Just over two years ago, on the occasion of the inaugural de Havilland lecture, Richard Clarkson gave one of the finest accounts of an aviation pioneer and his work that I have ever heard. When I was asked to give this second lecture, I felt more than a little conscious of the standard set by my predecessor and by the quality of the man thee lectures commemorate.

The purpose of this paper is to further illustrate the utility of a wind tunnel (see refs. 1 and 2) in providing performance date on aircraft engine installations. The discussion is limited to the test work accomplished in the Propulsion, Wind Tunnel Facility (PWT) at the Arnold Engineering Development Center (AEDC) at Tullahoma, Tennessee, USA

The NGTE Engine Test Facility has five test cells in current use and between them they can test aircraft powerplants over a wide range of operation at the precise conditions encountered in flight. Two basic testing techniques are employed—“connected testing”, in which air is piped directly to the engine compressor at the pressure and temperature conditions provided in flight by the intake, and “free-jet testing”.

The design and development of aircraft powerplants for sustained supersonic operation proves to be an exacting task which involves careful balancing of the requirements for high installed performance and system viability. The latter question may be dominated by the need to ensure flow compatibility at the intake/engine interface.

This brief survey endeavours to highlight the major points of the Edwards Report to provide background for the more detailed contributions and discussions to follow. It is perhaps worth repeating the terms of reference of the Committee:

“To enquire into the economic and financial situation and prospects of the British civil air transport industry and into the methods of regulating competition and of licensing currently employed; and to propose with due attention to other forms of transport in this country, what changes may be desirable to enable the industry to make its full contribution to the development of the economy and to the service and safety of the travelling public.“

It is my intention to be severely critical of the report insofar as it concerns licensing, but I hope that what I have to say will not set the tone for this symposium! It is extremely easy to be critical of the work of others, particularly in a field in which one feels one has some experience, but I shall do my best only to offer constructive criticism.

I think that Sir Ronald Edwards and his small team of very busy people deserve to be congratulated upon producing in a remarkably short time a Report that is well documented, well written, generally realistic in its proposals and free of prejudice on such issues as public versus private enterprise. As against this, it may be objected that the Report is inclined to accept rather too readily the orthodoxies of modern “consensus” politics and economics. By that I mean such views as that a mixed economy necessarily achieves the best of both worlds; that nationalised industries should operate as commercial undertakings; and that where nationalised industries are required for some special reason not to operate commercially, they should be compensated in the form of direct subsidy chargeable to the appropriate government department.

The terms of reference required the Committee to take account of safety when formulating its proposals. As a starting point the Committee had the report of a Special Review (published in 1968) entitled “The Safety Performance of United Kingdom airline operators”.

With this in mind, Edwards formulated as part of the long-term objectives of civil aviation policy that safety should be “equal to the best in the world” (paragraph 1053) —but although a great deal of attention was given to air safety, the Committee admitted that it had “not felt competent to consider the technical aspects of safety in depth” (paragraph 840).

Economic and investment opportunities in the light of, the Edwards Report! The subject must have been devised by an engineer. I do not understand it. What can economic opportunities mean? Economics is concerned with finding how best to apply the finite resources of mankind to its infinite wants. What opportunities of this kind does this Report give us? I think it will help make air transport more economic through its educating influence, principally on the powers-that-be.

It seems to me that the report contains 3 salient points in reference to domestic air services. These are:

1. 1. The unprofitability of domestic services generally.

2. 2. Competition on the trunk routes may have been beneficial to the customer in the short term but it may also have led to higher fares. (This need not however be true of the long term.)

3. 3. The absence of any coherent proposals for exploiting VTOL/STOL development in expanding domestic air services.

The theme of the meeting poses the question, “Is there a future for British Air Transport ?” I firmly believe that the answer to this question is “Yes, of course there is,” and that the only debatable issue is the size and vigour of the future British Air Transport Industry.

The design of a homing missile normally involves the incorporation of a dielectric window to form the nose region of the flight vehicle. Immediately this creates a situation in which a compromise is required between the conflicting needs of

1. (a) The aerodynamicist who requires a fairing of minimum drag, within the length limitations imposed, and which at the same time possesses a reasonably predictable shape. The shape must often satisfy rain erosion requirements.

2. (b) The heat transfer engineer who requires that the thermal load be spread as uniformly as possible over the fairing surface.

3. (c) The materials/structures technologist who requires the fairing to be manufactured from readily available material at reasonable cost.

4. (d) The microwave engineer who requires no fairing at all.

The modern high performance aircraft has thin wings, usually of multispar construction leading to a structure composed of a number of cells arranged chordwise rather than spanwise. The high performance gives a rate of climb that needs almost to be measured in thousands of feet per second rather than thousands of feet per minute, and hence the aircraft experiences an external pressure that is changing extremely rapidly with time.

The structure of turbulent boundary layers has recently been studied in detail. Using the hydrogen, bubble technique, Kline et al have detected intermittent formation of low-speed streaks very close to the surface, which lift away, thereby forming local inflexions in the velocity profile. These amplify disturbances, producing eddies which are ejected into the outer part of the layer. Black has proposed a turbulence model consisting of periodic horseshoe vortices within the layer, in which the longitudinal legs are stretched as they move through the comparatively quiescent layer.