1、REPORT No. 400THE AERODYNAMIC CHARA(YNHUSTICS OF A SLOTTED CLARK Y WING ASAFFECTED BY THE AUXILIAR Y AIRFOIL POSITIONBy CARLJ. WENZINQER and JOSEPHA. SHORTALSUMMARYAerodynamic force tests on a dotted LUwk Y wingwere conductedin the rerticulwind tunnel of the NationulAdwisoy Committee jor .Aeronuuiic
2、s to determine thebest posvlionfor a g+iwnauxilia airfciilwith respect tothe main wing. A systematic series of 100 changes inlocation of the auxiliary airfoil were made to ccmerall theprobable usefil ranges of aht gap, slot width, and slotdepth. The rwults of the inmxtigdun may be apedto the design
3、of automatic or controlled slots on unk.gsun”thgeometriccharacten”stic similar to thewi tested.4n increase cf .6 per cent in the maximum lift alkmethatof theplain wing w oldainedfor the slottedClark Ywing. At the gametime, the angle of attackfor maximumlift wag increused 13. It uus found that a maxi
4、mumincrease of about 30 wus possible in the highest stallingangle, but at a maximum lift coecient slightly lees thunthut oj the phzin w“ng. Hcuwer, with one aloi pom”tion,an increase of 26, togetherwith an increase in the maxi-mum lift coej%ient of 93.3 per cent, was obtained. Thebeet poei.tiow of t
5、he auxiliary airfoil were cmered by therange of the tests, and the position for desired aerody-namic characteristicsmay easily be obtainedfrom chartsprqared epeciallyfor the purpose.INTRODUCTIONLateral stability and controI up to Iarge angles ofattack form an important part in the program of re-sear
6、ch rdating to safety in flight now being conductedby the hTationaIAdvisory Committee for Aeronautics.A series of teds, comparing a large number of deticesfor obtaining IatmaI controI and stabili, has beenstarted in the atmospheric wind tunnels. A wing withslots and ailerons (one of the standard form
7、s in oolu-mon use will be tasted among the first, to serve as abasis of comparison for special devices.By the use of slots, a huge increase in the maximumM coefficient is obtained and the angle of attack israised considerably above that at which the plain wingwouh-i ordimwikvsfdI. The slots mevent t
8、he air flowover the wing f;om breaking away-at the USUSIstalling. Ispeed, and SQcause the wing to retain its Iift aud thecontroIs to function normally. A study w-asmade of the amilable data on slottedwings, the development of which has been due IargeIyh G. Lachmann and HandIey Page. The study showed
9、that the total ranges in geometric oharacteristios of theauxikwy airfoil had been about as foIIows (references 1to 12, inohsive):I IItemAodl%Andisry 8kfOstationsl1 I .,.Pg:dt Pu ratPa u P:ucedlt P; #$z;t “mchLw the mainwing was built of laminated mahogany. In the con-struction of the models, the ord
10、inates were held accu-rate to within + 0.01 inch of those specified in Figure 2.To provide a support for the auxiliary airfoil, a thinpIate wae mounted on each end of the main wing as=:_.shown iml?iia 3. These plates were drilled with 16,holh and fitted with slots as shown. A smalI platecontaining t
11、wo pins, one of which fittad any of theholes, and the other of which fitted the slots, wasfastened to each end of the auxiliary airfoil. Thus, itwas possibIe to vary either the width or depth of thowing slot, keeping the gap and one of the other vari-ables constant, A movable, thin metti-cIip was-hi
12、ngedat the trailing edge of the auxiliary airfoil at midspanand fastened firmly to the main wing to prevent theau.iag- airfoiI from deflecting appreciably under theapphed air loads.Four sets of the drilled plates were designed so that_tranges of the variables of slot position were coveredw follows:S
13、lot gap-1,5 to 3,5 per centchord.,Slot width-3.35 to 15.0 per cent chord.Slot depth3.5 above to 4.0 per cent chord below-the main wing chord.The above totaI range was investigated by 100 difTercntpositions of the auxiliary airfoil, in addition to the slotclosed condition, so that the best aerodynami
14、c char-acteristics might be obtained.The set-up of the semispan wing with the reflection.plaJMand other apparatus is shown diagrammaticallyin Figure 4. The drag forces were transmitted by twofine wires to a.pIatform bahmce mounted above the topof the tunneI, One wire was fastened to the wing near-th
15、e root, and the other wire was located l+hord Iengthfrom the wing tip. These wires, which were pmalleland vertical, passed inside two streamlined tubes cx-tdbg through the upper set of tunnel guide vanes. -The lift forws were transmitted by a system of rigidsteel rods and balI-bearing beII cranks to
16、 two balancesmounted on the tunnel test floor, The rod carrying.-.-. .,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.,. . . . . . . . . ., . . .,.Fnmrm8,-S1OW3OlarkYwhgProvided by IHSNot for ResaleNo reproduction or networking permitted without l
17、icense from IHS-,-,-710 REPORT NATIONAI,JM)VTSORYmost of the lift was fastmied by a pin joint l-chordlength from the wing tip. Two other rods were at-tached behind the reflection plane near the wing rootas shown in Figure 4, so as tcrbahmce the pitohhg mom-ents of the wing and, in addition, to carry
18、 the re-,mainder of the lifting forces. These two rods werehorizontal and were both perpendicular to the wingspan, being arranged to fom a parallel linkage system.The angle of attack was changed by turning a smallgear meshed with a quadrant attached to tie wing. The gear was fastened o a vertical ro
19、d forming one E in addition, rolling moments could be ob-tained by taking the differences between the productsof each baIance reading and the appropriate momentarms. This system was inelded so that the effective- COMl371lMlFOR AERONAUTICS . ditlerent combination. Several readings were takep.at l-deg
20、ree ktervals to cover the region of minimumdrag, d then the maximum lift was obtained ii asimilar manner. Tests were made also at a few inter-mediate amgles of attack in order to determine theshapes of the lift and drag curves.The lift balances were sensitive to within 0.06 pound,and the drag balanc
21、e was sensitive. to within 0.03 pound, The angle of attack setting was accurate to+ O.1O,and the d-ynamicpressure w - /5.0% “-iCbsed4TW WA”u, dqeesGUEE 5.-CL and CD vemue E Slot gap -IA w cent dfh-7/ .3.4zc -X - 60% “.2 $ - 9.0% “- 12.OZ“v - Kdfh 34.2-C x - .1.6 I,i + fA/! /“ f.4 - #,t% 1.2 , -1 P/
22、1f /1.o riG .8.6 Iv/i.;.4 sfoi wid)h34ZC.u x -6.0%m.2 - 9.0% “- 12.0%”/, /5.0% 0Slof Cklsed.Qn Io /0 20 30 40 50%*=FNUREl”-. mI .I.Z3F” ; ;2ti0;=4k! I I I hsfof- Ch.sed47*!MUWFIGURE21.-CL and CD TaWJS a. EM gaP-8Li per cent e. Slot depth-Apar cent c above cFIGUW. 22.-CL and CD a. SIOt gEP-iL6 per “n
23、t e. M depth-I.4Pr cent c llbore c/.81.6.4/.2- oz .- So% “/2.0.7“- IS.*Z“o# -o 10 20 30 40 50C4dq-eesFmIZEE24.-CL and Cnremn = SMgapd percentC. SIotdepth=LOpercent ciMowc-._. . -.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-716 REPORT NATIONAL ADV
24、ISORYobtainable at given positions of the auxilia airfoilwith respect to the main wing are given in Figgres 25to 29, inclusive. Each contour line connects pointsof equal value of the maximum lift coefficient or ofangle of attack for maximum lift. If the cukff point(point X, figs. 25 to 29) of. the a
25、uxiliary airfoil isplaced at the position for a desired CL a., tie cor-responding vrdue of the angle of attack for maximumlift wilI be given by the same position on the contoursof CWL=, Each Iigure thus Bhows the possibIe oom-biriations of maximum Iift coefficient and correspond-ing angle of attack
26、for maximum lift obtainable forany slot condition with a constant slot gap.The best obtainable values of the maximum liftcoefficient and of the highest angles of attack formaximum lift atven slot gaps, depths, and bestwidths are recorded in Table VI. The highest valuesof the maximum lift coefhients
27、are tabukted first,followed by the corresponding vaIues of the angles ofattack for maxum lift. Then the highest wduesof the angles of attack for maximum lift are given,followed by their corresponding values of the maximumlift c.oef%cienta, The curves of highest maximum Iiftcoefficients are shown in
28、Figure 30 and the curves ofhighest angk of attack for maximum lift are givenon Figure 31.DISCUSSIONAlthough these tests were not made at fulI scale, thescale effect is probably small because the ReyiioIdsumber is relatively large (609,000) and above thecritical range. This value is about one-third o
29、f thatfor an ordinary small airpkme while Ianding, the con-dition for which the results are of particular interest.The discussion of the resulte has been divided intofour main parts: First, a generaldiscussion of the effectof changes in the auxiliary airfoil position on thecurvm of lift and drag coe
30、fficients; second, a discussionof the effects of the position of the uxilia airfoilon the maximum lift coefficients; third, the eilects ofthe auxihry airfofl location on the angIes of attaokfor maximum lift; fourth, the choice of the optimumposition of the auxiliary airfoil. General,The shapes of th
31、e curv of Iift and dragcoefficients are affected by changes in the slot widthsfor given slot depths (slot gaps constant) as shown in.Figmw 5 to 24, inclusive. It wiIl be noted that largeincreases in the maximum Iift are possibIe undercertain conditions, and that under certain otherconditions Iarge i
32、ncreases in the angle of attack formaximum lift are obtainable. It can be seen thatsome of the lift coefficient curves are well rounded atthe peaks, while others drop off quite sharply afterthe maximum has been reached. Up to the stallingangle of the wing with slot dosed, it should be notedthat the
33、lift coefficient at a given angle of attack isgenerally somewhat lower for the wing with slot openthen for the one with slot closed. The charts indicateCOMMITTEE FOR AERONAUTICSaleQthat the sIopes of the lift coefficient curves for theslot om arrangements are, in ganeral, somewhatincreased by inreas
34、ing the slot width at a givendepth_ sIot gap constant). The tendency is to ap-proach the curve for the wing, th slot closed. (See -OWidth,percentchord . .tifhperCerIt6krd .Maximum llft wefiident, CL.,. Angle ofattack for maxbnom ILft,UC. ,.FIGGBE Z 1.60 I ! I.120ll!.oa46.0y“IEL!M2L 451L.027L 780L 76
35、2:ELWlL 636L 7HSLOT.- .-+-. .a. 6 E:Lo 6.4Lo 6.0LOLO :. ILO 15.026 a6 7.0i: -i : 1?:26 -4.0 16.o3.0 abao Mao -: ls.o; 12.oab -4.0 16.0-40 3.4-4 o a o-4.0-L o 2!-40 lio -t. medmmvahw.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AERONAUTICAL SYMBOLS
36、Length . . - iTme-.-Force - 4Power - PSpeed-_- -.W,9)m,P,Weight = mg1. FUNDAMENTAL AND DERIVED UNITS . Metric EngIishUtit Spbd Unit SymboI -meter - m foot (or rnfle)-_- ft. (ormi.)wend - seoond (or hour) - sec. (or hr.)weight of one kilogrmn - ,G weight. of one pound- lb.km/a-_-_-_-_ _-i-i-i- horsep
37、oer _ hp(!%r-_-_-_- -mi.h -ls_ m.p.i ft./w - For for a model of 10 cm chord 40 m/s,the corresponding number is 274,000.Center of pressure coefficient (ratio ofdistance of c. p. from leading edge tochord Iength).bgle of attack.Qgle of downwash.hgIe of attack, infinite aspect.ratio.Angle of attack, in
38、duced.Angie of attack, absolute.(Measured from zero lift position.)Flight path angle.721.-_.=Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-722 REPORT NATIONAL ADYISORY COW-E FOR .AERO4UTICE . . _-_.-Positive directions of axea and angles (forces an
39、d moments) me shown by arrows - .-,.,.; s;!= ii?“iss:;it$F+.DesignationLongitudinal - X ;Lateral - YNormal - z. -. -. Absolute coefficients of moment Angle of set of control surfuce (relntive to neu- -; -=.-. .D,P)pID,V,V,T,QDiameter.Geometric pitch. “P,Pitch ratio.Inflow velocity.” CB,Slipstream ve
40、locity. T?Thrust, absolute coefficient Cr= n.J.Q “Torque, absolute coefficient CQ=ZDPower, nbsolute. coefficient p= -&- -. . . . /6 jlSed power coefficient= .Efficiency.R&volutions per second, r. p. s. .().Effective helix angle= tnn-* -7. - 1 hp = 76.04 kgfmfs = 5501 kg/m/s =O.01315 hp1 nti./hr. = 0.44704 m/s1 ill/S= 2,23693 mir.5. NUhlERICAL RELATIONSlb./f t./sec. 1 lb. = 0.4535924277 kg.1 kg=2.2046224 lb.1 rd. = 1609.35 m=5280 ft. .1 m =%.2808333 ft.oProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
