, modifica tion L _____ __________ _____ ______ 43. 0 .50- 10 wh eels, modifi cat ions 1 a nd 2 __ __ __ _ __ ___ ________ 41. 0 . 50- 10 wheels, modi fica tion 1, 2, ft nd 3 _________ ________ __ 40 . 0 .50- 10 wheel , modific ati ons 1, 2, 3, a nd 4 __ __ ___ ____ ___ 28. 0 8 .50- 10 wh eels, modi fica tions 1, 2 , and 5 __ __ __ __________ 27 .0 X , Ol eo e xt e nd e d Y. c ollapsed --- 25 71. ' --- l' l GU HE :l5.- U rag and d imen s ions of gear 3c.

Dr a a of gear at 100 m .p.h. (0 1 os exte nde d) : Pou ", as .50- 10 wheel , a ll st r ut s st r ea m-Iined ____ _ __ _ __ _ __ _____ _ 45 . 0 .50- 10 wheel , st rea mli ne fai rin g "emove ti f oo m mem be rs L 51. 5 8 . 50-10 wheel , tea mline fa irin g r e mo ved fr om members I a nd II _ __ ________________ _____ _____ ___ ____ ______ _ 69 . 0 .5 0- 10 " he I ,s t ream lin fair ing remo\' ec \ from member s 8 .5 ~!ib a ~~;;I ~~-sb. . ea mii~ ; - f~; i~~ ~i - ;:e - ruO ~ ;; l - f;; O , ;; -- n l; ;i')t ie ~. ~ 90. 0 I . II. Ill. nn ei IV ____________ _ ____ __ _______ _____ ___ 98 . 0 REPOr.T NATIOXAL ADVI ORY COMMITTEE FOR AERO TAUTICS -----28%·--------~ W, 1%"x5}{," streamline X, Ol eo extended Y, Oleo collopsed Z, 1%/'x2'X6" streamline t u be - ---3 9 "---- ---~ F 1UUllB :!O. - l)ra!! IIIll I (li lll e"~ i o,," of 'l'n .. ~. Drug of g!'IIl" Itl 100 m.p . lb. (ll l co~ extcnued): .liO-10 whee l s, 39.0 pO ll n(ls.

v, %" streamline wire W, I%"x 5}1" s treamlme X, Oleo extended x Y, Oleo collapsed Z,I}1J"x2'}fo" streamline tube j w--

5"---1 ~--------- v9"-----------~

F((;L"HE 27.--D;·ug Hn(i dim(',,"ill"" of ;!PIIl'~. J)rag of g~nl · at 100 m.p.h. (oleo" extended): .. ;0--10 wheels , 38.0 pounds.

THE DRAG OR AInPLANE WHEEL " WHEEL l~ . \Ir:I ~GS, A£ TJ L .\ N TH N(l (m .\ T:S-I

2]

X, Oleo extended Y , Oleo cOll apsed Z, 1}6"xE'lr6" streamline tube x il II Ii, II III I 11 ' IVI IJ- r -;....9 1 /

-"<-H-- +- - -\----"'---1 - \ Ikt. -I---t-

-4

5 .. ··- 1

---- - .:J9 .. '-- --- - ~ FlOum : 28.- Dl'u g lind (li m ~ n s i ons of geu l' 6, D I 'ng of gea r 01 10 0 m,p,h, (o l eo s ~x l cn<led): .00- 10 whpel~, 50 . :) pOl1nd~.

x , Oleo extended Y, Oleo collapse d -12hi"-

3 '-1

Z, /J1J 'x 2:J%" ,- -------- ....

streamline tube I I I No.1 cuff - ___ _ I ; ~ fVo . 1 over strut I I

. -"

I I I I I I , ____ J

'- -t- .- -+19% .-J

~-~-28%'---- 5'---~ f:-- - -39 ·--- - --1 FIGURE 29.- Dl'ug ancl dim .e ll:-;iol1 s Or gPfi l' t .

J-' ou'lId,'l nl'Hg nt 100 Ill .p.h. (o l~ o .. e x tp n<l ~ d ) : 8,.iO- 10 wh ee l ~ ______________ _ 'i1. :; R. ;;O - IO wil r el s, modiflcnl iOIl 1 __ - ___ 56 . U REPORT NATIONAL ADV I SORY CO ,[MI1'TEE FOR AERUNA U TI S S, No. 1 streamline {"airing Over tandem tub es T, No. 2 , fitting cover e d £I, " 3 , V, N o.4 , wh ee l fair i ng A with s t r eaml i ne fa i ring o v er stru t intersec t i on w, 1 3~'~1 5!4" % " x lYe" stream- line tube X, Oleo extende d Y, collapse d Z, 1J1J" x 2'}f6" stream- line tube FIGURE 30.- Dra g and dime nsions of gear Drag of g ar at 100 m.p.h. (ol eos e xtend ed) : Pound s 8.50--10 wheels, a lone _________ ____ __ ___________________ 44.0 .50--10 whe el , witb modific ati on L ____ ____ ______ _______ 44.5 .5 0-10 wb eels, wltb modifica tions 1 and 2 ____ ___ ________ _ 43 .0 . 50 - 10 w heel s, with modific ati o ns I , 2, a nd 3 ______ _______ 41. 0 .50- 10 wheels, with modifi ca ti o ns 1. 2, 3[ and 4 ___ ______ _ 30.0 27-in ch tr e amlin e wheel , witb mo ditlcat ons I, 2, and 3 __ 44. 5 25 by 1 1-4 l ow -pres ur e wb eel , mo dification s I , 2, and 11 __ 4: {. 0 30 by 5 high-pr essure wheel s, modifica tions I, 2, and 3 ____ ,II. ~ , 32 by 6 high - pr es ur e wh eels. modifi ca tion I , 2, and 3 _____ 4~ . ;:; %" x 10" s fr90m l in e t u be ( Ol eo extended collapsed I }{," x 2 '115" streamline tube 37~"

x

, I , I I ' I I I,' I L.. , ,.. _ ) " ) I,, -{ I : ,. ') .1_ ,'

5,,1 39 ". - --- >l

l! ' IGURE Sl. - D rag and dlmen ions of gear 9. Dr ag o( g ear at 100 m .p.b. (oleos e xt e nd e d) : 8.50--10 wb eels, 4 5. 0 pound s.

THE DRAG OF AIRPLA E WHEEL , WHEEL FAIRI GS, A D LA DING GEARS-I Y, Wheel fairing A Z, %'s treom line wire 30 }(.'

+ 28% 0-1

-6' ,/Z 1<--- -39 "----+--~ li'lGUllE 32.-Drag and dimension of gear 10 .

Drag of gear at 100 m.p.h. : POUllWl Wheel fairings A ______________________________________ 27.0 Wheel fairings A, strut and wire fittings fa ir ed at fuselage __ 24 .5 Y , Strut section Z, Airfoil section A ir foil s e c l ion----- __ (or strut section - not shown ) ~-II)'f'-1 Se c t ion A-A Wheel f'oirings D, ---_, 37M" C- , ", B .. ,) " ..--- ...... ,/y

/1

v

1-1- -- - (+--, : ~-7}Z" -~ <_~--- .-- Z ~+14'1+-~ ---<-l..- --'---4- 1• ..1. ____ 1.. __ 1 A A f--------39·-------- -r -~ b'WUBlll 33.-Dmg and dimensions of gear lla Drag of gear at 100 m.p.h. : Pounds .50--10 wheels, "heel fairings B ________________________ 20.5 .50-10 wheels, whee l fairings C ________________________ 18.5 .50-- 10 wheels, wheel fairings D ________________________ 19. 5 27-inch streamline wheel s, strut section a l ongside wheeL ___ 25.0 27- lnch streamline whee ls, airtol! section alongside wheel __ 22.0 HEPORT .\ TW""AL ADVI SORY C'O]\[MTl'TEE FOR AERONAUTI S Y, Wheel fairing A Z, 27" streaml ine wheel , , , :< - 1<0---- -- 4I'o/t6" '------ >I FIGl ' R>: :H. - DI'>lg nnd dil11pnsion~ of genr 1111.

1'01111(/8 Dl'flg of gen r at 100 m.p.h . : : :17·incil st r n mline wh ee ls _____________________ _ _ _ 2 1. !)

8 .. 30-10 wheels _ _______ _ __________ _ 23. ;; H,.1{J-IO wheels, wheel fall'iJl~ .\ _ __ _ _ _________ _ 17. 5 U, I~" x .3" streamline tube v, /"x 2%" .. ..

W, Two Y2" wire X, I~ " x 514" strut Y, % " sfreom'/ne wire Z, ?!' 5" 30% " Brace I 6' x 18' Clark Y win9 BYz" I I<>--- ------,,,.c.-- -I--I---I--- 7' 4" ---..."L---- 37f1J" I W .. · ·• t.

I

8.50-10 wheel-· ·" 1<>--- --- 39'·' - ----. >1 FIGUIlE :lri.-Drag a nd dimen~io()ns of geal']:1.

Drag of gear at 1 00 m.p.h.: POliliti.

tl '1 1~~~ s~';·~~~I~ ft'~~ ~~e~ _ !~l~~i~'~~ __ ~~_~ \ ~~~_~~~~~~~_~~ I ~~~p~ \ . ;{ .0 .50- ] 0 whel'ls. wheel fairings A, c uft's OVe!' filtiugs. lInlce st ruts o ff ___ __ ____ _______ _ ______ __ _ __ ____ __ _____ ___ 3:1.0 ':iO- ]O wheels, wh ee l fai"in gs A. c ull's ove l' li ltings, b "lIce I Irul 8 OD ___________ _ ___________ _ ___ __ _ _ _______ 39.0 8.50 - 10 wlH'cls, wh el' l fnl l 'lngs .\ , wil'es a ll tl bruce sln ll s o iL 1 . 0 THE DRAG OF AIRPLA E WHEEL, WHEEL FAIRI GS, A D LANDI G GEARS-I y, No. 2, wheel fairing extended fa wing.

Z, No.1, expanding fillef.

6' x 18 ' C lark Y w ing I 8Yz" I Y

~,-']s,, -,~

FlGUR" RO. Jlrag- anti dim e nsions oC gea r 1a.

Dr ng at 100 m.p h. : J 'oll"d.~ .50- 10 whpeJ", whc('l fa "" Jlgs .1___ _ _________________ 20 . 0 8.50-10 wheels , whce l fairing s A, modification L_ ______ la. 0 8.50-JO wh ee ls, whee l fai rin gs ii, modification ~ __________ l:{.O X, Oleo exfended Y, collapsed 6 ' x 18' CI<?rk Y wmg )< ---- -+- .]S"--- - '"I I 8Yz" I !.'Iheel foiring C 5" !<'IGUJ'J,; 3i. - Drag and dimensions of gear 14a.

POllnds Drag of ge ar at 100 m.p. h. (olcos exte nd ed) : .50- 10 wh ee l~ _________________________________ _ _ 3D.0 8.50-10 wheels, wh ed fairin g (; _____________________ _ :W .O REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS X, Oleo extended Y, collapsed Z, IYs" x 2'}{s" streamline tube 6' x 18' Clark Y wmg k------jf---39 "---->i k-----3 9%" ------>i z .;:;0 - 10 wlleels, 41.0 POIllHls.

F IGUItE il8.- J),-ag and dime l "iolls of gear Hh . Drag of I'l'al' nt 100 m.p . h. (tlleu~ extplld d) X, Oleo extended Y, collapsed Z, IYs" x 2%;" streamline tube 6' x 18' Clark Y wing f<------1--39" ---->I I 8%" 1< - ---- 3.9~" ------ I - 5'4" 1%" z 5" 1-*- ----- 46Y4· ---- --~ _~ __ L_ ________ ~_~ 1'1(;[;1<" :;!l. Ur'" Ulld dilll~II' i ·o ll s uf g.,u .. 1· 1e. ])"'1): u[ g.'ar at 100 m.p.h. (u l ~,,' 'xlclldl'd) : K.'O 1 () wheel" ~1.11 pOllII"'.

I

;> Z Z ':J t:j >- :,; U2 H tv 8 P:t t;;1 t:j ~ ;> Cj) o >,j ;> ~ >;j t< ;> Z t;;1 ~ ;:q t;;1 t;;1 L' ~ ~ t;;1 t;;1 ('" >,j >- § Z Cj) t< ;> t:j Z ':J -:) th~ engine.

ncl n the th wing wi foot - "ing :) hy - ~ -I.

e G· by I S·Coot th .

th the wi inp and eng- a~e l .cd I'use fl cow fuselage th the )Il { .

~ ed ·on mountptl mount lH c combination r r l-!'C:'n ~ gea engine Lnlldin llnd Landing b.

d.

wing.

.

elage s ~u f'n~iJH'.

I(ear .

tllt\ wing.

HI1(l 40.-Landing t wing' l'oo Fr(;GIIE by l:'i - - -I.I~ ('l th with ng-(\ l J'usr th~ mOllnt('d on l 1a . ' II ;' \ ,l!t Lnnding n.

~ r-------- ------- - -------- -- --- ------- - ---- --------- -- ---- REPORT NATIONAL ADVISORY COMM ITTEE FOR AERONAUTICS

+--

~~ _e,Lt

- -

r- T

- I- - - - -- --- Broce struts off, cuffs over wire fitti ngs .

.-

1- ---------- Broce stru t s o ff wire -- e-

- I I la ,w i ng

f i ttings exposed. ' -- -- -- la , fus e/ a ge a lon e 1- -------- Broce struts on , cuffs __ ,- I-- - - - - - - - - - - 1 a , en g l ne ~-. ~ t---+---+---+-- -l I---- over wire fiftings..

--- - ---- - la " plus wing Broce struts on, wire -- - - -- la ' cowled eng i ne plus wi ng ___ 1----1- fittings exposed .

--- --- -11 a , wl ng I

--- ' . ?\ r

-- --- - - -- -- Wires and brac e

--- -- - - 11a ,fuselag ,e __ a }/_o_ n _ e 4- __ + __ -+ __ ~

struts off .

1-- ---- ----- - - ]]a , engme -!.. 1

-------- -11a , " p I USWlf)g l .

--- - - -- 11a cowl ede n g 1ne p us w l ng _ 50 1--- '

r---

t--

-

r-

"::-_ t :::::.

t-----

1:::-_-

r-....

t-- 40 ~~-~~-~-}-~~~ - ~ - t ~ ~ - ~ -~ --, - t~--- 40

--

- :::-

- 1---- t---

r::: _--::-

r--- - ==+-~-+--r--- - i-== ::::::. -- -I- _ I '"

f::: _"-:::- 1---_

--

I--- :,--- -- ------ , I---- ,

-

1-- - -- ,

t--- +-

-

--

-

:9 - --

--

0:

"-

o I... f--- t---- _ Q20t-. . - 0

--

-----

--

--=::::~----

- t---

-- --

--

--

OL--_ ~ 4---L--_L2~~--O~~--~2~-L--~4~-L~6

o -4 -2

o 4 6 Ang l e of p i tch , degr ees Angle of pitch, degrees FIGURE 41. -- Drag at 100 m.p.h. of land i ng gear s la and ll a FIG UllE 42. -- Drag at 100 m.p.h. of gear 12 mQ unted on tb e m eas ured in the pr ese nce of tb e 4Jh - by 15·foot w iug and fuselnge a nd tbe 6- by 1 - foot wing .

tb e e ngin e.

THE DRAG OF AIRPLANE WHEEL, WHEEL FAIRINGS, AND LANDI G GEARS-I

H

No.2 wheel ,/ " '-_ No.1

- ~ 8g : 1

- f oirinq ex-' - ~' expond in r;. - 40 tended tOting f ill et s

Originol I

4 00 -- -- -- Modificot ion 1 1- ------------ I " 2

rt. r - I' 1 0 ''-I

1'-' .. 2'0" - -::-;:

~ /

I-- 1

1'3 · _HtJ I 360

---

- , /

-

-

- -- r-

~~,

r-- /

---

- Gear 1211US

'" r-~

/

/

r- -

- -::-

-- - rectangular

-- 320

,

-

- wing ,

I

-

- --

-

, ,

/ 1

, , , , t ,

vi

,

L

.I

o

~"': 0.9 c ; -4 -2 0 2 4 6 t ,1.:

>,v

Anqle of pitch , degrees / ,- -

T

;\ ~ l

, O.l8 c / 1 FI GUn E 4 3.- Dl' ag at 100 m .p. h. o f gP,\I' 13 mount ed on lh e / ,

. ~ c = 2h //

I' 1 t

fu se lag e anel the 6- b.Y 1 · fo ol wing .

/ / 1 .1 ,

V /

Gear] 3 p l us ,

/

tapered / / wing ' , , , ,

/V //

,

./

, , ,

/

V , , ,

/ /'

/'

,

r-- 6,l ~8,lwinJ_) ,-'-t,_ Ri~i) eng \' ne _

)v r- I--- , , , V'

.....- V

, ... I I L..- . 5 J!f~' I I /' , 160 , ,/' /,/ , 1---- ,

t'---- I--

_/

-

- /'

-

,

--- ---

-~._Rectangular 'i,

I--- .-

l «'ft\\J 1 Cl ork Y w in g

--

/

Wheel fa ir i ng C " T apered

l--/

Clork Y wing / _/ ~ ,

~ 80

::--..

50 1 , I ,/

,----

t---=::: Gear 12

~ V-

/ r----. , ~ - r-- ( i ncluding , --.::::::::: ;,,- wires) :

i-rr-- -'

-----:..:: ':':::- ::::::::::" ~,

.....- ---

-

r-, ~ ,- .. Gear 13,

"- ',-

_/ -, ,

r-- f.-- - 'ma difi-

--

-- --

--

----

an

----

'-

--- f-- --

---

'- Cr (

---

---

-

o

.30 120 140 160 1 80 200 80 100

---

-

~ - ---

Air speed , m.p.h.

-'-

-- -- -

--~ ~ - - ~ l~IGUll.E 45 .- D l' ag co mpal'ison of a wil' - br acee\ willg and gea l' with a ca nti ' o le ver 'ving and gea r. A s~ umecl wing area, 2 50 sq uar feet; wing loa ding , l 12 pound' pe s qua re foot; a peet ruti o 6. Wing da/a taken fl' om ref · Cl20 erence 8.

14c in presence of cawled engine ,," " "rodial" -- --- -- ,-------14awith wheel fairing C r-- ----14b and14c - ---- 14a

I

o

-4 6 -2 0 2 4 Angle of pitch, degrees l ~ Io u nl ': ' H. - Dl'ags at 100 m.p.h . o f genrs 14a. 14b, and He moun t ed on fuse l age ancl the 6- by 18 fo ot wi ng.

nF.T'tlnT NATJO AI, ADVISORY COMMITTEE FOR AERONAUTICS 'l'ABLE IlL - DRAG OF HALF OF LANDING GE AR 2n W I TH .50-10 WII EE L A ~ D W H EEL j;'A IH INGS /6 Drag at i~~c::;s..et Drag at Wh eel fairing 00 .

80m.p.h 80m.p.b. lOOm.p.h .

I

/

Pounds Pounds Pound!

- /4 Wh eel unf ai r eu ____________________ .

11.5 I .0 A _____ _ _ _ _______ _ 10 .2 U 15 . 9 ~ A (mod ifi cation I) ____________ _ U.O 2.5 A (mod ifi ca tion 2) _ _ _ ___ _ __ ~ 9. I 2.4 A (modificati on 3)_ 10.6 .9 D> 13 ___ ___ _ _____ _ 9.7 1.8 14.5

/

- . s. 12 n (I-inch radiu s fillets) __________ _

9.0 2.5 C _____________________ _ "b 9.0 2.5 14. I

II

c: C ( I-inch radius fillets) _____ _ . :1 3.2 D ______________________ _ ~ 11.7 -.2 \ .3 E (H -inch r ad iu s fillets) ____ _ II. 2 .3 .... E (I-ioch r ad ius fillets)___ __ 11.0 .5

/

E ( I-ioch radius fillet s- m odificatio n E, ) QJ/O 9.8 1.7 E ( I-inch r ad iu s fillet s- m od ifi ca tion s E,

/

a nd E, _ _ ____ _ __ _

-5 9.2

2 .3 E ( I- inch radiu s fillet s- modifica tions E , "b and E ,). ___ _ ____ _ 9.4 2. I 14.9 QJ QJ F (H -in (' h gap) _________ _ 14.2 -2.7 22.6 F (gap closed) ________________ _

/

13.8 -2.3 -- - r-- - ~

V

~

I-- T AB LE I V. - DltAG DUE TO VAR I 01 H L A ' UI NG GE AR ~ .(: MOU I 'l'ED ON TEST I<'USn]T ,A GE, 0° P I 'rC H , 8.5Qc- 10

/

. s.

W HEELS / I/) I/) .- - Landing Dr agnt I.nndin g Dra g a\ QJ 0- J!t'n r no , 100 lII _ p . h . gea r DO . lOOm . p.h - - 0 - 4 ....

V

c: QJ Poulld ,.

POinul .~ / (J - - la 42.5 4 --.---. 39. 0 --- l Ih _~_ 45 .0 5 38.0

.-

6 _______ 50 . [) ~ Ic 44 . 0

/

7 _________ 2u_ 2 40 . 0 51. 5 8 _________ 47 . 0 44.0 2b 9 _________ 2c ________ 45.0 45 .5 \\b _______

!

4 3.0 2d 23.5 -- \4a , ______ 3a_ 43 .5 39.0 ---- 14b , _____ 44.0 41. 0 3ll.: 3c ________ 14c , ______

/

45 .0 41. 0

a 10 20 30 40 50

Percentage of airplane drag due to landing gear I Oears mounted on fu ,e lage a nd 0- by I -foot win g.

IC II:I'll> : 4(i .- A gen l' rul l'clalion s hip appl icabl e to l alHling g ea r s, show- ill "; the l'fI ~Cl o f parasi te dl':l g on the high ~pecd of airplulHs.

TABLE V. - T W J ~ E('T OF V. \R lO 1: , WTI E ] ~ L S 1: PO~ TIlE ('(,h"ust hor se p ow er u nd drag coefficIent of ail'plalle ",sumed con - DHAG DUE 'ro 'EYEHAL L ANDL \ 'G GE AR S MOL NT E D stant fOr s m a ll ('hanges in angle of aUack at high -s ppC(\ c OIlI\ition .)

O~ TEf:iT FUSELAGE, 0° PITC H Dr ag at 1 Decrease 1 Wheel 100 m.p . h. in drag TABLE I.-DRAG OF VARIOUS WHEELS A~D T IR ES 1 LANDt OGRARlb Dr ag at Decrease \\' heel a nd tire 1 o m.p.h. io drag Pound_ Percent .50-10 low pressure ____ _ --------- 45 . 0 27-inch st rea mlin e. ________ _ 4 .0 -6.7 POlLnd s P ercen t 25 by j 1-4 extra-low pressure _ 46 . 0 -2.2 8.50-10 l ow-pressure wbeel a nd tir e _____________ _ 6. l 30 by 5 high pressure ___ _ -4.4 47.0 27-inch s treamlioe wheel and tirc ___ -__ _ ___ , __ _ 5. 0 I .0 32 by 6 high pressur e ____ _ 4.5 -7 . 8 25 by II~ extra-low-pressure wbeel a nd tire _____ __ 7.1 -16.4 30 by 5 di sk wbe el and bigh-pr ess ure tire _________ _ 5.9 3.3 30 by 5 disk wh eel aod 32 by 6 hig b-pres s ure tire __ _ 6.9 -13 . 1 LA ' D! GGEAR3a T A BLE IT .- DRAG OF .:)0- 10 WIIEEL W I 'l'H VARIOU.' .50-10 low pressure _____ _ 43 .5 27·inch st re am line. _. _~_ 45 . 0 -3.5 WIIEEL FAIRINGS 25 by j I~ extra-low pr ess ur e _ 42 . 0 3. ,1 30 by 5 high pressure ______ _ 43.0 1.5 Decrea se Drag at Dr ag at LANDI G GEAR Wheel fairing no. 80 i~~rgg 100 m .p. h.

m.p.b. m.p.b.

.50-10 low pr ess ure ________ _ 44 . 0 ---------------- ------ 27-inch s treamline ________ _ 47.5 - . 0 25 by Jl - 4 extra-low pr ess ure _ 46.0 -4.5 Pounds Percent Pound s 30 by 5 high press ure ________ _ -\,1 Wheel unfaired _________ _ _______ _ 41. 5 6.1 9.7 A ____ _ ___________________ _ 32 by 6 high pr ess ure ____ __ _ _ 45.5 -3.4 3.5 42 . 7 6.1 A (modification A, )__ _ ______ _ 2.9 52.4 4 .3 A (modilication A, ) ______________ _ 1.7 72.2 2.4 13 ________________________________ _ 5.3 13.1 7.9 LANDI (l GEAR lib C ________________________________ _ 4 .6 24 .6 7. I D _____________ _ 7.7 -26.3 1l .8 D (modificalion D, ) _________ _ .50-10 low pressure . 23.5 5.5 9.9 .7

E ________________ . __ - --- ----- -----1

1--- . 5

27-inC'h sl ret llnlin p _ 0_. 2\' 5 6.4 -4.9 --- -- - - - -- - - -- - - - - - - -- - - - - - -- - - - - - - - - - - - - - - - - - ---- - -- ---- - --- - ------..., THE DRAG OF AI RPLANE WHEELS, WHEEL FAIRINGS, AND LANDING GEARS-I TABLE VI. - EFFE C T OF VAHlO U MODIFI C ATIONS TABLE Vr.-EFFE C T OF VARIOUS MODIFICATIO CPON THE DRAG DUE TO LANDI G GEARS MOUNTED UPON THE DRAG DUE TO LANDING GEARS M UNTED ON C!.'EST FUSELAGE, 0 ° PITCH ON TEST FUS ELAGE , 0 ° PIT C H -Continueu.

Drag at I Decrease

Condition of gear 100 . I Co nditi on of gear I D;~ at I I?ecrease I

m.p.h. In ( rag m.p.b. ID drag

I

LANDING GEAR 3n I FUSELAGE WITH 6- BY IS-FOOT WING LANDING GEAR 1 4a

Pounds Percent 8. 5()-10 wheels ____________________________________ _ 39_ 0 8.50-10 wheel 5, wheel fai ring 0 ___________________ _ 26.0 33.3 LANDINO OEAR 3b H.50- tO wheels- __ ____ __ _____________ ____ _ _________ _ 44.0 8.50- 10 wheel5. m od ifi cat i on L ___________________ _ 43 .0 2.3 8.50-10 wheels, modifications 1 and 2 _________ _ ___ _ 41. 0 6.8 TABLE VII - A .- ANALY S I S OF LANDING-GEAR DRAG 8.50- 10 wheels, modifications 1, 2, Rnd 3 __________ _ 40 . 0 9.1 8.50-10 wheels, modifications I , 2, 3, and 4 ________ _ 28. 0 36.4 .60-10 wheels, modifications I, 2, and 5 __________ _ 27.0 38.6 LANDING GEARS DESIGNED FOR ATTACHME TT TO FUSELAGE , AIR ' PEED = lOO M.P . H. , 0° PITCH LANDINO GEAR 3c

.. ~

Zl ; '" ;1l oj .50-10 wheels ______ __ ___ _________ ___ ___________ ___ ~ 8 ]l 45.0 0 -.:; g:, I " ..

'" -" <.> bO"

'" ""

.50- 10 wheel s, f ai rin g removed fr om L __ _________ _ 5 1. 5 -14.4 .r.; ..

'" i< - ",

~

o~ '0 OZl 003 8.50- 10 wheels, fairing r emoved fr om I a nd II _____ _ fi9.0 -31. 1 0 '0 ~ '0 bOlO .,,'" ..

8.->0- 10 wheels, fairing removed fr om 1. II , and IIL 90.0 - 100.0 .. "

.. '" .. .. oj'"

oj" '" ~ ~ ..,

'"

~f f: ~ ..

8.50- 10 wheel 5, fairing removed fr om r, II, III, a nd " "' ''' e -t;~ ij.:: g),

e "'~ '0'"

IV ____ __ _____ _ _____ ___ __ __ _____ _____ ___ _______ _ Landin g gea r '0 '0" 08'0 0 . 0 - 1 17 . 7 '0 1l~ ",S .,0 '0 '0'" .. ..,

"" ,,~ b.OO"Z

" " ,,"" 0>" ",..,.., S ~~ oj" ..,

"" 19:>

"" e

:> ~ :>

" ~'"

~ " ~ "" ,,'0

~ a. a. ;:;'0 5l 5l ~,,'O " a.

LANDING GEAR 7 1l

~ a

a a

1: ~ s-6 ~ 0

'" '" 0 lil

" 0 "

"

0 ::?1 0

" ::?1 .s Il< Il< Il< ::?1u

8.50- 10 wheels _____________________________________ 1 51. 5 8.50-10 wbeels, modification L __ __________________ 56.0 TRIPOD TYPES LA_ DING GEAR 8 Lb. Lb. Lb . Lb. Lb.

la ____ _ _________ 6.2 19.4 25.6 42.5 16.9 14.6 45.7 39.7 I. 66 Ib ____________ __ 4.3 19.4 23.7 45.0 21. 3 9.6 43.2 47.2 1.90 2a ______________ 8.50-10 wheels __ _____ __ _____ _ ________ ___ ________ ___ 44 . 0 6.0 19.4 25.4 46 . 0 20.6 13.0 42 . 0 45.0 1. 0 21J ______________ S.50-10 wbeels, modification L __ __ _________ _ _____ _ 44.5 - 1.1 7.9 19.4 27.3 47.0 16.8 41.2 42.0 1.73 2c ______________ 8.50-10 wheels, modifications 1 and 2 _____________ _ 43.0 4. 3 .19 .4 23.7 45.5 9.4 42.6 4S.0 1. 92

2.3 ~n

2d ______________ 8.50-10 wheel, modifications I, 2. and 3 ______ _ ____ _ 41.0 6.3 19 .4 25.7 42.7 17.0 14.6 45.4 40.0 1. 66 6.8 3a ______________ 8.50-10 wheels, modifications 1 ,2,3, and 4 _______ _ 5.7 19.4 43.5 18.4 12.8 44.7 42.5 I. 73 30.0 31.8 3b ______________ 5.4 19.4 44.0 19.2 12.2 44.0 1. 78

~:~

6 _______________

!U 7.9 19. 4 27 . 3 50 . 5 23.2 15.2 38.5 1. 85

7 _______________ 7.8 19.4 27.1 51. 5 24.5 15.0 37.5 47.5 I. 90 LA DING GEAR 10 8 _______________ 6.4 19.4 25 . 8 44.0 I .2 14.5 44.2 4 1. 3 I. 70 9 _______________ 6 .7 19.4 26.1 45.0 18.9 15.0 43.1 41. 9 1.73

---- -- -- -- -- ---- -- -

.50-10 wbeels, wbeel fairing A ___ ____ __ __ _________ I

27 .0 A ve rage ______ 6.2 19.4 25 . 6 45.6 20.0 13.6 42.7 43.7 1. 78 .50-10 wheels, wbeel fairing A, strut and w ir e fitti ngs fair ed at fu selage _____ __ _________________ _

I-----~·-~--

24 . 5 TRIPOD TYPES ( WITH WHEEL FAIRINGS) LA DING GEAR Jla 3a _____ _ _____ _ __ 5 .7 14 . 2 19.9 33.5 13.6 16.9 42.4 40.7 1.69 3b ______________ 5 .4 1 4.2 19.6 27.0 7.4 20.0 52.5 27.5 1.38 8.50-10 wheels, wheel f airing B __________ __ . ______ _ 20.5 _______ _ _______ 6.4 10.9 17 .3 30 .0 12.7 21.3 36.4 42.3 1. 73 8.50-10 wheels, wheel fairing C __ _____________ ____ _ 18.5 9.8

--- ---1-------------

.50-10 wheels, wheel fairing D, mo dification D, __ _ 19.5 4.9 A ve rage ______ 5. 8 13 .11 8. 930 . 211 . 219 .44 3.836 . 81.60 27-inch st ream line wheels, st ru t section alongside wheeL __ __ _____________________________________ _ 25 .0 -22.0 27- in ch streaml ine wbeels, air fo il section alongside wheel ___ __ ____ ________ __ _ ____________________ __ _ HORIZON1'AL-AXLE TYPES 22.0 -7.3 4 ______ _ ________ 6. 1 19.4 25.5 38 . 7 13.2 15.7 50 .0 34.3 1.52 LANDING GF.AR lib 5 _______________ 7.6 19.4 27.0 38.0 11 .0 20.0 51.0 29.0 1.41 A verage ___ __ _ 6.8 19.4 26.2 38 . 3 12.1 17. 8 50.5 31. 6 1. 46

8.50-10 wb ee ls ___ _______ __ ____________ _ ____ _ ___ ----I

23.5 S.50-10 wheels, wheel fai ri ng A _ __ _________ _______ _ 17.5 SING LE -S'l'RU'l' TYPES FUSELAGE WITH 6- BY 18-FOOT WING LA DING GEAR 12 lI a' ____________ ~.5 15.6 19.2 25.0 5.8 14.0 62.7 23.3 1. 30 lI a ,__ __ ___ _____ 3.5 15.6 19.2 22.0 2.8 16.0 71.1 12.9 l. 15 8.50- 10 wheels, wbeel fairi ng A, wire fittings ex- IJb _________ __ __ 3.8 15.6 19.4 2 1. 5 2.1 17 .4 72.8 9. 8 1.11 posed, brace st rut s oIL _______ __ . __ __ ___ __ ___ ____ 38 . 0

-- --- - --- --------

R.50- 10 wbeels, wheel fa irin g A, c ulT s over fitt ings, A verage ________ 3.6 15.6 19.3 22.8 3. 6 1 5.868.915.3 1.19 brace st rut s o (f __ __ _ ________ _________ _________ ___ 32.0 .50- 10 wheels, wbeel f ai ring A, cuffs Ove r fittings, brace st rut s on__ __________ __ ____ _____________ ___ 39.0 SI NG LE- S' l'R UT ' l'YPE S (W I 'l' H WHEEL FAIRINGS) 8.50-10 wbee18, wheel (airin g- At wires and brace st rut s ol L _________ __ _______________________ _ ____ 18 .0 FUSELAGE WITH 6- BY 1 8-FOO'l' WI TG LA ND I NG GEAR 13

.50- 10 wbeels, wbeelfairing A ____________________ I

8.50- 10 ", beel s, wheel fairin g A, modi fication L ___ _ 8.50- 10 wheels, wheel fai ring A, m odification 2_ ___ _ , St rut sectio ll alongside wbeel.

, Airfoil section alon gs ide wbeel.

REPORT NATIONAL ADVISORY COMMITTEE FOR AERO A UTICS TABLE VII - B.-ANALYSI:) OF LANDING -GE AI-t DHAG TABLE VllL -E I< ' l<E O '!. ' OF TWO TYPES OF LANDING GEAR' ON '1 IIE PERFORMAN CE OF TWO ULAS ES OT!'

LANDING GEARS DE IGNED FO R A'l'TA IHIENT TO WING AIRPLANES Air Spcet!=100 M.P.II. O· Pitch LOW-WI G CANT ILE VER MONOPLANES ~ ~ ~ 1l !l ;; a;

S "" ~

a'ld .,

'" 0

E " Example 1- Example II -

" "

~ "" "" -~

""" i

" " - ~ 0_ Hi gh-drag Low-drug C>!l ""

'" C>

C> C> '0 ",,8 ai rpl ane ai rpl ane

!~ ~~

.,,, ol

"' ~ ~Zf ~~

"" " "'-"

"" ~ ..

e" e

"" "" e 'O~ '0'- ~

e ij" -- -- - - --+ - ---- .0.(; L a nding gear

"'"" 'C '0"

'C "S '0 .,3 ,,0 'O~

., "

'0 ~'O b.OO~ '0 '0 Assumptions: ".Q ""~ .,.., ....

'g~ .,

1l ""e

..,,,

e :;A e Il igh speed (gear retracted ) , miles

.21" '<

"''''

~ " ,,'0 per hOUL ______ __ __ _ ____ __ __ _

~ C'O A A ~Q~ 13 5 220

" iil " A

" gj

@ @ gj 5 S ""ol ., S Thrust horsepower available __ - 400 400 2i

:»'0 Cl3

'" 0 0

"1 0 '-<

" Drag o( ai r plane aL high s peed

() () ~ .e " ~ ~o Po. Po.

(gear retra c Led ), pounds ___ _ 1,110 GS2

"" -- ---

Wing loading, pounds per s (jllilre ( ooL _________ _ TurpOD 'l'YPES 12 12 - ------ Lb. Lb . Lb. Lb. Lb.

AIRPLA , ES EQU IPPE D WI'l ' ll LOW-DRAG AND UraU-DRA G 14a ___. ____ __ __ ..

14.7 12 . 6 49.8 37 . 6 I. 60 4.9 1 9.4 24.3 39 .0 GEARS J4b. __ __ ________ 4.9 21.3 41. 0 16.7 1l.8 47.4 40.8 I. 65 1 9.4 14 0 ___ _ __ ____ __ __ 4.9 24.3 16 .7 12 .1 47.2 40.7 1. 68 19.4 41. 0 -- ---

-- - - -- -- - ----

Derived daLa: Av erage . __ . 4.9 19.4 24.3 39 .7 16 . 0 12 .2 48 . 1 39.7 I. 64 La ndin g-gear type . __ 13 (mod.

13 (mod. 14c Hc --- I ) I) - - - 1.0 - 1.0 - 3. 0 - 3. 0 A ngle of att a ck of wi n g, degrees TRrpOD TYPES ( WITI:l WHEEL FA IHI NaS) Drag olgea r 9tl00 miles per bour, pounds ,_ _ ______ 43. 0 I S. O 41. 0 17.5 ---- Drag o( gear aL hig h- speed condi - 27.3 208 . 0 74 . 6 14 8 _ I. 35 M S. 0 Lioo, pounds ~_

14 .2 1 --- - --- 19.1 1 26.~ T 0. 9 1 18.9 1 5 ~ 2fi .4

4.91

· -- f 1 Percentage d rag oi ai rpl a ne du e

to gear __ __ 23 . 4 2. 4 0. 3 1l.J red~lC - lion - in --- )~fgh P ercentage WIRE BHACEU (JNCLUDI a WI. a BRACINO) speed due to gear. - _______ --- 2. 2 3.9 .6 - - - Reduction in high speed due La gear, miles per hOUL ________ I 3.0 .9 1.1 .6 12 (witho ut Pe rcentage of tbru s t horsepower 9.7 brace st rut s) ._ 22 . 2 1 2. I 34.3 3 .0 3.7 5 .5 31. 5 1.10 23 . 4 absorbed by g ear. __ __ 2. 4 6.3 11.1 12 (wit b brace Tbrust horsepower abso rbed by st rut s) ____ ____ .9 53.4 26.9 19.7 1. 2 1 24.0 1 2. I 36. 1 45.0 44.3 93.6 gear _ 9. 6 25.2 -------- -- .-----_.----_.

CANT ILEVER (Wl' l' J:[ WHEEL FAIRI OS) I rn presence of win g and fu sel age , no engine.

- --- 13 (modifica- tion 1) _ ___ __ _ __ 2.0 10.9 12.9 13.0 O. I IS.2 8· 1. 0 0. 8 1.01 13 (modifica- tion 2) ____ _ ___ 1I.8 21. 6 1 3.0 -6.0 .---- ----. .60 ' ' 9.8 ---- , Lower ha ICwb ee l ( ai rin g.

I Computed (r om tests o( wheel (sirings A and A,.

U. S. GOVERNMENT PRINTING Offi C E: f9,.

--~----

--

" ....

"

"- ......

Z Positive directions of axes and angles (forces and moments) are shown by arrows Axis Moment about axis Angle Velocities Force (parallel Line ar to axis) Sym- Sym- Po sitive Designa- Sym- (compo- Designation symbol Designation Angular bol bol direction tion bol nent along axis) Rolling _____ RoIL ____ LongitudinaL __ X X L Y-+Z 1,1 p LateraL _______ Pitching __ __ Pitch ___ _ Y Y M Z-+X 0 u q

'" yaw _____

NormaL ______ _ ya""ing _____ Z Z N X-+Y ID r ,

'"

Absolute coefficients of moment Angle of set of control surface (relative to neutral

L M

N position), o. (Indicate surface by proper subscript.)

1 m

G = qbS G = qcS G,,= qbS

(rolling) (pitching) (yawing) 4. PROPELLER SYMBOLS Diameter D, p

P, Power, absolute coefficient G = pSD'

p, Geometric pitch

Pitch ratio p/D, Speed-power coefficient = ~ ~~: G" Inflow velocity V', Slipstream velocity Efficiency 71,

V"

l' n, Revolutions per second, r.p.s.

T, Thrust, absolute coefficient G = ~

r pn 1J-

<P, Effective helix angle = tan- (2!n)

Q, Torque, absolute coefficient G Q = ~nr.

on 1J- 5. NUMERICAL RELATIONS 1 hp. = 76.04 kg-m/s = 550 ft-lb./sec. 1 lb. = 0.4536 kg.

1 metric horsepower = 1.0132 hp. 1 kg = 2.2046 lb.

1 m.p.h. =0.4470 m.p.s. 1 mi. = 1,609.35 m = 5,280 ft.

1 m.p.s. =2.2369 m.p.h. 1 m = 3.2808 ft.