Forty years ago Flight Lieutenant John Nelson Boothman, AFC, RAF, won the Schneider Trophy outright for the Royal Aero Club of the United Kingdom, flying a Vickers-Supermarine S-6B (S.I595) on Sunday 13th September 1931. “The better the day the better the deed.”

To some, that win at 340.8 mph over a 270 mile course seemed the end of an era and the climax of the careers of both Reginald Mitchell, and of Henry Royce, the designers of the S-6B and of its 2300 bhp Rolls-Royce “R” engine.

In the event, as history has unfolded, the winning of the Schneider Trophy was but the opening page of a more significant story—the evolution of Mitchell's Spitfire, of Camm's Hurricane and of their Rolls-Royce Merlin engines. Those later Schneider Contests—from 1927 to 1931—led directly to the winning of the Battle of Britain in 1940—and to our presence here in a free world tonight.

Everyone agrees that the noise from aircraft has become an unreasonable nuisance to people living around airports. Because of it aviation is now extremely unpopular in some quarters and there is energetic public resistance both to the extension of existing airports and to the creation of new ones. The restriction on night take-off of jet aircraft from London airport is another illustration of the problem. This public attitude is understandable and it is tending to obscure the fact that transport aviation has made a great contribution to improving the quality of life. Taking one small example, without aviation the package tour holiday, which represents good value for money, would hardly be possible.

The purpose of this paper is to take the advantages of aviation for granted and to explain that it is technically feasible to build a subsonic aircraft and engine combination quiet enough not to annoy the public.

It is suggested that those wishing to familiarise themselves with the general history of Pitcher's work consult “Aviation” by C. H. Gibbs-Smith, HMSO, 1970, pages 85-90, and items 1 and 2 in the references at the end of this paper, although it should be remembered that this paper amends some of the information contained in these sources.

When dealing with famous men in history, perhaps one of the most persistent and difficult questions is that of their relative importance. It is very easy, in a bout of enthusiasm or contempt, to over- or underestimate the influence that a person may have had upon his contemporaries. This applies no less in aeronautics than elsewhere. The example of Percy Sinclair Pilcher (Fig. 1), the British gliding pioneer, is a case in point.

The question to be considered is the following—starting with the aircraft flying at the minimum conventional flying speed at a given height above the ground, how should the controls be operated and the flight path chosen, in order to bring the aircraft to rest on the ground in an optimum fashion? Optimum fashion can mean different things at different times but, in this context it usually means the simultaneous loss of speed and height in such a way that obstacles are surmounted but the total transi tion distance, time, or fuel used are minimised. The problem is one which may be solved mathematically by variational methods following Hacker or Brüning, but the approach in this study is a simpler one and is based on an intuitive search for near-optimum solutions by means of physical arguments.

Numerical solutions to unsteady flow problems have been developed, and often it is not possible to carry out a direct check on their accuracy. However, such a check was given in Ref. 3 using an analytical solution for zero spatial velocity gradient. The object of the present note is to present a different simple analytical solution which can be used as a special case for checking the accuracy of a numerical solution. Also, the solution is of interest itself as it corresponds to certain gas dynamic problems.

The analogy between the formation of large amplitude waves (hydraulic jumps) on the surface of shallow flowing water, and shock waves in supersonic air flow is well-known. In addition to the correspondence between the wave patterns the variation in water depth can be related to the pressure distribution.

This “hydraulic analogy” is usually demonstrated in the laboratory in a tank which produces a shallow flow of water over a horizontal surface, on which the appropriately shaped body is mounted. The resulting stationary wave patterns may then be examined. Fig. 1 shows a typical bow-wave on a double-wedge.

This section deals with the application of models developed in Part I to particular UK domestic and international routes. Most of the information used is in time series, a form of data which brings with it many problems. As well as the usual ones such as multicollinearity, serial correlation and simultaneity, the civil aviation market has its own characteristics which bring with it estimating problems. Special attention is paid to short- and long-run responses to income and price changes, to means of explaining secular trends in growth, and causes of fluctuations. When possible, generalisations concerning the size of parameters and the appropriateness of certain model forms will be made. The approach however is to treat routes and route groups as unique, with different passenger characteristics, development and histories. Such differences require different approaches and different models. Much of the discussion will be concerned with discussing the appropriateness of one or other model to routes of certain characteristics.