A theory of creep buckling is presented in which the instantaneous elastic and plastic deformations following the application of a load, as well as the steady creep deformations, are considered in an approximate manner. Equations are given from which the critical time, that is, the time elapsing between load application and the collapse of the column, can be computed.

In this paper a non-linear theory of the supersonic bangs from an accelerating body is worked out, using an extension of Whitham’s method. The strength of the bow shock is determined, and it is shown that the effect of acceleration on the pressure rise is appreciable at large distances from the nose for Mach numbers near unity. The results are compared with those of linear theory; the estimate for the pressure rise is found to be about a half of the linear value. The results also include an expression for the curvature of an attached shock at the nose, and a formula for the decay of a shock after it is detached from a decelerating body.

An historical sketch shows how the basic ideas of the jet flap were evolved. The exploratory work included the prediction that lift would be induced on an aerofoil by a two-dimensional jet deflected from the trailing edge, and that the magnitude of the total lift would be of the order of four times the direct jet lift. The prediction was confirmed experimentally and a first quantitative theory evolved. Meanwhile the hypothesis was put forward that, ideally, the forward thrust on the aerofoil would be independent of the deflection angle of the jet.

This paper is the first of a series of papers that will describe the development and present state of knowledge of the jet flap.

This paper is the second of a series of three. The first dealt with the steady forced harmonic motion of a simple oscillator with one degree of freedom when “ hysteretic damping ” is present; by this it is meant that a damping force exists which is in phase with velocity but whose magnitude is proportional to displacement. The present paper is devoted to the formulation of a general theory of small hysteretically damped vibration in which the existence is postulated of damping forces which act between pairs of points such that they are in phase with the relative velocities and their magnitudes are proportional to relative displacements. The theory is presented in general terms and use is made of Lagrange’s equations with a new type of “ dissipation function ”; this is comparable with that of Rayleigh for viscous damping. It is shown that this theory generally leads to simpler algebra than does that of viscous damping. Moreover, it will be shown in a later paper that the nature of forced and damped oscillation may be thought of in terms of modes more simply than is the case with the more familiar viscous damping.

Small, steady perturbations of general two-dimensional steady, shock-free, supersonic flows are studied and the perturbation fields of symmetrical nozzle flows are described in detail. The relation between errors in the shape of the supersonic part of the nozzle liners and the deviations from uniformity of the flow in the test section is given to an approximation sufficient for the treatment of a number of problems arising from experiment and in the design of nozzles.