It is a very great honour to be the 41st person elected as President of the oldest aeronautical society in the world. I am very grateful to those who have thus shown their confidence in me for this elevated position and to my company, Westland Aircraft Ltd, for its full support in so many ways to the Society, and in particular to me during this Presidential year.

Our Society's view of Presidential Addresses is a thoroughly democratic one in that they are not a fixed custom, as in many other professional institutions in the UK. Whether to have one or not is entirely up to the President of the day.

“The true inventor of the aeroplane and one of the most powerful geniuses in the history of aviation” are the words used by a modern French authority, Charles Dollfus, to describe Sir George Cayley (1773-1857), a scholarly Yorkshire baronet who until fairly recently was unknown to many historians of applied science. This curious state of affairs has been righted by the researches of the late J. E. Hodgson, of Dollfus, of the late Captain J. L. Pritchard, and of the present speaker, who have now secured universal agreement in regarding Cayley as the true inventor, or perhaps originator, of the modern aeroplane, and the originator of the science of aerodynamics as applied to aircraft. And, in 1962, the Royal Society itself admitted that “the absence of the name of Sir George Cayley from the Roll of Fellows is one of the most notable omissions”.

It is a great honour for me to be invited to give this lecture but it has been rather a problem to know how best to tackle it. It is a great temptation when you are my age, and you have been in the aerospace business as long as I have, to reminisce about the things that you have done in the past—and it is one that, in part, I could not resist. If by any chance any of the younger members of the community that still have their working lifetime in front of them can discern any sort of a message here and there in what I say, then I hope they will do so and that they will have the courage to do something about it.

Due to their high strength to weight ratio, sandwich panels have become increasingly popular in various areas of structural design. This is particularly true with the aerospace industry where high strength low density materials play an important role in the fabrication of major structural components. Along with the continual quest for strong lightweight structures, recent optimisation methods in structural design have led to a re-examination of the validity of the traditional conservative designs based on the usual linear assumptions of structural analysis and tend to adopt more realistic approaches incorporating geometric nonlinearity of the structure by using more exact finite-displacement, strain-displacement equations.

A problem of some practical importance concerns the interference between a wing surface in a free stream and a nearby streamwise vortex. This situation can arise for example, either in a helicopter rotor system, or when concentrated vortices, which are shed from a fuselage nose or from forward canard controls, interfere with an aft lifting surface.

An approximate non-linear analytical study is described in Ref. 1 in which the three-dimensional loading on a two-dimensional non-swept wing underneath a streamwise line vortex in low speed flow (as shown in Fig. 1) is deduced. Since publication of Ref. 1 a number of linearised theoretical studies have come to light.

During the past ten years I have been involved in the development of Naval SAGW as leader of the Seacat, Seaslug and Sea Dart Project Teams within the RAE Weapons Department. The RAE's general responsibility has been that of co-ordinating R&D authority, plus being R&D authority for specific parts of the missile, but the detailed range of responsibility, plus its title, has varied from time to time and project to project.

In addition to the co-operation between the various project teams in Weapons Department we have across-the-board teams developing mathematical modelling techniques and programmes, and my colleagues from industry and the Royal Navy in the audience will note a familiar emphasis on modelling in my lecture.

I accepted, with some alacrity, your Council's invitation to present this lecture since it reflected a growing awareness of the need to pay particular and urgent attention to the correct use of the human operator in the design of aircraft and their systems. My experience suggests we have paid only lip service to human factor requirements and have relied on the adaptability of aircrews to sort things out once the aircraft enters service. We are also faced with the paradox that, the cleverer we become at inventing black boxes to usurp man, the more important it becomes to define the role, the response, the performance and the limitations of man. Any human factor assumptions we make in the early conceptual stages will critically affect the course of the development. If these assumptions are poorly based we shall finish up with an aircraft of limited effectiveness and the exciting new developments in avionics, now being offered will be substantially wasted.