It is forty–eight years since the first powered flight at Kitty Hawk, thirty–nine years since the death of Wilbur Wright, only three since the death of Orville Wright. The entire history of aircraft design and operation lies well within the life span of many of those in aeronautics today. The particular segment considered in preparing this lecture covers a period over half the length of the total. It starts with a series of cloth–covered biplanes not too different in appearance from the one of 1903 and ends with supersonic swept–wing jet–driven monoplanes. Fig. 1 may serve to give perspective and set things in their proper time relation.

The Wright brothers undertook to design and build, simply stated, a machine that would fly. They had to design the entire aircraft including power plant and propellers. Basic research, applied research, development—all of these they had to carry out themselves. They had little to go on by way of prior knowledge and found they could not safely accept what others had written until they had themselves verified it They had meagre financial resources and little formal engineering education.

The Title of this paper gives only the broadest indication of the line it is intended to take. Other papers with similar titles have been read by those connected with the design or aerodynamic side, but this paper is mainly concerned in conveying the pilot's own view of the problems of high-speed flying.

The paper is divided under the following main headings:—

1. 1. The obstacles to negotiate at high and low altitude.

2. 2. The approach to high–speed investigation and means of obtaining test results.

3. 3. Present and future requirements of research aircraft.

4. 4. Pilot safety measures.

5. 5. Some requirements of a pilot engaged in high speed research and development flying.

For the most part it is intended only to cover research and development flying. This necessarily entails some reference to combat, which is in itself a separate field.

The problems confronting a pilot who sets out to explore the behaviour of contemporary aircraft at high speed are considered first.

A few years ago when high–speed aircraft were mentioned, speeds of 300 to 400 m.p.h. came to mind. The advent of jet propulsion has made those figures 100 per cent, out of date and today speeds are discussed more and more in terms of Mach number; for example, high–speed subsonic aircraft fly at Mach numbers of 0.85 to 0.90, aircraft are flying in the transonic region and supersonic guided missiles are proposed for speeds anywhere between M=1.5 and 2.5, i.e. ground level speeds up to 2,000 m.p.h.

It is proposed to review very broadly the suitability of propulsion units for these transonic and supersonic applications. What is the difference between ordinary power plants and those for high speed? The answer might be contained in another question—why are supersonic aircraft different from conventional types? The aerodynamicist will give an involved explanation concerned with compressibility, drag rise, shock waves, and so on.