It was while lecturing at Cranfield in the late 1970s and early 80s on the aerodynamic design of aircraft wings that the ideas discussed in this paper began to develop. My work on wing tip sails had led me to look in some detail at the flight of birds and their ability to vary wing camber. I realised that this was an attractive way to overcome the need to compromise between the design requirements associated with the different regimes of flight necessary with fixed geometry.

To be economically attractive, civil aircraft have to be capable of operating over a wide range of flight conditions. For example, an executive jet may be required to fly fast and low at light weight over a short stage length, such as London to Paris, on one day, and fly heavily loaded a much longer stage length the next, when it is desirable for the aircraft to fly high and at an economical speed.

Results are presented of an investigation into the interference effects associated with end plates of a type commonly used for the simulation of infinitely long (‘two-dimensional’) cylinder flow conditions around models confined with the working section of a wind tunnel. Experiments were performed with smooth circular cylinders of low area blockage in steady, low-turbulence, uniform airflow at a Reynolds number of 4·4 x 104 and involved the measurement of vortex shedding frequencies in the wake of the body, together with mean and fluctuating surface pressures, from which coefficients of local mean drag, r.m.s. lift and r.m.s. drag were calculated, and the use of a surface flow visualisation technique. The results reveal the aerodynamic characteristics of the disturbance induced by an end plate within the interference region which extends to 3·5 diameters from each plate.

A new integral equation, and the corresponding boundary-element method, is presented for the aerodynamic analysis of compressible, subsonic, potential flows around bodies in arbitrary motion, with applications to helicopter rotors in hover. The formulation is closely related to that introduced by Morino for the aerodynamic analysis of aircraft: in that paper, the surface of the aircraft is assumed to be in arbitrary motion with respect to a frame of reference that moves in uniform translation. Such a formulation is very useful for the analysis of aircraft undergoing small oscillations with respect to a reference configuration. However, for the analysis of more complex motions (e.g. helicopter rotors in forward flight), it is more convenient to use a frame of reference that moves in arbitrary motion (in particular, for the case of a body moving in rigid-body motion, a frame of reference rigidly connected with the body).

A general analytical solution for the buckling of laminated composite plates and shell panels for all combinations of free, simply supported and clamped edge conditions is presented. The solution is formulated in terms of stress function and transverse deflection. All the boundary conditions for the stress function are exactly satisfied. For the transverse deflection the prescribed boundary conditions are satisfied by including them in the expression for the energy integral. Several types of boundary conditions in which at least a pair of opposite edges of the panel are free and subjected to axial compression are considered. The Galerkin method, with beam vibration functions used as shape functions, is utilised to determine the buckling loads. The results obtained are used to examine the effect of bending-extensional coupling, aspect ratio and the curvature parameter on the buckling load.

Rocket motors are used to provide propulsive thrust for various types of aerospace vehicle. The thrust is developed by the supersonic jets of hot gas emitted through the rocket motor exhaust nozzles. Usually, for most flight trajectories of rocket-propelled aerospace vehicles, the exhaust jets expand freely into the ambient medium. There are, however, instances where the exhaust jets impinge on solid obstacles which are either unavoidably or deliberately positioned in the vicinity of the rocket motor exhaust nozzles. In these cases, the exhaust jets are deflected from their normal paths. When a rocket exhaust jet is deflected in this manner by a solid obstacle, the situation is usually referred to as rocket exhaust impingement.