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National Advisory Committee for Aeronautics, Technical Notes - Mercerization of Cotton for Strength with Special Reference to Aircraft Cloth

This report is the ninth on a series of systematic
tests in which various lateral control devices are com—_
pared, with particular reference to their effectiveness
at high angles of attack. The present tests were made
with ordinary flap-type ailerons on two wings with dif~
ferent amounts of taper, one medium and the other extreme.
On each wing both medium-sized tapered ailerons and short
wide tapered ailerons Were tested and, in addition. on the
wing with the extreme taper, medium and short wide aile-
rons having a constant chord were tested.

The tests, which were made in the N.A.C.A. 7 by 10
foot wind tunnel, showed the effect of the different plan
forms on the general performance and lateral stability
characteristics of the wings, as well as the effect of the
different aileron shapes on the lateral controllability.
It was found that the rolling control given by the aile—
rons on the wing with medium taper was about the same be»
low the stall as that for corresponding ailerons on rec~
tangular wings, but above the stall the rolling control
was somewhat lower than on rectangular wings and well be—
low an assumed satisfactory value. At angles of attack
below the stall the yawing moments caused by the ailerons
were somewhat lower on the wing with medium taper than on
a rectangular wing, but just'above the stall the adverse
yawing moments were greater. The ailerons on the wing
with extreme taper gave better lateral control at angles
of attack below the stall in regard to rolling‘ yawingll
and hinge moments than corresponding ailerons on rectangu—
lar wings or on the wing with medium taper, but just above
the stall the rolling moment; fell off almost completely
and adverse yawing moments 0 meat magnitude acourred.

A series o£;systematic wind—tunnel investigations,
one of which is covered by this report, is being made by
the National Advisory Committee for Aeronautics in order
to compare various lateral control devices. The various
devices are given the same routine tests to show their
relat‘ve merits in regard to lateral controllability and
their effect on_the_ lateral stability and on airplane per—
formance. The? are being tested first on rectangular
Clark Y wings of aspect ratio 6, and then on wings with
different plan forms and also wings with such Variations
as washOut and sweepback, which affect lateral stability.

Part I of this series (reference 1) dealt with three
different sizes of ordinary ailerons on rectangular wings.
One ofl.these ailerons was of medium size taken from the
average of a numher of conventional airplanes,_one was
extremely short and wide, and the other was extremely long
and narrow.. All the ailerons were proportioned to give
amproximately equal_controllability at angles of attack
below the stall with equal _up~and~down deflection. The
results were analyzed.