Pressure fluctuation measurements were made on an 18% thick biconvex aerofoil in the region of shock boundary layer interaction at various levels of free stream flow unsteadiness. Experiments were performed with free transition and transition fixed models at a shock Mach number of 1.44 and blade chord Reynolds number of 1.6 x 105. The transition free model with a laminar boundary layer showed the presence of periodic flows at low turbulence levels which disappeared with the increase in turbulence levels. The general effect of free stream turbulence on transition fixed model is one of broad band amplification of pressure fluctuation levels in the region of shock interactions.

A survey is presented of results obtained from experiments in the RAE 5m low-speed pressurised wind tunnel. The tunnel is capable of operation over a range of pressures (from one to three atmospheres) so that the effects of Mach and Reynolds number may be separated. This decoupling of scale and compressibility effects has made possible reliable extrapolation of test results to full-scale conditions (where this is necessary) as well as giving greater insight into the underlying flow mechanisms. The large size of the tunnel, combined with pressurisation to three atmospheres, has enabled some tests, on small combat/trainer aircraft and on bomb-like stores, to be carried out at full scale.

Three facets of the work of the 5m tunnel are described — work aimed at predicting or improving the high-lift performance of specific aircraft, work of a more fundamental nature concerned particularly with the optimisation of high-lift devices on generalised research models, and work on the drag of stores carried externally on combat aircraft.

An experimental study has been made of the conditions necessary to produce transition in a swept attachment-line boundary layer which is subjected to disturbances from trip wires of various sizes. The boundary layer considered is that formed on a long, untwisted, tapered wing which has been tested in both the backward swept and forward swept configurations. Results from these tests are compared with previous work on an untapered model. Some important similarities and some puzzling differences have been found. Finally consideration is given to the practical implications of this work. It is suggested that a forward swept wing may be capable of supporting a laminar attachment-line flow at a much higher free-stream Reynolds number than a corresponding swept-back wing.