I had intended to begin my lecture in a non-controversial manner by referring to the engine which the Wright Brothers used in their historic flight. It has been my understanding that they approached a number of automotive manufacturers in an endeavour to get an engine made which would meet their requirements, but on each occasion were told that their specifications could not be met. Eventually they were forced into designing their own power plant and this, I felt, provided an excuse for my subject this evening, should any of my audience feel one were needed. I subsequently find, however, that some doubt has been cast upon the suitability of this introduction by the writings of Israel Katz of Cornell University, who states that the Wright Brothers, in fact, used a re-worked Pope-Toledo automobile engine at Kitty Hawk. I do not propose to enter the argument which I am sure will ensue, and which I hope will result in the records being put right.

The generation of electric charges in hydrocarbon fuels during transfer has been recognised for many years as an explosion hazard, and the oil companies have taken precautions against this danger as a matter of routine. Usually the hazard arises only in the early stages of handling, and is associated with the fast pumping of large quantities of product, particularly into large refinery tanks and tankers. The possibility of a hazard usually becomes less as the product approaches the consumer, owing to the successively smaller quantities pumped.

“All-weather” operational requirements have added considerably to aircraft and missile design problems as the effects of various meteorological hazards, predominantly rain, are aggravated by high speed flight. The problem of rain erosion is reviewed with regard to the functional requirements of the components, the flight plan of the vehicle and the occurrence of rain over the geographical terrain of operation. The factors affecting rain erosion characteristics such as type of material, surface finish, shape of component, speed and rainfall intensity are discussed and empirical data derived. The influences on the problem of radar limitation in rain, the probability of rain occurrence and the effect of wind and wind-shear are mentioned. Details given of equipment for the simulation of rain erosion are concerned principally with the R.A.E. “whirling arm” and rocket runway high speed sled techniques. Correlation of test results from these facilities and flight tests are briefly discussed.

Degree of erosion of a material is defined in relation to the particular application of the material and details are given of the characteristics of numerous materials, both metals and non-metals. The utilisation of these materials for such applications as radomes, transparencies, high temperature materials, de-icing systems are briefly discussed together with methods of extending the rain erosion “life” of materials by design or by use of protective coatings.

In Ref. 1, Professor D. W. Holder describes a very interesting experiment pertaining to shock wave position and boundary layer separation in supersonic nozzles at low Mach numbers (M ⩽ 1·4). A closer examination of this experiment indicates that the results may only be applicable in the Mach number range of M < 1·48, not in the range of M> 1·48.

The following is a report of preliminary tests to determine the effect of vortex generators on the drag of a circular cylinder. It was thought that with suitable placement of the vortex generators on the cylinder, the laminar separation of the boundary layer at subcritical Reynolds numbers might be delayed, and a reduction in drag coefficient obtained.

This paper presents a numerical method, derived directly from the basic differential equations of motion and expressed in the form of recurrence-matrix of finite differences, that can be generally applied to all multi-degree-of-freedom structures subjected to dynamic forces or forced displacements on any masses at any instants of time. The movements of the system may be described by any form of generalised co-ordinates.

Using Glauert's three-dimensional aerofoil theory, an expression for the induced velocity due to the trailing vortices of an infinite cascade of wings of finite span has been derived. The reduction in the average lift coefficient due to these induced velocities has been evaluated for some cases. It is shown that for a cascade of low space-chord ratio, the reduction in lift due to the interference from the trailing vortices is quite considerable.