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National Advisory Committee for Aeronautics, Research Memorandum - The Static Longitudinal Characteristics of a Yawed and Cambered 45° Sweptback Wing at Mach Numbers up to 0.96

In order to increase the range of airplanes incorporating sweptback
wings, attempts have been made to reduce the drag due to lift of the wing
by employing various types of camber. A conical type of camber (camber
concentrated near the wing leading edge, as suggested in ref. 1) was
successfully used in reference 2 on a #50 sweptback wing of aspect
ratio 3.

Section data presented in reference 3 indicate that improvements in
lift-drag ratio may'be obtained at high subsonic Mach numbers by a more
uniform chordwise distribution of camber rather than concentrating it near
the leading edge as for the conical type of camber. However, both refer-
ences 3 and h show that a rearward distribution of camber results in an
increased negative pitching moment at zero lift which usually increases
the trim drag. This zero-lift pitching moment may be avoided by a Judi-
cious choice of the spanwise variation of wing twist and by the spanwise
variation of the ambunt and type of camber.

The present investigation was undertaken to evaluate a more uniform
chordwise distribution of camber for a swept wing than is entailed with
conical camber. The wing, which was tested in conjunction with a body of
fineness ratio 12. 5, had an aspect ratio of 3, a taper ratio of 0. h, and
M50 sweepback of the leading edge. The camber of the wing was varied
spanwise and the wing was twisted -5° from the root to the tip to reduce
the pitching moments at zero lift.

The tests were conducted in the Ames l2-foot pressure wind tunnel
at Mach numbers from 0. 60 to 0.96 at a Reynolds number of l. 5 million,
and for Reynolds numbers from 3 to 8 million at a Mach number of 0.22.

The tests were conducted both with and without roughness strips near the
leading edge of both the upper and lewer surfaces of the wing. The wing—
body combination teeted is identical in projected plan form to that
reported in reference 2. Comparisons have been made of the data of the
pres_ent investigation with similar data presented in reference 2 for a
conically cambered wing having a design lift coefficient of 0. 22.