The suitability of a piece of mechanism for a given job depended both on the nature of the job and on the solution offered. In aviation they had to consider performance, time of development, cost in production and serviceability in its widest sense. It was proposed to review these different aspects as they applied to the compressors for aircraft gas turbines.

The 820th Lecture to be read before the Royal Aeronautical Society, “Progress Towards Electrical Serviceability,” was given by R. H. Woodall, M.I.E.E., A.F.R.Ae.S., and V. A. Higgs, B.Sc., A.M.I.E.E., A.F.R.Ae.S., on 1st March 1951 at the Institution of Civil Engineers, Great George Street, S.W.I. Major G. P. Bulman, C.B.E., F.R.Ae.S., President of the Society, presided at the meeting and introduced the lecturers. Mr. Woodall is a Director and Chief Engineer of Rotax Ltd., and Mr. Higgs is Head of Technical Sales and Aeroplane and Automobile Sales of the British Thomson-Houston Co. Ltd.

It is evident from remarks made in previous papers or in discussion on those papers, that the Aircraft Industry is not entirely satisfied with the electrical accessories available for use in aircraft.

There may be some grounds for this dissatisfaction, but it is hoped to make it clear that the electrical equipment suppliers are very much alive to their responsibilities and that development on an ever-increasing scale is taking place in order to give the aircraft constructors the most reliable equipment possible.

The 805th Lecture to be read before the Royal Aeronautical Society was given on 19th October 1950 at the Institution of Civil Engineers, Great George Street, London. Major G. P. Bulman, C.B.E., F.R.Ae.S., President of the Society, presided during the first part of the meeting and introduced the Lecturer, Mr. R. Hills, B.A., A.F.R.Ae.S., who had been engaged for some years on low and high speed tunnel work and was in charge of the No. 2 eleven and a half foot tunnel at the Royal Aircraft Establishment, Farnborough.

It is almost four years since a series of papers on Naval Aviation was presented to the Royal Aeronautical Society in the full day session held on 7th May 1947. The first paper in that series, “Technical Problems of the Design of Naval Aircraft,” read by W. S. Farren, stated the fundamental problems clearly.

During the intervening years, the general trends in aerodynamic and power plant development have been reflected in the design of carrier-borne aircraft and are beginning to stabilise into a recognisable pattern. Thus, turbo jet and turbo-propeller engines are now accepted for Service use, there has been general aerodynamic improvement including the suppression of drag arising from the carriage of stores, and it is normal to find that prototypes are mounted on a nose-wheel type undercarriage.

The ubiquity of aircraft in being and yet to be, whether civil or military, manned or unmanned, makes them liable to exposure to wide extremes of atmospheric conditions. The range of temperature to which they may be subjected may possibly be from +90° to –90°C. (+194° to –130°F.), that of pressure, from one atmosphere to something approximating to one-tenth of this amount, while the water content (aqueous vapour plus water in suspension; for example, in a very dense tropical cloud), can, on occasion, be as high as 2.5 per cent. by weight and, at stratospheric heights, at least as low as 0.001 per cent. Such variations in ambient conditions are not without chemical and physical repercussions. The engineering problems which arise will be examined, therefore, from both these view points, and attention will be drawn to potential dangers and means suggested for their avoidance.

The flight of heavier-than-air craft has marked as it were the triumph of man over gravity; while, “the struggle of power versus weight” constitutes an outstanding feature of technical development. Aviation was effectively born on that day when the mechanical engineer was able to design a sufficiently light engine: in France, Ader who conceived and made use of a steam engine weighing only 6.5 lb./B.H.P. (3 kg./C.V.) is credited with the first flight, in October 1897, of a piloted aircraft. A few years later, the Wright Brothers bettered the exploit, thanks to a sufficiently light engine, this time a petrol engine.

The aeroplane in which Louis Blériot flew across the Channel is worthy of attention today, because it is typical of the 1909–1910 type of aeroplane.

Aeronautics has advanced a long way since that December day in 1903 when Wilbur and Orville Wright successfully completed the first flight test ever to be made on a powered aircraft. Since then much has been learnt about the science of aeronautics and great developments have taken place in the methods and techniques of aeronautical research. Wind tunnels have been built capable of testing models at very high speeds and at high Reynolds numbers, and many other powerful research techniques have been developed to assist in the design of aircraft. The behaviour of the aircraft itself in flight remains the final test, however, and there are still many problems which can be investigated adequately only in flight with a piloted aircraft.

In this lecture it is proposed to illustrate the contribution which flight research can make towards the advancement of knowledge of aeronautics by discussing some of the more important aspects of this work.

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.

A joint meeting of the Royal Aeronautical Society and the Royal Meteorological Society was held on 14th December 1950 at the Institution of Civil Engineers, Great George Street, London, S.W.I, at which the 814th Lecture to be delivered before the Royal Aeronautical Society was given by Dr. G. S. Hislop. Major G. P. Bulman, C.B.E., F.R.Ae.S., presided at the meeting and after welcoming the members of the Royal Meteorological Society and especially their Secretary, Professor Sheppard, and expressing his regret at the absence in America of the President of the Royal Meteorological Society, Sir Robert Watson Watt, he introduced the Lecturer, G. S. Hislop, Ph.D., B.Sc, A.R.T.C, A.F.R.Ae.S., M.I.Mech.E., Senior Assistant to the Controller of Research and Special Development, British European Airways Corporation.

A start is made by considering why the subsonic propeller was abandoned when aircraft speeds approached the shock stall. It is true that the shock stall also occurs on the propeller blades under these conditions, causing a loss of lift and an increase of drag, but this is not the predominant effect which produces the marked decrease of propeller efficiency associated with high-speed aircraft. The main aerodynamic difficulty associated with the shock stall on the wings of an aircraft is due to the separation of flow caused by the shock wave rather than the presence of the shock wave itself. This difficulty is reduced on a propeller, as any separation of flow which might occur on a propeller blade due to the shock stall, would tend to cause the air to be stagnant relative to the blade, and would thus experience a large centrifugal force by virtue of the propeller rotation. Thus the propeller shock stall would never develop to the same degree that it does on the wings of an aircraft in steady flight.

The 825th lecture to be read before the Royal Aeronautical Society, “ Planning ami Production Methods Used in the Construction of the de Havilland Comet,” by H. Povey, A.F.R.Ae.S., was given at the Institution of Civil Engineers, Great George Street, London, S.W.I, on Thursday 12th April 1951. Major G. P. Bulman, the President of the Society, presided.

Opening the meeting the President said they met that evening in the shadow of a grevious loss sustained by aviation throughout the world, and by the Society, in the unexpected death of Mr. W. G. A. Perring on 8th April through heart failure. The shock to those of them who worked with him and knew him well was still so deep that one could not try to pay an adequate tribute to his great services.

Throughout the world helicopters are being operated in a variety of roles today and, whereas ten years ago, there was not one type which had got beyond the stage of being an inventor's plaything, several types are now suitable for regular military and civil operations. At present, so far as is known to the author, public transport services using helicopters are confined to charters and scheduled mail services, with the exception of a scheduled passenger service which has been run by the British European Airways Corporation as an operational experiment since June 1950. The factors, both technical and economic, which have so far prevented the large scale introduction of public transport helicopter services, are being progressively overcome and in due course operators will find that manufacturers have made available suitable aircraft. The operators' task will then be to fly these aircraft in a safe and regular manner and give the public the best service possible.

Under present conditions, the author of any paper on rocket power plant engineering must inevitably apologise for a certain reticence as regards technical details, which is imposed by security requirements. These arise from the important applications of rocket propulsion for guided weapons and other military purposes, and are less stringent in regard to its use as a means for providing take-off assistance. It is with the latter subject that this paper will be mainly concerned when practical applications are discussed.

Most of the fundamentals are common to all uses of the rocket motor and it is hoped that a general survey of these may be of some value, especially since the field of rocketry has been relatively neglected in the technical publications of this country.

The Seventh British Commonwealth and Empire Lecture, “Air Transport in New Zealand and the South Pacific,” by Air Vice-Marshal Sir Leonard Isitt, K.B.E., R.N.Z.A.F. (Ret'd.), was read before the Royal Aeronautical Society by Mr. T. A. Barrow, J.P., on 4th October 1951 at the Institution of Civil Engineers, Great George Street, London, S.W.I. Major G. P. Bulman, C.B.E., F.R.Ae.S., Past-President, presided.

Major Bulman: He was sure that they would all regret that Major Halford was unable to be present; immediately after the reception following the Wilbur Wright Lecture, he had had an operation, and although it was successful he had to undergo a course of treatment which would keep him out of circulation for another five or six weeks. They hoped that at the end of that time they would enjoy his presence and leadership for the rest of his year of office.

It was for him a very real pleasure, despite the sad reason, to take the chair for the second time at a British Commonwealth and Empire Lecture. These lectures—instituted originally by Mr. G. H. Dowty—were given alternately by a distinguished representative from the Mother Country and from the Dominions and Empire. They had had one from Australia, two from Canada and now New Zealand.

Air Vice Marshal Sir Leonard Isitt had had a distinguished career in the Air Force, first with the R.F.C. and Royal Air Force and then with the Royal New Zealand Air Force, and had now turned his attention to civil aviation. He was Chairman of New Zealand National Airways Corporation and of Tasman Empire Airways and a Director of British Commonwealth Pacific Airlines. Unfortunately, because of the recent election in New Zealand he had found it impossible at the last minute to be with them. They had just received a cable from him: “Regret inability to be with you in England today. Please accept apology and best wishes.”

In place of Sir Leonard Isitt they had the pleasure and privilege of welcoming Mr. T. A. Barrow, J.P., who would read Sir Leonard's paper. Mr. Barrow had been Secretary of the New Zealand Air Board since 1937. He was also Vice-Chairman of Tasman Empire Airways.

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.

The term Aircraft Instrumentation is used to describe the special instruments which in a variety of circumstances are needed to determine aerodynamic, structural and power plant characteristics. Such circumstances may be flight tests of prototype aircraft, tests in the air or on the ground of the aeroplane, its structure or power plant, or the acquisition of statistical data on the conditions to which aircraft are subjected in civil or military operation. These special instruments therefore are additional to, and usually different from, the instruments needed in an aeroplane to enable it to fulfil its military or civil role.

In this paper an attempt is made to review present knowledge of the subject of boundary layers at high speeds, without delving too deeply into the theory, and to draw attention to the results of practical interest. The introductory remarks describe broadly the special features of boundary layers in compressible flow, namely the existence of both thermal and velocity layers and their interdependence, the sensitivity of the external flow to the layers, and their inter-action with shock waves. The results of importance arising from the theory of the laminar boundary layer and of its stability to small disturbances are then discussed, followed by a summary of the present inadequate state of knowledge of turbulent boundary layer characteristics. It is noted that progress in the latter must await the production of more experimental data. The paper concludes with a discussion of scale effects and the allied problem of boundary layer—shock wave inter-action.

The purpose of this paper is to explain the principles governing the behaviour of structures under transient dynamic loads, such as those encountered by aircraft structures during landing or flying in gusty weather. The paper is intended mainly for the young aeronautical engineer who may not be particularly well versed in this aspect of stress work.