REPORT No. 428

WIND—TUNNEL TESTS OF A CLARK Y WING WITH A NARROW AUXILIARYAIRFOIL IN DIFFERENT POSITIONS

By FEEDE. ‘WEICKANDMIIUED J. BAMIIKIE

SUMMARY

Aerodynumti forci? teet8 were made on a combinuiionof a Clark Y wing and a narrow auxiliary airfo-iJto.@the bat locution of the auxihry airfoil with Teqwct tothe main wing. The auxiliary waa a highly camlwdai~oi.1of nudium thi&ne-s8haoing a chord 14.6 per cenithat of ilw main wing. It W(Mtested in 141 differedposdbna ahead of, above, and behind the no8t?portion oftti main wing, the ra~e of the teatpoints being exiemdeduntil the beet aerodynamic conditio.n.ewere mowed.

A range of poeitium w fmnui?in which the &n.dwn of main wing and auxilia~ gam eubstaniiallygreater a+wodymzmtiej%bncy and highm maximum liftcoejEcian&(based on total area) thun tha main Clark Ywing done. In the optimum poei.tian -teeted,@rwider-ing both the muximum li$ and the 8pee&range rutw, thacombination of main wing and auxiliury gaoe an irwremein tlw maximum li&tcoej%ieti of W per cerd togetherm“th an &U7e(Z.8ein the ratio CLmW/&inof M pm centof tha reepectwe valuesfor the main Clark Y wing aLom.

INTRODUCTION

In an effort to provide m- for obtaining lowerlanding speeds and greater speed ranges, many deviceshave been developed for increasing the maximum liftwithout excessive increase of the drag. These devicesinclude pilot planes, slots, flaps, etc., most of whichhave movable parts entailing a certain amount ofcomplication. In this field recent tests have beenmade by the National Advisory Committee for Aero-nautic on a Clark Y airfoil with Handley Page ty-peslots, in which the slat portiorr was tested in a largenumber of diilerent positions to determine the best.(Reference 1.) A series of tests has also been made todevelop a tied slot for the same airfoil giving a rea-sonably high maximum lift coe5cient with the low-cdpossible minimum drag coefficient and having nomovable parts. @eference 2.)

The present investigation consists of further testsof the same type on a Clark Y wing with a narrow aux-iliary airfoil tested in n suflieient number of locationsand angular positions with respect to the main wingto determhe the optimum one. These teats, as well

as those previous-y mentioned, were made in theN.A.C.A. 5-foot vertical tunnel under the sameconditio&

b addition, these tests were made at the same airspeed and on a model having the same chord as thatused in a standard series of controllability and stabilitytests (reference 4) whioh are being made in theN.A.C.A. 7 by 10 foot tunnel. Aileron tests on awing with the auxiliary airfoil in the best position wiUbe included in the series.

APPARATUS AND METHODS

Wmd tunneL-The N.A.C.A. vertical wind tunnel,which has an open jet 5 feet in diameter and a closedreturn passage, is described in detsil in reference 3.

A “reflection plane” and half-span model wereused because a full-span wing of aspect ratio 6 and 10-inch chord could not be tested in the verticaJ tunnel.

The drag forces were transmitted from the wing bytwo fine wires to a platfom balance above the tunnel.The lift forces were transmitted by a system of bellcranks and rigid reds to two platform balances mountedon the tunnel test floor. A detailed description of thearraq@nent may be found in reference 1.

Models.—The main wing, whioh had a Clark Ysection, had previously been used in the tied-slottests of reference 2, and for the present tests the slotwas filled with “Plasticize.” The auxiliary airfoil,because of its small size, was made of shminum alloy.It was a highly cambered airfoil of medium thiclmessratio (12 per cent) and had a chord 14.5 per cent of the \chord of the main wing. It had previously been usedduring one stage of the iixed-slot developmat. Forthe present teats it was supported on the main wing bythin metal plates at each end and by a small bracket atmidspam The details of the supporting plates andthe ordinates of both main and auxilimy airfoils aregiven in Figure 1.

Tests,—The tests were made with the trailing edgeof the auxiliary airfoil in 24 different locations withrespect to the main wing. At each location of thetrailing edge tests were made with the chord line ofthe auxiliary at several different angles, ~, with respect

537

https://ntrs.nasa.gov/search.jsp?R=19930091502 2018-08-19T23:52:08+00:00Z

538 REPO13TNATIONAL ADVISORY COMMITTEEFOR &13RONAlJTICS

.

b the chord line of the main wing, making 141 podtions in all. The fit arrangement (pi. 1, fig. 1) ireluded only 12 locations of the trailing edge. Othelwere then added until the optimum was found.

Ii the main seri~ of tests the lift and drag wermeasured at various angles of attack for each positioof the auxiliary. Readings were taken at 1° intervalto cover the region of the minimum drag and msimum lift coeflicienta and several points were taken ibetween to determine the shape o’f the lift and dracurves. Pitching moments, which reqtied a .diglchange in the balances, were also measured for a fe~of the better positions of the auxi.by airfoil.

AUSlLL4RYORDINATES

Lower,K&rlf

2s3169.!?-5.23.c@.W:2

;:4.7sE.636.794&9207lao

CLARKY ORDINATRS

L4wer,w-v-t

250i%:E.42.In.m

o

j

8000

1AuxflhyChOld.Rawm I.—Clark Y wing with anxlhry akfdl and moontfns platm. (Best w

tion”for tka auxflhrg alrfoll k shown)

The tests were made at a dyn~c pressure of 16.3’pounds per square foot, which corresponds to an aispeed of SOmiles per hour under standard atmosphereconditions at sea level. The Reynolds Number tit]the above test conditions and the main wing chord o10 inches was 609,000, which is about one-third othat for an ordinary small airplane while landing.

RESULTS

The results are given in terms of the standanabsolute coefficients of lift and drag, and center opressure (CL, CD, and c.y.), the latter referring hthe chord of the main wing. k the computation othese coefficients the total area of the main wing pluthe auxiliary was used.

Curves of the lift and drag codicients plotte~against the angle of attack for all positions of thauxiliary with respect to the main wing are given iFigures 2 to 25, inclusive. Each &me includes th,

results for the various an’glea of the auxiliary at onelocation of its trailing edge, aud also the curves forthe main wing alone.

The valuea of Cm, CD.,., and the angle of attackfor C- are given in Table I along with the valuesof the HLtiOS CL#UD.l. and (~L*X) z /dDmln fOreach position of the auxiliary airfoil.

For facilitating the selection of the position of thea~q &fofi giving the ‘highest ValUeS Of (?LIIJSXj

contours of equal values of the maximum lift coeffi-cient are given in Figure 26. .The value at any pointrepresents the maximum that can be obtained withany angular position J. Similar cpntour chartsfor the equal values of the ratios &ux/UDml. and(CL_)’/C_n are given in Figures 27 and 2S, respec-tively.. Curves of the center of pressure plotted against

angle of attack me given for a few of the better posi-tions of the auxiliary in Figures 7 and S. The valuesfor the Clark Y wing alone me also included forcomparison.

Effeot of supporting plates.—The accumcy of thepresent tests was about the same as that of the previoustests with the same se&up (references 1 and 2) exceptfor the effect of the mther large end plates which sup-ported the auxiliary airfoil. To il.nd the effect of theplates on the results, the tests with one of the betterlocations were repeated with the supporting plrdeacut down (fig. 1, dotted lima). The results of thesetests showed that the effect on the drag and center ofpressure was within the limits of experimental errorand therefore negligible. The effeot on the lift co-efficients was noticeable but small, the valuea beingabout 2 per cent greater with, the large end plates.This value was considered sufficiently small to beneglected in the present comparisons.

DISCUSSION

The contour lines in Figure 26 indicate that theposition of the wmiliarg airfoil giving the tigheatvalue of the maximum lift coefEcient was that withthe tmiling edge about 3 per cent c ahead of the noseand 10 per cent c above the chord line of the mainwing, c being the main-wing chord. The highestvalue actually measured (CL= 1.S12) was found atthe point with the trailing edge of the auxiliary 5 percent c ahead of the nose and 6.5 per cent c above thechord line of the main wing, with 8 equal to – 300,Another region which gave a high maximum lift co-efficient was in the neighborhood of 17 per cent cahead of the nose and 12 per cent c above the chordline, where the highest value of (Yz_ was about 1.73,The highest actual test point in this region was 16 percent c ahead of the nose and 12 per cent c above thechord line with 8 equal to – 2.6°, an angle which isobviously better for obtaining a low value of ODIIIl~.

WIND+l?UNNDLTT3STf30RACIAJ?K Y-G 539

2.0 ~t%!b C/ord Y Lo ‘$----–—---+ +5° . o.——--_’~—-7. n+250, ..- 50T-~-&

L8 I I I I.9

1’ 1 1 I 1 1 1 I 1 1 I I 1 1 I1.

L

/,

CL/.

.

ci, Ciegres~OIXiE2.–0homcb3ddic9of wmbfnatfon Of main and adlfary wfnm wfth

tralllng edge of andfary 26 w cant ahord ahead of lwdfng edgo and 6J wCentObordabova OllordIfno of mnfn WfW

20 -I

~ fluin Clad Y ~ I 10A‘-----------6-+ 10° d.+ 5“—-—--0~—~—~. ~+ 7.5” .,. ,oOT..~—

f.8 .9

~5 O 5 10 15 =0 25 =U1 , ,

ci, degreesFI13UEE4.—0bmdaisUcsof combhmtion of nmfn and anrflfarY winm with

@hgtiwof~M Wmt WaWdoflmQW@md MJBcantohord above ChOIdIfne Ofh wfng

d, degreesFIGURE3.–CharaotaTktfc9 of mmbfnatfon of mafn and auflfa.ry WIU% wfth

trafUng odgaofanxflky 2Srmramtokd ahead ofldfngei fgeand13mmcant aheadabove okrd lfne of main wfng

2.

/.

L

L

L

c./.

.

a, degreesFmuaE 6.-OhamolmWfcs of mmbfnatfon of meh md auxfkry wings wfth

frafffng edgaofanxfMry 25 fmcantohord tieadof laadfng edgaand%’parcant ohord ahve ohoi-dffne of mafn TV@

540 REPOIfT NATIONAL ADVISORY COMMKFHIQFOR All130NAullX!s

20 Lo

[8 .9

16 .8

L4 .7

L2 .6

c. c.

‘OHi--t-H--

.5

.8 .4

.3

. .2

. . .1

, I‘5 O 5 10 15 20 25 30U

I I I 1 I ILPlain Clark Y~

I 1 A ‘—---45 = +5” 6.= o“ —0 I

lx ./

#fl>< .8 .4

.1

0G d~ees

FIGURE8.-ohemotmbthofc-nnhfmtfenofnmdnendenxflkywfnga wfth taJl-M@eofa=Uam15 rerwntchmd eheadoflmdbuc@e emd19Jrarcentohrudatmwehmd lfneefmnfnwfng

I I I IPlah Clwk I

I I—o

A--—-6=+5” 6=-25” —’+ .

20t-t %X11114

10

-—

.8 .4

%0 7* .6 .3

.4 .280

90 ‘2 ,1

cf.degreesmom 7.-ohmmhrMm efmmhfnetfon ofnmfn and anxilkgwfngs with troll-

fnged8e ofemiUery 16percentohmdahmd ofleadfng edgeend12pxwntOhoi-dalmwohordlfneefmafnwing

10

,9

.8

.7

.6

‘OH-+H-MiI 1 1 1

.6 I I I I I 1.3

2

I

oa, degrees

~Gm 9.-OhBraoterMfca efwmkdnetfen ofmefn and enxfflarg wfn@ tith trefl-fngmfge ofamilfmy 10percont ohemleh&xl oflmdlngwfge end6~contCherdabmohomlllneofrnnfnwfng

~WIJNNEL TESTS OF A CT.AR.KYWTNG 541

CL I I I I I/%

‘H-t-H-k.8 I I i I I I

2

. f

od, degrees

Fratmm10.-Olm.mckMfm of mmbfnatlon of maio and amDfarY wings withtrdlhu edgo of andlfnry 10w cantohordalkmdof Iaadingedgdand 10w cdOboldalmve chordunaoftim

~, degreesFIoum12.-Ohm-aotorMfmof cnmbfnatfon of mfdn nod mdlfary wfnsa with

Wg@@of~6Wmt _*dofltig@@md6Awmtobord above obmd fino of nudnwfng

cf, degreesFmum11.-obmmh&fu Ofcambbmtfon ofmafnand ooxllkywfngs with

-*of~lowmt-w Ofl-@@d MwmtOhordlinoofmnin wfng

ci, degreesFIOUBE13.-obm—WkMm of wmbfnation of nmln and aoxllky wfnm with-@@ofa-6wmtcMW of ImQed@-rmdiLSWmntohord abovaohord llneofmafnwing

.— —.-

542 RDPORT NATIONAL ADVISORY COMMIZTDDFOR ADRONAIJITCS

,

EiFLI

20I ‘/+/)*——

x----------.. =

~- —- .-$L8

YT

L6 8

L4 7

L2 6

CDCL

Lo 5

.8

,.6 3

.4

T#FFFL

Q5 o 5 10 t5 20 25a, degrees

FIJmJaE14.-ohar@er& tfcsofcombfnetfon ofmafneadam6fery -with

_@eof~3~mtM*d~Mtig~md4Kmt&i-datWachadl fn90fm01nwlng

of,degrees~G~ 16.-fJkmackMm et wmbfnaffen et meln and enxflky wfngs wfth

_amti~OEmtWAd&1_d@md15mmtohca-deboTechGTdlfneofmefJl Q7ing

a, degreesFmum 16.-OlmmotmktIcs ofcombfmtlon ofmdn and euxillery winge wtth

=d@~~OBmntdti Mti ItigtigemdlOmmntohomiahmohord llneofmafnw’fu

Ipill2I

o— P/sin C/ark Y~’ , 10A----- =+5” =– S“—z—x

---1 “7- 150t-’t-H”g

L6

/.4 .7r ,, 1 I 1 I 1

/!2

c. I I I \l I Y/1 i

Cn

tlRI

L 5

4

. 3

. 2

-. I

o

o!, degreesFmuaB 17.4hemCk—M m OKwmbfnetfen of main end andfary wlnge with

_* Of~Oxmt Watiddlmtig dmmd~wmntohm-daimve elm-d Ifne of mefn wtng

WTNDWUNN13LTW3TSOFAC%ARK YWING 543

. 1

0 5 10 15 20 2P

20

f.8

@ degreesFmmElS.-Olmracterf3ttm of wmbfnation of mafn and auilfary wings, Wfth trdlfng edm of 13*Y 6 P mnt ohm+ behfnd IMfng w3go

ond24.8percant obord aimvoohordlfna ofmnfnwfng

—.d, degrees

~GUEtl’J.~kOOhhtk of combination of mafn and onxflky * wftb tmflfng@o of auflfary 10w csnt ohord behfnd Imdfng edKOand 12E cant ohm’dabovoohordlhmofmafnwfng

d, degrees

fiQUEE20.-OMa@rktf u of combfnatfon Of mafn and muflfmy - Wfthfraf@edgo ofanxllky lOBcantc.herd lmhfndlo@ngMlgoand17rmcontchmd abovoohcad lfneofmfdn wing

2.0 LO

L8 .9

L6 .8I , 1 1 1 1 1 I 1 I I I I I

7ZD

q, degreq

EiGmB u.—O hamdorMca of cnmbfnatfonof mafn and amillory wirwa mfthtrailing 6@goofouxflky 10pcmit ohcad Mdndkadfngwfgee.nd=porcant ohord abovo ohordUnOof nmfn wfng

544 REPORT NATIONAL ADVISORY COMMITIWEFOR ADRONAU’ITCS

2.

L

J!

1

1.

c.

/.

.

.

u, degrees~GUEE Z2,~h8mCtd?dCSofcombinationofnmfnsndanxllky wingswfth

trailInge3ge ofamfILmy16 ~mutohmd baMndkdlng cdgeand28p3rLxlntchc udaboveokdlineofmfdllwing

u, degrees

.6

.4 .2

cY,degrees

~GUBE !2S.<hOmd@tiu of mmlinotfon of rmin ond anxflkrg dngg withtmfllngedge ofanxllkyful per cent ohord Mindlmdlnged goand 14 ~rC8ntohm’d abweohcdl ineo[mafnwhg

a, degreesFmuKE2s.-0lmmcfmMraofcmnblmtionofmah and aaxlkrywfoga with

tmflingedge ofamilkryn~ wntohord lWdndlmd.@e dgoond24~mntolmRd almveohord llne Ofmrdn wing

WIND-TUNNEL Tf!lSTS OF A CL4RK Y WING 545

The ratio U#O~l. is an indication of the stith-bility of a wing for giving a high speed range, and for agiven minimum speed and total weight shows therelative merits of different wing arrangements in thehigh speed obtainable. A chart having coritour limafor even vahw of the ratio C~Cm is given inFigure 27. The maximum values of this ratio wereobtained with the trailing edge of the auxiliary in the

32r /

Per cenf chord

310mE26,-Contoaraofoqaalvalae9ofCm- obtafnad with varfoaa mttbwx offrntlfngtige of amilfauafrfoif. The valaa at onyrmfntmrmsants thb~that w M obtafnod wftb anY an- IWftion

neighborhood of 17 per cent c ahead of the nose and14 per cent c above the chord line of the main airfoil.The best location actually tasted was that with thetrailing edge of the auxiliary 16 per cent c ahead ofthe nose and 12 per cent c above the chord line, equalvalues being obtained with the chord of the auxihqparallel to and at an angle of +2.6° to the chord ofthe main wing. (This position, it will be noted, is in

-— —F&r- c’s+ chord

..

Fxaum 27—ContoursofequelMU ofCdCDd. obtnfnd wfth varfonnEOttfUEOf -g 13@ Of~ afrf~. Tba Mae at 811YP3hIt m-btbe mnxbnti that w be obtafmxl with FUIYangular L@tkm

the second beat region for high maximum lift coeiii-cients.) The value of the ratio obtained at this pointwas 104.6, which is about 21 per cent higher than thatfor the main Clark Y wing alone (86.3) which seemsremarkably fortunate considering that the mtimumlift coeilicient was 1.706 as compared with 1.296 forthe main wing alone.

At the position which gave the highest value ofG’-, actually tested (5 per cent c ahead of the nose,6.6 per cent c above the main chord line, 6= –300),

the ratio CmJC~,n was 49.3—a value which wouldmake the combination practically unusable if theauxiliary airfoil were tied in position.

Selection of optimum position of auxiliary airfoil,—b the selection of the optimum position of the auxil-iary airfoil with re9pect to the main wing, it is ob-viously advantageous to have a high value of themaximum lift coefficient, permitting the use of a rela-tively small wing with the lowest possible weight. Itis also obviously an advantage to have the highestpossible maximum speed with a given minimum andboth of these points must be given consideration.The values of U- and C~C~m given for anyparticular trailing-edge location in Figures 26 and 27do not usually represent the same angular setting 6, .which makes the actual selection of an optimumposition rather complicated. One method of mtig

28r //.

/—

01 I I 1 I I I I I

3228 24 20 16 IZ2W:m: &d4 8 12 16 20 24

~a~ 2S.-Oontoara ef @ valuffl of (C~AW’~1~ obtafnad with vmfome.etthw of trallbu edge of auflfary afrfoff. The valua at my @t m-hh mdnmm that m Imobtafnad with anY _ @tfan

such a selection is, of course, to base it on one’s judg-ment, having studied the values for each positiongiven in Table I. In order to facilitate this selectiona criterion has been arbitrarily chosen which containsboth CL- and the ratio CAC~ and gives themequal importance by taking the product of the two.The resulting criterion is the ratio (C~)*/Cmti.

The contours in Figure 28 represent the values of thisratio for the best angular setting 6 at each location ofthe trailing edge of the auxiky. On this basis theoptimum location is about 17 per cent c ahead of thenose and 14 per cent c above the main chord line,which is the same a9 the location giving the highestvalue of CACtim and at the same time is in thesecond bigheat region for cLmax. Of the potits acti~y

tested, that giving the highest ratio of (Cd2/Cmi.was 15 per cent c ahead of the nose and 12 per cent cabove the chord line, the chord of the auxiliary beingparallel to the chord of the main wing. A value verynearly as high waa obtained with the same trailing-edge location and 6= + 2.5°. In either of these posi-tions the angle of attack for the maximum lift coefficientwas 24°, and the lift curve dropped sharply just abovethis point.

Chn-ves of the center of pressure against angle ofattack are given for values of 6 of 0°, + 2.5°, and – 5°

546 REPORT NATIONAL ADVISORY

for the optimum location of the trailing edge of themmilimy, together with the lift and drag curves inFigure 7. The center of pressure in each case ispractically constant at 20 per cent c back of the leadingedge of the main wing for angles of attack from about3° to that of the stall. At the stall the center of pres-sure goes suddenly back, giving a stable pitchingmoment. As the angle of attack is reduced below 3°the center of pressure travels back in the normalunstable direction, but at zero lift the unstable pitchingmoment is much less than that of the Clark Y wingalone. It is evident that an airplane -with a wing andauxiliary airfoil in the optimum position would requirea smaller horizontal tail plane to have satisfactmystatic longitudinal stability and balance at all anglesof attack than the same airplane wiiih the same mainwing but without the auxiliary. b order to &dwhether this range of center-of-pressure travel wasconfined to one location of the auxiliary, the valueswere also measured for one other location that gavehigh values of maximum lift coefficient and speed-range ratio. For this position the trailing edge of thermxil.iary was 15 per cent c ahead of the nose and 19.5per cent c above the chord .line and the chord of thenusi.liary was parallel to the chord of the main wing.The center-of,pressure curve is given in Figure 8. Thechara@ristics, it will be noted, are the same as for theother location of the auxiliary.

A matter deserving cmsideration in regard to theoptimum position of the wing and ausiliary arrange-ment is the high value of the drag coefficient at theangle of attack for maximum lift. This high valuemakes possible steep glides, which are advantageousfor making short landings. The value of L/D at maxim-um lift is only about 3.5 as compared with 8 for theOlark Y wing alone. These correspond to glide-pa%angles for the wings alone of 16° and 7°, respectively.Since the optimum combination of main wing and aux-iliary has, in the climbing rmge, values of L/D rationearly as high as the Clark Y alone, the favorable char-acteristic of a high drag at the higher angles of attackis probably due to the stalling of the auxiliary airfoil.

Ihsmuch as the iirst arbitrarily chosen combinationof wing and auxiliary airfoil was found, when the aux-iliary airfoil was put in the proper position, to giveresults substantially superior to those with single wingsor previo~ combinations, it is very probable that stillbetter combinations can be found. The present in-vestigation shodd therefore be considered aa only abegiming and shotid be followed by further tests withseveral carefully chosen airfoil sections, in which thebest relative size of the main wing and auxiliaryairfoil, as well as the best location in each case, aredetermined.

Comparison of optimum combination with slottedwings.-The earlier tests, including the best HandleyPage type slot and the best fied slot (references 1 amd

COMMl!X’DElFOR &GRONAUTICS

2) developed with the same basic wing under the sametest conditiom, give an opportunity to compare di-rectly the slots with the optimum combination of wingand auxihy airfoil found in the present tests. Thefollowing fable gives the data for the best combinationin each set of tests aa taken directly from the reports,

I

g%Ez:::’~:liil+ii I~gdot--- – —------------- t O1o1

(I&2#%%fcDb~71pa canttoallow for iropxfwt form with slot O1OS4CL

~Cellid~ts Mad on arm of xnalnwing alona.

k the computation of thbae coefficients the area ofthe original wing, assuming the slot closed, was takenin the case of the Handley Page slot, although withthe sIot open the arda was actually greater. The areaof the original wing was used in the case of the fixedslot which -was in effect merely cut through the originalproiile. The values for the wing with the auxiliaryairfoil are therefore also based on the area of the main-wing alone.

In order to enable a more accurate comparison to bemade, the coefficients have been recomputed on thebasis of the total wing area in each case, i. e., the areaof the main wing plu9 the area of the ausi.liary airfoil,or the slat, regardless of their positions with respect toeach other. These recomputed coefficients are Qivenin the following table.

IHrmdfeY Page ~ antomatio

I

Knot–_-.-–––.-_____ 0143 ;Fixed slot-------------- .021M ~EJ

114.2 lW. 870.4 120.1

Wing wfth auxiMaryafrfOIL._. . 01F3 z 104,6 17s.3

On this basic the highest maxirmuq lift coe5cientwas obtained with the wing and auxiliary airfoil of thepresent txwts. The speed-range ratio is not quite sohigh as with the movable Handley I?age type slot, butit is much higher for either of these than for the fixedslot or the plain Clark Y wing alone. The ratio(Cd’/O~h for determining the optimum combina-tion gives the Handley Page slot a shght advantage,but for practical casea this might be insticient toovercome the disadvantage of the extra mechanismrequired. .’

Effeot of adding a&iliary airfoil to conventionalmonoplane.-To obtain the best results with a com-bination wing and auxiliary airfoil they should, ofcourse, be incorporated while the airplane is in thedesign stage. It is interesting, however, to estimatethe effect of merely adding an auxiliary airfoil to anaverage conventional monoplane. It will be assumed

.

~LIHWL’SOFACLM3K YWING 547

for simplici@- that the gross iveight remains unchangedand that the difference in balance can be taken careof by shifting the load forward. If the minirntigliding speed of the original airplane were 50 miles perhour and the maximum speed in level flight 115 milesper hour, the addition of the auxiliiry airfoil in theoptimum position would decrease the minimum speedto about 41 roik per hour and the maximum apeedto 112 or 113 miles per hour. Alao the airplane withthe rmsiliary airfoil could glide at a much steeper anglewithout stalling, and the original tail would givesomewhat greater static stability than before. If anew wing without the auxiliary were supplied havingthe same total area and span as the original wing plusthe auxilhy, a laxger tail would be required to givethe same stability, the minimum speed would be about47 miles per hour, and the maximum speed about 113.

CONCLUSIONS

1. A position of the auxiliary wing with respect tothe Clark Y main wing was found which gave a msxi-mum lift coefficient of 1.81, 40 per cent greater thanthat for the Clark Y wing alone.

2. A range of positions of the auxilisry airfoil withrespect to the main Clark Y wing was found whichgave substantial gains in aerodpamic efficiency (effec-tiveness) as compared with that of the Clark Y wingalone. With the trailing edge of the auxiliary airfoillocated 15 per cent of the chord of the main wingahead of its leading edge and 12 per cent above themain chord ).ine, and the chord lines parallel to eachother, a value of the ratio d~c~l. of 104.5 wasobtained, which is 21 per cent greater than that ob-tained for the Clark Y wing alone.

3. The optimum position tested, considering bothC!.ux and the ratio cdc~~ was the same as thatgiving the highest mdue of the ratio G’Acb,n.This position gave a maximum lift coefficient of 1.705and a value of the ratio c4CM1n of 104.5, which areincreases of 32 per cent and 21 per cent, respectively,over the values obtained with the Clark Y wing alone.

4. This investigation should be extended to includediilerent sizes of the auxiliary airfoil with respect to

the main wing and cliilerant airfoil sections, a sufE-cient number of relative positions being covered to .determine the optimum with each combination.

LANGLEY MDMOU AerOnaUtiC LABO~TORY,NATIONW ADVISORY Co amamum FORAERONAUTICS,

LANGLEY I?IELD, VA., FeZnwury%, 19%2.

REFERENCES

1. Wenzinger, Carl J., and Shortal, Joseph A.: The Aero-dynamic Clmrao-lu of a Slotted Clark Y Wing aaAHected by the Auxiliary Afrfoil Position. T. R. No. 400,N.A.C.A., 1931.

2. Weick, Fred E., and Wenzinger, Carl J.: The Charaoterie-tios of a Clark Y Wing Model Equipped with SeveralFormE of Low-Drag Fixed Slots. T. R. No. 40’i’,N.AC. A., 1932.

3. Wenzinger, Carl J., and Harris, Thomas A.: The VertioalWfnd Tunnel of the National Advisory Committee forAeronautics. T. 1%No. 387, N. A. C. A., 1931.

4. Weiok, Fred E., and Weminger, Carl J.: Wind-TunnelResearohComparingLateral Control Devices, Particularlyat High Anglm of Attaok. I-Ordinary Aileronson Rec-tangular Winga. T. R. No. 419, N. A. C. A., 1932,

& Irving, H. B., Bataon, A. S., and Williams, D. H.: ModelExperiments on R. A. F. 31 Aerofoil with Handley ,PageSlot. R. & M. No. 1063, British A. IL C., 1926.

BIBLIOGRAPHY

Aeronautics Staff: Albatroes Aerofoil with Superposed SmallPlane. Report No. 159, Conatruotion Department, NavyYard, Washington, D. C., 1920.

BraMMd, F. B., and Clark, K. W.: Wind Tunnel Tests on aR. A. F. 15 Aerofoil with Pilot Planes. R. & M. No. 1145,Britieh A. R. C., 1927.

BracU3eld,F. B., and Clark, K. W.: Wfnd Tunnel Teets ofAerofofi with Pilot Planes. R. & M. No. 1213, BritishA. IL C., 1928.

Fuche, Riohard, and Sohmidt, Wilhelm: Air Forces and Air-Force Moments at Large Angles of Attaok and HOWTheyare AEected by the Shape of the Wing. T. M. No. 573,N. A. C. A., 1930.

Prandti, L.: Flllgel rnitefnfaoherUnterteilung. Ergebnkse derAerodyntichen Verauohsanstalt m GMtingen. II Lie-ferung, 1923.

548 REPOET NATIONAL ADVISORY COMMZITEE FOR ~RONA~CS

.

TABLE IIMPORTANT AERODYNAMIC CHARACTERISTICS AND CRITERIONS OF A MAIN AND AUXILIARY

WING COMBINATION FOR EACH TEST POSITION OF THE AUXILIARYPosMfonoftmflfngedgaofauxfumyaf r6aflfS ~hmwttiti wofm~mdabw ~tifieofhtig

afstkeangla katweanokardllnas ofruatn andadlfary afrfofl.g

26

26

2s

ls

ls

16

10

10

6

6

Jferk Y.116

13.0

IQ 6

27.0

&s

120

le. 5

6,0

lao

I&o

8.5

2L5

I.-.-.—

–6

:550;6

7.510067.5

~:

!5

–2

❑E 5—lo

o25

–1:–lo-5–25

!5

–It–5

oz’s5

:x-15–lo–5

;5

—2s-15-125–lo–5-:6

25

–2—16–5

o25

-4!

%–25-m—10

~–6

o5

I II

Pod= TkEtiof

Alrd Above

3 40

0 la o

0 lho

o X1.o

-5 24.8

–10 120

–10 17.0

–10 220

–u 2ao

–20 140

–m Klo

–m 24,0

6 IL%&ad

–35

:%–10

o

--J–35-w–25–E

–--i

:%.5–m–ls–lo-5–25

–!6–lo–7. 5–5–: 5

:1:–6

:

=%–20–_~

–30-m–m–17. 5–L5-126–lo–7. 6

––i-ls–lo–7. 6-6

–! 5

=:5

;65

=H

-–$—10–7. 5–5

:–10–5–26

o

CcdnI Ck. I a forOk. I

ao.m L&O

:% l%’

:M ~~.0191.0172 .m.0334.0232 ~g.a245

LEX:%%’ L360.0m7 L 149.M42 L443.WbS.m W

L 710:%.0225 kE.0179. Olw M%’; o&ll# L=

L 460.0223 L(!3O

La:%% L 674.0161 L5fb3.0168 L 46S.0167 L3S2.0240. 018+3 ;g. Ola. Olm L=

L300:%!! L3%2.0171.0173 i’%’. 016s.Of.%9 i~.m +.%.027’8.0242. Olw l%.0173 L372. OLW.0158 ?E

L 109%% L 40S

L432:K?!.0101 :;. Olbs.0160 L 315.0178 L3%3. Olss L332. Oml L220.0169 ~..0174.0176 L SW.0252 LLSI. Olea ;%. Olss.CO?s L 281.0166 L 4W.0161 L431.0183.0161 ;g.0173.0169 L 3&3. 0L$3 L 412.Olss L416.Olm L371

27.6 $;

%: 44.0320 47.637.0 4L34a o 4048.7 ~:53.8

107:0W Ua 687.1 107.1632 ~;65..5

47.21$~ 87.6

g; W69.5

IM.6 ~~ ;

%; W. 870.7 10.L4624 70.67a o 114,280.4 13a2MO 16Lo

144,8W ml828 114.467.7823 JR;9L 6 yti g7&7M1.z 7a3

%; M69.246.3 WI

3L O%’ ~;63.3 .

E: %:780 107.1Sf!.? 1~ :

2:24.6 %!54179.0 lE :W4 13L593.7 IWl oS-La M@.o

lW. 82: 1122824 K@.9

g! %[

74.474.8

M 6La34.2 Ilao89.0 lm. 6Sho u% o7a 6 Saj5447a 3lJJL6 ~;m. 562 117.0