Document
RESEARCH M€MORANDUM
NATIONAL ADVISORY COMMITTEE
FOR AERONAUTICS
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I I An investigatfon ie therefore being oonduoted In the Langley two-dimensional low-turbulence tUnnel8 in order t,o develop the optimum configuration of a 0.35-ChOrd s l o t t e d flap on a modified 65(,,) -111, atxfoll section and t o determine whether or n o t the dtweloped optimum f l a p configuration l e dependent upon the Reyno3.de number. Meaeurements to determine khe section pitching- tnMnent chsrscterfstioe, the effects of leading-edge roughness on the lift aharacteriatics, and, the lift characteristics f o r the flap deflected through a developed f l a p path 5 ~ y l e also bcludgd in this inveetigation a mMBoLs . .
a , aection angle of attack, degrees . * C airfoil chord section drag coefficient cd t . .
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R Reynulds nlopber x,y horizontal and vertical positions, respectively, of t h e flap leading-edge radiue center with respect t o Upper lip of elot In percent c , positive forward of md.below s l o t l i p , respective- (fig. I) Teets were made In .the Langley two-dlnermional low-turbulence pmeeure t u x l n s l to bterrpine the scale effecta an the l i f t and drag chamrcterietfcs of t h e airfoil section with the f l a p retracted and slot sealed for Reynolds numbers ranging Frosa 3 .O x Lo 6 t 0 . 2 5 .O x 10 6 L i f t msasurements were ,=de at e Reynolds number of "9 .O x 106 t o determine t h e flap position evld deflection for highest m a x i m u m lift .d b (optinmrm configuration) The scale effects on t h e i i f t characteristics of the O p t i n n l m flap ccmfigumticn were then investigated,f!or.the same range of Reynolds numbers covered in the teats of the airfoil with
t h e flag retracted end slot aealed. The t e s t methods and the m e w
uaed in correcting the t e a t data to free-air condftione are discwered in reference 3. !Be magnitude of the correctionsused in correcting I t h e t e s t data to f'ree-air canditfona was of the order of a f e w gercont The metximum free -stream W h number attained d-ng any I of the t e s t s did not exceed 0.i8.
A i r f o i l with Flap Deflected I The 3mrernent of magimum section lift coefficient increased from. 1.84 to 1 36 as the Reynolds number was U c r sed f r o u
approxi~etsly 3.0 x 10 6 to approximately 11.0 x 10 2 as. shorn in
figure 7. The variation of incremnt of maxim section liFt .
coefficient w i t h Reynolde number, however, was l e e s than the variation of wximum eection lift coefficient w i t h Reynolds number. ! € ! h e increment of maximum soctkon l i f t coefficient for Reynol.ds.numbers r-ng From 3 .O x lo6 to 25 -0 x 106 was approximately 1.3.
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I I I eectlon with a 0 -3i-cbrd slot+ied f l a p indicab t h e - following canclusians.
1 . The optinnun flag conffguration at high Reynolds nuaibere w a s found to be a f l a p deflection of 3 5 ' with the flap leading- edge radlua center located 1.98-percent chord behind and 3.2l-percent chord below the slot U p . The f l e p deflection wa8 lower and the f l a p was located rearward and upwd from the position found to be the optimum at a Regnoldrs number of 2.4 x LO6.
2. Shifts in the linear portion of the lift curve caused by variation in RegnoMs number,whi& oocurred only f o r the condition with the flap deflected, were either eliminated or reduced considerably .
I by altering the flap poeition.
I 3- The maximum section lift coefficient of the airfoil with the f l a p deflected in e position found to be the optimum at a, Reynolds
rnrmber of 9.0 x 10 P increased from 2 . 1 5 to 2.11 a8 the Reynolds nuniber
rJAcA RM rio. L7A24 !
Langley Memorial Aeronautical Laboratory Xational Advisory Coanaittee for Aeromutios Langley Field, Va.
" Clinton H. Dearborn Chief of E'ull-Scale Research Divisiori mPc . .
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1. Cahfll, Jones I ? . : Two -Dimensional I~lndJPunnel Lnvestigatfon
of Four m e 8 of Hfgh-LFft Flaps on an XACA 6-210 A i r f o i l Section. NACA TBT no. 1947.
2. R ~ c ~ s z , Stanley I ? . : Two-Dimensional Wind-Tunnel hVestig8tfOn
Of Modified NACA 65 -U Airfoil W l t h 35 -Percent Chord (1121 Slotted Flap To DetermLne Optimum Flap Configuration st a
Reynolds Number Of 2 -4 Million. XACA RM Mo . L7AO2, 1946
3 . Abbott, Ira E., von Doenhoff, A l b e r t E . , and Stivers, Louis S . Jr - : Stxrmazy Of Airfoil Data. NACA ACR No. L m g , I c . . .
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MACA RM No. L7A24 LE. r a d i u a r 0.842 N A T l O H u ADVDol 'ICs I of f l a p iomed by louer & m e r aurfaae surfaaa of plain airfoil.
Stationa and ordinates peraent a b f o i l a h w in Upper surfaoa fairs into plain airfoil seatloll at station 88.00 I ( a ) A i r f o i l d t h 0.350 slottedflap.
Center of flap leading-edge radius -
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P NACA RM No. L7A24 Fig. 7,8 " 0 4 8 16 20 Figure 7 .- V a r i a t i o n of maximum s e o t i o n lift c o e f f i c i e n t and inareatent of maximum s e c t i o n lfit o o e f f i c i e n t w i t h Reynolds nlmber f o r a rnodFfied XACA 65(112)-111 a i r f o i l s e c t i o n with a 0.350 s l o t t e d f l a p .
I i " 0 4 8 12 16 20 24 28 x 106 Remolds nunber, R NATIONAL ADVISORY COMHITTEE Fo9 AERON*UTKS .~igure 8 .- V a r i a t i o n of s e c t i o n lift o o e f f i o l e n t at a o o n s t a n t angle of attack w i t h Repol& number for a modFfied NACA 65(1121-~1 a i r i o l l s e c t i o n with a 0 . 3 5 ~ s l o t t e d f l a p .
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