Flight tests of the lateral control characteristics of an F6F-3 airplane equipped with spring-tab ailerons

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Title:
Flight tests of the lateral control characteristics of an F6F-3 airplane equipped with spring-tab ailerons
Alternate Title:
NACA wartime reports
Physical Description:
6, 11 p. : ill. ; 28 cm.
Language:
English
Creator:
Williams, Walter C
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:
Fighter planes   ( lcsh )
Aerodynamics -- Research   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
Summary: Flight tests were made to determine the lateral control characteristics of an F6F-3 airplane equipped with spring-tab ailerons, which were developed by the Grumman Aircraft Engineering Corp. and have been made a production installation on F6F airplanes. The flight tests showed that the spring-tab ailerons had desirably light stick forces and no tendency to overbalance. Although the tabs were not mass-balanced, no flutter tendencies were indicated at speeds up to 400 miles per hour, and any oscillations following abrupt control deflections were heavily damped. The spring-tab ailerons gave 80 percent higher values of effectiveness with a 30-pound stick force at 400 miles per hour than the original ailerons on the F6F-3 airplane. At speeds lower than 275 miles per hour, the spring-tab ailerons were less effective than the original ailberons because of restricted aileron travel as a result of the use of large deflection to deflect the spring Recommendations are made for modifications that would increase the aileron effectiveness at low speeds without affecting the lateral control at high speeds. The modifications consist of increasing the available aileron deflection and modifying the spring-tab arrangement. Such an arrangement might, however, be more susceptible to flutter than the production installation.
Bibliography:
Includes bibliographic references (p. 6).
Statement of Responsibility:
by Walter C. Williams.
General Note:
"Report no. L-149."
General Note:
"Originally issued April 1945 as Advance Restricted Report L5C23."
General Note:
"Report date October 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."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 003605252
oclc - 71066887
System ID:
AA00009389:00001


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iVA Ltr/I'q


ARR No. L5C23


NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS


WARTIME REPORT


ORIGINALLY ISSUED
April 1945 as
Advance Restricted Report L5C23

FLIGHT TESTS OF THE LATERAL CONTROL CHARACTERISTICS OF AN
F7F-3 AIRPLANE EQUIPPED WIH SPRING-TAB AILERONS
By Walter C. Williams


Langley Memorial Aeronautical
Langley Field, Va.


Laboratory


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-
4 viously held under a security status but are now unclassified. Some of these reports were not tech-
S ically edited. All have been reproduced without change in order to expedite general distribution.
L 149


DOCUMENTS DEPARTMENT


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NACA ARR No. L5C25 I

NATIONAL ADVISORY COMMITTEE FOR AEF.ONATJTTCS


ADVP.ICE RESTRICTED REPORT


FLIGHT TESPS OF THE LATERAL CONT1RL CHAPACTEEISTICS OF AF

F6F-3 AIRPLANE EQUIPPED iT.TH SPFING-TAB AILE?0?:S

By Walter C. w'illialrs


S UP1:, 'A R Y
SUMFARY


Flight tests were r:ade to determine the lateral con-
trol characteristics of an F6F-$ cairnlane equipped with
spring-tab ailerons, which were developed by the GruTman
Aircraft Engineerirg Corp. anid have been made a production
installation on FbF airplanes.

The flight tests showed that the spring-tab ailerons
.had d:sirably light stick forces and no tendency to over-
balance. Although the tabs were not mass-balanced, no
flutter tendencies were in-icated at cpeeds up tc L3DOO .iles
per hour, and any oscillations following abrupt control
deflections were heavily danced. T'ne spring-tab ailerons
gave 80 percent higher values of effectiveness with a
50-pound stick force at 400 miles per hour than the
original ailerons on the F6F-5 airplane. At speeds lower
than 275 miles per hour, the spring-tab ailerons .cnre less
effective than the original ?ilerons because of restricted
aileron travel as a result of the use of large stick
deflection to deflect the sprinE tab. FecorrLmeridations are
made for modifications that would increase the aileron
effectiveness at low speeds without affecting, the lateral
control at high speeds. The modifications consist of
increasing the available aileron deflection and modifying
the spring-tab arrangement. Such an arrantgnent r.iht,
however, be more susceptible to flutter than the produc-
tion installation.


TIrTRODUCTI ON


Flight tests were made to determine the lateral con-
trol characteristics of an F6F-5 airplane equipped v.ith
spring-tab ailerons, which were developed by the Grumm.an
Aircraft Engineering Corp. and have been made a production









NACA ARR No. L5C23


Installation on F6F airplanes. Considerable interest has
been shown in the use of spring tabs as a means of balancing
control surfaces on high-speed airplanes, because spring
tabs permit light control forces to be obtained at high
speeds without making the balancing action critical to
srrall changes in control-surface contour. These advantages
are obtained because the balancing action provided by a
spring tab is proportional to the applied control force,
and vary close aerodynamic balance of the control surface
i3 not required.


AIRPLANE AND AILERONS


The F6F-3 airplane is a low-wing, single-place,
single-engine, fighter-type monoplane. A three-view
drawing of the airplane is shown as figure 1. The spring-
tab Lilerons nave a Frisa type nose balance and are
identical to the original F6F-3 ailerons except that a
spring tab has been installed on each aileron. These
spring tabs are id-ntical in size and location to the
trim tab on the original r6F-3 ailerons; in the case of
the spring-tab ailerons, however, the tab on the left
,.ileron is a combination trim and spring tab. Details
of the spring-tab aileron arrangement are shown in fig-
ure' 2 and 3, which were furnished by the Crumman Aircraft
En Ti'neerinr Corp. Dimensions pertinent to the hileron
characteristics are as follows:

Ting span, feet . 2.8
Aileron span (each), feet . .375
Distance from center line of airplane to
irnboard cnd of aileron, percent semisoan 64
Aileron chord, percent wing chord . 20
Aileron area behind hinge line (each), square feet .7.4
Sorirg-tab area (each), square foot 0.46
Soring-tab span (each), feet . 1.75
Stick force required to deflect spring tab 10
pounds .. . 1.6

No preload was used in the spring of the arrangement
tested and the tabs had no mass balance. The variation
of stick position with right-aileron spring-tab angle
with the aileron held neutral is shown in figure U. The
tab angles are measured in degrees from the aileron. The
relation between stick position and right- and left-aileron
angle, with no load on the control system, is shown in
figure 5. The aileron angles are referenced to neutral.









NACA ARR No. L5C25


I ENTRU'MEDNTATION


Standard NACA photographic recordings lintr'xmr.ilts,
synchronized by an electric--l timer, were usd to neacsure
airspeed, rolling velocity, s leron stick force, and the
position of the spring tab, allsron, and stick. Corr ct
service indicated airsrneed Vi used herein is defined
-s
as


S

whe re

T = 45.o0

fo ccrpressibi lity corrction at sea level

qo impact pressu-re, mTrnasur-d dlffearnice between static
and t.ot.l-bead pr--sures corrected for position
error, inches of -'ater


TECT FESULTS At'D DTSCUSSIOLH


Tests were nmade to determine whetherr tihe spring-tnb
ailerons tended to os'l llat- or fli'tt3r in th-e o3?-ed range
to 400 ril s per hour. These tests consisted of :anaIuvrs
in which the pilt fboruptly dcfl icted and released3: the
aileron control :'.t various spsoeds. 'lypicil time histories
of the maneuvers are shown in figure b, vhich inl icntes
that any oscillation of the aileron or sprin,-: tab vas
heavily damoed and disappeared completely within two
cycles. The pilot reported no flutter in the speed. r.:nge
up to !00 miles per hour.

The lateral control characteristics were measured in
abruot aileron rolls with the rudder held fixed as
described in reference 1. These rolls were made at
increments of 50 miles per hour from anproximately 100
to 400 miles per hour. The results are given as thu
variation of helix angle pb/2V and change in aileron
stick force at various speeds vith the change in total
aileron angle in figure 7 and with stick position in
figure 8. No force data are shown in these figures for










NACA ARR No. L5C23


most of the end points on the 2b-curves because the con-
2V
trol stick was against the stops and the forces recorded
were a measure of how hard the pilot was pushing against
th: stops rather than a measure of the force required to
deflect the ailerons. Limited stick deflections were used
'-t 550 and LOO miles per hour in order that the structure
design loads of the system would not be exceeded. Figures 7
Uar.: S show that the aileron stick forces are quite light
A.nc. thcre is no tendency toward overbalance. It should
oe noted hovevar that, although the end test points in
figure 7 indicate partial aileron deflection, figure 8
shows that substantially full stI.ck travel was used to
obtain thbcse aileron deflections. This condition occurs
because considerable stick travel is used to deflect the
spring t.b.

In all flights for which data are presented herein,
the transmitter of an VACA electrical control-position
recorder was mounted externally on the right aileron to
r-easure the spring-tcb angles. A flight made without the
transmitter, however, showed tnat this protuberance caused
no change in the aileron characteristics. The results
of the measurements of spring-tab angles during the abrupt
rileron rolls are shown in figure 9 as the variation of
sznrng--tab angle on the right aileron with deflection of
that sileron. The similarity of these curves to curves
of .-rn,-r':oment coefficients for a Frise type aileron,
CLiZh ss is used on the F6F-3 airplane, indicate that the
tcb angle is proportional to the stick force required
to reflect the aileron. That is, for the down-aileron
deflections, the large tab angles indicate little aero-
dynamic balance; while for the up-aileron deflections
thi negative tib angles tend to oppose the aileron travel,
which indicates aerodynamic overbalance, until separation
occurs about the nose. Separation decreases the aerodynamic
balance ancd causes the spring tab to deflect in a direc-
tion to aid in deflecting the ailerons.

:he over-all efficiency of the spring-tab ailerons
is compared with tnat of the original F6F-5 ailerons in
figures 10 and 11. These figures present, respectively,
the ph/2V and the rolling velocity at an altitude of
10,000 fet obtained throughout the speed range with full
stick deflection or 30-pound stick force, whichever occurred
first. The data for the original ailerons were obtained
from a flight investigation (unpublished) of the handling
qualities of the F6F-3 airplane. These data show that










NACA ARR No. L5C23 5


the spring-tab ailerons are less effective than the
original ailerons at spe.eds lower than approximately
275 miles per hour. The loss in effectiveness of the
spring-tab ailerons is caus'cd by the lirr.ited aileron
travel, which results from the use of Irr-gc stick
deflection to deflect the spring tab. At speeds greater
than 275 miles per hour, the effect of ths lighter stl.ck
forces of the spring-tsb -illeron.s be: Dres iredom-inant
and, as a result, the aileron effectiveness obtained
with a 50-pound stick force st L.Oi miles per hour is
approximately 80 percent higher v'itn the spring-tab
ailerons than the aileron -tffs ctiveness obtained with
the original ailero-s.

The loss in effectiveness of the spring-tab ailercns
can be decreased at low speeds without affection ; the
desirably light stick forces at high speeds if a stiffer
spring is used and if, st the same time, the length of
the tab actuating arm (fig. 2) is so increased that the
ratio of stick force to tab deflection is kept the sanre
as in the spring-tab aileron tested. In this sLy,i -ested
arrangement, the stick reflectionn re-quired for full tab
deflection would be decreased and this c.ecrease would
allow larger oileron deflection. Such an arrange-.ment,
however, miu.ht make the tab installation more susceptible
to flutter (reference 2): that is, the tab would have a
greater mechanical sdvr.nta:e over the control system
than the spring-tab tested and, therefore, inertia effects
of the tab would be more likely to cause flutter. further
increases in aileron effectiveness a-t the lover speeds
could be accon'olished by increasing t.he down-aileron
deflection to the same value as the present up-aileron
deflection. Increases in the uo-aileron deflection
are not recommended, however, since figure in.irsates
flow separation saout the nose balance and any f."cre.se
in uo-aileron deflection might therefore result in
aileron buffet at full deflection. Altho'..u-h the increase
in down-ai.leron deflection might result in sc.r.e'jiuhat higher
stick forces throughout the speed range, some reduction
could be made in the spring stiffnes to reduce the stic.
forces to the present values Sand, at the same time, retain
increased alleron effectiveness at low speeds.

CON LT S IO::

Flight tests to determine the lateral control char-
acteristics of an F6F-3 airplane equipped with spring-tab
ailerons indicated the following conclusions:









NACA ARR No. L5C25


1. The spring-tab ailerons on the F6F-3 airplane
showed no tendency to flutter in the speed range up to
)4.00 miles oer hour, and any oscillations following
Rbrupt control deflection were heavily damped.

2. The spring-tab ailerons had desirably light stick
forces v.ithout any tendency to overbsiance.

5. The spring-tab ailerons gave SG percent higher
values of effectiveness with a 50-pound stick force at
400 miles per hour than the original '6F-3 ailerons. At
speeds lower than 275 riles per hour, the spring-tab
ailerons had less effectiveness than the original ailerons
because of restricted aileron travel as a result of the
use of large stick deflection to deflect the spring tab.

4.. The available aileron effectiveness with the
spring-tab ailerons at the lower speeds could be in-reased
without affecting high-speed lateral control by an increase
in the available aileron deflection and a modification
of the spring-tab arrangement. Such an arrangement might,
however, be rrore susceptible to flutter than the produc-
tion installation.


Lan,.ley Memorial Aeronautical Laboratory
I'tional Advisory Committee for Aeronautics
Langley Field, Vs.









REFERE 'CES


1. Johnson, Harold I.: TACA Procedure for Plight Tests
of Aileron Characteristics of Airplanes. FACA
EB "Jo. 3G24, 194L.

2. Collar, A. R.: The Prevention of Flutter of Spring
Tabs. Re,. Uo. S.M.E. 3249, British P.A.E.,
May 19L5.








NACA ARR No. L5C23


5 97/


13' 1" DIAM. THREE-BLADE
HAMILTON STANDARD PROPELLER
GROUND-LINE STATIC LOAD


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