The 1,157th lecture to be given before the Society, “Supersonic Aircraft—Promise and Problems” by M. B. Morgan, Esq., C.B., M.A., F.R.Ae.S., Scientific Adviser to the Air Ministry, was given on 17th March 1960, at the Institution of Mechanical Engineers. Mr. Peter G. Masefield, M.A., F.R.Ae.S., Hon.F.l.A.S., M.Inst.T., President of the Society, presided. Opening the meeting Mr. Masefield said he thought this would be one of the most interesting and stimulating lectures of the session. The subject of the supersonic aeroplane had been freely discussed in the United States and probably in Russia also. In this country they had been more reticent so he hoped they would have a really good discussion after this lecture. One significant point was that people no longer wondered whether a supersonic transport could, or should, be built but only whether it should cruise at a Mach number of 2 and be made in light alloy, or whether it should be around Mach 3 and be made of steel or more exotic materials. That sooner or later—and many believed sooner—transports would fly at supersonic speeds at 70,000 ft. was taken for granted.

Mr. Morgan was well known to them all. Born in Wales, he was educated at Rutlish, Merton and St. Catharine's College, Cambridge, where he took the Mechanical Sciences Tripos and won the John Bernard Seely Prize in Aeronautics in 1934. In fact, he and Mr. Morgan used to enjoy the Cam together and Mr. Morgan looked little different today than he had in those days. Mr. Morgan was apprenticed to Mather and Piatt Ltd. and also spent a short time at Vickers, Weybridge before joining the R.A.E., Farnborough in 1935. Since then he had specialised in aerodynamics, flight research and development, stability and control and, he had taken his Pilot's Licence in 1944. He was Head of the Aero Flight Section of the R.A.E. from 1946-1948, Head of the Guided Weapons Department from 1948-1953 and Deputy Director of the Establishment from 1954 until 1959. He had then been appointed to his present position of Scientific Adviser to the Air Ministry and had also been Chairman of what had come to be known as “STAC”–Supersonic Transport Aircraft Committee. He felt that they could have no better person than Mr. Morgan to talk on the Supersonic Transport.

The Fifteenth British Commonwealth Lecture “Some Recent Progress in Air Survey with Particular Reference to Newly- Developed Territories" was given by W. P. Smith, M.B.E., B.A., F.R.I.C.S. before the Royal Aeronautical Society at the Institution of Mechanical Engineers on 19th November 1959. Mr. Peter G. Masefield, M.A., F.R.Ae.S., Hon.F.I.A.S., President of the Society, presided. Introducing the Lecturer the President said: This lecture was the second of their four premier named annual lectures. The first was the traditional Wilbur Wright Lecture, the second this Commonwealth Lecture, the third was the Louis Bleriot Lecture and the fourth the Lanchester Memorial Lecture. Five years ago, as many of them would recall, His Royal Highness, Prince Philip, the Duke of Edinburgh, honoured them by giving the Commonwealth Lecture on ”Aviation and the Development of Remote Areas.“He thought that they could say that the subject of Mr. Smith's Commonwealth Lecture was in some ways a projection of the Duke of Edinburgh's lecture, under the title "Some Recent Progress in Air Survey with Particular Reference to Newly- Developed Territories.”

Mr. W. P. Smith was a Director and leading light of Fairey Air Surveys Limited. Naturally as befitted a Commonwealth Lecturer, Mr. Smith was a master of his subject—one could almost say that he was “monarch of all he surveys.” He was a Durham man, born in 1920; he was educated at Wellfield School, Durham, and went up to Oxford and took his degree there. During the War, Mr. Smith was in command of Survey Units in the Royal Engineers and after the War he transferred to the Survey Branch of the Control Commission, in Germany. Then, in 1946 he left the Army to join the new Directorate of Colonial Surveys as a Senior Surveyor, and went to West Africa on the Volta River Project. He worked in Africa for a period and then in 1950 he joined Fairey Air Surveys Limited, then known as the Air Survey Company, as many would remember. He was a General Manager then, and was now a Director. So Mr. Smith had spent all his working life dealing with the subject on which he was going to talk about that evening, and in particular, he had been in charge of that vast Kariba Hydro-Electric Survey, on the Zambesi. They could have no one better to talk about Air Survey, and it was said that “life is the art of drawing sufficient conclusions from insufficient premises.” Air Survey, and the sort of things Mr. Smith was going to talk about was, in some ways, a way of filling in some of those insufficiencies.

He had much pleasure in calling on Mr. Smith to deliver the Fifteenth British Commonwealth Lecture.

In the first half of the paper some of the basic aerodynamic engineering and piloting problems that have been encountered during the design and development of modern naval deck landing aircraft are enumerated and described. Such aircraft, of basically swept-wing configurations and high transonic or supersonic performance, have to be capable of being flown comfortably under full pilot control at the low speeds expected for carrier deck landings.

In Part II, the many devices of aerodynamic and engineering design will be described which have been evolved in an attempt to overcome or minimise the problems.

In the context of this paper, the term “large rocket engines” refers to those liquid propellant engines at present being built for use with ballistic missiles. The engineers concerned with their development however, are always hoping that the same units may be used for launching satellites and for the early stages of space flight.

Now it is axiomatic that in such vehicles the take-off thrust should exceed the weight. On the other hand, common propellant combinations only give an impulse of about 240 pound seconds per pound of propellants. Thus it follows that the duration of one stage of powered flight at constant thrust could not exceed 240 seconds, even if the net take-off acceleration were zero and the whole missile consisted of propellants. Allowing for sensible take-off accelerations, and for the weight of structure, engines and payload, a more realistic figure would be 150 seconds. As re-use of the engine system is not usually contemplated, the entire operational life of a large rocket engine is probably less than three minutes.

As man's conquest of the air was gathering momentum in the 1920s, there came a longing among explorers of the Arctic, to overfly the icy waters which had hitherto taken such a heavy toll in men and ships. Men who, like Wilkins, had already made their mark in sailing through the ice and walking over the eternal snows, looked to the aeroplane or airship as a wonderful observation platform and as a means of quicker travel. And of the great of many nations who tried their skill and courage in the early attempts to fly across the Arctic, George Hubert Wilkins stands out as greatest of them all.

It is singularly appropriate that Mr. Walter Tye should be in the Chair today, not only by reason of his membership of the Air Registration Board, that Cerberus which watches so efficiently over so many aspects of safety in the air, but also for a more personal reason. He recently received the “ Aviation Week “ Award for distinguished service in achieving safer utilisation of aircraft, and I should like to take this semi-public opportunity of adding my congratulations to the many which he has received.

In many of the offices of my airline one finds displayed a small plaque. On it appears, among other words, the legend “Safety is no Accident.” Although I am no great believer in the power of an oft-repeated formula to achieve miracles, I do believe that these words hold within them much of my flight safety philosophy.

Turbine-powered helicopters mark the most important step taken thus far in the transition from development to business for that segment of the transportation industry which utilises the capability for vertical flight.

Completing more than a year ot detailed study and evaluation, New York Airways recently announced its commitment to purchase ten multi-turbine Vertol 107 aircraft designed to cruise in excess of 150 miles per hour with 25 passengers. They will be introduced into service in the spring of 1961. With these machines commercial revenues could, for the first time, offset all operating charges and produce a fair return on the capital investment—without government financial support. The availability of the Fairey Rotodyne in 1964 will place New York Airways in a position to offer the public a substantially enlarged and even more useful service operating on a business basis.

I am deeply appreciative of the great honour you have bestowed upon me in asking me to address you tonight. When Louis Bleriot made his memorable flight I was a boy of six and, I am sorry to say, not yet at school. In fact, I had to wait until I was nine to see my first aeroplane which, believe it or not, was a Bleriot monoplane fitted with a Gnome engine and flown by another pioneer aviator, B. C. Hucks.

The simplicity of the aircraft and the apparent ease of flight made a deep impression on my boyish imagination. So much so that the same imagination was quite affronted when it first saw the pusher biplanes with which we prepared to fight the First World War. Having had nothing to do with it, I can now claim it took a further 25 years for the advancing march of aviation finally to confirm my childish fancy!

Boundary layer theory is the cornerstone of our knowledge of the flow of air and other fluids of small viscosity under circumstances of interest in many engineering applications, especially also in aeronautics. Many complex problems in aerodynamics, as for instance the problem of skin friction, which was theoretically attacked very early by F. W. Lanchester, have been clarified by studying the flow within the boundary layer and its effects on the general flow around the body.

Research work on boundary layers, as started by Prandtl in 1904. was for the first twenty years—up to Prandtl's Wilbur Wright Memorial Lecture to the Royal Aeronautical Society in 1927—almost entirely restricted to Prandtl's Institute at Göttingen. But since about 1930 boundary layer theory has been generally accepted, and in the past thirty years there has been an almost exponential rise of the number of contributors to its further development.

The author tries to trace certain lines, along which this important branch of modern fluid dynamics has developed in the past thirty years. In this connection the following topics are treated to some extent:

1. I. Transition from laminar to turbulent flow.

2. II. Boundary layer control for high lift and low drag of aerofoils.

3. III. Aerodynamic heating at high speed (high Mach numbers).

4. IV. Boundary layer efff cts on swept wings and on rotating bodies.

I. The theoretical investigations of the problem of transition start from Reynolds' and Lord Rayleigh's hypothesis of the instability of laminar flow. After many unsuccessful attempts Tollmien, 1930, finally succeeded in calculating the critical Reynolds number for the boundary layer on a flat plate. More than ten years later Tollmien's stability theory was completely confirmed by very careful experiments of Dryden and his co-workers.

II. After many wind tunnel experiments the investigations of boundary layer control for high lift of aerofoils led to the construction of two aeroplanes with boundary layer suction at the aerodynamische versuchsanstalt gottingen, in 1938, which were quite successful. later on, also, a considerable reduction of the skin friction of aerofoils was obtained with the advent of the laminar flow aerofoil.

III. In flow at high Mach numbers the velocity boundary layer is accompanied by a thermal boundary layer which is caused by frictional heating. The large increase in the temperature of a solid surface in a high speed stream which can be calculated from boundary layer theory only, poses a serious problem to aeronautical engineers (“thermal barrier”).

IV. The aerodynamic characteristics of swept wings and Delta wings are largely governed by the behaviour of their boundary layer. Some of the draw-backs of such wing plan forms can be remedied by boundary layer control, as for instance by a “boundary layer fence.” For turbo-machines the influence of the centrifugal forces on the boundary layer plays an important role for their aerodynamic coefficients.

I should like in this paper to review some of the work on helicopter vibrations which has been done at Southampton University in the past few years. This has been mainly concerned with blade vibration and there have been parallel theoretical and experimental programmes. Complimentary research has been going on in the United States and the results support each other in an encouraging way.

The results of experiments on the reattachment of a laminar boundary layer, separating from a rearward facing step in a flat plate aerofoil, are correlated with the properties of the short leading edge bubble which forms on thin aerofoils near the stall.

The experiments, comprising pressure measurements, Pitot explorations, liquid film and smoke studies, indicate that for all Reynolds numbers above the value given by the Owen-KIanfer criterion the reattachment is turbulent behind a stationary air reverse flow vortex bubble. It is also found that the reattachment is laminar for Reynolds numbers below the critical, which further supports Crabtree's interpretation of the Owen-KIanfer criterion in terms of the condition for the growth of turbulent bursts.

This paper is a brief summary of an investigation made to check the effect of lift on the shock noise of aircraft flying at supersonic speeds. The method of Hayes has been combined with the theory of Whitham to predict the asymptotic shock strength of wings carrying lift and of combinations of bodies and lifting wings. (A similar, but not quite as general, method was derived by Walkden in Ref. 6.) Whitham's formula, including only the volume term, has been used extensively to predict the boom intensity of aeroplane type bodies and the agreement with experiment has, so far, been quite reasonable. The test data obtained to date extends only up to about 40,000 ft. altitude and the calculations of this paper show that under those conditions the shock noise of the aircraft tested so far will, in most cases, be dominated by the volume term. It is shown that at higher altitudes lifting effects will dominate for even the small fighter and they will dominate over most of the altitude range for large bomber and supersonic transport aircraft. The boom intensity due to lift decreases with altitude as h–¾ which compares to pa½ h–¾ in the volume case (pa = pressure at altitude h). It is insensitive to Mach number (for M > 1·4), wing loading, wing plan shape and lift distribution. A simple rule for calculating the shock noise due to combined volume and lifting effects is proposed which is applicable to configurations with wings located towards the rear of the fuselage. The rule states that the shock noise of an aircraft carrying lift is equal to the shock noise due to volume (neglecting lift) or the shock noise due to lift (neglecting volume), whichever is the greater. A chart is presented from which rapid estimates can be made of the shock noise of lifting wing-body combinations.

There is a scarcity of specific design data which can be presented to the aircraft designer to enable him to assess the most suitable structural aluminium alloy for a high speed civilian transport aircraft. The problem is essentially due to the relatively low range of elevated temperatures, in which he is interested, coupled with the very long life requirements for a commercial transport aircraft flying at speeds at which it is possible to consider the use of aluminium alloys.

Although the firm with which the author is associated has a vast experience in the development and knowledge of aluminium alloys for aero-engine and gas turbine purposes, it has never been required, in the past, to consider engine applications much below about 200°C, and the design data, which was determined over many years and provided as a service, satisfied the engine designers if the period of test was up to 1,000 hours. On the other hand, to the designer of aircraft for subsonic flight, kinetic heating is no problem at all, and he is quite satisfied with a knowledge of the room temperature properties of the various alloys.

This paper briefly reviews the progress made with the Imperial College hypersonic gun tunnel since August 1958 when it came into operation. The tunnel and instrumentation are described together with the results of various measurements made both in the barrel and in the working section. More detailed reports will be published later.

The Revival of interest in flight by man's own muscle power brings back to me some early attempts to solve this problem some 30 years ago.

Needless to say I was—and still am—sold on this idea ever since reading Lilienthal's famous book as a youngster in school. Then came the Wright Brothers and the early years of flying and the years of the First Great War at the end of which I found myself as an Aerodynamicist, designing wing sections and calculating induced drag according to Prandtl's newly discovered wing theory.

The end of the war found us meditating about gliding and the possibility of soaring flight. And so came the Rhoen, and the “Sturm und Drang” of the years on the Wasserkuppe.

In the present era of supersonic and hypersonic flight, structural analysts are well aware of the new problems that arise from the exposure of aircraft and missile structures to elevated temperatures. The task of solving these problems is in its early stage of development. Since the problems are diversified in nature, a different method of solution has to be developed in each case. It is probable that in some cases radically new techniques may have to be devised. Until such time, the structural designer is forced to take a realistic view and use satisfactory extensions of existing methods of analysis.

Forty-two years ago—on 2nd August 1917—the first deck landing on a ship under way was made. A special platform had been constructed on the battle cruiser Furious, and it was on this prototype flight deck that Squadron Commander E. H. Dunning made the first successful aeroplane landing aboard ship. On touching down, his aircraft—a Sopwith Pup—was restrained manually by the (presumably) willing hands of a large number of officers and men. Two days later a second attempt ended in disaster. But from this beginning, like so many initial steps forward in aviation, a sad one, grew the Fleet Air Arm as we know it today.

With the Co-Operation of 1,600 members of the public a series of aircraft noise assessment tests was made at the 1959 Farnborough Air Show to obtain further information on the way in which the perception of these noises is influenced by subjective effects. This provisional analysis shows that Beranek's empirical method for assessing the perceived noise level is adequate for the comparison of existing types of fixed-wing aircraft. A secondary part of the experiment, dealing with noise simulating the ducted-fan engine, is also described.

The purpose of the work was to investigate the effect of the finite width of plate on the elastic-stress distribution due to a central crack in a flat plate loaded in tension.

The range of investigation: (i) Two-dimensional photoelastic tests were carried out on flat-plate specimens. The photoelastic specimens were geometrically similar to the 10 in. wide fatigue specimens used by Frost and Dugdale, with the central crack simulated by a slot bounded by holes of small radii, (ii) A theoretical solution of the problem was derived and compared with the present and other photoelastic results.

It is shown that the effect of the crack-length/plate-width ratio on the elastic-stress concentration at the head of the crack can be expressed by the following formulae: