A novel low-speed wind tunnel which produces unsteady “gust” flows is described. The walls are sinusoidal in shape and are moved in the flow direction with a velocity Ww less than the mean velocity Wm of the free stream. The tunnel is useful for testing isolated aerofoils and aerofoils in cascade in non-convective gusts (Ww < Wm) so that comparisons with predictions by thin aerofoil theory may be made. However, it does not simulate precisely the unsteady flow that occurs in axial flow turbomachines.

The usefulness of a probe which can sense the absolute value of the stagnation pressure in supersonic flow has long been recognised. In the past such a probe has not been available and therefore it has been necessary to infer this fundamentally important flow property from measurements of other properties. This paper describes a probe which has been developed specifically to measure accurately the stagnation pressure of a supersonic gas stream. Measurements of the performance of the probe to date show that it is capable of measuring absolute stagnation pressure with an accuracy of 0.1 per cent in the Mach number range 1.5 to 2.1. No measurements have yet been made in the transonic range, but at low subsonic speeds the probe has demonstrated its ability to measure dynamic pressure within an accuracy of 0.1 per cent at a Mach number of approximately 0.13. The permissible range of misalignment in pitch and yaw before the pressure recovery begins to deteriorate are functions of free-stream Mach number and are usefully wide.

The properties of weak shock waves in a vibrationally relaxing gas are discussed with particular application to waves in carbon dioxide. An account of various methods of generating weak shock waves in a shock tube is given. The best method requires the insertion of a perforated plate in the low pressure section of the shock tube. A suitable choice for the open-to-total area ratio of the plate leads to transmitted waves in the appropriate strength regime. These waves were observed using a Mach-Zehnder interferometer and were either fully or partly dispersed by vibrational relaxation. Values for the relaxation frequency of carbon dioxide at room temperature were obtained.

A simple formulation is established for the determination of vibration characteristics of pre-twisted beams by the matrix displacement method. An important point in the analysis is the assumption of complete polynomial displacement distribution in the principal directions. In particular, two twisted elements which employ quintic polynomials are introduced and used in the calculation of natural frequencies of pre-twisted beams for several boundary conditions. The results demonstrate rapid convergence.

Results are presented of an experimental study of the pressures on the flat windward surface of a Gothic wing at a free-stream Mach number of 3.5 and at moderately high angles of attack, including the effects of yaw. The results show that the perturbation in pressure due to yaw is almost independent of the streamwise distance from the vertex. As a result, it has been possible to calculate the pressure distribution on the yawed wing using the appropriate yawed conical wing results, the zero yaw results being calculated by the “equivalent” delta wing method. The calculations show reasonable agreement with the experiments and confirm that the perturbation due to yaw generates a stabilising rolling moment.

A method for the analysis of flapping-wing flight using lifting-line theory and actuator disc theory is proposed for the prediction of aerodynamic loads, propulsive efficiencies and optimum lift distributions.

The trailing vortex wake system generated by a lifting wing of finite span is modelled with a pair of laminar, viscous vortex models of a new type. The embryonic form of this viscous wake model is matched, at several interior collocation points, to the inviscid Betz model of the wake convolution process that transforms the wing trailing-edge vortex sheet into a pair of axisymmetric trailing vortices. In the near-wake and intermediate-wake regions downstream of the wing, the viscous wake model indicates that the trailing vortex characteristics (particularly the peak swirl velocity and the circulation profile) are strongly influenced by details of the wing span load distribution. Using simple eddy viscosity concepts, the viscous wake model achieves good qualitative agreement with test results from a limited selection of published experimental wake investigations. The present laminar theory appears to offer a useful basis for developing an engineering prediction method of aeroplane wake characteristics.