The Ninth Lanchester Memorial Lecture was given by Professor W. A. Mair, MA, FRAeS, on “STOL—Some Possibilities and Limitations” in the Society's Lecture Theatre on 12th May 1966. The Chair was taken by the President, Mr. A. D. Baxter, MEng, CEng, FRAeS. Before the lecture he presented the Society's Gold Medal for 1965 to Professor M. J. Lighthill, DSc, FRS, FRAeS, for “his outstanding original work in many fields of Aeronautics”, explaining that Professor Lighthill had been unable to be present at the Wilbur and Orville Wright Memorial Lecture in December 1965 when the Society's main awards for the year were presented.

The President then said that this was the first meeting of the Society since his installation as President and it was a very pleasant way to start his year in office with first, the presentation of the Gold Medal to one distinguished scientist and second, the introduction of another as the Lanchester Memorial Lecturer.

There would be many members of the Society who would remember Dr. Lanchester, his attendance at lectures and his contributions to the discussions. It was true, however, that the real stature of such men was rarely recognised at close quarters and often only in the light of later developments was the importance of their work realised. It was 20 years since Dr. Lanchester's death and their Memorial Lecture was in its ninth year. Each year, each President had added a tribute to this great man. He was a man of many parts—a scientist, musician, poet and engineer and aeronautics owed much to him. It was fitting that the Lecture had established a tradition of surveying some field of research associated with aerodynamics, in which Lanchester was so eminent. He thought that Lanchester would approve of both the subjects discussed and the distinguished men who had honoured his memory by presenting them. Before introducing Professor Mair he wished to welcome Mrs. Lanchester and Mr. George Lanchester and his wife, and Mrs. Mair.

Professor Mair must be well known to most of them. After graduating in Mechanical Sciences at Cambridge in 1939 he had joined the Royal Aircraft Establishment at Farnborough, where he scent some six years in the Aerodynamics Department doing research on high subsonic speed, both in the wind tunnels and in full-scale flight. In 1946 he had gone to the University of Manchester as Director of the Fluid Motion Laboratory and since 1952 he had held the Francis Mond Chair of Aeronautical Engineering at Cambridge. His chief interest there had been mainly in low speed aerodynamics and his authority in that field was widely recognised. In 1963 he had been appointed Chairman of the Powered Lift Committee of the Aeronautical Research Council.

On 29th March of this year, The Society of British Aerospace Companies celebrated the completion of fifty years' activity. It was on 29th March 1916 that The Society of British Aircraft Constructors was incorporated —junior to The Royal Aeronautical Society and The Royal Aero Club, but senior by two years to the Royal Air Force. The Society continued under that title until 26th February 1964, when its name was changed to “Society of British Aerospace Companies.” The new title retains the well-known initials SBAC but more accurately covers the wide range of interests of the Society's Members—not only the manufacture of aircraft, but of engines, missiles, electronics, hydraulics and pneumatics, electrical equipment and all other components and materials essential to such a technologically advanced industry. The new title also brings the Society into line with comparable associations in the United States, France, Germany, and Italy.

I am very happy to have this opportunity to tell you about Polaris, which has had such a tremendous impact on the world situation. It will be appreciated that I cannot divulge anything of a classified nature, and that this places great restriction on what I can say. Nevertheless, I hope that what I can say will be of interest; it will be slanted towards the weapon aspects, as this is my prime responsibility.

I will start with some background information on how our programme started and the special measures we found necessary to stand a chance of getting our task completed in the timescale.

The paper re-examines the economics of the various types of orbital booster, ranging from completely expendable to completely recoverable vehicles. Previous studies have compared vehicles of equal payload. Here we have introduced the concept of the cost optimum vehicle. It is shown that the lower the degree of recoverability, the larger the optimum payload for a given total payload in orbit. Cost comparisons are then developed using the cost optimum vehicle in each case.

Additionally, in our previous work we have confined ourselves to the economics of operating the launch vehicle. A recoverable launch vehicle generally automatically implies a capability for recovering the payload. The case for the recoverable vehicle becomes more and more attractive as the salvage value of the payload increases. The break-even points for a number of Payload Salvage Values (PSV) are presented.

Data are included which show the high costs of present day satellite vehicles. These amount to tens of thousands of dollars per lb. If we assume that the PSV of such satellites is $7000 per lb the break-even point for the Aerospace Transporter is about 5 x 105 lb cumulative payload in orbit (COP). The cost of manufacturing such a satellite payload would be upwards of $5000m, which is several times the cost of producing and operating the launching vehicle. It therefore appears unlikely that the Aerospace Transporter will be employed simply to launch conventional satellites. In this connection it should be remembered, however, that the payload capability will revolutionise the approach to satellite design. Attitude control, the structural envelope, etc, will be provided by the launch vehicle in many cases. Thus the mission capability of the payload will be greatly increased. Furthermore, relaxations in payload weight constraints, which could lead to increases in payload reliability and decreases in cost, appear to be possible with such a vehicle.

There are, however, some payloads which must be recovered and the most significant of these is man. Once recovery of the payload becomes mandatory the recoverable vehicle is always superior to the expendable vehicle. This is true no matter how small the number of shots. Thus once we are convinced of the future of man in the exploitation of space, the case for the recoverable vehicle (Aerospace Transporter) is unassailable.

The capability for recovering the payload should add greatly to the value of other orbital operations. An obvious case is that of photographic reconnaissance. Here we have a mission requiring a large number of regular launches and recovery of at least part of the payload. An economic assessment should show the Aerospace Transporter in a very favourable light. At the end of this section the point is made that, although we can see a great many possibilities for utilisation of the Aerospace Transporter payload, this aspect will be so revolutionised that we feel in need of advice from specialists on a number of questions. For example: What types and sensitivity of sensors will be available in the next 15-20 years? How would a relaxation in the weight restrictions affect payload philosophy? How could the intelligence of man be employed? and the most important question: What would be the value of such operations to agriculture, water management, population control and other activities on earth?

The last part of the paper deals with the sensitivity of a number of types of Aerospace Transporter to weight growth and vehicle life. It is shown that VTO vehicles are, if anything, less susceptible to weight growth than HTO vehicles. It is also concluded that there is little point in adding weight to increase the life beyond 50-100 re-uses.

One of the novel problems presented by supersonic transports is the control of the complex powerplants needed to achieve optimum efficiency over a very wide range of forward speeds.

The subject is a large one and its proper understanding involves the disciplines of aerodynamics, thermodynamics, servo-theory and finally human engineering, because its end product is a set of knobs, levers, lights and dials which must be usable by the flight crew.

This paper is intended as an elementary introduction, using the special case of the Concorde as a basis. First, an attempt is made to give the aerodynamic and thermodynamic reasons for the large number of powerplant variables which the control systems must manipulate. On this basis, a functional specification of the control systems is established and, finally, the crew's job of propulsion management is described step-by-step in the course of a typical mission.

An immediate requirement within the aerospace industry appears to be the development of a practical system for the evaluation and control of complex projects. No amount of qualitative evaluation will present management with the answer to the problem of making complex decisions. The Generalised System for Project Control and Evaluation presents an approach towards evaluation of quantitative indices of “value” and “cost effectiveness” that can be optimised, possibly by operational research methods, to produce information that can be used by management in the making of realistic decisions.

Most teachers of gasdynamics with whom the writer has discussed the Prandtl-Meyer analysis find difficulty in giving a lucid exposition to students; the standard treatment tends to be long, and mathematical rather than physical, so that steps in the process of integration are difficult to remember. Lockwood Taylor gives a short treatment; but he begins from Ackeret's formula, which is in effect the differential equation to be treated; and he avoids the actual integration. These considerations have prompted the writer to publish the following treatment, which though self-contained is quite short, and—being mostly graphical—gives some insight into the physics of the problem.

Two recent papers by Bradshaw have drawn attention to instabilities in the flow through wind tunnel screens. In Plate 1 of ref. 2 a smoke tunnel photograph shows the manner in which the jets coalesce behind a high blockage, two-dimensional cascade. In the present note, three points relating to this flow will be discussed.