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National Advisory Committee for Aeronautics, Technical Notes - Wind Tunnel Investigation of Effect of Yaw on Lateral Stability Characteristics - I - Four NACA 23012 Wings of Various

Four N.A.C.A. 23012 wings were tested at several an-
gles of yaw in the N.A.C.A. 7— by 10-foot wind tunnel.
All the wings have rounded tips and, in plan form, one is
rectangular and the others are tapered 3:1 with various
amounts of sweep. Each wing was tested with two amounts
of dihedral and with partial— span split flaps.

The coefficients of lift, drag, and pitching moment '
are given for all the models at zero yaw. The coeffi—
cients of rolling moment, yawing moment, and side force
are given for the rectangular wing at all values'of yaw
tested. The rate of change in the coefficients with an—
gle of yaw is given in convenient form for stability cal—
‘culations.

Mathematical equations have been available for some
time and convenient charts are given in reference 1 for
predicting the lateral stability of airplanes. The prac—
tical use of the equations or charts, however, depends
upon the knowledge of the lateral—stability derivatives
for the particular airplane in question. Among the fac—
tors affecting the values of these derivatives are wing
and fuselage forms and interference between the various
parts of the airplane.

The effect of various tip shapes and amounts of di—
hedral for a rectangular Clark Y wing are given in refer—
ence 2. A theoretical prediction of some of the lateral—
stability characteristics for wings is given in reference
3. The present investigation of N.A.C.A. 23012 wings was
made to determine the effect of taper, sweep, dihedral
and partial— —span split flaps on the lateral— stability char-
acteristics that depend upon sideslip.

Lateral—stability characteristics of the.wings and
equations for computing approximations to these character—
istics are given in the report. The force and the moment
coefficients are also included.

The tests Were made in the N. A. C. A. 7— by 10— foot
wind tunnel with the regular 6— component balance. The
closed— throat tunnel is described in referenc-e 4 and the
balance is descr-ibed in reference 5.

The models are made of laminated mahogany to the
N.A.C.A. 23012 profile. Plan~form and elevation drawings
of the wings are given in figure 1 and a photograph of one
of the tapered wings mounted on the balance is given in
figure 3.