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National Advisory Committee for Aeronautics, Technical Notes - Wind Tunnel Research Comparing Lateral Control Devices, Particularly at High Angles of Attack - X - Various Control Devices on a Wing with a Fixed Auxiliary Airfoil

This is the tenth report on a series of systematic
tests comparing lateral control devices with particular
reference to their effectiveness at high angles of attack.
The present tests were made with two sizes of ordinary ai—
lerons and different sizes of spoilers On a Clark Y wing
model having a narrow auxiliary airfoil fixed ahead and
above the leading edge, the chords of the main and auxil—
iary airfoils being parallel. In addition, the auxiliary
airfoil itself was given angular deflection for the pur—
pose of providing rolling moments for lateral control.

The tests were made in the N.A.C.A. 7 by 10 foot wind
tunnel. They included both force and rotation tests to
show the effect of the devices on the lift and drag char—
actsristics of the wing and on the lateral stability char-
acteristics, as well as on lateral control. They Showed
that none of the -aileron arrangements tried would give
rolling control of an assumed satisfactory value at all
angles of attack up to the stall except at the expense of
abnormally high deflections and very heavy hinge moments.
The most effective combination of ailerons and spoilers
gave satisfactory values of rolling moment at all angles .
of attack below the stall and the values did not fall off
as rapidly above the stall as with ailerons alone. With
an arrangement of this type having the proper relative
proportions and linkage it should be possible to obtain
reasonably satisfactory yawing moments and control forces.
Deflecting one-half of the auxiliary airfoil doanard for
the purpose of control gave strong favorable yawing mo—
ments at all angles of attack but gave very small rolling
moments at the low angles of attack.

A series of 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
relative merits in regard to lateral controllability and
their effect on the lateral stability and the performance
of an airplane. They are being tested first on rectangur
lar Clark Y wings of aspect ratio 6, followed by wings
with different plan forms, wings with high lift devices,
and also wings with such variations as washout and sweep—
back, which affect lateral stability. The first report
of this series (reference 1, Part I) deals with three
sizes of ordinary ailerons, one of these a medium—sized
one taken frOm the average of—a number of conventional
airplanes and used as the standard of comparison through~
out the entire investigation. other work that has been
done in this series is reported in reference 1, Parts II
to IX.