There can be no doubt that Sir Sydney Camm has left an enduring legacy, both within the aerospace industry as a whole and in the RAF in particular. Indeed, the fact that the RAF has been flying one or more aircraft designed either in part or wholly by Sir Sydney Camm for the majority of the 75 years of our existence provides ample testimony to the extent of that legacy (Fig. 1). A military theme for this paper would therefore seem to be entirely appropriate.

The challenge, of course, stems from the reduced threat of global war and the rather greater likelihood of further conflicts such as that seen in the Gulf (Operation GRANBY). These developments have required the RAF to undertake a radical reappraisal of its size, composition and operational posture.

This paper describes the incompressible flow through contracting ducts as used in windtunnel circuits. The value of the velocity gradients that are critically adverse to the boundary layer development are specified and the contraction profile is derived for two-dimensional flow. Solutions to the flow through three-dimensional contractions of circular, square, and square to rectangle shape are obtained. These lead to simple rules for scaling the profile of two-dimensional flow to provide three-dimensional shapes having short lengths with the required velocity distributions. The development of both laminar and turbulent boundary layers is calculated to provide criteria for the avoidance of separation.

This paper presents the results of an investigation of the flow around rectangular and chamfered cavities at high subsonic and low supersonic speeds. Pressures measured on the faces of the cavities are integrated to find the pressure drag of the cavities. The types of cavity tested range from simple sawcuts to cavities so long that the two ends can be regarded as independent and the results for these are compared with the sum of the drags of isolated forward and rear facing steps.

Although the Reynolds numbers of the tests are similar to those in flight conditions the maximum depth of the cavities tested is only 6 mm so that the pressure resolution on the vertical faces of the cavities is limited. In spite of this it is estimated that the maximum error in the drag of any particular cavity is less than the skin friction drag on a smooth surface equal in area to half the plan area of the cavity.

The proper treatment of the pre-entry and post-exit streamtubes of supersonic aircraft and their “corresponding” windtunnel models was considered in some depth for supersonic fighter designs, and investigated in wave drag research, but as a result of the cancellations of the major supersonic fighter programmes the results were not published. This note sets out the salient conclusions.

The development of the first supercritical air intake cowl is also outlined.