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National Advisory Committee for Aeronautics, Technical Notes - Span Load Distribution on Two Monplane Wing Models as Affected by Twist and Sweepback

The results presented in this note show the effect of twist
and sweepback on the span load distribution over two monoplane
wing models. The tests were made in the Atmospheric Wind Tunnel
of the Langley Memorial Aeronautical Laboratory. The data are
taken from the results of an investigation dealing primarily with
lateral stability. As presented, they are suitable as an aid in
the structural design of certainlmonoplane wings.

In designing an airplane wing for maximum structural safety
and efficiency, a knowledge of the actual d1stribution.of the air
loads along the span is essential. If the wing is provided with
either twist or sweepback, the distribution is no longer the same
as for a straight wing. However, comparatively little informa~
tion as to the changes thus produced has been published heretofore.

This report has been prepared for the purpose of making aVail—
able for design a limited amount of data on the aerodynamic char—
acteristics of two monoplane wing models as affected by changes
in twist and sweepbackt The results are taken from a series of
pressure distribution tests made primarily for the study of later—
al stability. The tests were conducted in the AtmOSpheric Wind
Tunnel of the Langley Memorial Aeronautical Laboratory (Reference).

The shapes of the two semi—span models and the locations of
the points at which the pressures were measured are shown in Fig—
ure l. One of the models, which Was designated the N.A.C.A. 84
wing, had the N.A.C.A. 84 airfoil profile from the root to the
tip. The other, the N.A.C.A. 86 wing, had the N.A.G.A. 84 pro-
file at the root and the symmetrical N.A.G.A.—M2 profile at the
tip. These profiles are shown in Figure l, and their ordinates
in per cent of chord are given in Tables I and 11. As may be seen
from the figure, both wings had essentially rectangular plan forms
except at the extreme tips which were so designed that any tip I
cross section normal to the mean camber line was a semicircle
whose diameter Was the wing thickness at that section.