The velocity field around a circular cone in supersonic flow is determined by considering fluid injection and suction through the porous wall of the body. By using a new method of linearisation of the equations of motion, analytical formulae are obtained which yield almost exact results, as compared with numerical calculations. In addition, the method proposed suggests new problems related to fluid injection and suction which are important for practical applications.

The results of an experimental study of the buckling and vibration behaviour of tensioned sheets with a rectangular opening are presented. The buckling phenomenon involves the existence of a non-uniform pre-buckle stress state in the vicinity of the opening. The local buckling load has been estimated on the basis of the modified Southwell method. The effect of parameters like cut-out size, sheet width, sheet thickness and cut-out corner radius has been investigated. The data from the vibration experiments indicate that the load versus frequency behaviour is dependent on the size of the test specimen and the opening shape. It has been observed that, for certain combinations of plate and opening parameters, the load versus frequency plot has a minimum corresponding to the local buckling of the free edge of the hole. For other plate and opening parameters it shows only a kink corresponding to the local buckling of the free edge of the cut-out. The buckling load for the opening shapes obtained from both the static and dynamic experiments are compared, showing good agreement.

The base pressure correlation proposed earlier by the authors, to take into account the effects of the boundary layer and of the boat-tail angle, is utilised in the design of two-dimensional aft bodies for minimum drag in supersonic flow. The general advantages of boat-tailing are indicated and charts of optimum profile parameters and minimum drag are provided for use in preliminary design. The effects on aft-body drag of possible reversion of the boundary layer at a sudden expansion are discussed, and the relevance of the optimum shapes found to the lifting case is indicated. The calculated optimum geometry is in good agreement with the experimental results of Fuller and Reid.

Observed variations of eddy viscosity in the outer regions of turbulent boundary layers are here explained in terms of the reorientation and stretching of vortex elements. The explanation, which is purely qualitative, gives a clear and plausible physical picture.

This paper reports on an investigation of the effect of local elastic buckling of stiffener outstands on the overall behaviour of stiffened plates. A simplified mathematical model has been developed, based on the post-buckling analysis of the stiffener, and gives a simple expression which indicates that, for the plate geometry investigated, the maximum load carried varies asymptotically between the local critical load of the stiffener and a reduced Euler load. Also, there is a marked imperfection sensitivity arising from the interaction of the local and overall buckling modes. Experiments were carried out to confirm the analytical prediction for the elastic buckling behaviour of the stiffened plates. The models were constructed of Araldite, to allow large deformation within the elastic strain range. Experimental results showed very good agreement with the theory.

An alternative analytical method is applied to interference problems of an aerofoil very close to the ground, such as a free surface, a solid wall, and a slipstream. The method of matched asymptotic expansions on the small ground clearance is used in the governing integral equation and this analysis is different from Widnall and Barrows’s analysis. They used the matched asymptotic method in the differential equation. To show that the present method is reasonable, the problem of a ground-effect aerofoil in uniform fluid flow is considered and it is found possible to obtain the same results as those of Widnall and Barrows for the case of small ground clearance. By comparing with some earlier studies, it is found that the asymptotic method used with small ground clearance is valid for a clearance less than about 0.3 of the chord length. Next, the interference of ground-effect aerofoils in the channel wall, in a free jet stream, and in a slipstream are examined, and it is found that the present method can be easily applied to these problems.

An analysis is presented for the post-buckling behaviour of simply-supported, laminated cross-ply rectangular plates subjected to biaxial compression. The solution to von Kármán-type large deflection equations of the plate is expressed as a double sine series for the transverse deflection and a double series of clamped-clamped beam functions for the force function. All the boundary conditions, including those involving the normal bending moment at the edges, are satisfied exactly. The series solution is found to converge rapidly. Using only the first few terms in the series, numerical results for square graphite-epoxy unsymmetric laminates under uniaxial compression is presented graphically.