Abbott, I H

English

NASA Technical Reports Server

ILE COpy 
NO. 2-W 
" 6Z 65703 
Me Dec. 1941 
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 
ORIGINALLY JSSUED 
December 1.941: a.a 
Memorandum. Report 
LD'l' AND DRAG ClIARACTERISTICS OF A LOW-DRAG AIRFOIL WI'm 
SLO'l'I'l!!D FLAP SUBMI'lTED BY CURrlSS-WRIGHT CORPORATION 
By 1. H. Abbott 
Langley Memonal Aeronautical La.bora.to~ 
lIulgley F1eldl Va. 
WASHINGTON 
co y 
To be returned to 
tne files of the National 
A ory Committee 
or Aeronautics 
ashington, D. C. 
NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of 
advance research results to an authorized group requiring them for the war effort. 'fhey were pre-
viously held under a security status but are now unclassified. Some of these reports were not tech-
mcally edited. All have been reproduced without change in order to expedite general distribution. 
https://ntrs.nasa.gov/search.jsp?R=19930092771 2020-06-17T00:55:57+00:00Z
NATIONAL ADVISOlY Cm .. HUl'rrEE pon AKWl:AUTICS 
r.ffiMORANDUl-.'I REPO:1T 
for 
Materiel Division, Army Air Corps 
LI:?'l' AI· D DRAG CHA1:1 CTEJIS':nCS (/::;' A LG'J DRAG Arr~FO IL VVITH 
SLOTT.2;D FLAP SUWUTTED BY CLIF,11ISS··ViRIGIIT CORPORATION 
By 1. H. Abbott 
IlJTR (iDUC'.!: I vlJ 
A 24- inch chord wooden inodol equipped witb a slotted 
flap and sub:::nit ted by Curtiss-Wright Corporatlon Vias teste d 
in the ~angle~ two - dimensional tunnel by reque s t of the 
Materiel Division , U. S. Army Air Corps . The model 
re9resented a ~ing section of the p- 60A_air p l ane and wa s of , 
or approxinately of , the IffiC 66 , 2-118 ~ection . Tho mode l 
was equipped with a 0.25c slotted flap wi t h the lip on the 
upper airfoil surface at approx5.mateJ.y 90 percent of the 
ai~foil chord. This flap deflected in uuch a mann~r as to 
keel) the slot closed until a doflec tiou or over 15 c~e';r'ee s 
w' s obtained . Tho r_axim'..1J?l flap deflection V;8.o-> no;,linally 
30 eegre cs with an a c tual l init of 32.5 degree~ set by the 
model construction . The l,lOdel was equipped 1'lith pr essure 
distribution 0rifices . 
The test s reported h erein were lL1:l.te d to measurer1ents 
of lif t and drag at v arious f l ap def l e ct ions because these 
measurenent s could be ob t ained quickly as compared with 
- 2 -
p~e3sure distribution measurements. Mos t of the data yere 
obtained at a Reynolds nlUilber of about 6,000, 000 . D!'ag 
c oefficients uere obtai~ed by the wake -survey method . 
L:Lft coeffic tents nere obtained by neans of an integrating 
lift manor:.e ter vihich i~tegr3.ted the lift r80.ct10n on the 
floor and ceilin3 of tho wind-tunnel test s ec tion . l 
RESULTS AliD DI[,CU3')ION 
Lift characteristics obtained at flap deflections of 
0, 5, 1 0 , 15, 20 , and 50 degrees are shoun in figure 1 for 
a ReynoJ.cls nWil' er of about 6,000,000. A few points ob -
tained noar ,:l8.ximUY.l li1't are included for a flap def18ction 
lAt the t;tme this report \18.S originally published, 
some of the correct::.ons requireci for reducing the test data 
to free-air can itions hacl not been deterlllined . The values 
of section lift c00fficient Ct given in f i gures 1 and 2 
should accor di.n c,. ly '.,e corrected by the equation 
C1 = 0.993c1 + Z lI(c oJ.-r6ctod) II 
where the valuos of K are obt8.ineo. from the follov.rin3: table 
Flap de.lection 
6; 1\. 
( deg) 
f--._-
0 0 .001 
5 . 006 
10 .013 
15 .017 
20 . 022 
30 .051 
32·5 . 032 
--1 
- 3 -
of 32 . 5 degrees . A maximJJn lift coeffici~nt of 1 . 51 was 
obt~ined with the flap retracted, and of 2 .5 8 wi th the flap 
doflected 30 degrees . Increasin;:; the fJap deflection to 
32 . 5 deGrees increased the ma;:i,mun lift coefficient t o 2 . 67. 
Tests at other' v alues of the Reynolds nunbe:..'" oharred 
pr n.c tic ally no variOction of -ehe l!1d.~cimUJtl lift coeffic ient 
with Reynolds number be'Ci<!een 3.0 ana 7 . 5 million for a f l ap 
deflection of 30 degrees . 
Drag c oofficient s are plotted in fi gure 2 against lif t 
coefficient over the l ow- drag ran~es for the v arious fl a p 
deflections . The data show tha t this flap is useful in 
extending the low- drag range to hisher lift coefficients . 
All drag c1.ata presented for fl ap deflections of 5 and 1 0 
degree:-:l , and t h e lowes t dra~ curve pre3ented for a flap 
deflection of 15 degrees were obtained ~i thout any modi -
f ica.tIon of the gap vl/h." ch appeared i n the 10\'1e r surf a ce as 
t e f l ap ~as deflected . At a flap deflection of 15 degrees , 
t hi s 0ap increesed in size to such an extent as to perr;1i t 
errors to appear in dra,~ mC:J. surer,lCnts rl2.d.e 'J:)y the wake -
s urve y method bec ause of possib le s panv.:l se f1m." of l ew- energy 
a ir uith~n the gap . Dams were accord.ingly inserted in the 
gap on each side of the sur vey station to preven t such span-
'idse 1"'101;11 , and check points 'We r e obtained a t the high- lift 
end of the 1 0w - dr8g range . The draGS thus obt ained nere 
r--- -
SO;'1f)what higher than those or~ginally obtain8d . The gap 
was then completely filled and faired over . The drag in 
tb:Ls condi tion was somew:bat 11'i gher tJ:1an tl:oat ohtatlle d in 
e1. ther of tho other cond: tions . It is 1,)elieved t ;'la t the 
hi~hest drags should be taken as the conservative one s 
for thi s flap Q,efle c ti Oil , Dams "'JeY'G placed in the fl lo t s 
to pre v8nt s pnll\lI,ri3G f l ow~l for D 11 hlgher fla9 defle c ti ons , 
Lan.=;le ~l Ller. orir..l Aeron:1u t ical L2bora tory, 
~futional ~dvtDory Co~~ittee lor Aero Butics , 
La:1':-' ley }'ield , VirGini::'" Decenber 2 , 1 9~- 1. 

lm£f rnm mtl 
ftl rm m: tH 
!m q ~ 
rim m ~ 
t:t:t:t:l.m 
m 
Ii! ~EI !± 1# 
~~ ;m 
Fft:I: rm 
1++ 
tt :!Wi ~ 
[II WIt ~ 
rn em tttJ 
ill tim :m: 
m~m!J 
+11 
m FR 
tf I m 
~g m 
S:lEt mi 
H !:It 
§m Iff 
$ 
+H m 11ft$ **I :t:J FfFF 
~ ~ 
tt:t~ 
oo~. 
ti 1m EElil ~ 
I+i ;p:p:!I ..... m 
el3lm 
- ~ 
I::tl 
m:t:! 1-1+ = rm I 
m t$ ~ 
+H ~ I:t; E~ 
iii !:iEEE ;t 
I±f ±mm !:i3 
!:t: 
milmi 
+:: I [f! 
tU:H 00l lml I 
m:i Em ~ 
I 
Iii 
d ~ 
tt 
lit ~ 
ffi m m a ~ 
~ :HE tIE 1-1+1 J+Ill e~ 
~m 
I±I 
= !:!:I~ m 
I 
III 
:t:f 
IIi 
= ti±1 W B 


Lift and Drag Characteristics of a Low-Drag Airfoil with Slotted Flap Submitted by Curtiss-Wright Corporation

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server