c sa:: F"iLE COpy

TE CiINI CAL NOTES

NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

No. 417

WIND -TUNNEL TESTS OF A HALL HIGH- LIFT WING

By Fred E. Weick and Robe r t Sanders Langley Eemorial Aeronautical Laboratory

Washingt on Hay , 1932

https://ntrs.nasa.gov/search.jsp?R=19930081213 2020-04-12T04:40:44+00:00Z

. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

. " '

TEC}INI CAL NOTE NO, 417

WIND-TUNNEL· ~ESTS OF ~ HALL HIGE-LIFT WING

By Fred E. Weick and Robert Sanders .:' w ••

SU M"AARY

Wind-tunnel tests have been made to find the lift, drag, and center-of-pressure characteristics of a Hall hiGh-lift wing mode l. The Hall wing is essentially a split-flap airfoil with an internal air pas sag e. Air en­t~rs the passage throug h an opening in the lower surface somewhat back of and parallel to the leading edga, and flows out throug~ an o~ening made by deflecting the r ear portion of t ~ e unaer s u rface downward as a flap. For or­dinary fl i ght condi tions the front opening and the rear flap can be closed, providing in effect a conventional air­foil (the Cl ark Y in this case). The tests were made ' w~th various flap s ettings and with the ~ntrarice to the pasiage both open an~ clo s ed. ~he hi ghes~ lift coefficient found, CL = 2.08, wa s ob ta ined with the passage closed.

IN'TRODUCTION

The present Hall high-lift wing is She result of a de­velopment which started with a s tudy by Theodore P. Hall of the possibilities of converting the upper and lower sur­faces of the conventional wing into sepa~ate airfoils, form­ing in effect a biplane combination wi:h a s mall gap • . (Re~ erence 1.) rhe development was continued with the construc­tion of an airplane incorporating the wing shown in Figure 1, which was entered in the Guggenh eim safety competition, (Referen ce 2.) The flaps on this airplane ~ere later made automatic in operation. More recently, further wind-tun­nel tests have been made on a small model of the Hall wing in its latest form (similar to that . 1"n fig. 2). In both the wind-tunnel and flight tests substantially higher lift coefficients were obtained with the hi Eh-lift arrangements than with conventional wings, but the a~proximate nature of the fl~ght . tests and the low scale of the wind-tunnel tests made further experiments desirable.

2 N.A.C.A. Technical Note No. 417

The present tests have been made as part of a series on various high-l ift devices in the N . A.C.A. 7 by 10 foot wind tunnel. The latest form of Hall hiBh-lift wing was t es ted ~ith the flap set at various angles , and the en­tra n ce to the internal passage both open and closed .

APPARATUS AND ~ETliODS

The Hall wing model, which was constructed of lamina­ted mahogany (figs. 2 and 3 ) had a chord of 10 inches and a span of 60 inches. Nar r ow ribs in the internal passage ~ ere sp a ced about 3 inches apart . In the center of the wing a 4- inch cell was made solid for mounting. The rear flap ~as s upported on hing es ahead of its leading edge. Thus when deflected there was a gap bet ween the flap and t~e lo we r surface of the wing, which is not the case with the wing on the Cunningham- Hall airplane . (Fi g . 1 . ) In the model the flaps were hing ed at eight points along the span and provided with small quadrants having holes drilled 10 0 apart for deflections from 0 0 to 50 0 • For one test the slope of the upper surface of the passage just above the front portion of the flap was increased from 26 0 t o 45 0 by me e ns of Plasticine . (Shoun in fig. 3 and in an insert of fig. 2 . ) The front entrance to the passa g e was closed by means of a cover plate , making the win g in effect a conven­tional airfoil with a split flap. The cover plate was used o n the model to replace a forward vane or valve; with the plate removed the inside form of the p assag e simulated that with the vane displaced 30 0 upward.

The 7 by 10 foot wind tunnel is o f the open-j"et type and is described in detail together with the balan c es and standa rd test procedure in reference 3 . The Hal l wing mod­el , whi ch lacked rigidity be c ause of its hollow construction, wa s supported by a fine wire at each wing tip in addition to the usual center support . The tests were made at an air s p eed of 80 mi les per hour, correspo ~ding to a Reynolds Num­ber of 609,000.

RESULTS AND DISCUSSI ON

T b. e val u e s 0 f C l' "CD, and c . p • are p lot ted a g a ins t ang le of attack for t he various flap settings with the pas­sage op en in Fi Gure 4 and with t h e p assage closed in Figure

----------------------~--~----~-~-------------------~

N.A'.C.A. ' Technical Note , No. , 417 3

5. No " tunnel-wall ' correcti~n was made. !' . • ,

Lifi- - From the cross p lots of the maximum lift co­effi c i en t s a ga inst flap setting given in Figure 6 , it c a n be s een t hat the highest value of CL max with the pas­sag e op e n is 2.05 and occurs with a flap ang le of ~bout 4 5 0 • Th 'is ' i-s a '60 per cent increase over the maximum lift c o c ffi 61 ~nt of ' l.28 obtained with the basic Clark Y ~ w1ng . Wit ll 't !:J. e passage closed the highest value of 0L "' is 2 . 08 with a flap setting of about 480. max

Changi ng the slope of the upper surface of the pas­s a Ge j u s t a b ove the front portion of the flap fro m 26 0 to 45 0 ma de no ap p reciable difference in the characteristics o f t h e wing.

It is interesting to cOlnpare the highest value of C obt a ined with the Ha ll for m 'of flap (2.08) with L max th e v a lue obtained in tests of a conventional tr a iling-edg e f lap on a Clark Y airfoil. , (Reference 4.) The tests wh ich we re ma d e at the same air s p eed and with models of the same chord , gave a value of CL max of 1 . 95 with the plain f la~

The c h or d of the conventional flap , was 30 per cent of the wi ng ch ord, and the flap was depressed 45° . , Th~ actual cho r d o f the Eall flap was 34 per cent of t h e wing chord b~ t th e over-all distance from the hinge axis to the tr a i l­ill~ edge was 41 per cent of the wing chord.

Dr~. - The minimum drag coefficient of, the Hall wing mo d el u ith the cover plate in place and the flap neutral wa s 0.01 61, as compared with the value 0 . 0150 obtained un­d er th e same test conditions with a solid Clark Y airfoil. Tln:!,s th e ext ra drag due to the flap supp ort sand to the s light imper f ections of section accompanying the split f orm o f fl ap was approximately 7 per cent.

A point of interest is the high drag at maximum li f t wi t h th e flap do wn. At the peak of the lift curve the va l­u e of LID ~ ith the flap in the position g iving the hi gh­e s t maximu m lift was less than one-half that of t h e plain wi ng a t the peak of its lift curve , making possible a mu ch ste ep e r ap p roach for a landing .

Ce~i~~_Qf_~~~~~~. - Th e ce n t e r of pressure with th e f l a p d own 20 0 or more u as b a ck a b ou t 10 per cent of the ch ord from its location with the flap up. This was appro~

4 N.A.C.A. Technical Note . No. 417

i mat ely true for ~ny angle of attack above 0° phether the passage th r ough the wing was open or c l osed.

CONCLUSIONS

1. The highest lift coefficient obtained with the model of the Hall h i g~-lift wing tested . waS of the order of that obtained with a conventional trailing-edge flap.

2. S l ightly higher values of the max i mum lift coef­ficient ~ere obtained with the passage through the wing closed than wi th it open.

Langley Memorial Aeronautical Laboratory , National Advisory Committee for Aeronautics,

Langley Field, Va., March 31 , 1932 .

REFERENCES

1 . Hall, ~heodore P .: Hall Conve r tible Air fo il. Thesis . . t ~ as sa chuset ts Ins t itute of Te chnology (Cambridge),

1928.

2. Anon.: Final ReIort , The Daniel Guggenheim In ter­national Safe Aircraft C~mpetition , January 31, 1 930 .

3 . Harris , Thomas A. : The 7 by 10 Foot Wind Tun n el of the N . A. C. A . T.R. No . 412, N. A . C. A., 1931 .

4 . Weick, Fred E . , and Shortal, Joseph A.: The Effect of Mult iple Fixed Slots and a Trailing-Edge Flap on the Lift and Drag of a Clark Y Airfoil . T .R. No . 427, N. A . C . A ., 19 32 .

I l O(}fo c -1 ~--== ==-- I I - ----0.-====== L-- l !% c-----J

~I'I .! - . --------- -- - ----:~- I

~ I ------- ~ ------ ' . - _1. _- -_ . _---- _. __ -- - ~

--10;0 c ,!" 1 5~ c ---~ .~' - -r------------·· • I I . ~ I 1 : . ~ 3i o

r -8 ~ . ~ -"", :J • vfo C >/ ~ ~

~ ......... I . :;g

c

~" ....... Section is Clark Y wHh f l ap s neutral

"'" '-y

Fig.l Section of wing used on Cunningham- Hall airpl ane .

~ . il> o il>

f-3 (;) o p-' ::; f-'. o III r-'

~ o cT (!)

'-' ",. , o fi'> r-' -,J

I->j f-"

C1tl

t--'

1/ . ~ 1 ~oo ------ ;< - G . tj;:)

\ .12511 ~ I y! 26 0 1 2 . 37 11 -1.

I _ ---,,.- 1 2~ 11 ~ I

:<--- 1. 3211

_1___ " ~ • 0 _~ l , I f 1.78 '1 I ::--'- ~-- -- - ~I .51 r 5 92" Flap h i nge./'kr:-68'. ' - "--'-'-' =-~

• ! t- ---- 3 ~ 1I _=_ 1 c . . ;r -- --------1

",.' 1

C-~upper !Lower : I ~s id

ISta- lo r di- 'or d i - Ior di­tio!?-~ nat e \ nat4~ate II ~c9-+I nch ! I nch lI nch 0 . 0001 0 . 35010 . 350

. 1251 . 545: .1931

. 2501 . 650 I .147 i

. 500, . 790 i . 093 ! \ .750! . 885 \ . 063 t 11. 000 1 . 960 , . 042 1

\1. 500 1. 069 I . 0151 12 . 0001 1.136 i . 003

i ~Jpper '\ Lower I I n side I I

Sta- lo r di- ordi- i or d i- ~ Fl an ! tion \nate \n a t e \n a t e :Sta-!Or di- l 3 . 000! 1.170'0 . 000!0 .~ionlnate I ; . 0001 1.1;0 \ . 000 I . 92 I I nch! I nch i' ;:) . 0001 1 . 0 ;:)2 . 000\ . 84 ,0 . 25jO .16, 6 . 000 I . 91 5 I . 000 I • 72 , . 50 . 22 I 7 . 000 • 735 II' . 000 I . 58 I' . 75\ . 26 'I

8 • 000 • 522 . 000 \ 1. 00 I • 29 1 I' 9 . 000 • 280 I . 000 . 2 .00. 21 'I

9 . 5001 .1491 . 0001 \3 . 001 .13 0 . 000 . 01 2 I . 000 I :3 . 40, . 01 ,

L. E . r adi us = 0 .15 i nch

, , , , ,

, , , , ,

, , , \ ,

, , , , \ , , , , \

' ,~

F i g,2 Section of Hal l high-lift wing model . Dotted lines indicate flap set at 500 and c losed passage .

~ · tJ> o · lJ> · 1-3 Co

g. ;:! r" ()

~ h ' ~I

o c+ o ~ o .p. r' :'l

b;j r"

O'll . 1:\)

N.A.C.A. Technical Not e No. 417 Fig. 3

. ~ .... ~

~ IH .... M

1: ~ ....

• .s:: M

i IH 0

M CD '0 0 ::e

~ . ItO ....

IZt

•

· 1'>1

H

S o H 'H

()

.p s:: (l) ()

H (l) p~

]'lap setting

-- - _ .+-.-l----+-

1. 6 1---+---+

1. 4 ---+----+-

0.4

Fig. 4 30 ° -- -- ------v 40o---X

500- -- .-- -- - - +

~:~ -,-=-4 ~

~~T-

1---l---'~+----+·2 •

+

15 20 25 30 c , degr ee s

Fig . 4 Char acteristic s of 10 i n . by 60 in. Hall wing with passage ouen and f l ap at various angles uncorrected f or tunnel wall ef~ect.

N.A .C.A. Technical Hote No.417

o 00

'\7 --30 0

x- --400

0.2.:,......c:==!--

Flap setting 500 --- + 590 - - - - - - - - --f:::,

Fig. 5

I __ -i- - I . I 1 F -!.-- t r-- ..-0" __ -f-'-~--T-' -+----+----I

o I LJ-~:-r- 1_1 ___ --'-_---L--1-1 ~----'-----' -10 - 5 o 5 10 15 20 25 30

a., degree s

Fig.5 Characteristics of 10 in. by 60 in. Hall wing with passage closed and fl ap a t various angl e s uncorrected for tunnel wall

effect.

N .A.C. A. Tecl nical Note ~Jo . 417 Fig.6

0------ Passage open !J- -- - - - -- Passage closed

---~-T-'---- -l--'-T--' --~I----' 2 . 1J0 r---

1

-t--l-~~-· - ~+-r ~ +f -- -r-- -- -- 1--- - - - - - : f----t--+--I---

2.40

I--r-I---+ ._-- i - - -- -[--2.20 . Il--I---- --~---t--t -1---, --

1----+ _ _ 1 ____ 1 _ 1-__ _ __________ - e-- 1 ___ -L--.j' t- -j ---- -- -,~ - - I

I L 0:~ - 61 2 . 00 f----I--+I-- --1--~71--r----- 1--- --t--

CLmax . 1- ./ / , i -'--r' ---I V // I !

1,80-1 7:7-"- -~~I-~--- ---- --t-~~ / / t- +-+--

1// / I ~ / I I

1. 6C

l, W ! / ·-·-:---r-~-- -----~--- -+- -- +--I +--r- i - --I---t--t---+----- 1----1-- -L 1 I I I '

:':l_...1.-__ -_ -~t ____ -~~u_--~-:~ =-1----1 o 10 20 30 40 50 60

Flap angl e ,degr ee s

Fig.6 Variation of maxi mum lift coeff icien t with flay &~gl e .