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Wind Tunnel Tests of Ailerons at Various Speeds - II - Ailerons of 0.20 Airfoil Chord and True Contour with 0.60 Aileron-Chord Sealed Internal Balance on the NACA 66,2-216 Airfoil

SUMMARY

Hinge-moment. lift. pressure difference across the
balance, and pressuretdistribution measurements were made
in the two-dimensicnal test section of the stability tun—
nel on a 0.60 aileron-chord sealed internal—balance ai-
leron on the NASA 66,2-216. a = 1.0 airfoil.

The primary object of these tests was to determine
the effect of speed on the action of this aileron. The
airspeed was varied from 150 to 360 miles per hour, corre-
sponding to Mach numbers of approximately 0.197 to 0.475,
respectively. The vent gap was varied from 0.0025 wing
chord to 0.0100 wing chord.

The variations in section hinge—moment coefficient.
section lift coefficient, and pressure coefficient across
the balance with Mach number, angle of attack. aileron an-
gle, and vent gap are given graphically. The pressure
coefficient across the balance has been given in order that
the desired amount of balance can be more readily obtained.
Gross plots have also been included to show the general
effect of changes in Mach number and vent gap.

An increase of speed in the range tested generally
increased the slopes of the curves of hinge-moment coe_ffi—
cient and lift coefficient and also caused a considerable
decrease of the unstalled range of the aileron.
INTRODUCTION

The forms of ailerons in use today have given perform-
ance that was satisfactory according to previous require—
ments. With the development of current combat airplanes.
however. large increases in speed and wing area, together
with the demand for higher rolling velocities. have intro—
duced difficulties such as overbalance at high speeds on
some of the existing aileron installations.

This difficulty with balance is apparently the result
of compressibility effects on the almOst exact balance re—
quired at high speed. It has been considered desirable.
therefore, to reinspect some of the currently used or re-
cently proposed balance arrangements from these considera~
ticns. The EAOA is therefore undertaking a study of some
of the more promising aileron forms at higher speeds than
those employed in previous development. As reported in
reference 1' an aileron of 0.20 airfoil chord with 0335
aileron—chord bluntznose balance has already been tested.
The present investigation was made to determine the effect
of speed, up to a Mach number of 0.475, on the section
characteristics of a 0.20 airfoil—chord aileron of true
contour with 0.60 aileron—chord sealed internal balance on
the HAUL 66,2—216, a = 1.0 airfoil, and also to determine
the effect of variation of vent gap on the aerodynamic
characteristics. The 0.60 aileron-chord balance was chosen
because unpublished data from Ames Aeronautical Laboratory
has indicated that satisfactory hinge-moment characteris-
tics would be obtainsd on this type of aileron with this
airfoil section.

Curves showing the variations of aileron section hinge-
moment coefficient, section lift coefficient, and pressure
coefficient across the balance with aileron angle are plot-
ted for five airspeeds that correspond to Each numbers of
0.197 to 0.475. Gross plots showing typical effects of var-
ious parameters on the aerodynamic characteristics are in-
cluded for comparisons. A comparison of this aileron with
the bluntinose aileron of reference 1 on the same airfoil
is also included.