Ames, Milton B , Jr

English

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NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
WAllrrm]l lUIPOR!I’
ORIGINALLY SSUED
iMarch 194 as
Advance Restricted Report
WIND-TUNNEL INVESTIGATION OF CCNTROL-SURFACE CHARACTERISTICS
v- THE USE OF A BEVELED TRAILING EDGE TO REDUCE
THE HINGE MOMENT OF A CONTROL SURFACE
By Robert T. Jcmes and Milton B. Ames, Jr.
Langley Memorial Aeronautical Laboratory
Langley Field.,V&.
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WASHINGTON
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 ekfort. They were pre-
viously held under a security status but are now unclassified. Some of these reports were not tech-
nically edited. All have been reproduced without change in order to expe~~ ~~ re)jdi~t::bqgo~: :: ‘;
L- 464 LANGLEYMEMC)NAL.AMRC)N}.UTiC.f,..
LABORATORY
Langley 13ekL V&
https://ntrs.nasa.gov/search.jsp?R=19930092871 2020-06-17T01:08:16+00:00Z
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3 1176013543187
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SUMMARY
INTRODUCYIOiT
seV6?rt31 ~F2aYS ?2Lg0 the NACA had occasion, to test a flap
-s
with a pnrticui.a,rly thin$ sharp trailing edge. ln this case
the hinge moments were higher than usual and agreed better
with the thee:’y. Thus , it appeared that the discrepancies
. in the hinge moments obtained in the -~sual tests might have
been due to minor differences in the shapes of the trailing
., ,.
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*-
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3-.
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.
Table 1 gives the orfi.inates of the standard section
(derj..ed from tli~ 3TACA 0009 airfoii by drawing straight
lines from the b5-percent station back to the removable
tail block). !?he dimensions of the removable tail pc~tions
3 are shown 5.11 figt7.T13
z a~.~ the ordinates of the bulged flap
3 are given in tc.>le 110 As ShOWil in f~@3i?C 2$ the fl~lp WS.S
J1 of the plain r.n%alanced type9 30 yercent of the airfoil chord
in width. The tes ts were made with. the gap both sealed and
open,
The procedure Gf the test’s was simil~r to that followed
in reference 1. They were made in the NACA 4-foot by’ 6-foot
vertical tunnel: modified as described in reference 2. The
lift, the drag, and the pitching moments were measured on
a three-’compone:t tialance.l The hinge moments were measured
electrically with a ~,e;h~b~ated torque rod built into the
model . The model extsr:(led completely’ across the closed
test section of the tuncelg so that the flow was very nearly
t~’o-.dimensional. The tec+ts were “made ah a dyne.mj.cpressure
of 15 pounds per squara foot ~ corresponding to a velocity
Of about 1?6 mi:l!esper hour and a test Reynolds number. of
l,~~!),ofi~o The flap deflection was varied in 5° in~;gments
from Oo to 3(J0, In some casss chock pojnts at from
neutral were obtainzdO T~!ft, drag$ airfoil pitching moment,
and fla:p hicge mometits were measured throughout the anglc-
of-aitack rzm.ge, f:~~in Fcsitive to n~gative stall of the
airfoil, at 2° j.n.~erval~ Of angle of attack.
Precls3.on i
The naximum er=Gr in the angle of attack or in flap
setting appears to ‘be about aaez~o An experimentally
d.eterminecl cor:tiection has been a;~plied to the lift but not
to the hinge moments. The hinge moments are probably
slig~ltly higher than would be otitaiiled in free air. It
should be nct~d thafi the d.zJagO’f the basio 0S09 airfoil
is somewhat higher than is. obtained in other tests at the
same Ileynold.s number.
Symbols
c1 airfoil section lift coefficient (1/qc)
Cd. airfoil section profile-drag coefficient (do/qc)
Cm airfoil section pitching-moment coefficient (m/qc2)
‘%
Ch
a.
tif
2
do
m
h
c
Cf
c~
flap section hfnge+nonent coefficient (h/qcf2)
angle of attack of infinite aspect ratio
flap angle with respect to airf6il
airfoil section lift
airfoil section profile drag
airfoil section pitching moment about quarter-chord
po~n.tof airfoil
flap section hinge moment
chord of airfoil w~th fl.~psaeutral
flsp chard
chcrd of ‘beveladportion of flap
E+otfcJndata are p?.cttedin figure 4, Figures 7 and.
6, CVJ2!’’i@0”kt(_4df’rOT1 ih section da.%: &GW t~iC21. ‘.W2.Y.ia-
tzons of lift mrl.hinge ucwmt anti il:.~b+trato the magnitude
d tkL@ eff~~t ob-&i~@i!.aWitina moiier%taaafiWiitiflan extremely
blunt LF:WWI. It Wj.XJ.he fiotedthet the reduction in hinge
mommt Gutwefghs -&c)IOHS i?~lift a~d also t~t the reduction
in &jJ&o is &-eater than the re~uction in aq.& ,
Tl+elift of the airfoil with the ccmtrol tree is therefore
actually gjj*eaterfcr the blunt traiiing edge than for the
pkcln flap. The results for the plain flap are taken from
reference ij part 1.
We results given for the flap with beveled trailing
edge RrG for the gap-eealed conditicn. The data obtained from
the tests wj.tinthe gap opon are yraeente~ inref’erence ~.
Table 111 mwwmvl.zes sevaral irrgcrtantcharacteristic
of the shapes tested. The values given h the table apply
to a fairly wide angular range. An idea of the dev~ation~
from lir~es.ritymqy be obtained by inspection of figure k.
The rem.dts show an interesting difference in the
beha~lor of the elliptical and the beveled trailing e~gea.
The bluntest elliptical shapes whtch was ~imply a circular
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It is frequently found that full balance cannot be
obtained iu a satisfactory mannei’ Iy the use of a single
. devtce; for example, a large de~ree of balance with the
. inset-hinge type of ccntrol surflace requires such a long
overhang that the parcissiblc doflecticn of the tlap is
limited. ~~~e us~ of a large horn ‘b%lence introduces
structural difficulties. It i-shelpful$ therefore, to
6. .
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2. Ames, Milton B. Jr, and Sea~.s, Richatd 1.: Pxessure--
. Di=tr’ibution Investigation of an N;A..C;A~ CQ09, Afrfoil
with a 30-l?ercent-Chord Plain Flap and Three Tabs.
T. N. ~0. ‘?59, N.#.CA,1940.
30 Sears, P,ic-lard 10 : “Tin~-Tu~nel Data bn the Aerodynamic
Chaze,ctei-istics of Airplane Control Surfo.cese N’ACA ‘
Ac3 No. zL08, 19430
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z
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Sila”k!.ons ordinates
[from hinge axis) 1
0
l_g~
4.82
7’.85
100,O-J
1.5.2.5
19.70
25.15
30.00
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— —.-——.
Modifications
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.oo~
.002
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.092
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.090
.088
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.095
0.066
.070
.080
Un-
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—..— .
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Figure l.- The effect of flow around the trailing eiigeon the lift
distribution.
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F’ Ioc?00 =1 z
1
I 2.16
—— -— ._ _
0.20cf elltp+ical
—— -— .— _
O./Ocf elliptical
3.00
I
—- — .— - —
“1--== 4
R=8.46
-— -— .— —
I
I 0./5cf beveled
I
I R==6.,67
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-— -— -— _
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-— —
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L O.IOC$ beveled30.00 -~ ‘t“s-3.00
F/aps with elllpfical i+-ailing edges Flops wifh beveled trailing edges
Figure 2.- Trailing-edge modifications. Dimensions are in percent of airfoil ohord.
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Figure 3.- I’lowaround beveled trailing edge showing similarity to the effect of a hak.ncing ta%.
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Air foil sec fion lift coefficient, .cZ
Figure 4c.- Trailing-e+-e :>eve~,O,I+Tcfo
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Figure 4d.- Trailing-edge bevel, O.10cf.
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Airfoil section pit thing-momenl
Ie of off ock, UO, o’eg coe f ficienf, Cm Flop aeciion hinqe-momen t coefficient, c~.
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Airfo;l section lift coefficient+, q
Fig2re 45.- EMlged flap.
Angle of affacfr, a_O,deg,
a
1
5 ;“& i c1 a Cb
, ~ “
111-++-+dlll
Airfoil se cfibn pitching-moment
coe fficien~ c. Flap secfion
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hirme-moment coefficienf, ch
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b. “~& I I I I I I lN\l n I \l
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Angle of attack, do, dog
Fi@re 5,- Typical vari,ations of Zift and h$nge moment with angle of
attack. &f=0°.
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b,
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1
c
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FiQgu.re G,-
~ 6 12 lE 20 “
Flap deflection, ~f, deg
~ical variation::. of lift and hinge moment with flap
deflection. ~ =
:


Wind-tunnel investigation of control-surface characteristics V : the use of a beveled trailing edge to reduce the hinge moment of a control surface

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