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,RESEARCH MEMORANDUM
NATIONAL ADVISORY COMMITTEE
I t I The L-esults of the first phase of t h i B investigation,which cwered the developaent of t h e optimum f l q ? confimwation at Reynolds number of 2.4 X lo6, have been i,elIo;.ted? in imference 2.
The second phase of the investigation cove:~aC the deve1opQen.t; of the Optimm flap configuration at high ReJmolGs nan3ers and t e s t a o f the airfoil with the fla5 retracted md tho condition with t e
optimum flcg configuration at Reynolds nUmbe2s r;~ t o 25.0 X 10 2
I The r e s u l t s of those tests have been repwteC- i n reference 3.
This paper presents the results of t e s t s miie t o iletemine the section pitching-moment c h ~ a c t e ~ i s t i c s , t h e li?t characteristics for a develoyed f l a p path, and the effects 02 leadiqyecige roughness on t h e s e c t i o n l f f t chasacte:-ietics. These @ore- mentioned t e s t s conclude& the investigation.
NACA RM No, Lml8 , section & a g coefficient 'd section 1 3 . 1 3 coefficient c l .
'section pitching-mcanent coefficient Cmcr4 R Reynolds number * .
X> Y horizontal and vertical ,positions, -emectively,,of center of the flag leadFng-eQe radius with respect t o u2ue:- l i p of s l o t in yercent C, l o s i t i v e forward of ana belaw s l o t u p , respctive-, (fig. I> The 2-foot chord model tested b t h i e i n n s t i g a t i o n was a modified NACA 65 (n2>-U1 airfoil s e c t i o a m t h a 0.35~ s l o t t e d The airfoil section had beenmodizied bF .-amoving the ' f l a p .
traling-edge cusp esd 829 therefore aimilcc: t c m NACA 65
( 1 1 2 ) -
a i r f o i l section(refezence 4). Ordinates POT the ?lain - f o i l I section and the slotted flap a m gi-ren i n %&lea I and 11, respectfvely.Figure I is a sketch of the aizcoil and flap and also shows the reference pointe d e f i n i q the f l a g position.
A flap path was develowd by deflecting the fir? through a circular path fn such a m a n n e r t h a t a t a flag CePlection or" 35O the center of the flap leading-eQe racXus rraa located.
1.98-prcentc behind and 3.21-percent c belmr t h es l o t . l i p .
This flap deflection and position had been f o m d t o be the optimum .
at high R e p o l d s ntrmbere (reference 3) %e location of the I pivot point about which the flag w w deflected is s h o w in figure 2. The model w a s constructea of almin-m U o y and cnmpletely spanned the 3-foot-wide tunnel test section.
Test8 were made i n the Larigley two-dimensional low-turbulence ~ ~ S E I U ~ - Q tunnel to determine t h e m a l e e f f e c t s on the section pitchfqymcanent chmacterietics of the ai;Toil Eection with the f l a p retracted and slot sealed f o r Reynol6-s nwnbezs ranging frcan
3 . o x 10 to 9.0 X 106. L i f t meaawements 7m-e made at a
Beynolda nmber of 9.0 >: 10 6 t o determine the section-lift chur-actez.ist9cs of the m o d a l f o r flap deflections u2 t o 3 5 ' .
' The effects of standard roughn.ee8 (reference 5 ) on.the l i f t chazacteristics of the 0ptirm.m flap conflaxration and on the lift Ch€1~aCteri&iC8 of the model w5'Lk the f l a : ) i d X W t e d and s l o t sealed. were detei-mined f o r R Reynolds nmbei- 03 6 . 0 X lo6.
The effects of standard roughneaa on the section d;'q character- iatfcs of the model wikh the f l a p retracted s l ? & el& sealed were also dete;Plined for a Regnolde number of 6.0 :: 106. The t e s t methods and the m e t h o b ueed i n c o x r e c t i r g t h e t e s t data t o free-alr conditions =*e discussed i n reference 5. The magnitude of the corrections used In correcting the te3t data to free-air conditions waa of the order of a few serceak., The maximum free-atmam Mach numba:L- attained during of t h e . tests did not exceed 0.17.
PitchingMcmmnt Cha-cacteristica I The eection pitchfng-mmentcharacteilisticB I Q ~ the a i r f o i l section with the f l a p deflected a r e presented i n ffgure It.
Includedwith the section pitching-mcment data, lregented i n .
figure 4, a r e the eectiion l i f t chmacteL-istlce o b t a h e d from reference 3- For the flap aeflected ConZiCuration %lie elope of the pitching-mament cume becomes posi,tive8 at t x q l e s df attack f ' r a n about 2O t o s l i g h t l y above the stall, but BLL>therincreases NACA BM No. ~ 7 ~ 1 8 i n the section of attack cause a reversel of the slope and theslope of the pitching-moment curve becomes necative. Tlhe , value of the section pitchinglncanent coefficient is approximately 0 . 1 higher than that obtained for the N A C R . 65-210 a i r f o i l section with a 0.250~ slotted. flag (slotted flq] 1, 2efer.ence I ) and approximateb- 0.05 lower than that obtained 20s the mACA 65-210 airfoil section with a 0- 3l2c double 81okteiL fla:, (reference I) .
The maximum section lif’t coefficient vas, however, qproxfmately- 0 . 1 higher than that obtained f o r the NAGA 65-210 aii.foil with the slotted f h p and apTroximateu 0.1 lmrel- t h m t h a t o b t a h e d fa- the XACA 65-210 a i r f o i l with the aouble slotted Tlap (reference 1) .
Lfft Characteristic6 for Intermediate F 1 q Deflections The section l i f t characteristics of the model with the flag b f l e c t e d up to 350 f o r a Reynolds number o~ 9 . o :: 106 a r e px-esented i n figure 5. Measurements of ,the l i f t chax-acterfstics for flap deflections -eater than 350 weLw not m a b because, as discussed in reference 3, FncreaBingl the f l q deZloction beyond gave no increase in the m a x j z ~ m flection E P G coefficient at a Reynolds number of 9.0 X lo6, A t a fla., cleflection of 2 0 ° and a t section angles of attack higher than abouk -4O, two values of the section l i f t coefficient Irere obtained et ecch m e of attack, f
&though the values of the rmxhmsm section lirt ooefficients were
nearly the same. R e r u n s of these teste shad!. that the condition giving the lower l i f t coefficients was the moi’e stable of the two.
T u f t studies at a flap deflection of 20° indicated that the irregular behavior of the lift coefficients wa6 amociated wLth p a r t i a l stalling of the ffa2 cawed by the :-elztively poor slot shape for this flag deflection.
Effects of Le&%-Edge Eo-eas The section lift md drag chmactei*ist;icS at a R e y n o l b number of 6.0 X 10 fcc the airfoil section with standard rou&ness are pzasented i n figui-e 6. Lncluded with thedata presented i n figure 6 are the section chazactez-istica f o r the smooth condftion which wa-8 Obt&hl€d fram i-el”o;-ence 2. The decrement in the mRxirm?m section l i f t coefIicie&, caused by leading-edge roughness f o r the flag-defleckeL conation is approximately the same as that f o r the fla-.,-zet::mAml condition.
The decrement i n maxirmrm. section l i f t coeEicfen”; i s approxinately the same as that obtained f o r the NACA 65-210 a i ~ ~ f o i l section with the 0.2% slotted flag designated as elotted f l a p I i n reference 1. The minlmwn section drag coefPic2en-h f o r the smooth condition and the condition with leaCLi&-erlge :o@mees a r e the same as those estimated f x g n consideration oi: Sata f o r ~imllar airfoil sections p e s o n t e d in T i g v ” e 8 Sl&&, 511I-7, and S148 of reference 5.
The results of tests of a modified MACk & j -111 a i r f o i l
section with a 0.35-shord s l o t t e d flaz in⁣a.i;e L+ t , le following
conclusions: 1 . The section pitching-moment coefficient va8. approximately 0.10 Mgher . than that obtainea f w the MAC.!! 5”j-210 a i r f o i l with a L).250-choi-d slotked flap ,and a22roxinmtiely 0.05 1mmr than that obtained f o r the NACA 65-210 .airfoil sectLon v i t h a ’ 0.312-chord doukle alotted. flap.
2 . At a flap deflection of -20° and sect-lon angles of attack higher than about -kO, two vPlues oi? the section lift I coefficient at each a n g l e of attack were obtainsi? because of inconsistent stalling of the flap althoLgh tho neximxa section I lift coefficient l’m8,ined near* the same.
b ?. The decrement in the ‘maximum aec’;fon 1iP-t;. coefficient obt&ed by qqlying standard roughnees to the. ai;*ioil with the flap deflected 3 5 O w a ~ ag$roxlma’cekf the mane qs t h a t obtained f o r t h e airfoil wfth the T l q retyacted.
I bw NACA RM Wo. ~ 7 ~ 1 8 7 I I I I I NACA RM No. L7B18 S t r t l o n s and ordinatesgiven -011 o h o g ‘ - h peroent I I ORDIHA’ES BOK 0.35-CHOI(D FLAP I : Upper surfaeo fairs l n t o p l a i n a l r f o l l a e o t l o n
I ut statlon 8a.00
i ( a ) A i r f o i l dth 0.35~ slotted f l a p .
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NACA RM No. L7B18 Fig. 4 I: I I !
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I I 0 0 0 0 . 0 0 . 0 .a. 0 Fig. 5 i.
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