Hinge moments of sealed-internal-balance arrangements for control surfaces

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Title:
Hinge moments of sealed-internal-balance arrangements for control surfaces
Alternate Title:
NACA wartime reports
Physical Description:
16, 35 p. : ill. ; 28 cm.
Language:
English
Creator:
Fischel, Jack
Langley Aeronautical Laboratory
United States -- National Advisory Committee for Aeronautics
Publisher:
Langley Memorial Aeronautical Laboratory
Place of Publication:
Langley Field, VA
Publication Date:

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

Notes

Summary:
Summary: Tests were made in a seal test chamber to determine the hinge moments contributed by the fabric seal in an internal-balance arrangement employing a thin-plate over-hang. These tests were performed with various widths of fabric sealing various widths of flap-nose gap, with a horizontal, a vertical, and a circular type of wing structure forward of the balance, and with various heights of balance chamber. This investigation is an experimental verification and extension of a previous analytical investigation. The present investigation indicated that the moment of the seal may be a balancing or an unbalancing moment and may be an appreciable part of the total balancing moment of an internally balanced flap, depending on the overhang deflection and the configuration of the internal balance. Variation of the width of the fabric seal, the sealed gap, or the location of the seal attachment to the wing structure affected the seal moments through most of the over-hang deflection range. The shape and size of the balance chamber affected the seal-moment characteristics in the deflection range where the seals contacted and were constrained by the chamber walls; the values of the seal moments were usually reduced when the seals were constrained. The results indicated also that an optimum balance configuration would employ a seal width such that the seal would barely touch the chamber ceiling when maximum overhang deflection is attained.
Bibliography:
Includes bibliographic references (p. 15).
Statement of Responsibility:
by Jack Fischel.
General Note:
"Report no. L-52."
General Note:
"Originally issued August 1945 as Advance Restricted Report L5F30a."
General Note:
"Report date August 1945."
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
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All applicable rights reserved by the source institution and holding location.
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aleph - 003614873
oclc - 71262061
sobekcm - AA00006257_00001
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AA00006257:00001

Full Text
CJ-t


NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS


WARTIMlEl REPORT

ORIGINALLY ISSUED
August 1945 as
Advance Restricted Report L5F30a

HENGE MOMENTS OF SEALED-IITERNAL-BALANCE

ARRANEMEHTS FOR CONTROL SURFACES

II lEXERIME0TAL INVESTIGATION OF FABRIC SEALS

IN THE PRESENCE OF A THIN-PLATE OVERHAlG

By Jack Fischel

. Langley Memorial Aeronautical Laboratory
Langley Field, Va.


S NACA WARTIME REPORTS are reprint
; adaie research results to an authorize
Svously held under a security status but
S really edited. All have been reproduce
!; i,.. '-.... "...


WASHINGTON

s of papers originally issued to provide rapid distribution of
ed group requiring them for the war effort. They were pre-
are now unclassified. Some of these reports were not tech-
ed without change in order to expedite general distribution.


DOCUMENTS DEPARTMENT


L 52





































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


http://www.archive.org/details/hingemomentsofse001ang




-I2 4'20 Il


NACA ARR T7o. L5F0Oa

NATTOrAL ADVISORY COMMIT EE FOP AERI.IUTITC


ADVA2'E FECSTErCTELD REPCPT

EINGtE MO.1ENTS OF SEALED-I iTER!AL-E.ALAI:CE

AFRA!iGE:E ENTS FOR CO"NTFOL SURFACES

II EXPERI:. FTAL INVESTIGATION OF FABRIC SLAL3

IT THE PRESENCE OF A TFI.N-PLATE OVERHANG

By Jack Fischel


S ?M .fA R Y


Tests were made in a seal test chamber to determine
the hinge moments contributed by the fabric seal in a.
internal-balance arran-erment employing a thin-plate over-
hang. These tests were performed '. ith various s ,.wic:ths of
fabric sealing. variouss widths of flap-nose rcas, with a
horizontal, a vertical, and a circular type of winrg
structure forward of the balance,and with various heights
of balance chamber.

This investigation is an ex-erimental verification
and extension of a. previous analytical investigation.
The present Investigation indicated that the moment of
the seal may be a balancing or an unbalancing moment and
may be an apprecisble pprrt of the total balancing, moment
of an internally balanced fllp, depending on the overhang
deflection and the configuration of the internal balance.
Variation of the width of the fabric seal, the sealed gap,
or the location of the seal attachment to the wing struc-
ture affe-ted the seal m-ments through most of the over-
hang deflection range. The shape and size of the balance
chamber affected the seal-moment characteristics in the
deflection range here the seals contacted and were con-
strained by the chamber walls: the values of the seal
moments were usually reduced when the seals were con-
stra-.r.ed. The results indicated also that sn optimum
balance configuration would employ a seal width such that
the ses.l ,ould barely touch the chamber ceiling when
maximnurm overhang deflection is attained.







2 NACA ARR No. L5F30a


INTRODUCTION


One of the devices employed for balancing control
surfaces, especially ailerons, of modern high-speed air-
planes is the sealed internal balance (fig. 1). T'.uch of
the experimental work that has been done in the develop-
ment of the sealed internal balance has been summarized
in reference 1, which includes a brief consideration of
seal effects. In reference 1 (and in all previous internal-
balance work), the balancing effect of a seal in an
internal-balance arrangement was accounted for by an
approximate method that is, by assuming the balance
chord to be the distance from the control-surface hinge
axis to the center of the sealed nose gap, regardless of
seal width.

An analytical investigation to determine the cqntri-
bution of the seal to the balancing moment of a sealed-
internal-balance arrangement indicated that the approxi-
mate method was generally in error over most of the flap-
deflection range (reference 2). This analysis also
indicated that variation of either the seal width, the
sealed-gap width, or the shape of the wing structure
forward of the overhang has an important effect on the
balancing moment contributed by the seal.

The present investigation is an extension of the
investigation reported in reference 2 and was begun in
order to check experimentally the fabric-seal analysis
reported therein. The present investigation covered a
larger deflection range than was covered in reference 2;
in addition, the effect on the seal moments of a con-
fining balance-chamber roof (the contour of the airfoil)
and an off-center attachment of the seal to the wing
structure were determined.

The moment contributed by the seal in each of the
configurations tested is presented as a fraction of the
moment of the thin-plate overhang over the complete
deflection range. A comparison is made of the seal
moments obtained experimentally and analytically (refer-
ence 2) with seals and sealed nose gaps of similar size
in the presence of each of the three different types of
internal wing structure with no vertical restrictions.
In addition, a comparison is made between the experi-
mentally determined and the computed hinge-moment coef-
ficients of an internally balanced aileron, and an







NACA ARR Fo. L5F3Oa


example is presented to show the relative accuracy of
hin--e-moment data comp1'.ted t", tie Epr.oyiimate method and
those computed from the res.'.its of the present investi.a-
tion.


SYM30LS


ms seal-roment ratio (, /': )

cha, il.eron section hinge-imoment coefficient (ha/qc 2)

Ach increment Irn aileron section ninge-.mouent coef-
a ficient produced b3 an internrl-Oblance arrange-
ime t

PR pressure )oeffic'ent across balance pressuree
belcw balance minus rrelsure aLove tal:lance
divided by dynamic pressure)

8. thin-plate overhang deflection, ,.egrees: nositiwe
-when deflection is increased from neutrJl by
pressure across balance

6b liimitinr: deflection of thin-plate overhang,
7 :e,-rees i'deflect ,ion just crior to contactt
bet ,een leading ed.e of overhang, an;d roof of
test chanter- 'con:tonr of airfoil))

6 aileron deflectio.:n wth reset tc airfoil chord
line, degrees

M licm-.ent of thin-plate ovesrhan (uled with subscripts
exp and comp to indicate expei~'-ental and coii-
puted, respectively), fcot-pounds

M, moment of seal, foot-pounds

g width of sealed g&p between points of sttachr;ent
of seal when 5b = 0, fr action of c1

s seal width, fraction of cb

ha aileron section hinge mcmrr ct, foot-pounds

t thickness of overhang at hin.e axis, fraction of c






NACA-ARR No. L5F0Oa


c airfoil chord, feet except when otherwise indicated

c aileron chord behind the hinge line, fraction of c
a
Cb overhang chord from flap hinge line to leading edge
of overhang, fraction of c

q dynamic pressure, pounds per square foot (-lpv2
'2 /
V absolute velocity of air stream, feet per second

p mass density of air, slugs per cubic foot

M Mach number (V/a)

a velocity of sound in air stream, feet per second

a angle of attack, degrees


APPARATUS AND -.7ETFODS


The seals were tested in a specially prepared seal
test chamber that simulated the construction of an
internal-balance chamber ahead of the flap hinge line
(figs. 2(a) and 2(b)). The span of the overhang was
24 inches and the chord was 10 inches from the hinge line
to the leading edge. The thin-plate overhang was rigidly
attached to a torque tube that was, in turn, attached to
a dial outside the test chamber and deflected the over-
hang through the test range. A clearance of 3/64 inch
was allowed at each end of the overhang span to prevent
contact with the side walls through the deflection range.
A small clearance behind the hinge line between the torque
tube and the test-chamber structure was sealed with a
small fabric seal; the moment produced by the seal was
considered in the calculations. The difference in normal
pressure existing across the seal and overhang of an
internal-balance arrangement was simulated by the con-
trolled pressure produced in the part of the test chamber
below the overhang by a blower, while atmospheric pres-
sure existed above the overhang. The pressure across the
overhang and seal was indicated by a micromanometer and
this pressure was maintained at approximately 17 pounds
per square foot by a door on the blower intake. The
distribution of pressure in the region below the overhang








:T.CA ARR Fo. L5730a '


and the e.:l .-,as deter .mned from a trief surv-ey to be
uii'.for_.i within a'*ro.ir -tely 1 percent: a orecsure drop
of approximately 15 to e0 percent ';was found to occur
within 1/16 inch of either and of the overhar'? span,
about which a flow took place, but the effect of this
pressure difference on the hinge iorr.ents is believed to
be negligible.

One of the chordwtse chamber v:alls was made of
plexiglass through v.hich photographs were taker, of the
seal profile under various conditions.

The hinge moments of the balance arrangement vere
determined oy means of a calibrated, torque-rod system
built fr,- this setup ffigs. 2(a) and 2(b)). The over-
hang deflection was determined by the reading of the
overhang-deflection dial with respect to a pointer
attached to the outer wall of the test chamber (fig. 2(a)).

Three topes of balance-chamber structure ahea-d of
the overhsn, were used in the investigation. These
surfaces are sho'wn in figur. 2(a) and are referred
to herein as bac'plates. The baci'plates were of uniform
heiht and soon: their chordl'ise positions w:'ere varied
darin-a the tests to Rive various sizes of gan. The
seals tested vere made of K1oroseal, which is an air-
tight, flexible, fatri3 rseterial, .nd had a varying
chord width .r.r a span e-ual to that of the overhang.
A thin metal strip ves fsste-nc1d alone: the soan at both
ends of each seal to attach the seal to the osackplate and
to the leading edge of the overhlir (fir. 21ie).

The vertical balance-charber restriction (contour
of the airfoil) was siirulated b.j a horjiontelly held
plate; the distance of this plate above the o'erhang andc
seal was varieJ to give tre proper value of 6, For
uniformity and agreement with reference 2, all the linear
dimensions of the balance confi-iurstion are expressed as
a fraction of the overhand chord.

A list of the balance configuretions tested is
given in table I. Since the pressure difference across
the balance of a control surface does not always reverse
when the control is neutral, tests v.ere rmade at negative
deflectionsun to -12 and the test were run with the
overhang deflection varying in 20 end h0 increments uo
to 500 or the maximum deflection allowed by the sels or







YACA ARR No. L5F0Oa


overhang. The results are applicable to both negative
and positive flap-deflection ranges, however, and the
change in direction of the balancing moment is deter-
mined by the deflection at which the sign of the pres-
sure difference across the balance changes.

In obtaining the hinge moment due to the seal, the
moment of the overhang had to be subtracted from the
total moment of overhang and seal measured by the torque
system. The moment of the overhang alone, without any
seal present, was obtained over the deflection range by
closing the gap between the overhang nose and the back-
plate to a very small value. Because of the large
leakage area for this condition, a pressure difference
of only about 10 pounds per square foot, considerably
less than the normal test pressure, could be maintained.
The overhang moment thus obtained experimentally was
compared with the overhang moment computed from the thin-
plate dimensions and the pressure difference across the
overhang. The experimental moment was found to be approxi-
mately 1 percent higher than the computed moment. The
seal moments were therefore obtained by subtracting the
computed overhang moment, corrected for the 1-percent
discrepancy, from the total moment measured in each test.

The computations for obtaining the seal-moment
ratio are indicated in the following equation:


Ms = total exp 1.01 1bcomp
ms b 1.01 Mb
comp


RESULTS AND DISCUSSION

Seal-Frofile Photographs


Some typical profiles and positions of the seals
with a pressure difference across the balance are shown
in figures 3 to 7 with a vertical backplate, in figures 8
and 9 with a circular backplate, and in figures 10 to 15
with a horizontal backplate. The constraining effect on
the profile of the seal caused by the vertical and
circular backplates in the positive deflection range is
shown in figures 3, 4, and 9; whereas figure 10 indicates







N.ACA; ARR !No L5F50a


that the horizontal backdlate had little or no confining
effect. Similarly, figures 5, 7, 8, 11, and 12 indicate
the confining effect of an overhead restriction simulating
the top or bottom of the balance chamber. When a seal
was free to billow unrestricted by backplate or overhead
limit, the seal generally tended to assume a circular
shape. This fact, which formed the basis for the ana-
lytical work of reference 2, is illustrated in figure 10d)
by a circle superimposed on an enlargement of the photo-
graph of figure 10(b).


Desired Seal-Moment Characteristics

A desired variation of the seal-moment ratio m
with overhang deflection is one that offers a positive
value of the slope 6ms/66o with deflection. (See refer-
ence 2.) This variation of ms with deflection would
tend to compensate for the decrease in the variation of
pressure coefficient across the balance PR with deflec-
tion (that is, the decrease in 6PR/66b) as the ,deflec-
tion increases and to provide more nearly linear balance
hinge moments and control forces.


Experimental Seal-Moment Characteristics

The se-al-moment characteristics over the deflection
range for various sizes of fabric seal and sealed nose
gap, without and with overhead limits, are shown in
figures 14 to 21 when the seals were tested with a vertical
backplate, in figures 22 to 26 with a circular backplate,
and in figures 27 to 54 with a horizontal backplate.

WVith all three types of oackplate, the moment exerted
by the seal in the balancing configuration is appreciable,
particularly with large seals and large sealed gaps.
This seal moment may be a balancing moment amounting to
as much as 40 or 50 percent of the overhang balancing
moment, or it may be an unbalancing moment amounting to
as much as 50 or 40 percent of the overhang balancing
moment, depending on the overhang deflection and the
configuration of the internal balance. Negative values
of ms were sometimes obtained with all three types of
backplate in the negative deflection range and over a
small portion of the positive deflection range near zero







8 KACA ARPR No. L5F50a


deflection (figs. 1, 15, 22, 27, and 28). In these
configurations the seal overlapped a part of the over-
hang, which equalized the pressure on both sides of this
part of the balance and tended to reduce the amount of
effective balance available. A configuration illustrating
this tendency was not photographed, but this condition
is approached in figure 9(a), except that the seal
actually lies flat against the overhsng when ms is
negative in the discussed deflection range. Except rhen
a sealed-gap width of 0.5 is used, the'slopes of the
seal-moment curves at small positive values of deflec-
tion are usually positive and indicate an increasing
balancing effect in this range. This increase in
balancing effect is independent of that obtained by the
increased pressure difference across the balance when the
flap is deflected or when the angle of attack of an air-
foil is increased and is a function of the seal. At high
positive values of overhang deflection, as the seal
became taut, the seal-moment ratio of the unrestricted
seal decreased and became negative and the direction of
its force was opposite to that of the overhang balancing
force (figs. 3(d) and 10(c)).


Effect of the Balance Configuration on the

Seal-Moment Characteristics

Effect of seal width.- The effect on the seal-
moment characteristics of varying the seal width, with
other variables kept constant, is shown in figure 5
and is also evident from figures ll to 19, 22 to 24, and
27 to 32. For a given sealed-gap width, m depends
on seal width. The curves indicate that ms decreases
in the negative deflection range and generally at small
positive deflections and usually increases at large
positive deflections as the seal width increases. The
curves indicate also that, for a given sealed-gap width
and as the seal width increases, the maximum value of ms
generally increases, except when the circular backplste
is used, and the maxim~ui value of ms occurs at an
overhang deflection that increases with seal width,
regardless of the backplate.







i.3A Ar 1 5. L50F a


Effect of ssaled-cap width.- The -effe-t of sealed-
gap width on seal-moment cnar'-cter-istIr is 'ndiccLted in
figure 56 and in figures 1i to 1I, 22 to 21, and 27 to 52.
For a given seal vwidth, thi se ,l--rom;r nt rA'ti, -en- rll. y
increases with sea]ed-gep width at small deflections and
decreases at large deflections.

Effect of backplate.- The seal-moment characteristics
obtained with the rhree tac',:latzs for i'ven se aled- -ar
and se-l qwidths generally differ only in the deflation
range in v.hich the seal lies against the basckplate; hence
the values of ms in this ran.3 depend on the t;pe of
backplate contsct-d and the effect this basVklste has on
the seal profile. A compsarscn of tha seal moments
obtained over the deflection range with onlstant gaps
and seals for the three different backplate arrangements
is given in figure 37 for the condition in -which no
vertical restrictions are used. The cnarszteristics
exhibited b'. the seal ,,ith a vertical bcckpiEote and a
circular bacl:plate are quite similar (see also figs. 14
to 21 and 22 to 25) and indicate somre ln.eerity over a
part of the deflection range. The horizontal bac-: plate
has little or no effect on the moments produced by the
seal; these moments are usually larger at s;'-ill deflec-
tions and smaller at large deflections than those obtained
with the circular or vertical backplate. The effect of
the backplate aoppers to dirmi.nish with an increase in
size of the sealed gap and the seal, and the character-
istics obtained with the three backplates differ oy only
a small amount 'with rrediuir a:nd large 'aps and. seals
(figs. 37 and 1. to jh). At s-emall gsps, the effect of
a backolate constraining th seal is to cause the maximum
moment of the seal to be reduced and to be developed at
a higher deflection (fig. 37( )).


Effect of vertical restrlction.- Limniting the height
of the balance chamber reduced the values of m, over
that part of the deflectIon range in wh1i ch the seal con-
tacted the roof of the chamber (figs. 11 and 1i to j1).
Increasing the seal width or the overhang deflection in
this condition or decrc-asinv' the value of the limiting
overhang deflection 5b caused a greater reduction in ms
as more of the seal contacted both the chs:roer ceiling
and the backplste. The deflection at which the seal con-
tacted the chamber ceiling and the seal moment started
to decrease was greater with the horizontal backplate






NACA ARR No. L5F30a


than with the two other types tested. When no vertical
restriction was present, the maximum values of ms
usually occurred at higher values of overhang deflection
and the values of ms were greater over the deflection
range affected than when a restriction was used to simu-
late the roof of the balance chamber. It appears,
therefore, that an optimum balance configuration would
employ a seal width such that the seal would barely
touch the chamber ceiling when maximum deflection is
attained. (See figs. 5 and 8.)

Off-center seal attachment.- The seal-moment char-
acteristics obtained with a .T53cb off-center attachment
of the seal to the backplate are shown in figures 20, 21,
25, 26, 33, and 34 when tested with the three types of
backplate used in the investigation. (The value of
0.34cb of the off-center seal attachment corresponds to
an offset of the position of seal attachment to the
backplate to the top or bottom of the balance chamber
when 65b = 200.) In addition, a comparison of the seal-
moment characteristics obtained in the presence of the
circular backplate with the seal attached to the wing
structure at the center and off-center positions is
shown in figure 25. The seal-moment characteristics
obtained with the off-center seal attachment were gener-
ally unfavorable over the deflection range because a
decreasing balancing tendency or an increasing unbal-
ancing tendency is indicated, regardless of the type
of backplate or of the point of attachment. Vvhen attached
above center, the seal invariably lay against the back-
plate and overhead restriction at positive deflections
(figs. 7 and 12); when attached below center (figs. 6
and 13), however, the seal had a moment vector that would
decrease positively, then increase negatively with over-
hang deflection. These effects account for the unbal-
ancing characteristics of this type of seal attachment.

The effect of attaching the seal off center to a
circular backplate when the seal did not contact the
balance-chairber ceiling was to shift the seal-moment
curve by an angle the sine of which was equal to the off-
center displacement (expressed as a fraction of the over-
hang) divided by the radius of the backplate arc (also
expressed as a fraction of the overhang). The curves
of figure 25 approximately verify this conclusion; the
computed offset angle was sin- 0' = 15.20, and
1.3








'ACA ARR No. L550Oa


the d.:ct of figure 25 indicate thia.t the offset a ngle is
about I) fince :n off-center sea-l attac~n-'. t produces
an unbalancing effect tlht mTy be reader t itl the
ir. greased balancing effect on the overn.nng caused ;oy
flap deflection or the increase in the ragle of attack,
this type of seal attaschimeint is believed to be undesirable
and should be avoided.


Coroparison of Analytical and ExperimTrntal

Seal-Moment Characteristics

The similarity letvween the analyst i~cl reference 2)
and exoerimentsl seal-moment characterisricr is evident
in figure v7, wihi:h shows t!-h agreement between these
results. The analytical and experimental results were
compared for several configurations in addition to those
herein and similar agreement was obtaiied.


Computation of Seal-.1onment Characteristics

by Approximate methodd

The seal-moment ratio computed by the anproxins.te
method (reference 1) for various s zes of sealed gap is
shown in figure Z5. This method of cDmputing the seal-
moment ratio is iLndeoendent of the seal width and assumes
a balance chord equ'.:l to the overhang chord plus one-half
the width of the sealed gap measured when the flrp is in
the neutral position. The insccurlcy of this metnod is
apparent by a comparison of the values shocvn in figure 3,
with the dat. of figures 14 to As 'ndicatd ni ref-
erence 2, the error involved _n using the approx: .ate
method may be a considerable part of the hingpe-rmoment
coefficient or control force of the balanced control
surface: it is therefore believed that this method should
not be used.


Application of Seal-'oment TData

Inasmuch as the investigation reported herein was
made with the various limitations and configurations of
an internal-balance arrangement and the data presented
are representative of the seal effects in such configura-
tions, the figures are believed to be applicable for
design purposes in calculating the hinge-monent character-
istics of various balanced flaps with thin-plate overhangs,







12 NACA ARR No. L5F50a

if the pressure difference across the balance and the
plain-flap hinge-moment coefficients are known. In
order to obtain the seal characteristics of those con-
figurations not tested, it is possible to interpolate
between the seal-roment curves for an intermediate gap-
or seal-width confizur&tion. As indicated in reference 2,
these results are believed to be applicable also to over-
hangs having nose shapes with fairly srall angles, but
the limiting nose angle has not yet been determined.


EXAMPLES

Comparison of experimental and computed hinge-moment
coefficients of a balanced flap.- The aileron configura-
tions shown in figure 39 were selected to illustrate the
computations necessary for a practical application of the
seal-moment data to the balancing moment of an internally
balanced flap. The plain-sealed-flap bnze-mrient data for
the 0.20c aileron were used in the co-:utations, together
with the pressure coefficient across the balance PR
(from unpublished data) given in figure 40, the seal-
moment data presented herein, and the geometric dimensions
of the balance. In figure l., the computed balanced-
aileron hinge-moment coefficients are compared with the
balanced-aileron hinge-moment coefficients obtained
experimentally.

The comp uted balancing moments were obtained by the
following equation, which is based on the geometric
dimensions of the balance arrangement for a unit span
(two-dimensional)


cha 2 1+ m2 (2)



S (0o.744)' (1 + ms) (0.S175)


= 0.555(1 + s 0.0352








TACA ARR No. L5F50a


Values of P for use in this equation were obtained
from figure LO. The width of the seal used inr the
investigation tas not measured but was believed: to have
been appro.Ar'.stel~ 0.4. Values of ms for computing
the exact balancing moment over the deflection r:-nge
for a seal v'5dth of O.L. end a sealed-gap width of 0.0556
were interpolated from the data of figure 22 and 'fi-
ures 11. and 1C. (The characteristic? of the sealsr. with
vertical and circular usckelaEtes re somevwhat similar
at this sal vIidth and selled-gap vidth.)

The balanced-aileron hinge-moment coeffilcients
were outsirned by the equation


Cha = C. + Acha
chblanced sileron plain aileron

and figure 10 shows fair agree.mnt bet-.een: experimental
and co:mputed results. The discrepancy between the
balanced-aialeron characters tics obtaineodexperiiamantally
and those corputed is probably- caused by the differennce
in the size of the vent % ap (..005c for plain aileron,
O.01 icr balanced asleron) r-. by5 possible small dif-
ferences in mrodel configurat...on '.:.ch as sesa ".idth,
chord of ovearhanR, .nd. thic'lr.e s cf o'.'erh ng.


C.r.parisorn of the co.-muted bol n3ed-flso hina:e-
moment coef finients wiAi th and 'rithut baslFne-chab.ier
restrictions A comoarison of t!h, cormnuted cal aoncd-
flpI hina'e-ncment coefficients, with cu.rves showing the
effect of the vertical chamber re-striction either nreg-
lected or considered, is presented in figure L1i to
illustrate te t type of balanced-fslp hinge--'orrent coef-
ficient that would be obtained if a very -!ide sei were
used in a c*onfiouratfion of .*.:: ;l-; snall balanced ileron.
For t &se cput itions, iverhanc cL}rd of 52C ?, seal
width of 0.6, 5bl = 210, an-, a sealerl-,_so width of 0.1
(values of ms obtained from figure 22(c)) wers assi.m;d
installed on the plain sealed ai l.on of figure 3,- and he
other jatr, supplied in figures 5? ?nd IC, were ass-t.L-ed LO
remain the same. (See fig. Li.) The method of computa-
tion ...as the sane as that previously outlined. Neglecting
the effect of the vertical balance-chamber restriction
(that is, with no limiting value for Ob) results in







14 AA ARR ';:i. L5FY)Oa


considerable error at large deflections, when the seal
contacts the balance-chamber ceiling. (See fig. 4l.) The
optimum seal width would be such that the seal would
barely touch the chamber ceiling at the maximum overhang
deflection (see section entitled "Effect of vertical
restriction") and, for this aileron configuration, fig-
ure 22 indicates that a seal width of about 0.5 would be
optimum. Up to deflections of 180, the curve for
aileron-hinge-moment coefficients computed for s = 0.5
and 6b = 210 is approximately the same as that shown in
figure L1 for s = 0.6 and no limiting value for 65;
for deflections beyond l18, this curve is almost parallel
to the curve shown in figure L1 for s = 0.6 and b= 210.

The error involved in the use of the approximate
method is also illustrated .in figure Ll; the approximate
method indicates that the seal contributes more balancing
moment than that actually produced over almost the entire
deflection range.


CO 07! -. SI 0 NS


As an experimental verification and an extension of
a previous analytical investigation, tests were made to
determine the hinge moments produced in an internal-
balance arrangement by fabric seals of various widths
that seal flap-nose gaps of various widths in the
presence of a thin-plate overhang. The tests were con-
ducted with horizontal, vertical, and circular types of
balance-chamber wall forward of the balance and with
various heights of the balance chamber. The investiga-
tion indicated the following conclusions:

1. The moment of the seal may be a balancing or an
unbalancing moment and may be an appreciable part of
the total balancing moment of an internally balanced flap,
depending on the overhang deflection and the configura-
tion of the internal balance.

2. Variation of the width of the seal, the sealed
gap, or the location of the seal attachment to the wing
structure affected the seal moments through most of the
overhang deflection range.








NACA ARE No. L5FDFa 1


5. Tre sh-)e and size of the b.al-ance cia.miber affected
the s3-,l-roment L: har-ct.teristics in the ,'eflec tioi r-.nce
at ''.ch th, se .c.1 c ,n ., te.., .-a.1 er- o.-ns '-r.ined by
the chamber walls; to.e v'.l'u s t' the -' i .-ri,,ents w::re
usually reduced .'then the s'als erce r.on tr.inei.

,.. An o .timum b-~alanc3 ce.nf r at..r :, mp..,,,s p,. ..1i
width cue- th.;t th s.oal oarc-ly touches th.3 chai.i r
ciiiin :I wrvn.n mJ;uxi'.um overh:-ng ijflectLon is v.tt:rined.


Langley i;norin l aeronautical Labcor'-tory
ilational AdIis.jry Cormilitte. for aeronTl,.tics
Lar.lly F-ield, Va.
























1. Rogallo, F. _., snd L.wrv~r, Jchli '.. '-~:7m jf Data
for Intdr.ally 1 al.iaced A.l. rori. !:i-C. RC., fiE2ceh


2. Murr ay, Earry E., and r- r:in, Vr P r'. : -* fing.. [:. '.rLs
of e-.aJ cd-Intern:.'l-- l..tul'.-:" -rr,-., :irmni ts Ior lo..:Trol
iLu''cCe.' I 'heore tic :.. Inv s tigati:o: ZA'.A
ARF-; lo. LSF30, l?l. 5.






NACA ARR No. L5F30a


TABLE I.- BALANCE CONFIGURATIONS TESTED


Location Width of Width of
of seal sealed gap seal 6b Figure
attachment fraction of cb) (fraction of cb) (deg)
(fraction of eb)

Vertical backplate

0 0.4 None, 15 14(a)
0 .6 None, 16, 21, 26 14(b)
.1 None, 16 15(a)
.1 .6 None, 16, 21, 26 15(b)
.2 .5 None, 16 16(a)
Center .2 .6 None, 16, 21 16(b)
of .2 .8 None, 16, 21, 26, 30 16(c)
backplate .3 .6 None, 16 17(a)
I .8 None, 16, 21, 26 17(b)
i .7 None, 16, 21 18(a)
4 .9 None, 16, 22, 26, 30 18(b)
.5 .7 None, 16 19(a)
.5 .9 None, 16, 21, 26 19(b)
0.34 above and 20 2
below center "3 .8 20 20
of baokplate .5 .9 20, 25 21
Circular backplate
0.1 0.4 None, 16 22(a)
.1 5 None, 16, 21 22(b)
.1 None, 16, 21, 25 22(c)
Center .3 .6 None, 16, 20 23(a)
of .3 None, 16, 21, 26 23(b)
backplate .3 8 None, 16, 21, 25 25(c)
5 7 one, 16 24(a)
.5 .8 None, 16, 21 24(b)
.5 .9 None, 16, 21, 25 24(c)
0.53 above and 2
below center j .8 20 2
of backplste I 5. .9 20, 252
Horizontal backplate
S 0 0. None 27(a)
0 .6 None, 16 27(b)
0 .8 None, 15, 20, 25 27(0)
.1 .4 None 28(a)
.1 .5 None, 16 28(b)
.1 .7 None, 15, 20, 25 28(c)
.1 .9 None, 25, 30 28(d)
.2 .5 None, 16 29(a)
Center .2 .7 N-ne, 15, 20, 25 29(b)
of < .2 .9 None 26, 31 29(c)
backplate .6 None, 16 50(a)
.3 .7 None, 15, 20 50(b)
.5 .9 None, 25, 51 0fc)
.6 None, l l'ea)
.7 None, 15, 20 1lb)
4 .9 None, lo, 21, 25 511()
.5 .7 None, 15 32(a)
.5 .9 None, lb, 2), 26 321D)
0.a3 above and .1 .7 20 5
oelow center j 5 9 20,26
of backplate _____


NATIONAL ADVISORY
COMMITTEE FOr AERONAUTICS






NACA ARR No. L5F30a


Flap


(a) P/an form of a semispan wing.


.hang


(b) Section A-A.


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS



Figure I .- Schematic diagram of a typical internal-balance
arrangement for an aileron on a tapered wing.


Fig. la, b






NACA ARR No. L5F30a


Fi g. 2a





NACA ARR No. L5F30a Fig. 2b




Ainge moment
equ/pmen

S&,


Figure 2(b).- Three-quarter rear view of testing apparatus.






NACA ARR No. L5F30a


Fig. 3a-d


5-0


djJ


r/l


* u
U






C--
a





.-











0o
a
c>
cid

a,


3



Cl)

.n


o C.,
1I

o C.
LL O






NACA ARR No. L5F30a


I R


o0
0
,



I:
L,,- g
,-r
N g

... m .,


Fig. 4a-d








NACA ARR No. L5F30a Figs. 5, 6, 7,8







CMCD Q
S.0 .00


m -I 0
0 0 I -


"""~ o} oe_ .-




I d c 11 I
ca co coon.



-00




:a W I
0 c 0 too


I :J -











0* 0

















o a'- r [ I
0 tr) r to














f 9M
IN ca- 1old
:~b.











NACA APP No. L5F30a Fig. 9a-d

















0o

0o co











a)
a




























.0


a,



S-
-4
-. a
a-,

U
-4











C'-











NACA ARR No. L5F30a Fig. 1Oa-d













CD 0






A. 0 A
O U2U,

00






:4 t
-. v r. E .0 c
0O Oc c










.0






v4







00.















it










bO
E-.
US ~ -





U]
-4

F..









NACA ARR No. L5F30a


o
0
o




0








































0
I3










































0
0




a,


Figs. lla,b,12,13


0









0o

uO

0















0:1


o,
r-
Go









Cd
-4





02
0 II





3-






:a










-4







*(
T-


e,

o


a< a



0 C O


cd 0 .



0
-40 0-- U








0 1C


o o IO
.EI 4, 0)


to

II

*
0



OI
0

a,> 02

0 V3

U
.0
0) 1-0









NACA APR No. L5F30a


Fig. 14a,b


(a) b = 0.4.


(Do) = ,).
Figure LA.- Hlr.i-r-i.rii ca.rafcrielCe 3f 6eLV iILL rcPL'ai c LCEDLSLe.
= u.







Fig. 15a, b


NACA ARR No. L5F30a


(a) a = 0.4.


COMMITTEE FOR AERONAUTICS
Figure 15.- Hinge-moment characteristics of seals with vertloal backplate.
6 = 0.1.








NACA ARR No. L5F30a


IBJ .U ..I.


(0e) a = D.8.
Figlre 16.- HKlne-moment. ehbacterlLatce of seale otLb vertical backplatE.
g = O. 2.


Fig. 16a-c








Fig. 17a,b


NACA ARR No. L5F30a


(a) a = 0.6.


'b) a = 0.8.
Figure 17.- Hinge-moment characteristics of seals with vertical backplate,
S= 0. 3.









NACA.ARR No. L5F30a


Fig. 18a,b


(a) e = 0. 7.


(bnJ = 0.9.

FLgure 1.- HLne--moment iearacLeriltlc of sea l tn vertical bDackriise.
S= U.4.








Fig. 19a, b


NACA ARR No. L5F30a


(a) a = 0.7.


(b) a = 0.9. WoMmni ru a
Figure 19.- Hinge-moment characteristics of seals with vertical backplate.
= 0.5.







NACA ARR No. L5F30a


Figs. 20,21


Figure 20.- H lge-muomoen cnaracterisice o ef ea&s LLacaed 0..4cb off center to
vaerloal baokpLae. a = 0.8 ; g = 0.,; b, = 200


FLiUrE :L.- irge-ooment clarBacterleice oif Cbic aitaLbed O.Z-"C. ofz cenLEr to
vertlca. bscDCzoL~. = 0.?; g = 0,5.







Fig. 22 a-c


NACA ARR No. L5F30Oa


(e) a = 0.6.

Figure 22.- Hinge-moment characteristics of seals with circular backplate.
g-= 0.1.








NACA ARR No. L5F30a


Fi g. 23a-c


(c) B = 0.8.

Figure 2.3.- HLor~-momentr cnaracterieti~ s of se.al slIa ecrcuLar backplate.
g = 3.








Fig. 24a-c


NACA ARR No. L5F30a


(c) s = 0.9.

Figure 24.- Hinge-moment characteristics of seals with circular backplate.
S= 0.5.









NACA ARR No. L5F30a


Figs. 25,26


FLgure 25.- inga--momaen characir.eistles of ealce atiacrne i- 0.'b off clear to
oLrouLar backpla.a, 8 = 0,6; g = 0..


FlTure 'j.- Hlri--orienTu cnir&acterrliie rC.f c~.Ai LtrjcE-i 0. 34CO off cnrL-r to
eLreulr bpcgilate. 6 = O.q g = 0.-.








Fig. 27a-c


NACA ARR No. L5F30a


(c) a = 0.8.
Figure 27,- Hinge-moment characteristics of seals with horizontal backplate,
S= 0.








NACA ARR No. L5F30a


(a) a = O.A.


(0. '..,. COMMITTEE FOR AERONAUTICS
Flgure .8.- Hlrie-omert -fLr. ct.r.La -r sil 4itL ecrl1rTi ,CK.iate.
-i = .1.


Fig. 28a,b







Fig. 8 c, d


NACA ARR No. L5F30a


(0) s = 0.7.


(d) s = 0.9.
Figure 28.- Conoluded.








NACA -ARR No. L5F30a


Fig. 29a-c


t.J = u.. COMMITI[ fTo ARMOnIUTCE

Filzr :,'re .- i-ir='au r" ..l chral -,:, :i i.-Li i t L bOr ::rtil D C r i:.l








Fi g. 30a- c


NACA ARR No. L5F30a


-



------ ---
I-
ztr-
1- .....


- :1' :i- .


I_ LI i4


~,L~III :4~irI TI ~':~7'Ii~T i~f{~: ~


(.1 a E u.


RF F


+A~A+iWilI1L~.A ~t:Jw~Th~'~ -J4~L4-~- L4


(b) = 0.7.

I A i -L--1 VT T~i= --0-


- -I-?LC~- 4 C_-


" -F---

---
~lFF I li


f. :1 4


I..


AIIi4I- i-f'1-9


- f:: __.-~+


----I...


- ----- ------- L-Iit. -


- -

--I LjdBL~B4~l~i i-~~L iiIA-I. 1ha4


i 'A 1:= --i:.


r7t.414: hH~ 1N-.I-H- I H~ 1-


d b: 1 F 4- 10 F


(c) a = 0.9.
Figure 30.- Hinge-moment characterletics of seals with horizontal backplate.
g = o.


I B-


SI r -
A1 -


IL-


- -
:T!
:^ -- : ;

-7 -
^-^^^I : aS
01.


77


I' Ir
-i

.- j,

:^-- -:


- t- I.;j:


j 4-
IL-


-- -I r- 4__ i Otit-1
____ FF4. I


N. NATIONAL _Qu VI O -
:COMHItTE[ F,.' A&EO.auTICS
rillb ~O-iO I


I:-- -II P* .03 U fl- i' Zi~ -ifM -i.i-U-


-mill


-r .I
^*i-. y gp p


- .- T
iid= 1


I-:


2i~
-7ME


1


I- :


. .


^**^-*J"H
*L : I" i 4 i-.l I. 77 --


I-_!


; 1. 1 m


_- -


A :I I ~L 7 1 I


II


I


I


'LLP 90


- -^ g'.y ran-.rr jf-a_ g,-<. :Q-1


-- 71


iti; I, :-;-i;"; J ; :1~i at:


K:li'lr y- i'tiii !'=n::l t;ii :- -:-i


-4- =. 53


EN 0 1-s?


a-


r-. r I-,- L T-s -, 1t


T-T


.*;- I


tB-T lt -Il !l.


- -F 1 =


Lr-


-]-- _.


---:i_ I r~ -
I


t ~


L. I'l:=-.. i'-


;,: .ifc-U- a.y


i 1 I., 1 -=;I I ,- I I I


I I I I -I


.;:at.. 'I/ eafI'H


17


-'1 I-








NACA ARI No. L5F30a


Fig. 31a-c


(a) 6 = u.o.


(,) e = ., J (CDOMIrTE FOI AI RONAUTiCS
Figure JI..- Hire--Moome cArCar6Ccrie Cf desi, iu, noruilntal DClKpieU..
7 = u.-.








Fig. 32a,b NACA ARR No. L5F30a






































(a) = 0.7.








---- T- -t I--=
__ -






















NATIONAL ADVISORY
(b) = 0.9 COMMITTEE FOR AERONAUTICS

Figure 32.- Hinge-soment characteristic f seals nsith horizontal backulate.
g -0.5.
-'- --------















=AM--
,--_ =-









(a) = 0.7.


























-Figur E-H~emm~ hrcel c feas t oiotlbe le
-:j=3-T-7








NACA ARR No. L5F30a


Figs. 33,34


F ~


Figure 33.- aLOge- -moment charocLa ritlIeC of BE&!ia aLTaL bed "0b off ce ntr to
norizontai backpplat. = 0.7, = ,7, = 0.L; b = ''.


i ki


- 1 ..j. i -' -.*-


LLj~-4444-~- I~1 f44-~


I I;


FLrur. :*.- TAr:?L-eAit JT.rlile r.i L *. t off center LC.
n, r _.::.* L [li: C.Ljl = -C-a t = ?.t.


-41..


T-b- T


StITIONAL ADU~A SOu'r
COM|TEI[ FI0 O AEIOMATl1CST=


_~~_~~~~~ ~~ ~ ~~__~ ~_~ __~~~______~_~ _


HI:


4--,-- -, l- 1 .-


:t -J


- -------


-- -- -- -- :.


M- M-1- --


IM --d


-1.


3-fEM-7F -


111MR-1-14-1 Id


+:_:- -__ -T__-







Figs. 35,36


NACA ARR No. L5F30a


Figure 35.- Effect of seal width on hinge-moment characteristics of seals.
Vertical backplate; g = 0.2; no limiting value for 6b.


.w-COMNITTEE FOR AEROi
Figure 36.- Effect of sealed-gap width on hirige-moment characteristics of seals.
Vertical backplate; s = 0.6; no limiting value for 6b.








NACA ARR No. L5F30a


Fig. 37a


(a) = u.I; a = 0. .
Figure 17.- Cc parlson of hln.re-mo.inr. carcTr ~6rLle6 for Bseali
*lth vertnabL, norl-z.roeL, aand Oroular rCiCSpieL66.







NACA ARR No. L5F30a


(b) g = 0.3; s = 0.6.
Figure 37.- Continued.


Fig. 37b








NACA ARE No. L5F30a


(c) E 0.5, = 0. .
F'laur'e 7.- Co.nuded.


Fig. 37c


NAT ONAL ADVlISOY
COMMHiTTEE FrC A ONUiIIC-







Fig. 38 NACA ARR No. L5F30a


Figure 38.- Seal-moment ratio computed by approximate method (measuring
balance chord to center of gap) for various sizes of sealed-gap width.







Fig. 39a,b


NACA ARR No. L5F30a


.E---Olc &aent 9p


(a) Sealed internally balanced aileron.


I c=.20c
leading edge c = 4.00'

(b) Plain sealed aileron, NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS
FiLvure 39.- True-contour aileron sections for
which illustrative data are presented.







NACA ARR No. L5F30a


--- Plain sealed aileron (re


------- Balanced aileron (computed from seal-momen
data)


Aileron deflection,8a, deg


Figure 40.- Comparison of section hinge-moment characteristics
measured on sealed internally balanced aileron with charac-
teristics computed from plain sealed aileron. True-contour
ailerons of 0.20c on an airfoil, a = 0o; M = 0.36.


f .08


' .04


0


04


.-08


./Z

I-16


Fig.. 40







NACA ARR No. L5F30a


.04





0
- .04
O

IZ.




I-08



-16
I y


Seal-test data ; 5b *
------ eal- lest data; G none
- -- Appro rmate meinod


\ NATIONAL ADVISORY
COMMITTtL F AERONAUTICS


-20 -16 -I/ -8 -4 0 4
Aileron deflection ,Sa,deg


d /Z 16 20


Figure 41.- Comparison of section hinge-moment characteristics
of sealed internally balanced aileron computed from seal-
moment data and by approximate method. True-contour aileron
of 0.20c on an airfoil. a = 0; M = 0.36. (Pressure data
and plain-alleron hinge-moment data from fig. 40.)


Fig. 41







UNIVERSITY OF FLORIDA
I l I I l1 II I II 1 III Il I
3 1262 08104 959 4




rUNlIVERSITY OF FLORIDA
DOCUMENTS DEPARTMENT
123 MARSTON SCiE.NCE UBRARY
RO. BOX 117011
(AINESVILLE, FL 32G11-7011 USA