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Wind Tunnel Tests of Ailerons at Various Speeds - I - Ailerons of 0.20 Airfoil Chord and True Contour with 0.35 Aileron-Chord Extreme Blunt Nose Balance on the NACA 66,2-216 Airfoil

Hinge—moment. lift. and pressure-distribution
measurements were made in the two-dimensional test section
of the NADA stability tunnel on a blunt—nose balance-type
aileron on an NAOA 66.2-216'airfoil at speeds up to 360
miles per hour corresponding to a Mach number of O. 475.
The tests were made primarily to determine the effect of
speed on the action of this type of aileron. The balance-
nose radii of the aileron were varied from 0 to O. 02 of
the 'airfoil chord and th's gap width was varied from 0.0005
to O. 0107 of the airfoil chord. Tests were also made with
the gap sealed. .

The variations in hinge momenta and lift with Mach
number. angle of attack. and aileron deflection are given
in the form of curves of section hinge-moment coefficients
and section lift coefficients plotted against aileron '
deflection for the varione conditions tested. together with
cross plot: showing the general effect of Mach number. gap
width. and balance-nose radii.

The results shoe that there was a considerable in—
crease in the stalled range of the_aileron with increased
speed. Up to the stall. the variation in hinge-moment
coefficients and lift coefficients for the speed range
tested was small but the variation may be appreciable when
stiok forces at high speeds are considered.
rrrsonucrlon

Large increases in the size and speeds of current
combat airplanes. in addition to high maneuverability re-
quired in combat. have made it necessary to balance almost
exactly the hinge moments of ailerons and at the same time
to maintain their effectiveness. Although most types of
aileron balances in use today operate satisfactorily at
low speeds. difficulty. such as overbalance at high speeds;
has been experienced with some existing aileron installa-
tions. This difficulty is apparently caused by the large
amount of balance coupled with the changes in hinge moment
that result from compressibility effects. Consideration
of these problems has made necessary further research on
some of the currently used or recently proposed balance
arrangements.

The NASA is therefore undertaking a study of some of
the more promising aileron types at higher Each numbers
than were employed in previous developments. This report
deals with the section characteristics of a blunt—nose
balance type of aileron of 0.20 airfoil chord with a 0.35
aileron balance and of true contour used on an NASA 66.3-316
airfoil. The amount of balance. 0.35 aileron chord. was
chosen because. from the data given in reference 1. it was
estimated that this amount of balance would give almost
complete balance on an airfoil of the NAGA 330 series at
a low angle of attack.

The section lift coefficient at and the section
hinge-moment coefficient cha were measured at various
airspeeds up to 360 miles per hour. corresponding to a
Mach number of 0.475. These measurements were taken
through an angle—ofFattack range-from ~5° to 10° and an
aileron deflection range of £200. The influence of the
gap width between the aileron and wing and the influence
of the radii of the projecting corners of the balance were
investigated. The data are presented in the form of curves
of c; and cha plotted against aileron deflection with

cross plots to show the effect of the aileron parameters.