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National Advisory Committee for Aeronautics, Report - Lateral Control Required for Satisfactory Flying Qualities Based on Flight Tests of Numerous Airplanes

An analysis has been made of the aileron control char-
acteristics of numerous airplanes tested in flight by the
National Advisory Committee for Aeronautics. In the
correlation of satisfactory and unsatisfactory characteris-
tics with measured values, it was found that the helix angle
pb/EV, which expresses the lateral displacement of the wing
tip in a given forward travel of the airplane, was the meas-
ure of the aileron efiectiveness appreciated by the pilots.
It was also found that regardless of size or category of the
airplanes tested, which included pursuit, transport, train-
ing, and bomber types, a value ofph/ZV of 0.07 represented
a criterion of minimum satisfactory aileron ejectiveness.

By the use of previously developed theory, the observed
values of pb/2V for the various wing-aileron arrangements
were examined to determine the efective section character-
istics of the various aileron types.

A few years ago the National Advisory Committee
for Aeronautics instituted a program for the study of
airplane flying qualities. The primary purpose of the
research program was to determine quantitatively what
constitutes satisfactory flying qualities and the stability
and the control requirements that an airplane can be
expected to fulfill. Accordingly, the investigation has
consisted mainly in determining these characteristics in
flight tests of various airplanes. These airplanes were
made available largely by the Army and more recently
by private companies through the cooperation of the
Civil Aeronautics Authority.

Stability and control characteristics have now been
determined for a large number of airplanes of varied
types. The data obtained not only show what consti—
tutes satisfactory flying qualities but also, through
analysis, show how various design features influence the
observed flying qualities.

In the analysis of these data and in the preparation
of reports, it has been convenient to consider separately
the various phases of control and stability. Thus, the
present report is confined to the results of the analysis
of aileron control. In addition to the data obtained in
tests performed specifically to determine flying qualities,
data obtained in previous lateral-control investigatidns
have been included in the analysis.