The large amplitude wing-rock of a ground attack aircraft was investigated by the use of a small perturbation, linear stability analysis and a non-linear simulation of the aircraft dynamics. The linear stability analysis compared the results from a complete 6 degrees-of-freedom (DOF) coupled equation set with the results obtained using a 3-DOF dynamic stability axis set. The results showed an oscillatory instability that was caused by frequency coalescence of the primary pitch and yaw modes.

The simulation produced a rolling motion similar in nature to wing-rocks experienced in flight. The large amplitude oscillation was generated by the non-linear variations of the aerodynamic loads rather than by the instability predicted by the linearised dynamics. Specifically, the appearance of nonzero lateral moments at zero sideslip as well as shock-induced jumps in the rolling moment against sideslip curves were major contributors to the motion. These features of the static aerodynamic data are thus considered better warnings of the possibility of large amplitude wing-rock than is the negatively damped Dutch roll oscillation predicted by the linearised analysis.

The aerodynamic performance of man-powered aircraft has been considered by a number of authors including (Lilley and Spillman (1960), Lissaman et al (1979), Wimpenny (1979)). The present paper attempts a simplistic approach and gives a comparison between these simple formulae and the performance of the various designs of man-powered aircraft for which design information is available, or from measured data in flight. The latter information is generally in agreement with that tabulated in Reay (1977) and Sherwin (1971). The data on the Gossamer Condor and Gossamer Albatross were obtained from Lissaman et al (1979) and Jex and Mitchell (1982). A review of achievements in man-powered flight before the Channel crossing was given by Clark (1978).

The paper also discusses briefly the performance of manpowered aircraft with energy storage for assisted take-off and as a contribution for cruising flight. It is hoped the paper will give a broad picture of the aerodynamic performance challenge set by the Kremer (1983) World Speed Record Competition.

Ghosh's large-deflection hypersonic similitude and piston theory for plane flows have been extended to axisymmetric flows: a new piston motion in conico-annular space as an extension to Sedov's axisymmetric piston has been proposed and a set of ordinary differential equation for 1-D unsteady motion obtained. Wedge and cone flow solutions are obtained without the constant-density assumption of the earlier theory; the pressure ratio is expressed as a closed form function of the similarity parameter whereas the previous constant density theory gave an iterative procedure. The present theory unifies small disturbance theory and constant density theory.

Experimental results obtained in jets from notched nozzles in a co-flowing free stream are presented. It is confirmed that even at low jet speeds the notches produce trailing vortices and it is found that the effect on the free stream on the vortices is surprisingly small.

New wind tunnels appear fairly infrequently and are usually of individual design to meet specific requirements and constraints. Detailed information on existing tunnels can be of great benefit to the designer, enabling him to avoid expensive pitfalls and to capitalise on the successful features that have evolved over the years. For this reason, and to advance wind tunnel design generally, new designs should be reported. The following account is presented in this light, even though the low speed tunnel described is unremarkable, being of conventional design and modest proportions. Indeed, its design follows closely the guide-lines laid down for such tunnels by Bradshaw and Pankhurst, guide-lines which themselves draw on the cumulative experience gained from previous low speed wind tunnels. The satisfactory performance of the tunnel is in no small measure the result of this approach.