The Fifty-Fourth Wilbur and Orville Wright Memorial Lecture, “The Well-Balanced Structure”, was given by Sir Alfred Pugsley, OBE, DSc, FRS, HonFRAeS, on 9th December 1965 in the Lecture Theatre, 4 Hamilton Place, London W.I. The Chair was taken by Sir George Gardner, KBE, CB, HonDSc, HonFRAeS, President of the Society, who opened the meeting by expressing the sympathy of the Society to their colleagues in America on the death of Dr. Hugh L. Dryden on 2nd December; not only was he a distinguished man in his own country but he was a close friend of many in this country and an Honorary Fellow of the Society.

As has become the custom, the Society's main awards for the year were presented before the lecture. The presentations were made by the President and the citations were read by Mr. A. D. Baxter, MEng, FRAeS, President-Elect; the scrolls of three Honorary Fellowships and of two Honorary Companionships, and nine medals were presented. (The names of the new Honorary Fellows and Honorary Companions and the list of awards, with their citations, were published in the December 1965 Journal, pages LXXX and LXXXI.)

Introducing the Lecturer, the President said that the year of the Wright Brothers’ first flight had been the year of birth of a number of people who had made great contributions to the development of aeronautics; one of these was Sir Alfred Grenvile Pugsley. He obtained a first class honours degree in engineering of London University and then trained as a civil engineer and Student apprentice at the Royal Arsenal, Woolwich; there could be no doubt about his full qualifications as a “chartered engineer” according to the new standards. In 1925 he joined the design and research staff at Cardington working on the R101 and not only had he played his part in the design of various parts of the airship's structure, he had also taken part in the full speed trials of the airship. In 1931 Sir Alfred joined the scientific staff of the Royal Aircraft Establishment and worked on structural problems, particularly in the field of aeroelasticity. From 1941 to 1945 he was head of the Structures and Mechanical Engineering Department at Farnborough.

He was appointed Professor of Civil Engineering at the University of Bristol in 1945 and was Dean of the Faculty of Engineering from 1951-54, and Pro-Vice-Chancellor from 1961-64. Sir Alfred had acted successively on the Councils of the Royal Aeronautical Society, the Institution of Structural Engineers, the Institution of Civil Engineers and the Royal Society, and was President of the Institution of Structural Engineers in 1957-58. He was Chairman of the Aeronautical Research Council from 1952-57 and was a member of the Advisory Council for Scientific Policy from 1956-59. He was knighted in 1956 and was made an Honorary Fellow of the Society in 1963.

The present aerodynamic study of “hangar” type engine test cells originated with a request for assistance following difficulties experienced in the commissioning of a Dart engine-test facility. The major improvements obtained resulted from a systematic programme aimed at understanding the basic problems involved. Extensive use was made of model techniques during this investigation.

Detailed flow studies in two other hangar type cells, in successful operation, disclosed certain vortex features which were common to all three cells. Hence in view of a dearth of information on the aerodynamics of such cells, it was decided to deal with the general design problem and to sup-port the study with selected results from the experimental work referred to previously.

The main purpose of the investigation has been to clarify the definition of hovercraft wavemaking resistance and to improve understanding of the physical mechanism. The most literal definition of wave resistance as the force which makes the waves is proposed and its practical and theoretical implications are considered. Various interim accounts of this work have already been written, but the time now seems appropriate to assemble and review the overall picture which is emerging.

The pattern of forces on a hovercraft over water is often difficult to analyse because of the complicated interaction between wavemaking, jet air momentum, cushion pressure, wetting and other effects. It is important, however, in making power predictions that the physical interpretation and corresponding scaling laws of the various forces should be understood. A significant feature of the present approach is that a positive and unambiguous basis for identifying the wavemaking force is offered and compared with theoretical predictions. This force, according to the definition proposed, is assured a proper compliance with the physical laws which govern the waves generated and the corresponding scaling and interference effects, which are predicted by theory.

The twenty-first British Commonwealth Lecture, “Private Enterprise in British Air Transport”, was given before the Society by F. A. Laker, ARAeS, on 14th October 1965 in the Lecture Theatre, 4 Hamilton Place, London W.1. The Chair was taken by the President, Sir George Gardner, KBE, CB, HonDSc, BSc, HonFRAeS. Introducing the Lecturer, Sir George said that after a brief start in automobile engineering, Mr. Laker had switched in 1938 to aircraft—with Short Brothers. He thought that Mr. Laker really came into prominence in 1947 when he formed Aviation Traders Ltd, and not long afterwards Air Charter Ltd, which later merged with the Airwork Group. Mr. Laker had kept on expanding his interests and formed British United Airways of which, as they knew, he was Managing Director. Mr. Laker was a qualified pilot, as well as an engineer and flew his own Cessna aircraft round the various bases of his organisation. He was also President of the Society of Licensed Aircraft Engineers and Technologists.

The first serious attempt at refuelling in flight was made in the USA in 1923 under the direction of Major (later General) H. H. Arnold, in which two aircraft were equipped as tankers, each with a 50 ft length of hose, and a flight of 37 hr 15 min was achieved. Towards the end of that year the first serious attempt in Europe was made in France.

There was then a lull until January 1929 when the US War Department sponsored some duration flights, the best known being that by the Fokker “Question Mark” under the command of Major (later General) Carl Spaatz which remained airborne for 150 hours. This flight was followed by a spate of US commercial pilots’ attempts until in 1930 the endurance record stood at 647½ hr. Most of these flights in themselves were of little practical value but they aroused the interest of Sqn. Ldr. (later Air Marshal Sir Richard) R. L. R. Atcherley, RAF while taking part in the National Air Races in the USA in 1930. On his return to Transjordan, where he was stationed, he set to work devising an improved method of contact, the results of which were patented. He also planned to demonstrate his new method with an attempt on the duration record but was refused permission by the Air Ministry.

Just after the turn of the century, after many struggles, the heavier-than-air flying machine first rose from the earth, part of the success being due to the development of the comparatively light internal combustion engine. The materials of the airframe being mainly wood, including bamboo, and a few pieces of mild steel plate.

For a few years the materials of construction altered only a little and the knowledge of those materials and their behaviour was limited and confined to that which had been established during the course of mechanical engineering.

The mechanical engineers had been able to include fairly substantial factors of safety in their calculations which covered many variations and possible errors in materials, loads and workmanship and also—probably unknowingly —problems which could arise from fatigue.

My interest in Aviation first developed in 1914 when I was living in Frankfurt opposite the aerodrome learning German. I often witnessed the landings of the German Zeppelin airship, the “Viktoria Louise”, which used to return there from numerous commercial flights throughout Germany. Even in those days sightseers could journey up and down the Rhine in this stately airship, in which every comfort was provided, including a first class dining saloon.

The day before war was declared I returned home and joined the Royal Naval Air Service and was eventually commissioned as Flight Sub-Lieutenant in October 1915. I was posted to the Airship Section which had recently been taken over from the Army by the Royal Navy to work in conjunction with destroyers in submarine spotting.

Towards the end of the days of the Royal Naval Service, 1919, I was posted to Barlow, where HMR33 was under construction. Barlow was in Yorkshire, near Selby. I knew where Selby was, as a Sunderland man. Selby was “way down south, near York”.

Barlow must have been the best RNAS station to be posted to, just a small group of officers and ratings, the potential crew of the wonderful new airship HMR33.

When we arrived, the “ship” was about half to three-quarters built, and, among other things, our duties were to make ourselves useful and get to know the construction of the whole airship. We took a great interest in our official duties, but some, I believe, were also interested in the girls working on the ship, which, after all, added a bit of romance, especially to an RNAS station.

“Built like a—battleship”. I always remember this cryptic remark from one of the deck crew of the Courageous after the first deck landing on this Carrier of the Blackburn Skua well over twenty-five years ago. I still don't know whether this was a compliment or not, but it aptly fitted the rugged aircraft required for the very arduous Naval duties. The Skua was in fact the first monoplane specifically designed for the Navy, and it followed a long string of biplanes starting with the Dart, a torpedo carrying aircraft designed at Brough as a “private venture” immediately after the First World War.

None of these machines were particularly attractive in appearance, restricted as they were in span, length, height and so on, and handicapped with folding wing requirements, and the provision of an alternative float seaplane undercarriage that in most cases determined a large proportion of the main structure of the aircraft.

The Royal Aeronautical Society has a history of 100 years. I can look back over a membership of more than half that time, since I was made a Fellow in 1911.

My start in the aeronautical world began in 1910. I was appointed Engineer in charge of Design at Farn-borough by its chief, Mervyn O'Gorman. He was a far-sighted and inspiring man, under whom it was a pleasure to work. The War Office had lost faith in aeroplanes and our work was to be confined to lighter-than-air craft. Sam Hiscocks was the able chief draughtsman of a very small drawing office with whose help we managed to make three airships. The latest was called the Delta, and had a speed of 45 miles an hour. This may seem absurdly slow but it was faster than many aeroplanes flying at the time. The Delta was eventually taken over by the Naval Air Service and was used for submarine spotting during the First World War.

Having been asked to recount a brief history of the origin and conception of the Aeronautical Technical School Movement, I wish to pay the highest tribute to the philosophy, example, logical methods and encouragement of those men from whom I had the good fortune to receive my own training and under whom I was privileged to serve. Their sterling qualities were co-ordinated and embodied in the establishment of the first Civil Aeronautical Technical School and have led to the achievements of countless of its pupils.

The basic principles of the School have remained unaltered but they have been adapted and amplified, with success, to meet the requirements of subject, numbers, nationality, language, character, creed and environment, for a variety of projects for Governments and Industry, involving the training of individuals and small classes up to many thousands of trainees—maximum results in the minimum of time being the objective.

The title chosen identifies the period when flying was an adventure; when the design and construction of aeroplanes and attempts to become airborne on them, whether successful or not, created the pleasure and satisfaction that is felt by the “do it yourself” enthusiast who, with little previous experience to guide him, ventures more or less into the unknown; when every failure and disappointment is a spur, a stimulus and a positive urge to try again and do a little better next time. This period began seriously not much more than sixty years ago.

In this age when people are being whisked to the ends of the earth at speeds approaching Mach one and when tremendous efforts are going forward to propel them there two or three times faster than that, it is almost incredible that the progress which we have seen take place could have been possible in such a comparatively brief period.

In control theory, stability is investigated by established techniques such as the root-locus method. The same techniques may be applied to the control equivalent of a mechanical system and will show the transient state of the system. Vector methods such as are used to solve vibration problems may also be extended to give transients.

This note gives a vector representation of the transient vibration of a one degree of freedom system possessing inertia, elasticity and viscous damping. For the transient which is set up by a change in the steady vibration of the system, the initial amplitude and phase angle are readily found by vector methods. This information is sufficient to define the transient.

Ever since the realisation of the matrix Displacement Method, the introduction of a kinematically satisfactory spar element has remained a difficult and, as yet, not fully resolved problem. Two cardinal points have to be considered in establishing a suitable spar model: first, it must reproduce adequately both shearing and bending deformations, and second, it must satisfy everywhere the kinematic compatibility conditions, especially at the junction with the wing cover. Of course, if we were to restrict ourselves to a uniform rectangular element, the corresponding theory could be written down in a few lines. However, from the practical point of view, it is essential to take account, ab initio, of taper, and this necessitates some subtle considerations, especially if we have to allow for asymmetrical taper, as becomes indispensable with some modern flying vehicles.