Uncertainties in the use of the discrete-vortex method in modelling the time development of the wake of a circular cylinder at very high Reynolds numbers are investigated. It is shown that simply introducing vorticity at generally accepted separation positions at a rate of ½Us2, Us being the velocity at separation, gives wholly unrealistic wake predictions. In the base region pressure fields occur which would promote separation in steady flow and so a first approximation for ‘secondary’ separation is incorporated into the model. This brings pressure distributions and vorticity structures at subcritical and supercritical Reynolds numbers into good agreement with experiment. The convection of the vortices is calculated using the cloud-in-cell technique and comparisons are made with direct summation methods.

The types of pitch/yaw coupling which may result from roll motion of a conventional tail-controlled cartesian missile have been categorised. The consequences of the couplings upon:

1. (a) the response to a step demand for manoeuvre, and

2. (b) the decay of error in a beam-rider system are presented.

Potentially the most damaging forms of coupling are due to

1. (a) mis-match of the Invariant Frames of airframe and servos,

2. (b) angular mismatch between parts of the system, and

3. (c) gyroscopic coupling.

A general procedure for the analysis of thermal stresses in a polygonal elastic plate due to heating over a small circular or rectangular area is presented. The method employs eigenfunctions of angular regions together with a least squares procedure to establish continuity. Numerical results are given.

An exact analysis is first given, within the spirit of elementary theory, of the torsional modes of a uniformly tapered solid wing whose section shape - as distinct from size - is constant. Numerical results are presented for the first five torsional modes for various values of tip chord/root chord. It is shown that the frequencies are fairly insensitive to the magnitude of the taper and a corollary to this, which is also investigated, is that an analysis based on a partially stepped representation of the taper yields close estimates of the frequencies but can yield massive differences in the higher mode shapes. An analysis is also made of warping restraint and distributed inertia effects.

Detailed measurements have been made of the boundary-layer development on a small two-dimensional aerofoil with supercritical flow and a weak shock wave, together with similar measurements on the tunnel side wall opposite the aerofoil surface. The Reynolds number of the test is similar to that found in the turbines of jet engines and there is a strong favourable pressure gradient ahead of the interaction of the shock with the boundary layer as often occurs in turbine blade passages. However, whereas the boundary layer on the aerofoil is thin and of the same thickness as that on a turbine blade, the thicker boundary layer on the wall is more typical of that on the hub or casing. The experimental results are compared with results from a wide range of calculation methods. One interesting conclusion from these comparisons is the fact that prediction methods which perform well for the thin boundary layers on the aerofoil do not necessarily perform as well for the thicker boundary layers on the wall.