John Dudley North must be almost the last of the select group of aircraft enthusiasts who started practical aviation in this country in the early years of the century. He was certainly the last to be actively concerned with the day-today activities of his company up to the day of his death, only outlived by Sir Thomas Sopwith and Oswald Short. “To become a pioneer in a youthful spirit of adventure is one thing. To use pioneering shrewdly and deliberately as a business policy is quite another. John North was able to do both.” So wrote Walter Gaunt in a special article published in January 1955 in the periodical Business.How this was achieved is some measure of my present task.

Your President and Mr. B. D. Blackwell of the Rolls-Royce company were brash enough to have suggested that I present the Halford Memorial Lecture. And 1 fear that I was impetuous in having accepted. I am sorry that I did not know Major Frank Halford, but from what I have read and from those with whom I have discussed his achievements, he was indeed a leader, an engineer, a designer, a man of much foresight, without whom our world of air transport would not have progressed so far. I know he would have been interested in the engine design trends which form the subject of my discussion—The Development of Small Gas Turbines for Aircraft Auxiliary Power.

The calculation of the response of an aircraft to atmospheric gust has two main purposes. These are, first, to make possible an assessment of the peculiarities of the response of a particular aircraft (e.g. the length of the discrete gust which produces maximum load), and secondly, to provide an estimate of the gust loads which the aircraft must be designed to withstand, in both the static and fatigue senses. (In this paper, however, the fatigue aspects are not considered.)

The density of air traffic, particularly in the USA, is now X increasing at such a rate that the overloading of the Air Traffic Control system seems inevitable. Fig. 1 shows the expected increase in the size of the US civil air fleet and its operations over an eleven-year span, from 1966 to 1977.

Since January 1st 1968, there have been 58 mid-air collisions in the USA, including 19 this year. The majority of these were under positive Air Traffic Control in the vicinity of airports. Some form of airborne system to prevent collisions seems essential for the safe operation of aircraft in the 1970s.

A considerable amount of discussion and development has been carried out in the USA during the past 14 years, and some prototype equipments are now flying. The purpose of this paper is to describe the technique employed in these systems, and to suggest an original principle as a design basis for a collision avoidance system (CAS).

Control of flight is essentially control of lift. When one proposes—as we shall do here—to tamper with one of the most fundamental principles of aircraft control, it is evident that this may have far reaching repercussions and that such a venture cannot therefore be undertaken lightly. The elevator has been the primary longitudinal control since the earliest pioneering days and has served the aircraft well from its modest beginnings to this age of supersonic flight. Why do we want to change and what do we want to take its place; how will the pilot react to an altogether novel way of controlling the aeroplane? These are the questions one is bound to ask when direct lift control is suggested as an alternative and these are the questions which we shall attempt to answer here.

The analysis of axisymmetrical thin shells has always been an important part of the theory of structures, and recently the problem of the cooling tower has aroused considerable interest for practical engineering reasons. Various solutions have been obtained, using either the finite difference or the finite element methods, with varying degrees of success. Amongst the latter, elements such as the TRIB 3c from the ASKA library and the axisymmetrical elements from the SABOR programme, with either a straight or a curved meridian line, have given reasonable displacements. But, by the nature of these elements, the stress distributions are discontinuous across element boundaries. Other existing elements, e.g. the arbitrarily curved triangular shell element SHEBA developed by Professor Argyris's team at the ISD in Stuttgart, are also suitable for the purpose and yield an excellent estimation of the stresses.

For many space applications, such as communication, weather, military, and scientific experiment satellites scanning precise regions, it is necessary to maintain a satellite in a fixed orientation relative to the earth. Unfortunately, a correctly positioned satellite deviates with time from this preferred orientation due to perturbing environmental forces. This explains considerable interest in libra-tional stability study in recent times.

Among the numerous methods developed for librational control, a passive technique depending on the gradient of the gravitational field has gained attention. Depending on the orbital distance, environmental effects, such as, aerodynamic, radiation, and magnetic torques, become significant compared to the gravity-gradient restoring moment. A need to determine the influence of these disturbing forces is thus evident.

Rapier is a very important element in our armoury of defence against attack from the air. At low to medium altitudes the attack comes from all-weather, contour-following, very fast and very expensive aircraft, through much more numerous and diverse conventional aircraft limited to fair-weather operation, to helicopters and reconnaissance drones.

The perfection of radar makes the high open sky a dangerous place to be. Aircraft are best used, like any other weapon, when they enjoy the greatest advantage. They will therefore, fly high enough to see their objective (stationary or slow-moving targets) but low enough to gain concealment from radar surveillance.

The title of this paper was not of my own choosing, although I could not resist the challenge which it presented. It illustrates immediately one danger of which industry must beware—that of under-rating the extent of protection which the laws of this country afford to inventors and innovators. The limitation to Patents and Designs implied by the title, will be exceeded and there are included in the following remarks, Copyright and Trade Marks, both of which can contribute to the protection of industrial innovations.