Effect of fabric deflection at high speeds on the aerodynamic characteristics of the horizontal tail surface of an SB2D-...

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Title:
Effect of fabric deflection at high speeds on the aerodynamic characteristics of the horizontal tail surface of an SB2D-1 airplane
Series Title:
NACA WR
Alternate Title:
NACA wartime reports
Physical Description:
17, 34 p. : ill. ; 28 cm.
Language:
English
Creator:
Schueller, Carl F
Korycinski, Peter F
Langley Aeronautical Laboratory
United States -- National Advisory Committee for Aeronautics
Publisher:
Langley Memorial Aeronautical Laboratory
Place of Publication:
Langley Field, VA
Publication Date:

Subjects

Subjects / Keywords:
Elevators (Airplanes)   ( lcsh )
Aerodynamics -- Research   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
Summary: Results are presented of an investigation of a full-scale horizontal tail surface to determine the elevator-fabric deflection at high speeds and the aerodynamic effects of the fabric deflection. Two fabric-covered elevators, differing only in rib spacing, and a solid wooden elevator were tested. The first elevator had a rib spacing of approximately 4 inches. The second elevator had a rib spacing of approximately 8 inches, which is more nearly typical of the spacing currently used. Tests were carried to a maximum Mach number of 0.68 except for model configurations for which the maximum allowable loads were reached at lower speeds.
Bibliography:
Includes bibliographic references (p. 16).
Statement of Responsibility:
by Carl F. Schueller and Peter F. Korycinski.
General Note:
"Originally issued June 1945 as Advance Restricted Report L5F01a."
General Note:
"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. They were previously held under a security status but are now unclassified. Some of these reports were not technically edited. All have been reproduced without change in order to expedite general distribution."

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University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 003804830
oclc - 123898212
System ID:
AA00009383:00001


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Full Text


ARR No. L5FOla


NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS





WA I TIME REPORT
ORIGINALLY ISSUED
June 1945 as
Advance Restricted Report L5FOla

EFFECT OF FABRIC DEFLECTION AT HIGH SPEEDS ON THE
AERODYNAMIC CHARACTERISTICS OF THE HORIZONTAL
TAIL SURFACE OF AN SB2D-1 AIRPLANE
By Carl F. Schueller and Peter F. Korycinski

Langley Memorial Aeronautical Laboratory
Langley Field, Va.

UNIVERSITY OF FLCO;,lD'
U--,U ,ACNTD[A E rT.INT
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.4 ~-,,L 7 L.: 1F s 1 j-I 1 S \,A
'-1; N A C A.;i ,:: ..i

NACA


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 effort. 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 expedite general distribution.


L 170




































Digitized by the Internet Archive
in 2011 with funding from
University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation


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ITACL ARR No. L5FOla

NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS


ADVANCE RESTRICTED REPORT

EFFECT OF FABRIC DEFLECTION AT HIGH SPEEDS ON THE

AERODYNAMIC CHARACTERISTICS OF THE HORIZONTAL

TAIL SURFACE OF AN SB2D-1 AIRPLANE

By Carl F. Schueller and peter F. Korycinski


SUMMARY


Results are presented of an investigation of a full-
scale horizontal tail surface to determine the elevator-
fabric deflection at high speeds and the aerodynamic
effects of the fabric deflection. Two fabric-covered
elevators, differing only in rib spacing, and a solid
wooden elevator were tested. The first elevator had a
rib spacing of approximately inches. The second ele-
vator had a rib spacing of approximately 8 inches, which
is more nearly typical of the spacing currently used.
Tests were carried to a maximum Mach number of 0.68
except for model configurations for which the maximum
allowable loads were reached at lower speeds.

No appreciable fabric deflections occurred for the
elevator with 4-inch rib spacing. A maximum fabric bulge
of 0.6 inch between ribs was measured for the elevator
with 8-inch rib spacing at a Mach number of 0.55, an
elevator angle of -5.7 and an angle of attack of 9.70
Local failures of the fabric attachment to the elevator
ribs occurred. By moving the elevator vent holes from
the vicinity of the trailing edge to the leading edge,
the bulge was eliminated for these test conditions at
the expense, however, of some increase in fabric depres-
sion on the pressure side of the elevator.

Marked increases in the elevator hinge-moment coef-
ficients occurred as the test Mach number was increased.
For the elevator with l-inch rib spacing the hinge-moment
parameter Ch6 (rate of change of hinge-moment coefy
ficient with elevator deflection) increased from a value
at low speed of -0,005 to a value of -0.009 at a Mach
number of 0.68. The effect of fabric deflection for the









WAC- l A1R Ho. LrO71a


elevator vith C-inch rib spacing caused an additional
'--' rse increment in hin e-maioent coefficient as the
speech -ras increase. I-. effectiveness of the elevator
with '-inch rib soacic did not change al. clably with
Iacl number. As a result of fabric deflection, however,
the effectiveness of the elevator with 8-inch rib s acing
decreases 'j.sr_ ly at !ach numbers above 0,56. ir.e adverse
effect of fabric deflection on elevator hinre iomeint was
decrease sli htly by locating the vent holes in uhe
loadinS eCd: rather r than at ;Che trailin e.'._ of the
elevator,


I : tODJCiTIOJ


t- ts we.e miade to determine the effects of elevator-
fi:.'ic leflecbions at hii.h speeds and of cor ressibility
on th erodyna:.c cha:.acte i.stics of a full-scale hori-
zonta tl til surface. he necessity of such an invcsti-
r;a-tia has been &e'.oonxtrtedc by tle excessive and irregu-
lar l.ilne orcnt; cncoiutered CLuring hiCh-speed naneuvers
a ir. Tra'L.rous instances of contiol- .'. ."'aceC feliure on
sor.ie of ths riore recent; hi"gh-.pe .d a iplanes eqil
wi.'1 fabric-covered control a 1 aces,

h.e present report "iver1 : results of tests on
three Jelevators v.ith. idntic ,.l external dirensiions. -1e-
vators 3. an:i 2- were fabric ,overed, aii. 1ii spacing of
ap ro: .ately and 8 inches, res ectivel-, ..nd were used
to deei~ tine the fabric deflection. The thlid elevator
.:as eolade of solid r.ahoa Eny, included two rox's of pressure
orifices, and w. s used to deteri-ine te tho extiJnal -:-:sure
distribution. -..:!. elevator '.s teste. t rou .lch number of 0.2 to 0., ., elevatur an:le of 'O to -9,
and stabilizer an.le of o0 to 9 L. estS of any combi-
nationl of the aforementioned variables jwere limited
the ma::ilrm'u allowable loads. In eddibion, elevator 2 was
tested with the original vonts sealed and v:nts at the
leadinS edge or at 10 percent elevator chord c to
deter: ine the effect of vent location on fabric deflection.

The tests were conduct at the Lanrl 1y 16-foot ,-
speed tmunel, Langley ilemorial Aoronaubical Laboratory.









:TACA ARR No. L,5?01a 3


COTFICTI:7T AND SYl'T-:TL3


CD drag coefficient (D/qS)

Ch hinge-mcment coefficient (EI/qc0e2b)

CL lift ccefficient (L/qS)

ipit ching--mornent coefficient
\qSc' /
D drag of entire model

F hinge moment

T lift of entire model

c' ,/L pitching mor-ent about quarter-chord point of
mean aerodynamic chord

b span,feet

c chord of horizontal tail surface except when
designated otherwise by subscript, feet

c' mean aerodynamic chord of horizon-ta -tail

Ce root-mean-square of elevator chord behind
hinge line

A dynamic pressure -pV ]
k2
p mass density fair, -slugs -per- cubic foot

V velocity, feet per second

Total model area,-square feet

.1 Mach number
/P p
P pressure coefficient i -4-i

p static pre-ssure at any point

c angle -of attack- of stabilizer-, -
Sangle of elevator chord with respect 'to
stabilizer chord, degrees

-, elevator-e "ffectiveness-par'ameter -
S\ CLa/









NACA ARR No. L5FOla


Parameters:





CL r( C,




Ch (6Ch



Chg = oCh

The subscripts outside the parentheses represent the
factors held constant during the measurement of the
parameters.

Subscripts:

b balance

e elevator

f flap (elevator + balance)

i internal

o free stream


APPARATUS AND '.ETHODS

Test model.- The model was a full-scale left-hand
horizontal tail surface of the SB2D-1 airplane. The air-
foil section used was based on the I-.CA 0020-64 airfoil
profile modified to have a maximum thickness ratio of
10.7 percent and a straight taper behind the 65-percent-
chord station. Since a semispan model was used, it was
necessary to locate the center line of the airplane in
the plane of the tunnel wall to produce air-flow con-
ditions corresponding to those of flight. This result
was accomplished by adding a 20.5-inch stub wing to the
tail surface. Figure 1 shows the model installed in the
tunnel and figure 2 presents the physical characteristics
of the model.










:'.ACA ARR No. L5701a


The stabilizer was metal covered and included a
fabric seal to prevent air from flowing between the rear
r rrt of the stabilizer and the elevator leading edge.
iSee fig. 3.) The model was not aerodynamically smooth.
r.1-azier head riets, access and inspection doors, and
cosidTerable waviness characterized the stabilizer surface.

-,c elevator had a modified elliptical nose and a
straight taper behind the iiv-. line ending in a trailing-
e:_e angle of 120. The coordinates for the elevator con-
tour are presented in figure 3. Elevators 1 and 2 were
cf metal construction and fabric covered. Details of the
rib locations are shovn in figure 4. The average rib
s-acings are aoproximat3ey 4 and 8 inches for elevators 1
and 2, respectively. Both elevators had one L-inch-
oiameter drain hole in each elevator panel on the lower
s.face a;: r-oximatel 1 inch from the elevator trailing
ed.e. Since each elevator oanel had one hole, these
co:nings also served as air vents. Elevator 5 was made
cf solid mahogany and was dimensionally equal to ele-
vators 1 and 2. Two rows of pressure orifices on the
upoer and lower surfaces, 55 and 70 inches from the longi-
t.linal center line of the airplane, were built into this
el vator.

Hinge-morent measurement.- Figure 5 is a schematic
view of the model installation and illustrates the
,-:.)aratus used to measure the elevator hinge moment.
This sketch shows the extended elevator torque tube
-ssing through a hole in the side of the tunnel and into
too self-alining bearir_-s mounted on the tunnel balance
frame. The elevator hinge moment was transferred through
t-3 elevator torque tube to a 10-inch crank and then
through a jackscrew to the scale platform. The jackscrew
,as also used to vary the elevator angle. The platform
scale was attached rigidly to the tunnel balance frame
a.nd since all other related parts vere also attached to
the tunnel balance frame, hinge-moment measurements could
rn:t interfere with the measurements of lift, drag, and
pitching moment. All force and moment data were recorded
S i.multaneou sly.

Fabric-deflection measurements.- Stripes I-inch wide
-re painted chord se on Loth surfaces of the fabric-
covered elevators to permit the measurement of the fabric









U'..,C. AR No. L5FOla


deflection. (See fil. 1.) Solid stripes were painted
over each rib and broken stripes midway between the ribs,
on the up~-. and lower surfaces. These stripes are
straiz- t and parallel for the static condition (see fig. 6)
but because of air loaad the fabric deflects and the
stripes tend. Cameras in fixed positions were .:,"-oviJed
to photograph the elevator surfaces simultaneously and
thus prcvide records of the fabric deflection. ILe
deflection of the ;a'.ted stripes was measured from
enlar. :iencs of tie photograpis.

F bric-tension m.easurements.- The fabric tension for
each elevator i: el was measured with an instrument
designed by the Flight Research Division of the Laboratory.
A detailed description of tr'e in.trunent and the technique
of measureeiint are given in reference 1. T-e fabric
tensions were measured Lefore and after tLe tests to
determine any cLan e in fabric tension resulting 'rlom
repeated stresses that were applied to the ifobic during
testir. Ti'r.lc I presents a sua:ary of tLh measurements
and indicateL that the change in iJaric tension for ele-
vator 1 is within the accuracy of the measurements.
Elevator 2 had a slightly lower fabric tension after
testing, but this difference may te a temperature cr
humidity effect.

Pressure mneastremients.- The pressure distribution
over the elevator was obtained with elevator 3, which
contained tv:o rovs of orifices. The external pressures
over the upper surface of the stabilizer were obtained
by the use of two .r;ssure belts located at the 55-inch
and 70-inch stations. All stations were measured in
inches from the longitudinal center line of the airplane.

Two 0.050-inch-diameter tutes were installed in ele-
vators 1 and 2 at the 47-inch and 97-inch stations to
measure the elevator internal pressure.


TEST PIRO l' RE


The -eneral procedure in conducting the tests was
to set tie desired t.~1le of attack and elevator ar,_1c at
the begin.j.in- of each test. LDta were then recorded at
each of tn- following speeds: T ch number = 0.20, J.55,
0.45, 0.50, 0.55, 0.00, 0.65, ar.n 0.66 or until the
maximum allowable load on the tail surface was attain-d.










:IACA ARR No. L5?01a


The stabilizer root angle :rerrma';ed fixed during the test.
'The elevator root angle was measured and recorded at each
test :.pint, since it varied slightly because of twist of
tt'e torque tube and deflection of the scale platform.
1s angles of attack and elevator angles are believed to
be accurate within 0.10


REDUCTION OF DATA


Force data.- The lift, drag, and pitching-moment
coe'flcie.An presented in this report are based on the
v in]; rea of the complete model (see fig. 2) including
the stub wing. All data were taken with the elevator
seal in, the elevator vents at the trailing edge, and
the trim tab neutral, unless specified otherwise.

The force data were corrected for tunnel-wall
effects by the use of the reflection-plane theory given
in reference 2. The model 'thickness was such a small
part of the tunnel diameter that tunnel blockage correc-
tions were negligible. Since the elevator 'torque tube
ccul-' twist and the scale platform deflect, the elevator
en-le changed with hinge moment. Calibrations of the
twi i. of the elevator torque tube and the deflection of
the scale platform with elevator hinge moment were used
tL c-.i-rect the indicated elevator angles to actual angles.
The corrected data were cross-olotted and the values at
selected angles of attack and elevator angle were then
plot'ted against Mach number. Since a large part of the'
'iteai presented is plotted against I.:ach number, figure 7
;hs been included to show the average dynamic pressures
anl tLe average Reynolds numbers corresponding to the
test !Nach numbers. The Reynolds number is based on the
assuu'.:Ld mean aerodynamic chord of i.41 feet. It should
ce m-entioned that the changes which occur with speed are
nrt cure Mach number effects but include effects due to
'istoltion of the nodel under load. The effects shown
thereiore apply only to the particular combination of
*,n'n:iic pressure and Mach number tested herein. The
results, however, are plotted against i',ch number, and
the dyamnic pressure at any Mach number may be obtained
from figure 7-

Fabric deflection.- A special film viewer was used
to enlarge the olotographic negatives of the elevator
surfaces. Vertical scales were attached to the elevator
surfaces at each broken stripe and photographed for all









^'.CA AER No. L5F01a


model configurations to obtain films of the static condition
(zero deflection). A quantitative measure of the fabric
deflection was obtained by comparing a photograph for the
static condition (ze2o deflection) with one made during
a test. fihe displacement of any stripe was then measured
and recor-mc.


RSI'L;LTS aND DIClT' SSICN

Fabric Deflection


Elevator 1.- Figure 8 is a photograph of the fabric
deflection on the upper surface of elevator 1 (4i-inch rib
spacing) at a = ', 6 = .2, ard M = 0.66. The i-.Lric
deflection is not apjreciable at any point along the ele-
vator except for a s.aall bulge occur rn. near the inboard
Si...... No ether photographs are snown for this elevator
because the fabric deflection was not serious during any
of the tests with tli:.s elvator.

Elevator 2.- -uiyre 9 is a photoraph of the fabric
deflectin'of :o50th sutrfaces of elevator 2 (8-inch rib
spacing) at a = 0, = 5.30, and Ir = 0.55. Consid,
erable bulge occurred on the top surface behind the hinge
line. This bulge changed to depression on the rear part
of the elevator. Since the fabric was sewed to the ele-
vator ribs, the solid'stripes should show no deflection.
A number of solid stripes, however, are deflected. (See
fig. 9(a).) Deflection of the solid stripes indicates
failure of the fabric attach..ant at these points and is
the Cegirnn-:r.ir of a condition tfat world result in complete
failure of the surface if the air loads -were increased.
Figure 10 is a photo ;'a.ih tie fabric deflection at
a = 30, 6 = -0.70, and M = 0.62. In er-eral, the
upeer surface .s slightly bul..c just bei~ind the i._-n.e
line. The most serious biu-e occurs at tihe inooard hinge
and is believed to ue a result of weak f.. ric attachment
around tae hinge-pocket cut-out rather than of local-
suction peak pressures. Figure 10 also shows tLe fabric
pulled away from tii ribs. (.iote solid stripes.)

Fi-.-es 11, 12, and 15 are plots showing the vari-
ation of the fabric deflection witi recent t of elevator
chord and include only the u)rtion of the elevator chord
for which the fabric was deflected; therefore only the
end poinLs of zero deflection are shown, lh-ese ctta are










NAIA ARP To5. T"Lila


for a r-* r-sentative span:vise station (77.1-inch station).
7-"i're 11 ..reents the fabric deflection for various 7{ach
numbers t elevator anTles averaging -1.50 and a-= 0.
Although the elevator angle chan=cd slightly (0.50) with
seed, it is apparent from figure 11 that increasing the
snced increases the fabric deflection. The maximum
fabric deflection of the lower surface hEs been plotted
separately for each speed in figure 14 and shows that the
fabric deflection varies linearly with dynamic pressure
for elevator 2 at a = 00 and 5 -1.50.. Figure 12
presents the fabric deflection for various elevator angles
at a = C0 and = 0.55. Increasing the elevator angle
negatively increases .the fabric bulge on the lower- surface
while the deflection of the upper surface changes from
bulge to depression.. Figure 13 presents the fabric
deflection for various angles of attack' at M = 0.55
and F = 0.55. The maximum fabric deflection' attained
during these tests was a 0.6-inch bulge on the lower sur-
face of elevator 2 .t a 7.0, 6 = -.70, and MI = 0.55
(fig. 15).

Pressure distribution.- !.ebric 1.-ile tends to be
unstable since it causes an increase in the local negative
pressures, which in turn cause an increase in the fabric
bulge. This adverse effect is magnified at high speeds
and has been observed to result in failure of the fabric
attachments to the elevator structure and finally complete
failure of the fabric. An investigation to determine the
external pressure distribution over the elevators and the
location of air vents that would result in negative inter-
nal pressures and a reduction in elevator fabric bulge
was therefore undertaken. Elevator 5, which was dimen-
tionally equal to elevators 1 and 2, was tested for this
purpose.

The tests of elevator 5 indicated that the pressure;
distributions at the 33-inch and 70-inch stations were
very nearly the same on the elevator but differed appre-
ciably near the stabilizer leading edge. This difference
may be attributed to surface irregularities. Removing
the elevator seel increased slightly the positive pres-
sures on the lower surface of the elevator balance area
for positive elevator angles but had little effect on
the pressures over the other portions of the elevator.
The external pressure distributions at M = 0.20 and
the 33-inch station for three elevator angles are pre-
sented in figures 15, 16, and 17 for a = 00, 0, and
6, respectively. These figures indicate that vents in










TACA ARR No. L5F01a


both the upcer and lower surfaces at the elevator leading
edge or at apr)ximaately 10 percent of the elevator chord
behind the hinge line ce will result in negative average
internal pressures. Although the average pressures at
these points are not the most negative, they are consist-
ently negative end are least affected by changes in ele-
vator angle.

Effect of various vent locations for elevator 2.-
The cr i:' -il ee r,--:.r v.~Its w~r rL sealed, a ,c thte effect
on internal pr-.-ssure and fabric deflection of the elevator
as a result of locating a vent in each elevator panel at
the leading ed.c or at 10 percent of ce on the upper
and lower su.-faces was determined. The variation of the
internal pressure of the elevator with elevator angle is
presented in fi'ur-e 8 for three vent configurations. A
comparison of these curves shows that the average internal
pressure coefficient Pi for.the- original vent configu-
ration is changed from -0.02 to -0.08 for vents at 10 per-
cent of ce and to -0.25 for vents at the elevator leading
edge.

Figure 19 presents quantitative comparisons of the
fabric deflection along the elevator chord for the three
vent locations at a = 00, 6 = 4, and M = 0.55. The
maximum bulge on the upper sur ace is reduced from
0.4 inch for the original vent configuration to 0.2 inch
by using vents at 10 percent of ce and to 0.26-inch
depression with vents at the elevator leading edge. o
measurements were made for the lower surface with vents
at 10 percent of Ce but visual observation indicated
that the fabric was depressed for this condition, as
would be c:-ected.

Figure 20 is a photoi-C.ph of the fabric deflection
with vents at the elevator leading edge for a = 00,
6 = 4o, and M = 0.55. Crin.nr,.ison of figures 20 and 9
shows that the upper-surface bulge is changed to deores-
sion wAith vents at the elevator leading edge, except for
a small local bulge at the upper surface near the inboard
hinge. It is apparent fr')m figures 19 and 20 that loca-
tion of the vents at the elevator leading edge will
eliminate the danger of the fabric pulling loose from
the ribs and failing for elevator 'n;les up to at least 40.










I ACA ARR No. L5F0la


Aero:'uamilc Characteristics

rasic data.- The lift, drag, pitching-moment, and
Linge-momer t coefficients are plotted against Mach number
in figures 21 and 22 for elevators 1 and 2, respectively.
These data are presented for a = 0, 3, 6, and 90, and
a maximum range of 5 = 60 to -90. The fact that the CL,
Cm, and Che values for a = 00 and 5 = 0 are not
zero is due either to asymmetry of the model or to small
errors in setting the neutral angle of the stabilizer,
elevator, or trim'tab.

The increase in the lift or pitching-moment coeffi-
cient with Mach number for both elevators is less than the

increase predicted by Glauert's factor (1 M2)-/2
This differences believed to be a result of the twisting
of the stabilizer and elevator toward their zero angles
due to the aerodynamic loads. The drag-coefficient
curves show the usual large increases in the vicinity of
the critical Mach numbers. The data show pronounced
increases in elevator hinge-moment coefficient with
increasing Mach number. Integration of the elevator
pressure-distribution diagrams showed increases of approxi-
mately the same magnitude. The rate of increase of hinge
moment with Mach number was more than twice as great as
v.ould be predicted by the use of the Glauert factor. In
general, the changes in the aerodynamic coefficients with
Mach number were gradual and consistent. TIe critical
Mach.numbers for the various model configurations could
not be greatly exceeded in these tests and consequently
the abrupt and drastic changes that have been noted in
tests of small models at high supercritical speeds were
not encountered. The only indication of such changes
occurred for elevator 2 near the highest test speeds.
(See figs. 23 and 24.)

Variation of lift with a and 6.- The variation
of the lift-curve-slope parameter CLa with Mach number
for elevators 1 and 2 is presented in figure 23. The
slopes were measured from plots of CL against a in
the region of a = 00 to 3. The values at low speed
of CLa are considerably lower than the value estimated
from two-dimensional data for'a wing of this section and
plan form, principally because of the discontinuity of
the airfoil contour at the stabilizer trailing edge and
the elevator leading edge.










ITLCA ARR No. L501a


T'h- change in CLr with ;.ch number for elevators 1
and 2 is shown ini f'c're 24 and indicates good agreement
between the two elevators at low sF .- s. For elevator 1,
C5 increases gradually with speed. At the maximum Iach
number attainable (0.68', the data indicate that CT
S. s beginning to decrease. The variation of CLT with
. c. h number for elevator 2 indicates a marked adverse
effect of fabric deflection at 1.sch numbers above 0.60.

Elevator effectiveness.- The variation of the elevator-
effPctiveness perameter with :-ch number is shown in
figure 25 for elevators 1 and 2. The curves show a small
decrease in effectiveness as the seed is increased from
M = 0.20 to M = 0.15. Beyond Machl umbers of 0.45 the
effectiveness for both elevators increases. The effec-
tiveness of elevator 1 ic still increasing at M = 0.68
but falls off sharply beyond values of I = 0.56 for
elevator 2. Since elevator 1 had negligible fabric
deflection and elsF a tor 2 had serious fabric deflection,
the adverse effect shown is a result of fabric deflection..
The theoretical effectiveness for a plain flan hinged at
its leading edz ha. been computed acco:-rdng to t ;- thin-
airfoil theoTr (see. reference 5), and is shown in figure 25.
The actual elevator effectiveness is approximately 71 per-
cent of the theoretical value for a plain flap at moderate


Pitching moment.- The variation of the pitching-
moment parameter .iCm/6 CL with 'Mach number is shown in
figure 26 for elevators 1 and 2. The value of this
pgrameter is a-proximately the position of the aerodynamic
center of the airfoil with respect to the. uarter-chord
poi t of the assumed mean aerodynamic chord (fig. 2)..
The cha. in the .;nter-of-lift position caused by ele-
vator deflection is. given by the oar met'r (CFr/ /CL) a
The ;sri t ion of chls oaramrtor with "-ch number was
about tIhe csm.c for both elevators; that is, the center
of lift was shifted rearward. The change in the c.nter-
of-lift position caused by angle of attack is given by
the paramrter (OCW/oCL) Increasing the "L'-ch number
caused a greater increase in this parameter for ele-
vator 2 than for elevator 1, probably as a result of the
fabric deflection on elevator 2.









IT'CA. ARR No. .L5Fola


Einge moment.- The change in Cha with T::ch number
is shown in.figure 27 for elevators 1 and 2. In general,
the agreement of the data for the two elevators is good,
although an almost constant small difference exists
between the values for the two elevators. Small differ-
ences in contour between the two elevators could cause
this difference. The small low-sesed value of Ch (-0.001)
decreased about 70 percent between .2 = 0.20 and M = 0.60

The variation of Ch5 with :i-ch number is shown in
figure : 28. Large increases in the negative values of
Chi 6ccu'red with increasing speed for elevators 1 and 2.
The value of Ch6 for elevator 1 (L-inch rib spacing)
increased from -0.005 to -0.009 between M = 0.20 and
M = 0.68. The difference between the low-speed values
of ChE for the two elevators is believed to be caused
by minor physical differences such as a small bump that
existed on the upper surface of elevator 2. This bump
was 5.5 percent of the elevator thickness, was located
at 6.5 percent of the total elevator chord from the nose,
and tapered to zero at the elevator leading edge and at
the hinge line. Figure 28 also shows curves for elevators
having zero and 100-psrcent aerodynamic balance. The
curve for zero aerodynamic balance was calculated
according to thin-airfoil theory (reference 5) for a
plain flap hinged at its leading edge. Elevator 1 had
50-percent aerodynamic balance at M = 0.20 but, because
of the adverse Mach number effects, the balance was
reduced to 8 percent at M = 0.68. The control forces
required for such an elevator would thus approach those
that would be obtained with an ordinary unl-n.zed flap,
when it is assumed that the value of Ch for such a
flap does not change with Mach number. In the absence
of boundary-layer changes, it might logically be assumed
that the elevator hinge moment would increase with speed
according to Glauert's factor. The low-speed value has
been increased according to this factor (1- M2)-1/2
and the data are plotted in fi ;L--e L. A comparison of the
two curves shows that the rate of increase in Ch6 with
Mach number is about double the rate of increase pre-
dicted by Glauert's factor. Elevator 2 had 43-percent
aerodynamic balance at M = 0.20 but zero aerodynamic
balance at M = 0.60. The increase in Ch5 is markedly
greater for elevator 2 than for elevator 1 because
of the adverse effect of fabric deflection. The









T:ACA ARR No. L5FCla


cdfference in the increases of Ch5 with Mach number
for the t1'o elevators aoeers to be aen effect of fabric
deflection, since fabric deflection was -he principal
difference between the two elevators. This difference
is nlctta. at the to of fir-j- 28. The effect of fabric
deflection on Chh v:es to cause an increase of -0.002
from M = 0.20 to T = 0.60. This increase wras about
j0O percent of the low:-speed value of Chg for the ele-
vator tested. An increase of this magnitude would be
still more serious for a highly balanced tail surface
for which the initial Chg mnSht be of the order of -0.001.

Effect of vents on hinge moment.- As was shown in
figure 19, the fabric deflection varies with vent location.
The best vent location from a consideration of safe fabric
deflection was found to be at. th( elevator leading
edge. ; c.rer 25 *sovs the, variation of the l-:-.ge-moment
coefficient with elevator engle, at l = 0.55, for the
three vent locations tsst.--. and with all vents sealed.
The edta presented in this figure shcw that the vents
located at the elevator ]rading edge produced the smallest
value of Chg. The beneficial effect of vents at the
16ading edge (reduced in.crnal pressure) is probably a
result of changing the as-mmretrical elevator-surface
deflectins, which resulted in acpreciaole elevator camber,
to :.ore syrm-etrical deflection's with less camber. (See
fi-. 19 and reference 4.)

effect of elevator seal.- A limited amount of data
with the elevator seal rmOoved was obtained over a small-
range of elevator rngle at a = 00. Thse data indicated
no apr c-able effect of the seal on the elevator hinge
mc. nt.

Tab effectivenes'.- The effectiveness of the elevator
trim tab through the speed range is shown in.figure 50.
The data for a tab angle of -100 show a gradual decrease
in effectiveness with increasing speed the ACh
decreasing'from 0.O)'4 at M: = 0.20 to O.G00 at :i = 0.65.
The effectiveness remains approximately constant from
M = 0.20 to I = 0.60 for a tab angle of 8.3.


CC:ICTLUSICI'S

An investi-?.tion of the characteristics of a full-
scale horizontal tail with fabric-covered elevators at









TACA ARR No. L5F0la


Mach numbers rangi'rg, from 0.20 to 0.6L has led to the
following conclusions:

1. Elevator 1 (4-inch rib spacing) had no appreciable
fabric deflection in the speed range of these teets.
Elevator 2 (8-inch rib spacing) nad a max.imuln fabric
o.ji eof 0.6 inch between ribs at a Mach number of 0.5,
an elevator angle of -7.7o, and an anl.;, of attack of ~:;.
Local failures of the fabric attacLment to the elevator
ribs occurred with elevator 2.

2. Vent holes located at the elevator leading edge
on either side of the seal, rather than in their original
position on the lower surface near the trailing edge,
eliminated the bulge for a moaerate range of elevator
angle at the expense, however, of some increase in fabric
depression on the pressure side of the elevator.

35 Elevators 1 and 2 produced very large increases
in elevator hinge-.: oment coefficient as the Mach number
was increased. Th.e value of C-, (the slope of the
-3
curve of hinge moment against elevator deflection) for
elevator 1 (4-inch rib spring) incrEased from -0.005
to -0.009 between Mach numbers of 0,20 to 0.68.

4. In addition to the increase in fiinge o:io.ent
resulting from ince' sing spcd elevator 2 (b-inch rib
spacing) had an increase in hinge .ioient due to fabric
deflection. The fabric deflection for this elevator
increased the value of C- by -0.002 at a .lch
number of 0.60. Fabric deflection also caused an early
loss in elevator effectiveness. Elevator 1 maintained
its effectiveness up to the maximiu:a test speed (a Mach
number of 0.68) but the effectiveness of clev;tor 2
decreased sharply at Mach nur-.tbers above 0.6.

5. The adverse effect of fabric deflection on ele-
vator hinge mno-ent was decrCeased slightly by locating
the vent holes in the leading edge rather than at the
trailing edge of the elevator.


Langley ''rorial Aeronautical Lab:oratory
i:tional Advisory Coammittee for Aeronautics
Langley Field, Va.









-ACA ARR No. L5FOla


1. Ieihouse, A. I., and Kemp, W. B.: effect of
Fabric Deflection on -dcider Hinge-Moment Charac-
teristics as Detei-mined by ".:n-T'i.rnel Tests.
rTCA ARR No. Tr544, 194.

2. Swancon, Rotert a., aTd Toll, Thomas A.: Jet-Boundary
Corrections for Reilection-"lane Models in Rectan-
gular -'ind n 'irels. IACA AhR ']o. ^-._22, 1943.

3. Perring, ";. G. I.: '"; s Tiheoretical relationshipss for
an Aerofcil with a multiply Tinged Flap S.ystem.
iR. & 7,. No. 1171, ritiLsh A.R.C., 1928.

4. Irathevs, Charles 7.A: An Analytical Investigation of
the Effects of Tlovator-Fabric Distortion on the
Longitudinal Stability and Control of an airplane.
r'.CA .1.CR Jo. LtC, 19T .









ITACA ARR No. L5FOla 17
TABLE I
LLEVTATOR FABRIC TEi SIONS

[Accuracy of measurement, 0.2 lb/in.]

i -------- ------ r .-- ---- -- --
Tension
(lb/in.)

Test
condition
Upper surface Lower surface

I.. I ."
Ki., n. LnT l A'. [i. n.


Elevator 1

i--'---~--r---/
'Before testing 7.4 6.5 8.6 6.8

After testing 7.6 6.7 8.8 7.6



Elevator 2


Before testing 7.2 5.2 7.5 6.8

After testing 7.0 6.0 6.7 6.0



NATIONAL ALV IECORY
COMMITTEE FOR AERO:-TAUTICS




r" -













?JACA ARR No. L5FO1a Fig. 1























S.-I
.r







0

aC



.I
m i

C) .c-I
CEQC
mo





a)







cd
.. *a











(D










b4
.--I




rx.
0 *-t






S. ,








NACA ARR No. L5F01a Fig. 2
















|0







a a v
3o
cr C r












0. C
i |
F6 9 0





0





ot
I- j .













5 o .
LCL
L \ j I








NACA ARR No. L5FO1a


_J

Q
Il

z
Z
t-



Lu
O
LL

-1
0
_J

U-

I.
ro)

L.
20
ilZ


0|88 88888
wrBPdn~id~i~Y


Fig. 3





























ELEVATOR I


ELEVATOR 2
NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS



FIGURE 4.-RIB SPACING FOR THE TWO

FABRIC COVERED ELEVATORS.


NACA ARR No. L5F01a


Fig. 4











NACA ARR No. L5FO1a Fig. 5


















0
La 4












II-
..







10

ww
cD
F-





w


L-
0





LO


w

0





U-
\,d








NACA ARR No. L5FO1a


(a) Upper surface.


(b) Lower surface.


Figure 6.- Static condition for elevator 2.


Fig. 6a,b









NACA ARR No. L5FO1a


UJc


15xiO6


480 14
440-- -- -H -13












320-- ----12- O
2400 -- -- -- -^ -f -- -12
3200 10
360 ------- 6/







240 -------8








160, 6



120 5



80 -

NATIONAL ADVISORY
CONNITTEE FOR AEIONAUTICS
80 ---1


.2 .3 .4 .5 .6 .7
M

Figure 7-Variation of the overage test Reynolds number and

dynamic pressure with test Machnumber.


E
z
bI

3
C
(0
32
0

>>
C
10
0:
*
S



Fig. 7











rjACA ARR No. L5FO1a 'ig. 8









0








Qo
0


> cQ







<-4
do


II






<0
n w













,--) b0
a-)















cO D
c-o
*0







O C










,-4
c' a )d
to-


-4 .-
rO ali
4' mc

.0k
aj -w
4';

Lioa








NACA ARR No. L5FOla


(a) Upper surface.


(b) Lower surface.


Figure 9.- Fabric deflection of elevator 2 (8-inch rib spacing).
M = 0.55; a = 00; 8 = 3.30; elevator seal removed; elevator
vents at trailing edge.


Fig. 9a, b








NACA ARR No. L5FOla


(a) Upper surface.


(b) Lower surface.

Figure 10.- Fabric deflection of elevator 2. M = 0.62;
a = 30; 8 = -0.70; elevator vents at trailing edge.


Fig. 10a,b











NACA ARR No. L5FO1a


cl 0 OcU
I


C I




4- I
Lot-



























4












I


"ul 'uo!payap 0!Jqo;-JoIDorI3


Fig. 11


0
o




0 c
04--



0 e
o .










UU
4 -




<2 ,c



o o






a a


C
> c






* o
o o
Q 0

g Oe
S- .O




we


SInC

E S.

W 0 >



*s





=1C







0-0


o






Ou8
I a












0 +
II










0+


Co


0 No V"
a










NACA ARR No. L5FO1a


Fig. 11 Cone.


SI






















41
















-s< -
uI u: !l 0ap


I" TD I'
Oulqo;- JoIDA0l8


0
o







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o
0





0
U




e



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o








so
0





-o


E
S










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0
c







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0




o .










4.
.



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S
fe Q)











a a)
D I
o 3


t CM










NACA ARR No. L5FO1a


o

CJ























































cUO
I*


t
TI
--
-4r-













I
































( W,4
-. ..


C


0 -


































I










(T- --








(M 0 iC


I I I I I 1 0
t N O CN
I.


",u! 'suo!lollep 3ijqo;-JooA9el3


(flt(
. r-
o.O


.0"








II
.3G.


0.0






0 *


Fig. 12










NACA ARR No. L5FO1a


































c
110










cII
-0 -













O.3







e+
-j
li + ::=
02 (_^ -
tb-. ^-

sI -I-
31. ^ -
-O W_ -
__0.0_



0 +_1_ _


Fig. 12 Cone.


I I I I I I I I I I I I I I I I I 0

4. C4. o C o 0 q OM 0 C

ui 'uo!laml8p o!Jqo J0A8|A13






























































































t~ ON O N .N ON o ON
I I' I I"


*u! 'uo!PIalap o!JqD-Jo oDA|13


NACA ARR No. L5F01a


Fig. 13


0
0.0




C
a)
s _











0
C
CO











I a
r10

C
r-

C




m 0
0
>30
0S>
0 _
In

,0 0
S01~
0


o>
I..

0)

















V


?2
.CO)



a
C:



















a c
E
C0
.2

5,

O- .2



'55E
010

0Q)1

^30

UI
o _.


s0
C^ -5
oS



o> c
> .0
0~ C
10) 0*:





0'l
g," c

il*: 0


U)
.2 o







VW




"3
c.I





Cl0.0




a0
Si








NACA ARR No. L5FO1a


O 0





1
x z








- U(1
nI

0 -l


I I)






-C4


"U! '9ooplns JGMoI
8944 o uo!il39|;p wnuj!xolN


C

0
a,


0
L.




..O
.0
4-
0



0
-T




0.


4-
I I'









Q |
i5 "


Fig. 14








NACA ARR No. L5FO1a


NATIONAL ADVISORY
COMuNTTEE rM MlNUTICS






Figure 15 .- Pressure distribution of elevator 3 for three elevator
positions. a:=O*; M=0.20; gap sealed ; 33-inch station.


Fig. 15









NACA ARR No. L5FO1a


-1.2



-1.0



-.8



-.6


Figure 16.-Pressure distribution of elevator 3 for three elevator
positions. at 3; gap sealed; 33-inch station; M=0.20.


Fig. 16








NACA ARR No. L5FO1a


-1.6


-14


-12


-1.0


-8


"---- --
c














a_--------------------C ------------ -
-C





(deg)
S-0.4
S- 3.8
I3.1

Toiled symbols denote lower surface







+














NATIONAL ADVISORY
COMMITTEE FO AEIIONAUTICS





Figure 17.-Pressure distribution of elevator 3 for three elevator
positions. a: 60; M- 0.20;. gap sealed; 33-inch station.
Fiue _-Pesueditibto of elevtr 3 fo thre elvto
postins ^r ^ M .0 .go ele;"3ic to


Fig. 17







NACA ARR No. L5FO1a Fig. 18



E
111 "
-L I
2 w

-j > B





9 "-o

/ "
\CI O-o
-I n >










SJO \
--- -s---s---- r
--
1 -- I -- \ -- -- ------------ o0 g






e "t o"
SC O











co E 0O
0000










c- 00
I I 0
00






I z





!d '&U813400O OsJf d









NACA ARR No. L5FO1a


wQ N 0 wO


Fig. 19a-c


0 C-i
c 1O


I. I


u!i' uo!4oaliap o!iqoj JOCoDA3


0
0 a0


e
,0




0

.O o

c'
-o




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U)






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5 )


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c
0 0

.C
0

o o2




o 0*
0 .SS 0






o 0



*Q
I0








o aE
OC
a-0
ir








NACA ARR No. L5FOla


(a) Upper surface.


(b) Lower surface.


Figure 20.- Fabric deflection of elevator 2. M = 0.55;
a = 00; 8 = 40; elevator vents at leading edge.


Fig. 20a,b







NACA ARR No. L5FO1a


.08 I
Videg) I


(deg)
(deog)


.2 .3 .4 .5 .6 .7 .2 .3 .4 .5 .6 .7


(oa)c-- 0.


(b) ac=30


Figure 21.-Variation of the aerodynamic characteristics with Mach number for
ranges of elevator ongle and angle of attack; elevator I.


* C\


Fig. 21a,b









NACA ARR No. L5FO1a


05 -.-------I

04-


Th


-i W-t


-4+


H-t--


-- "- .0. --"-
-2








-2 -9

NATIONAL ADVISORY
". COMMITTEE FOR AEONAUTICS
I I I


2 .3 .4 .5 .6
M


(c) a=6.


.2 .3 .4 .5
M

(d)a =99


Figure 2/ .- Concluded.


--4


103 -


--


. .----


Fig. 21c,d


I"-"-


--4-


--- 1-


ip









NACA ARR No. L5FO1a


J(
d
(deg)


6
(deg)
-a i__--


2-

0 .. .
-- ,- 8_-l--
o o-j 111111111 : LU L L L


-/ot IlIII I


.2 .3 4 .5 8

o M=00.
(a) a=0.


.2 .3 4 .5 .6
M
(b) o=3.


Figure 22. Voriation of the aerodynamic characteristics with Mach number

for ranges of elevator ongle and ongle of attack; elevator 2.


--- ---- --








6
2
-- 0 --
o






4 -2
2 -4
-0 -" -
-2 -9
-6
-6 --------
NATIONAL ADVISORY -
COMMITTEE F0R AERONAUTICS
I I I l l


_ __ ~1 r I~ r ___ I 1 T


1 11111


111I 111 1 11 1


Fig. 22a,b









NACA ARR No. L5FO1a


.(J2-

.05--



4
2
03

-2 --
02-


.8


4
6 2

4 ----
.4 -2-

-9
-4 ---- -- NATIONAL ADVISORY
-6 CONITTEE FOR AERONAUTICS
_I I!


.2 .3 4 5 .6
M
(c) a=60.


Figure 22 .- Concluded.


.2 .3 4 .5 .6
M
(d)a=90.


Fig. 22c,d







NACA ARR No. L5F01a
NACA ARR No. L5F01a


(deg)


-4
/--2-
______ "-4


Elevator I
I I I I I I II I I


.2 .3 .4 .5 .6 .7
M NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS
Figure 23.- Variation of the lift parameter CL

with Mach number for elevators I and 2.


.07


.06


.05







E
S.07
.CL

.06


.05
.05


Fig. 23






NACA ARR No. L5FO1a


(de
(deg)


.040


.030


.020


(a) Elevator I.


(de()


.040
..)


.030



.020


.010
.2


.3 4 .5 .6 .7


(b) Elevator


Figure 24.--Variation
CL with Mach
ands 2.


of the
number


lift parameter
for elevators I


Fig. 24a,b








NACA ARR No. L5FO1a


(0


(~"~P'1


'sseueA!COe8;e JODOAel3


0
II




0









oD
0
c











-o
'I






C
00





N-
o l

-L.

t0-

b-0
IL
u*-
L.


Fig. 25








NACA ARR No. L5FO1a


30 (op/Wp)


(0 4~.C%
QZ Q! Q


S(' p/ 'OP)


L.
J0



0

k.

C
,o
0


t. cc

..-


r o.
C-C
->

CC%
0
e)




0
I-



-E


I.

cJ
0


LL


Fig. 26







NACA ARR No. L5FOla


LA

01


I


IL-


0I






I
I /
/ (







0
0
I I -
------ ----- --- Q ---- --- l| --- --- --
_I_
Ld


ID 0


0-



c





0
C




'O


e \E
c
C
I,
0
r)



04
ia,



rCJ


Fig. 27


I







NACA ARR No. L5FO1a


aerodynamic balance


LI
0


.2 .3 4 .5 .6 7


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS

Figure 28 .-Voriotion of the hinge-moment parameter
Chc with Mach number for elevators land 2 ; ca =0
or 30.


Fig. 28







NACA ARR No. L5FO1a


sealed --


IVents 1/4 in
,leading ed


N.


Cf
SCe
cb cee



Vents at trailing
i. from edge, lower
ge surface only

-Vents at 0.10 Ce -

- Vents at trailing edge


_-_D-^i3^_LIJIZ


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS

-__ Vents at__
leading edge -

Vents at 0.10 ce

SAll vents sealed
- --- II _


-4


-2 0
Elevator angle, deg


Figure 29 .- Effect of elevator vent location on elevator
hinge moment; cc = 0; M=0.55;elevator 2.


Fabric


0
4-




E

0
E-
a)
a)


.04



.02



0



-.02



-.04



-.06


Fig. 29








NACA ARR No. L5FO1a Fig. 30










u0




o
/ CL
U


-D




I no











CD 1- 0 D It
C
0



S 00

E----- -- ---- )
07
4*-
4-

------------ ------------___--- Ip "


i--




r





UNIVERSITY OF FLORIDA

3 1262 08106 456 9

3.1


fL' JIERSITY OF FLORIDA
.: i.l.MENTS DPFRfTM1ENT
1- K:: ..-: S.1,E .~-E LIBRARY
S.. 117011
* -.L'. LLE, FL 321611-7011 USA


















I




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