The object of this paper is to discuss the evolution of the wartime fighters the Spitfire and Seafire, designed by the Supermarine Works of Vickers–Armstrongs Ltd. In particular, it will be confined to the design and technical side of the problem. The production undertaking, which resulted in the manufacture of over 22,000 of these aircraft in 33 different types, would undoubtedly need a paper of its own.

In order to make the matter clear it is proposed to begin with a brief history of the early development of high speed aircraft by the firm. The next logical step is to survey the Spitfire family as a whole and to trace the relative importance of the different types, giving some indication of their line of development. Finally, an attempt will be made to analyse the factors which maintained the efficiency of these aircraft at a high level for a period of ten years.

The heading of this lecture is the “Development of Air Transport During the War” but because time is limited I have had to exclude any mention of the ferry organisation which was responsible for the delivery by air of many thousands of aircraft. The work has however been, described in “The Atlantic Bridge.” The period with which I propose to deal is the 21 months ending in September, 1946. In this short period, in response to the demands of war, the Transport services of the Royal Air Force flew rather more passenger miles than did British Civil Aviation in the preceding 21 years up to the same date, and carried in addition great quantities of freight and military stores. This volume of transport flying, packed into a few short months, gave rise to many problems but also afforded unique opportunities for testing out new ideas and new equipment. My purpose tonight is to give a brief account of what was accomplished, and against this background to examine some of the lessons which were learned and the ideas for the future to which they gave rise.

In his article “The Expanding Domain of Aeroelasticity,” Professor Collar explains how, in the course of a few years, the subject of aeroelasticity has grown from a mere collection of problems of common interest to the aerodynamicist and the structural specialist to become a main branch of aeronautical engineering. Aeronautical engineers owe Professor Collar a debt of gratitude for defining in the clearest terms what aeroelasticity purports to be, and for removing the vagueness and uncertainty which so often permeates any new branch of science or engineering, especially when it is derived from long–established subjects, as aeroelasticity is from aerodynamics and theory of structures.

As is to be expected from one so distinguished in the aeroelastic field, Professor Collar writes especially from the standpoint of the aeroelastic specialist. Engineers with a different background, while accepting the broad principles which Professor Collar lays down, may see their applications and development in a different light.