1、J1rNAT ONAL ADVISORY CO.MMITTEE iFOR AERONAUTICSTECHNICA1.,.,.,“.,.ImFEcT,OFREE.(2)airplanetimwas unaffectedat zeroliftbut at lowliftcoof-ficieutsthe neutalpointwasmovodforwardabout 2 poroontof themesaaerodynamicchordand at liftcoeffici?ntsbeyondthe”low-drag;range the forwemlshiftfn the neutral poin
2、t tie more”severe;(3)thewing st W= delayedbut,c?nce,s%=ted,progressed morerapidly;and (4)themaximumliftcoefficient,ifthewings”weretimmed,wOtiabe slightlyincreas6d. , ,. .,INIllODUCTION .In selecthg the airfoilsectionsto be employedin the designof a taillessairplane,en importantconsiderationis thewin
3、gpitchingmomentswhich,fortrfmrequirements,mustremainmoderate. Becauseof theirlowdragqualities,NACA6-seriesairfoilsaredesirableforhigheed, andlong+rangeoperationsand,if symmetrical,havemoderatepitchingmoments. The liftcoefficientsenoompasingthecruisingconditionsare,however,generallyabovethe low-dragr
4、angeof practical.s=tricel airfoils.Addhg camberandreflextngthemeanlineoffersa possibillty of shiftingthe low+rag rangeof thewingto inoludehigherliftcoefficientswithoutmateriallyaffectingthepitchingmoments Testswereconductedinthe LangleylfootProvided by IHSNot for ResaleNo reproduction or networking
5、permitted without license from IHS-,-,-,“.,2 :VJi:,“r:qp,c .:. 0.3werelessforthe symmetricalwingthanforthe camberedwiw.This effectof rcmghnessillustratestheneedformaintaininga smoothsurfaoeconditionin orderthatthebenefitof a camberedmean linemay be utilized.Pltchlng+mmentcharacteristics.-Atlowvalues
6、of liftcoef-fieient,”theapplicationof leading+dgerouness caused a forwardshiftintheneutralnointof 1 to 2 uercentof themeanaerOdti10chord. Athighvalue;wereapproximatelytheof llftcoefficienttheneutral-pointl-mationssamewiththewingsroughas with the wings.Provided by IHSNot for ResaleNo reproduction or
7、networking permitted without license from IHS-,-,-NACA, f10. 1ti2smooth,but the 10EMinma%fmumliftnessincreasd the rateof cheageof7coefficientr9sultingfromrough-neutral point withliftooefficlent. . . V39.543z6065!;808590E96979899100,OrdinateUppersurface1,652,052.4530263.924.495.025.496.337.068,519.60
8、10,43log11.2i11.3211,0910.619.88:.;:6:565.253.912*731.36a71 73.39.26.14.08.04.04Lowersurfaced“. 69-1.oy-1041-1a71 99-2.42-2a7179-3,13-3.43-3a71 97-4.43-5*39-6.15-6.79-7.27-7.57-7.70-7.66-7.45-7.06-6,52-5.83-5.04-4.16-3.26-2.35-1.48-.97-,67-.51-*37-.23-:13-.04d . #.4 ,”-. - Tip SectionStation0.3.61.0
9、2.0:z81015202530:;95455055$:80859093;2979899100OrdinateUppersurfaceI.5621.9372.3243.0853,7114.259;.:$5:9956.6838.0569.0929,87310.39210.67610a71 71710.49810.0479.3588.4637.3896.2124.9723.7D02.4441.285a.690a.367.244,135:.073.036a.Lowersurface-0.657-.991-1.339-1.887-2.288-2.645-2.962-3.21j0yg-5:107-5.8
10、27-6.429-6,882-.169-7.289-7.258-7.058-6,681-6.173-5.522-4*775-3.938-3.089-2a71 229+403:;:-.346-.222:-.1220aIn orderto facilitatemodelconstruction,the ordinatesfortherearlo-percentchordofthetip sectionwere increasedabovethesebasic .valuesto providea 0.13 aerodynamic woshout uboutO. 25 chord =353aspec
11、t ratio = Z 34.Figute 1.- G60metry of wings. (All dimensions in inches. ) ;PPProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-38620?5 M.AC. (b) Cambered wing; oerodYnomic washout abouf 0.25 chord= 4: aspect ratio = 7.36. +Figure /. - Concluded.N+M1,1.
12、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fre 2.- Symmetrical wing mounted for testingintheLangley19-footpressure tunnel.NProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. .00408 ./2 ./6 O 4 8 /
13、2 /620 .040-mCD c cmFiEum 3.-Effaot of -oil mcdfimticm m a71rcdio ah8ruJtwi8ties; RR 1,860,0M: N = 0.13.1+z.0Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.Fig. 4 NACA TN No. 1212DIi Crass flow inkk lretionof arrowsn$, Rough flowEzziIntermittentlys
14、talleda753rMt$tel yAngle ofattad(,m,deg(x=8.7*I,., . . .+.”a= .,m=lo.9m= 5,1”cc=18.3*(u) .Smmetr/2al wing .cc=10.8.(b) Combered wing, A,lWBO,-a mUCWurKcfigure4.-Sta/ing *characteristics of wings; /7-4,680,000;/kf=o./3.1Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
15、nse from IHS-,-,-. NACA TN No. 1212 Fig. 5*.028.024.Om.016cD* Symmetrical wingIQorce tests.0/2 -fk-h!omentumdrag.004 r- / CamberedwingForce te9t8u-Momentum dragteats0):2 0 .2 .4 .6 .8 1.0CL NATIONAL ADVISORYCOMMITTEEFORAERONAUTICSH.gure 5.- Effect o airfoilmodificatlonsontheprofile-drag.coefficient;
16、R=4.,800,000;M = 0.13.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fig. 6 NACA TN No. 1212.0080.008cdo.oo4o.0/2.008%*.00400/2008C(IO-004c1RCL!=(3.35r)DL / / .o- d.CL = 0.56t)Do = 0.0066NATIONAL ADVISORYCOMMITTEE FOR AERONAUTICSmm /r/6 CL = 0.74 CD
17、O = 0.0098/00 o /00 /00 o /(wLeft Right Left RightPercent semispon(a) Symmetrical wing.Figure 6.-Variation of section profile-dragPercent semispon.(b) Cambered wing.coefficient along span; R=4,760,000; H = 0.13.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
18、 IHS-,-,-. . . . .G.4 O 4 8 1/? 16 20 0 4 8 12 16 20 24%77 v%-ecosymwJtiOal wing Cmabered wing.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. .I I I.1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,
19、 . . .,04 0 -,04 .04 o-m” NATIIXMJ. ADVISORYamnlEE m AEmmTu6o 0 0 0 0 0cm G#nsgmm trlonl Wing(0) % ,Mt .Lhmbamdwing“#guM 7.- cludaa.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fig. 8 NACA TN No. 1212a75 Cross flow in direction of artYJWSK3;$: R
20、ough flowa75Intermittent Iystalleda75ornjd.$elym=l L9“=-%=0”8Angle of attacK,a,clegm= 5.5CZ=IO.8*(x=14.0“=% “00o(c?)Sytnmetrku/ wing, (b) Cumbered wjng,NAT IOIMJ. ADWSORYCmwrm WI AuwAulKsF/gure 8.- Sto/ing characteristics of wings with leading-edgeroughness, R* 4, 730,000; M= 0./3.Provided by IHS No
21、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-.-1,4 Symmetrical wingCambered wing a71/ /.2 / ! cmux /. o Wing smooth.8 Wing rough.11111111111111 -F? NATIONAL ADVISORYCOMMITTEE FOR AEROMJTICSFigure 9.- Effect of Reynolds number on maximum lift coefficient withand wi
22、thout leading-edge roughness.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fig. 10.(724.020.0/6O* .0/2,008.0040NACA TN No. 1212Symmetrical wing I r-t 4-l I A I (a) Cruise condition; CL=0.7.0/2etrlcal ulng.008 eed wingc .D(J I /1 .004 t / NATIONAL ADVISQRYCOMMITTEEFOAAERONAUTICS01 I I I I234567 8X106/?a71(b) Highspeedcondition;CLs 0.2.Figure10.-EfSectofReynoldenumberon$0 at highspeedandcruisecondltlonwith and withoutletidlng-edgeroughneaa.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
