Measurement of the pitching-moment derivatives for rigid tapered wings of hexagonal planform oscillating in supersonic flow

Abstract

Pitching-moment derivatives have been measured, using a free-oscillation technique, for a series of thin tapered wings with both streamwise and raked tips. Wings of three aspect ratios (A.R. = 2.74, 2.00 and 1.25) were tested with three positions of the pitching axis (h = 0.4, 0.5 and 0.6). The Mach number ranged from 1.38 to 2.47 and the Reynolds number and frequency parameter were less than 1.6 x 10power6 and 0.03 respectively. Tunnel boundary-layer effects were avoided by the use of reflection plates. A smaller test programme was also carried out on the effects of a body (non-oscillating) in close proximity to the wing with two alternative nose shapes. The theory predicted the trends of the derivative variation with Mach number. The numerical agreement was much improved when allowances were made in the theory for finite thickness of the wings. The effect of the body on the derivatives was very small; the only significant difference found was in the stiffness derivative at h = 0.4.