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VI2TD-TUITFEL INVIZSTIGATION OF THE LIFT CHARACTERISTICS DB AB NACh 27-212 AIRFOIL EQUIPPED ?lITH TYO TYPES OF FLAP By X o b e r t S. Swanson a n d Marvin J. S c h u l d e n f r e i dn i n v e s t i g a t i o n h a s b e e n made i n t h e BACA 7 - by 10- f o o t wind t u n n e l of a l a r g e c h a r d BACA 27-212 a i r f o i l w i t h a 2 0 - p e r c e n t - c h o r d s p l i t f l a p and w i t h two a r r a n g o - m e n t s of a 2 5 . 6 6 - p e r c c l t - c h o r d s l o t t e d f l a p t o d e t e r m i n e t h c s e c t i o n l i f t c h a r a c t e r i s t i c s a s n f f c c t o d by f l a p dc- f l e c t i o n f o r t h e s p l i t f l a p a n d ag a f - f e c t e d b y f l a p d e - f l e c t i o n , f l a p p o s i t i o n , and s l o t s h a p e f o r t h e s l o t t e d f l a p . F o r t h e two a r r a n g e m e n t s o f t h e s l o t t e d f l a p , t h e f l a p p o s i t i o n s f o r maximum s e c t i o n l i f t a r e g i v e n , Com- p a r a b l e d a t a on t h e BACA 23012 a i r f o i l e q u i p p e d w i t h sim- i l a r f l a p s a r e a l s o g i v e n .
On t h e b a s i s o f naximum s e c t i o n l i f t c o e f f i c i e n t , t h e s l o t t e d f l a p w i t h an e a s y s l o t e n t r y was s1ightJ.y b e t t e r t h a n e i t h e r t h e s p l i t f l a p o r t h e s l o t t e d f l a p w i t h a s h a r p s l o t e n t r y , With b o t h t y p e s of f l a p t h e de- c r e a s e i n t b c a n g l e of a t t a c k , f o r maximum s e c t i o n l i f t c o e f f i c i e n t , w i t h f l a p d e f l e c t i o n i s l a r g e f o r t h e HACA 21-222 a i r f o i l a s compared w i t h t h e BACA 2301.2 a i r f o i l .
A l s o v i t h b o t h f l a p s , t h e maximum s e c t i o n l i f t c o e f f i c i e n t o b t a i a e d w i t h f l a g s i s much l o w e r f o r t h o NACA 2'7-212 a i r - f o i l t h a n f o r t h e NACA 23012 a i r f o i l , I N T R O D U C T I 0 1 7 The N a t i o n a l A d v i s o r y Committee f o r A e r o n a u t i c s h a s beefi c o n d u c t i n g a n e x t e n s i v e i n v e s t i g a t i o n of w i n g - f l a p c o n b i n a t i o n s t o f u r n i s h b n f o r a n t i o n a p p l i c a b l e t o t h o a e r o d y n a m i c a n d t h e s t r u c t u r a . 1 d b s i g n of h i g h - l i f t d e v i c e s f o r i m p r o v i n g t h e s a f e t y and t h e p o r f o r n a n c e of a i r p l a n e s .
F o r t a k a - o f x and i n i t i a l c l i m b a w i n g - f l a p c o m b i n a t i o n .capable o f . p r g d w c i n g m o d o r n t e l y h i g h E i f t w i t h low d r a g i s d c s i c a b l o , b u t f o r l a n d i n g a d e v i c e p r o d u c i n g h i g h l i f t w i t h 3 . v a r i a b l e d r a g i s proba-bly p r e f e r a b l e . O t h e r i m - a p o r t a n t f e a t u r e s are: no i n c r e a s e I n d r a g w i t h t h e f l a g n e u t r a l ; s m a l l change i n p i t c h i n g moment w i t h f l a p d e f l e c - tion; low operation forces; and freedom from possible ic- ing hazarcls, The investigation up to the present time has been on conventional airfoils of various thicknesses from 12 to 30 percent. (see references 1 to 6 . ) From these tests it was found that for a moderately thick airfoil very little improvement in the wing-flap combination was obtained if the split-flap chord was greater than 20 percent (refer- ence 1) and the slotted-flap chord.was greater than 25 per- cent (references 2 to 6 ) .
Although the split flap cannot meet some of the re- quirements, its simplicity makes it one of the most widely used types of flap. The sl.otted flaps are apparently cap- able of meeting more of the specifications than any other type of flap tested by the ITACA.
The present paper gives the resulks of an investiga- tion of the lift characteri.stics of a .laminar-flow airfoil ( B A C A 2'7-212), equipped with a 20-percent-chord split flap and with two arrangements of .a 25.66-percent-chord slotted flap, MQDELS Plain Airfoil The basic airfoil was built of laminated mahogany to the ITACA 27-212 profile and has a chord of 3 feet and a span of 7 feet; the ordinatos for the section are givcn in table I. The trailing-edge portion of ths airfoil is easily removable so that the modol can b o quickly altered for tests of various flap arrangements.
Airfoil with Split Tlap The simple splLt flap used was a 20-percent-chord .. flap built of straight plywood and did not conform to the airfoil profile, The flap was arranged far setting at de- flections from O0 to 75O in 15O increments. The flap de- flection 6f. is measured al0hg the a r c betyeon the trail- ing edge of $ho airfoil and the trail5ng edge of the flap, as shown in figure 1 . ' , S l o t t e d - F l a p A r r a n g e m e n t s and S l o t Shapes The f l a p 2,nd t h e , s l o t s h a p e s were b u i l t of l a n i n a t e d mahogany. The s l o t t e d f l a p u s e d i n t h e p r e s e n t i n v e s t i g a - t i o n w3s m:,de c o m p s r a b l e w i t h f l n p 1 of r e f e r e n c e 2 and h a d a 25.66-percent c h o r d . The f l a p i s d e s i ~ n c t e d f l a p 1, and t h c o r d i n 2 , t ~ s n r e g i v e n i n t a b l e 11.
The s l o t s h a p e s wcre mndo c o m p a r a b l e w i t h t h o s l o t sfio.pes of r e f e r e n c e 4. The s h a r p - e n t r y s l o t i s d e s i g n a t e d s h a p e .c and t h o e a s y - o n t r y s l o t , sh.apc b ( f ig, 2 ) . The p i c c e s f o r m i n g t h e s l o t s h a p e s wcre b o l t e d t o t h e nnin ~ + i r f o i l i n p l a c e o f t h c p l n i n t r a i l i n g c d g c , and t h e f i c p s were n o u n t c d on t h e a i r f o i l b y means of s p e c i a l h i n g e s t h a t p e r m i t t e d a wide v r . r i a t i o n i n t h e l o c a t i o n o f t h e f l n p w i t h r e s p e c t t o t h e s l o t l i p . ' The n o d o l s were n o u n t c d i n t h c c l o s e d t e s t s e c t i o n of t h e BRCA '7- by 1 0 - f o o t wind t u n n e l ( r e f e r e n c e x 2 a n d 7 ) s o t h z t t h e y completely s p a n n e d t h e j e t e x c o p t f o r s m a l l c l c n r z n c e s zt ~ n c h end. The main a i r f o i l was r i g i d l y a t - t a c h e d t o .the Isal-nnce f r a m e by t o r q u e t u b e s , which e x t e n d e d t h r o u g h t h e u p p e r and t h 3 l o w e r b o u n d a r i e s of t h e t u n n o l .
The a n g l e of a t t a c k of t h e model was s e t from o u t s i d e t h e t,unnel by r o t a t i n g t h e t o r q u e t u b e s w i t h a c a l i ' b r a t e d d r i v e . S i n c e a p p r o x i m a t e l y t w o - d i ~ e n s i o n a l f l o w i s ob- t a i n e d w i t h t h i s t y p e of i n s t a l l a t i o n , t h e s e c t i o n c h a r - a c t e r i s t i c s of t h s model u n d e r t e s t c a n b c d e t e r m i n e d .
A l l of t h e t e s t s , e x c e p t t h o s e p e r f o r m e d t o d e t e r m i n e t h e e f f e c t of s e a l s , w e r e n a d e a t a dynamic p r e s s u r e of 16.31 pounds p e r s q u a r e f o o t , which c o r r e s p o n d s t o a ve- l o c i t y of a b o u t , 8 0 ' m i l e s p e r h o u r u n d c r s t a n d a r d atrnos- p h c r i c c o n d i t i o n s an8- t o a n a v e r a g e t e s t Reyno1d.s n u n b e r of a b o u t 2 , 1 9 0 , 0 0 0 , B e c a u s e of t h e w i n d - t u n n e l t u r b u l e n c e , t h e e f f e c t i v e R e y n o l d s n u n b e r was a p p r o x i n a t e l y 3,500,000, F o r a11 t e s t s t h e a e y n o l d s number i s b a s e d on t h e c h o r d of t h e a i r f o i l w i t h t h e f l a p r e t r a c t e d and on n t u r b u l e n c e f a c t o r of 1 . 6 f o r t h e t u n n e l .
P l a i n A i r f o i l I The l i f t of t h e p l a i n a i r f o i l was measured o v e r t h e c o m p l e t e a n g l e - o f - a t t a c k r a n g e from -60 t o t h e s t a l l .
T e s t s a l s o made t o d e t e r m i n e t h e e f f e c t of s c a l e on t h e maximum l i f t c o e f f i c i e n t o v e r t h e r a n g e a v a i l a b l e i n t h e BACA 7- b y 1 0 - f o o t wind t u n n e l .
. s A i r f o i l w i t h S p l i t F l a p t The a i r f o i l w i t h t h e s p l i t f l a p was t e s t e d a t f l a p d e f l e c t i o n s Prom 00 t o '750 i n 15O i n c r e m e n t s . A s i n t e s t s of +he p l a i n a i r f o i l , t h o l i f t was measured o v e r t h e com- p l e t e .angl.e-of-attack r a n g e from -6O t o t h c s t a l l . Tho e f f e c t of s c a l e on maximum l i f t c o c f f i c i c n t was d o t a r m i n e d f o r t h e 60° . f l a p deflection, . .
A i r f o i l , w i t h . S l o t t e d Flap's Thc a i r f o i l w i t h t h e s l o t t e d f l a p was t e s t e d v i t h b o t h s l o t s h a p e s over a l a r g e r a n g e of f l a p p o s i t i o n s a t d e f l e c t i o n s from O 0 t o 600 i n 100 i n c r e m e n t s . The l i f t was measured t h r o u g h o u t t h e complotc a n g l e - o f - a t t a c k r a n g e from - 6 O t o t h e s t a l l f o r a 1 1 l o w f l a p d e f l e c t i o n s and a t s e l e c t e d optimum p o i n t s f o r h i g h f l a p d e f l e c t i o n s . T e s t s were made t o d e t e r m i n e t h e e f f e c t of s c a l e on t h e maximum l i f t c o c f f i c i c n t f o r t h e s l o t t e d f l a p w i t h t h c o a s y e n t r y ( s l o t 1-1) vhcn d c f l c c t c d 40° and l o c a t e d a t t h e optimum . p o s i t i o n f o r maximun l i f t .
RESULTS AND DISCUSSIOW The t e s t r e s u l t s a r e g i v e n i n s t a n d a r d s e c t i o n n o n d i - m e n s i o n a l c o e f f i c i e n t form c o r r e c t e d a s e x p l a i n e d i n r c f - e r c n c c 2 .
C! s e c t i o n l i f t c o e f f i c i e n t , ( ~ , / ~ c ) whcro 1 s e c t i o n l i f t q dynamic p r e s s u r e ( 1 / 2 p ~ 2 ) c c h o r d of b a s i c a i r f o i l w i t h f l a p f u l l y r e - t r a c t e & .
and a n g l e of a t t a c k f o r i n f i n i t e a s p e c t r a t i o a.
6 f f l a p d e f l e c t i o n The v a r i o u s m e a s u r e m e n t s made i n t h e t e s t s a r e be- l i e v e d t o b e a c c u r a t e w i t h i n t h e f o l f o w i n g lim.its: 6f - . . - - - - - - - - - .. - 520.2 , 1.
F l a p p o s i t i o n - . - - - - - - - Lt0.001 c
P l a i n A i r f o i l Tho s e c t i o n l i f t c h a r a c t e r i s t i c s of t h e p l a i n NACA 27-212 a i r f o i l from t h e t e s t s i n t h e t u r b u l e n t 7- by 10- The s e c t i o n l i f t c h a r - , f o o t t u n n e l a r e g i v o n i n f i g u r e 3.
a c t e r i s t i c s of a p l a i n a i r f o i l whon d e t e r m i n e d i n t h e more t u r b u l e i i t v a r i a b l e - d e n s i t y t u n n o l ( r e f e r e n c e 8 ) showed a maxin~urn l i f t c o e f f i c i e n t of a b o u t 0.2 l e s s t h a n t h a t ob- t a i n e d i n t h e 7- by 1 0 - f o o t wind t u n n o l a t t h e same o f f e c - t i v o Reynolds numbcr. Tho a n g l c of a t t a c k f o r a g i v e n l i f t c o e f f i c i e n t i s a p p r o x i n a t c l y 1 / 2 0 l e s s f o r t h e model of t h o MACA 27-212 a i r f o i l i n s t s l l c d i n t h e v a r i a b l e - d e n s i t y t u n n e l and t e s t e d u ~ i d c r t h r e e - d i m e n s i o n a l f l o w c o n d i t i o n s \ b u t ' c o r r e c t e d t o t w o - d i m e n s i o n a l .flow c o n d i t i o i z s .
A i r f o i l w i t h S p l i t Blap The s e c t i o n l i f t c h a r a c t e r i s t i c s of t h e a i r f o i l e q u i p p e d w i t h a s p l i t f l a p a r e g i v e n f o r e a c h f l a p d e f l e c - t i o n i n f i g u r e 4. The mnxinum s e c t i o n l i f t c o e f f i c i e n t d e t o r a i n c d i n t h e v a r i a b l e - d e n s i t y t u n n o l < r e f e r e n c e 8) f o r a n NACA 27-213 a i r f o i l w i t h a s p l i t f l a p e c f l c c t e d 60' w a s . ~ b o u t 0.17 l c s s t h a n t h a t o b t a i n e d i n t h e 7- b y 1 0 - f o o t wind tunlie1 a t t h e .same e f f e c t i v e R e y n o l d s number. The a n g 1 e . o f a t t a c k , f o r a g i v e n l i f t c o o f f i c i o n t i s a p p r o x i - m a t e l y lo l c s s f o r t h o n o d e 1 t e s t e d i n t h c v a r i a b l e - d e n s i t y t u n n e l , The d c c r c n s o i m t h e a n g l c o f a t t a c k , f o r t h e ranxinun s e c t i o n l i f t . c o e f f i c i e n t , w i t h f l a p d e f l e c t i o n i s l a r g e compared w i t h t h a t of t h e l?ACA 23012 a i r f o i l ( r e f e r e n c e 1 ) a n d n a y b e of i n p o r t a . n c c i n t h e c a s e of s t a l l i n g w i t h p a r t i z l - s p z n f l a p s .
A i r f o i l w i t h S l o t t e d F l a p D c t c r n i n a t i o n of o n t i n u n p o s i t i o n s f o r n c a i n u n l i f t . - Thc d a t a p r e s e n t e d i n t h i s s e c t i o n a r e t h e r e s u l t s of t h e maximum-lift i n v e s t i g a t i o n of b o t h s l o t s h a p e s i n w h i c h t h e f l a p , a t a g i v e n d e f l e ~ t i o ~ , was l o c a t e d a t v a r i o u s p o i n t s o v e r a c o n s i d e r a b l e a r e a w i t h r e s p e c t t o t h e s l o t l i p of t h e main a i r l o i l . The d a t a a r e p r e s e n t e d a s c o n t o u r s o f t h e p o s i t i o n of t h e n o s e p o i n t of t h e f l a p r e l a t i v e t o t h o s l o t l i p f o r a g i v c n . 1 i f . t c o e f f i c i e n t . The n o s e p o i n t of t h e f l a p i s d e f i n e d a s t h e p o i n t of t a n g e n c y o f a l i n e dravrn p c r p c n d i c u l c r t o t h e a i r f o i l chord. and t a n g e n t t o t h e l c a d i n g - e d g e a r c of t h e f l a p when n e u t r a l , a s shown i n f i g u r e 2.
- The c o m p l e t e maximum-lift d a t a f o r s l o t t e d f l a p s 1-n a n d 1-b d c f l d c t c d L O O , 200, 300, 4 0 0 , 500, a n d 600 a r c g i v e n i n f i g u r o s 5 and 6. An i a s p c c t i o n of t h e s e f i g u r e s shows t h a t t h e c o n t o u r s c l o s e d o n l y f o r t h e 400 f l a p do- f l e c t i o n f o r f l a p 1 - a ( s h c r p e n t r y ) a n d f o r t h e 20°, 4 0 ° , a n d 6O0 f l a p d c f l c c t i o n s f o r f i n p 1-3 ( e a s y e n t r y ) , F o r t h e o n a l l c l e f l e c t i o n s , t h e p o s i t i o l r f o r maximum l i f t c o c f - f i c i o a t i s n o t v e r y c r i t i c a l a n d o n l y 2 , s u f f i c i e n t number of p o s i t i o n s w e r e t a k e n t o c,ovor a n y p r a c t i c a l p a t h a l o n g w h i c h t h c f l a p i s l i k c l y t o b e o p c r a t o d . As f o r t h e s p l i t f l a p , t h e d e c r e a s e i n n a g l o of a t t a c k f o r maximum s e c t i o n l i f t c o e f f i c i e n t w i t h f l a p d e f l e c t i o n i s l a r g e compared w i t h t h a t of t h e ITACA 23012 a i r f o i l .
It nag a l s o be n o t e d t h a t t h c optimum g a p b e t w e e n t h e a i r f o i l and t h e f l a p t e n d s , i n g c n e r c l , t o d c c r o n s e a s t h e f l a p d e f l e c t i o n i n c r e a s e s .
From t h o s e c o n t o u r s , it s h o u l d b e possib3.e f o r t h e d e s i g n e r t o c h o o s e t h e b e s t p a t h f o r t h o f l a p t o f o l l o w f r o m a c o n s i d e r a t i o n of maximum l i f t c o e f f i c i g n t a l o n e .
I f , b e c a u s e of s t r u c t u r a l c o n s i d e r a t i o n s , i t i s i m p o s s i b l e t o u s e t h e b e s t a e r o d y n a m i c p a t h , t h e l o s s c a u s e d by u s i n g a compromise p a t h c a n b e r e a d i l y e v a l u a t e d , S e c t i o n l i f t c h a r a c t e r i s t i c s of s e l e c t e d optimum ar,ranwements,.- The s e c t i o l z l i f t c h a r a c t e r i s t i c s o f s c l c c t e d optimum a r r a n g e m e n t s o f s l o t t e d f l a p s 1 - a a n d 1-3 a r e g i v e n in figures ?'and 8 * The optimum arrangenents,were chosen from considerations a f maximum lift coefficient alone.
Additional data are included for arrangements that are asrodynamically less desirable in,.order to a12ow for devi- ations in the flap path to simplify the construction, A table included in each figure shows the nose position of the flap for the various dbflections, and these positions are plotted o n the diagram. The path hereinafter referred to as the "selected o p t i m p path" is shown by the broken line through the poirits and is a n assumed compromise be- tween aerodynamic and strycEural.considerations. The lift characteristics shown in.thess figures are typical; com- plete data f o r other positions of the various flaps a t the sevkral flap deflections are available upon request.
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A comparison of thc two slotted-flap arrangements and the split flap, a s lift-increasind devices on an NACA 27-212 airfoil, is shown in figure 9, where increments of maxin~un lift coeff icients with respect to the plain air- f o i l are plotted against flap deflection. The slotted flaps are moved along the selected optimum path. Note that there is only a small gain in the maximum lift coef- f icient deflections greater than 40°.
Although slotted f l a p 1-b is the better flap f o r all f l a p deflections,the split flap is almost as satisfactory as a lift-increasing device and is mechanically simpler to construct and operate, For this reason %he split flap seems to be the best compromise from the standpoint of structural and of lift-increasing considerations.
Effect of Scale on the Maximum Lift Coefficient Thc.effect of scale on the maximum lift coefficient of the plain airfoil, of tha airf.03 1 . with 'split flap deflected 60°, and of the airfoil with slotted flap 1-b located at its optimum position for 40° deflection is shown in figure LO along with some results from the variable-density tunnel (reference 8 ) . Tho difference between the results of the two tunnels a t the same effective Reynolds number is unex- plained but has been previously noted for other airfoils.
Inspec$ion of the curves shows that the increment of maximum section lift coofficiont is not constant with the effecfive Reynolds number but decreasas slightly as the Reynolds numbcr increases, The break in tho curve for the plain airfoil a0 t h e offoctivo Rcynolcls number 2 , 6 3 0 , 0 0 0 i s a p p a r e n t l 2 7 ' d u e ' t o a c h a n g e f n a i r f l o w i n t h e . maximum l i f t r e g i o n , which a l l o w s t h e a i r f o i l t o go t o a h i g h e r a n g l e of a t t a c k w i t h o u t s t a l l i n g a t t h e h i g h e r B e y n o l d s numbcrs.
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Comparison w i t h t h e NACA 23012 A i r f o i l Figura 11 shows t h a t a much h i g h e r maximum s e c t i o n l i f t c o e f f i c i e n t i s o b t a i n a b l e w i t h t h e XACk 230.12 a i r - ' . f o i l ( r e l e . r e i i c e s 1 and 2 ) c q t ~ i p p e d w i t h s p l i t a n d s l o t t e d f l a p s Bhan vrikh t h e NACA 27-212 a i r f o i l e q u i p p e d w i t h sim- . i l a r f l a p s . I t must b c remembered, h o w e v e r , t h a t t h e max- i m u m l i f t i s b u t one of t h e s o v e r a l f a c t o r s i n v o l v e d i n t h e f i n a l s e l e c t i o n of an a i r f o i l f o r a g i v e n a i r p l a n e .
C OI?CLUD LNG RENARKS . . .
On t h e b a s i s of maximum s e c t i o n l i f t c o e f f i c i e n t , t h e s l o t t e d f l a p w i t h a n o a s y s l o t e n t r y was ' s l i g h t l y b e t t e r t h a n c i t h e r t h e s p l i t f l a p o r t h e s l o t t c d f l a p w i t h a s!iarp s l o t ~ n t r y . P o r b o t h t y p o s of f l a p t h e dc- c r c a s c i n a x g l e of a t t a c k for.maximum s e c t i o n l i f t w i t h f l a p d e s l c c t i o n i s l a r g e on t h o NACA 27-212 a i r f o i l as compsrcd u i t h t h e NACA 23012 a i r f o i l . I n a d d i t i o n , t h e maximum s e c t i o n l i f t o b t a i n o d w i t h f l a p s on t h e NACA 27-212 a i r f o i l i s much l o v e r t h a n t h a t o b t a i n e d w i t h f l a p s on t h e NACA 23012 o i r f o i l .
a n g l e y Memorial A e r o n a u t i c a l L a b o r a t o r y , B a t i o n a l A d v i s o r y Committee f o r A e r o n a u t i c s , Langl'ey F i e l d , Vn..
,..
REFEREPFCES 1. xcazingor, Carl J,, and Harris, Thonas A . : Wind-Tunnel Investigation of N,A.C.A. 23012, 23021, and 23030 Airfoils with Various Sizes of Split Plap. Rep..B?o.
668, NACA, 1939..
2, Wonzingor, Carl J,, and Harris, Thomas A . : Wind- Tunnel Investigation of an N.B.C.B. 23012 Airfoil with Various Arrangornonts of Slotted Flaps* Rep.
No, 664, ITACA, 1939, 3 . Harris, Thomas A , : Vind-Tunnel Investigation of an B.d.C.h* 23012 Airfoil with Two Arrangements of n Wide-Chord Slotted Flap. T,N. No. 715, NASA, 1939, 4. V?enzinger, Carl J,, and Harris, Thomas A. : Vind-Tun~xcl Iavostigation of an lT.AoCc~L. 23021 Airfoil with Various Arrangements of SlottoC Flaps. Rep. Bob 677, R A C l l , 1939.
5. Duschik, Frank: Xind-Tunnel Invest igat ion of an M.B.C.A, 23021 dirf oil with Two Arrangenents of a 40-Pcrceat-Chord Slot ted Flap. T. i f . 30. 728, ITLlCA, 1939.
6 . R e c a n t , I. G, : Wind-Tunnel Investisntion of an lT.h.C.Ab 23030 Airfoil with Various Arrangenents of Slotted 3'lnps~ TON* Bo. 755, BACA, 1940.
7 . Harris, Thonns A.: The 7 by 10 Foot Wind Tuililcl c f the iTationa1 Advisory Connittea for Aeronautics. dep, GO. 412, WBCA, 1931.
8. Jacobs, Enstnan 8.: Preliminar~ Report on Laninnr-Flow Airfoils and Bew M ~ t h c d s Adopted for Airfoil and Boundary-Layer Investigations.. ITAC~L conf. rep., 1939.
O r d i n a t e s f o r MACR 2 7 - 2 1 2 A i r f o i l ( S t a t i o n s a n d o r d i n a t e s i n p e r c e n t of a i r f o i l c h o r d ) ?<% - ?. .# ,. - . . . .
----- . c f
L o v e s s u r f a c e ; { . 1. ._ Upper s u r f a c e
---- - ( / \ , > ' 0 0 1.45 2.02 2.86 7 5 3.50 1 0 4.01.
1 5 4.85 20 5.50 2 5 6 0 2 3 0 6.47 35 6 . 8 2 4 0 7.08 4 5 7.24 5 0 7.35 5 5 7.35 60 7 2 6 6 5 7 . 0 4 70 6.72 7 5 6.20 8 0 5.48 8 5 4.39
9 0 I 3.00
1.46
9 5 1
97.5 . 7 0
1 0 0 I . 0 8
--- L . E . r a d i u s : 0.70. S l o p e o f r a d i u s t h r o u g h end. of c h o r d : 0.12.
TABLE I 1 O r d i n a t e s f o r S l o t t e d Flap 1 ( S t a t i o n s a n d o r d i n a t e s i n p e r c e n t o f a i r f o i l c h o r d )
S t a t i o n 1 Uppzr s u r f a c e [ Lower s u r f a c e
C e n t e r o f L.E. a r c Fig, l,2 N A C A ~i@;ure 1.- Section of N A C 4 27-212 airfoil with split flap,
Lip .OOlc
:-thick
.8273c I ' , .R=.06e
Flop /-a
, Lip .OO/c
Flap /-b
Figure 2.- Sections of NACA 27-212 airfoil with
two arrangements of slotted flap 1, Increment of secfion mox/mum /iff coefficient, A el,, .
Fig. 4 Figure 4.- Section . l i f t oharacteristics with a 0.aoc split flap.
Fig. 5 a,b F i g w e 5 a to f.- Contours of flag location for c~,.8lotted flap l-a.
Fig, 5 e,f BACA I I 8 6 4 2 0 2
\
(e) P ercen f uirfoi/ chord \ (f) df m 600 Figure 5 e,i.
P i g . 6 c,6 8 6 4 2 0 (4 Percent o;rfoi/ chord Percent airfoi/ chord
(el \ '
Big. f P l i v e 7 . - Section lift oharacterietice Of the HACA a7-a1a airfoil with 0.8586~ mlotted f 1 . p Angle o f of fock, ag , d e g Fig. 8 Figure 8.- Swtion l i f t ohar8oteristice of the XACA 27-212 airfoil .lotted flap l-b at eelwted p 0 8 i t i O ~ .
r . - Fige. 10,11
Figure 10.- Scale effect on maximum lift coefficient of NACA 27-212 airfoil with .20c split flap and 0.25660 slotted flap 1-b at optimum location.
Figure 11.- Comparison of slotted and split flaps on NACA 27-212 and 23012 airfoils.
.6 . 4 .2 0 10 20 30 40 50 60 70 Flop deflection, 4, deg