The paper provides a simplified picture of the processes occurring in liquid bi-propellant rocket motors. Droplet vaporisation, chemical reaction, and drag between gas and droplet are considered for a one-dimensional model. Quantitative theoretical results are presented for the variation of droplet size, droplet velocity, gas temperature and gas velocity within the chamber, particular attention being paid to the calculation of L*. The theory is applied to the German V2 rocket motor. Practical conclusions from, and extensions to, the theory are discussed.

The effect of the ground on a jet-flap aerofoil in two-dimensional flow is investigated, with particular reference to the conditions under which the jet flow hits the ground. Experimental results are included for the change of lift and pitching moment for 58·1° and 31·4° jet-deflection angles, with a limited investigation into the downwash changes behind the model with a 58·1° jet-deflection angle. It is concluded that there is a definite limit to the jet coefficient, which may be used at any ground position, if the problems of a sudden change of lift and pitching moment are to be avoided. There remains the unresolved difficulty of the downwash variation at the tail arising from the presence of the ground.

A provisional assessment of the performance of a jet-flap aircraft near the ground is made, and shows that for a 58·1° jet-deflection angle there is a definite limit to the minimum flying speed for any given distance of the wing from the ground.

The fact that there appears to be a maximum pressure lift coefficient, independent of the jet-deflection angle, which may be obtained at any ground position, is investigated. An attempt is made to provide a theoretical explanation of this on the basis of the critical condition of blockage underneath the aerofoil.

When a vibrating structure encloses a volume of fluid, the acoustic effects within this volume modify considerably the response characteristics of the structure, provided that the cylinder is vibrating in radial modes only. Measurements made of the displacement caused by a particular sound wave are of the same order as the values predicted. The calculation of the response of the cylinder to an acoustic wave also yields the sound field inside the cylinder and, again, the results are in general agreement with practical experience.

The characteristic functions for beam vibration modes are used to derive an approximate solution for the calculation of thermal stresses in rectangular isotropic flat plates subjected to arbitrary temperature distributions in the plane of the plate and constant temperatures through the plate thickness. The thermal stresses are obtained in the form of generalised Fourier expansions in terms of the characteristic functions, and their derivatives, representing normal modes of vibration of a clamped-clamped beam. Since these functions have recently been tabulated, the practical application of this new method to the thermoelastic stress analysis of plates presents no difficulty.

Some recent theoretical work on slender pointed wings at zero lift is co-ordinated and extended. The wings considered may have any pointed plan form shape, provided that the trailing edge is straight and unswept. The root section profile and cross-section shapes are arbitrary, provided that, on any one wing, the latter are “descriptively similar” (diamond or parabolic biconvex for instance), though not necessarily geometrically similar. The chief aim of the work is to find wings with simple geometry, low wave drag and pressure distributions which are unlikely to be seriously affected by viscous effects. Wave drag and pressure distributions are calculated by slender-wing theory. General formulae, which are both simple and instructive, are given for the wave drag and the overall pressure distribution, with particular emphasis on the root pressure distribution. Results for a number of wings of special interest are presented and discussed.