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• August 26, 2016 Create Date
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National Advisory Committee for Aeronautics, Report - The Aerodynamic Characteristics of a Slotted Clark Y Wing as Affected by the Auxiliary Airfoil Position

Aerodynamic force tests on a slotted Clark Y wing
were conducted in the rertical wind tunnel of the National
Advisory Committee for Aeronautics to determine the
best position for a given aunIiary ain‘oil with respect to
the main wing. A systematic series of 100 changes in ,
location of the auriliary airfoil were made to cover all the
probable useful ranges of slot gap, slot width, and slot
depth. The results of the innestigation may be applied
to the design of automatic or controlled slots on wings
with geometric characteristics similar to the wing tested.

An increase of 41.5 per cent in. the maximum lift above
that of the plain wing was obtained for the slotted Clark
wing. At the same time, the angle Qf attack for maximum
lift was increased 13°. It was found that a maximum
increase of about 30° was possible in the highest stalling
angle, but at a maximum lift coqfiz‘cient slightly less than
that of the plain wing. However, with one slot position,
an increase of 25°, together with an increase in the maxi-
mum lift coefficient of 23.3 per cent, was obtained. The
best positions of the auxiliary airfoil were conered by the
range of the tests, and the position for desired aerody-
namic characteristics may easily be obtained from charts
prepared especially for the purpose.

Lateral stability and control up to large angles of
attack form an important part; in the program of re-
search relating to safety in flight now being conducted
by the National Advisory Committee for Aeronautics.
A series of tests, comparing a large number of devices
for obtaining lateral control and stability, has been
started in the atmospheric Wind tunnels. A wing with
slots and ailerons (one of the standard forms in com—
mon use) will be tested among the first, to serve as a
basis of comparison for special devices.