Low-Speed Wind-Tunnel Measurements of Oscillatory Rolling Derivatives on a Sharp-Edged Slender Wing Effects of Frequency Parameter and of Ground

摘要

A sharp-edged wing of gothic planform and aspect ratio 0-75 was oscillated in roll about the wing axis of symmetry, and the oscillatory rolling derivatives determined over a very wide range of frequency parameter.nIf the frequency parameter is increased until the wavelength of the rolling oscillation is comparable with the wing chord, there is a marked increase of roll damping and reduction of roll stiffness at high incidence. Within the practical low-speed flight range of slender-wing aircraft designs, however, although some reduction of the stiffness derivative below its static value is likely at the highest values of incidence and frequency parameter, the damping coefficient is expected to be sensibly independent of frequency parameter at constant incidence. At practical values of frequency parameter the presence of ground leads to an increase of both roll damping and roll stiffness. While, at 10° to 15° incidence, there is little effect of ground if the trailing-edge clearance exceeds 0-4 of the wing-span, both the damping and stiffness are more than doubled at a practical touch-down clearance of 005 to 007 of the wing span.