Measurements of the direct pitching oscillation derivatives for three cropped delta and three arrowhead planforms at subsonic and transonic speeds

Abstract

Measurements of the direct pitching oscillation derivative coefficients on three cropped delta and three arrowhead planforms have been made at subsonic and transonic speeds in the N.P.L. 9½ in. High-Speed Tunnel. The cropped delta wings had aspect ratios of 3.0, 2.0 and 1.5, whilst the arrowheads, of constant aspect ratio 2.575, possessed varying degrees of leading- and trailing-edge sweepback. The measurements were made about two model axes for each planform and the effects of changing amplitude of oscillation from 2° to 1° have been investigated in the transonic region. Comparison with subsonic theory is reasonably good for the damping and stiffness derivative coefficients measured about the forward axis but agreement for the latter coefficients is poorer for all the rearward axis positions.