In this paper the many aspects of tyre performance criteria are discussed, as they have developed over the last decade. The corresponding tyre developments that have been effected to date are set out in considerable detail, together with the forward developments which are currently engaging the skills of modern tyre designers.

For the most part the paper deals with the present standard aircraft tyre, of conventional or cross-ply construction (Fig. 1), but the future role of the radial ply tyre (Fig. 2) is treated in some detail.

It was easy for me to choose a subject for this lecture. First, turbulence is an important part of engineering fluid dynamics which has not so far been treated in the Reynolds-Prandtl lectures; secondly, it is the most obvious link between the careers of our two heroes; and thirdly it is the only scientific subject on which I am even remotely qualified to lecture before such a distinguished audience. The first and second propositions are sufficiently demonstrated by the annual consumption of something of the order of 1010kg of kerosene to overcome the effects of Reynolds’ stresses in Prandtl’s boundary layers. Have any two human beings ever had such a spectacular memorial? (Yes, Lanchester and Prandtl, to whose induced drag we sacrifice another 1010kg of fuel each year.)

The aviation industry, by definition of its products and their utilisation, is international. It may shortly become interplanetary. BOAC, by whom I am employed, operates its aircraft all over the world and employs staff in more than fifty countries. Our staff includes a very wide cross section of trades and professions, from aircraft cleaners to pilots, architects and lawyers, but with a few exotic exceptions, our industrial relations do not differ substantially from any other modern industry in the UK.

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.

The Convention for the Suppression of Unlawful Seizure of Aircraft—to give the treaty its official title—was drafted by a subcommittee of the Legal Committee of the International Civil Aviation Organisation (ICAO) in September/October 1969, considered by the Legal Committee itself in February/March 1970, signed at a diplomatic conference meeting at The Hague on 16th December 1970, and came into force on 14th October 1971 amongst those States that had ratified it. While the coming into being of the Hague Convention has been fairly expeditious, so far only 15 States (Bulgaria, Costa Rica, Ecuador, Gabon, Hungary, Israel, Japan, Jordan, Mali, Niger, Norway, Sweden, Switzerland, USA, USSR) have accepted it. It is to be hoped that the United Kingdom, which took a leading part in developing this Convention, will do so before long, especially as the necessary legis-lation has already been passed—the Hijacking-Act which received the Royal Assent on 5th August 1971.

Probably the most significant happening in 1971 was the formation of Engineering Sciences Data Unit Limited, which began to function on the 1st April. This is important in two ways; in the first case it enlarges the capacity of the Unit in the production of Items both in the aeronautical field and in other branches of engineering, and secondly it may well set a pattern for other organisations wholly owned by the Society. During the nine months of the year during which the Company has been in operation, the Unit has made satisfactory progress, progress which augurs well for the future, and the Council wish to record its appreciation of the work done by both ESDU Ltd, and the subsidiary of the Thomson Organisation, Engineering Data Sales Limited, which is responsible for marketing the Data Items produced by the Unit.

The advantages to a Navy of an aircraft which can operate from a relatively small deck area are enormous and it is not surprising that the British as a maritime nation were in the forefront of the development of rotary wing aircraft for use at sea. However, the first man to land a rotary wing aircraft on a ship other than an aircraft carrier was an ex-Royal Air Force Officer R. A. C. Brie and the ship was the Italian cruiser Fiume.

F-111 aircraft are in service with both the Tactical Air Command and the Strategic Air Command in the USAF. The aircraft performs primarily in the fighter-bomber role for TAC and as a strategic bomber capable of high and low altitude penetration with SAC. Over 100 000 flight hours have been accumulated by the F-111 fleet including a limited amount of combat flying. The broad spectrum of service requirements for the F-111 include short field take-off and landing capability, all weather and deep interdiction, close air support with large payloads, high altitude high speed air defence, and world-wide deployment with minimum tanker support. Major technical advancements were necessary in meeting these requirements, including most notably a variable-sweep wing. The unswept high aspect ratio positions provide for maximum range and endurance and short take-off and landing distances. The wing in moderate sweep positions provides an efficient configuration for sustained high subsonic and high altitude supersonic flight. Supersonic flight at sea level at speeds in excess of the capability of any other aircraft plus supersonic speeds at altitude in excess of Mach 2.0 are achieved in a most highly swept low aspect ratio wing position.

On 13th November 1945, my distinguished countryman, Sir Hudson Fysh, KBE, DFC, delivered the first British Commonwealth and Empire Lecture inaugurated by the Royal Aeronautical Society. Significantly, in 1957 the title of this lecture series was changed to “The British Commonwealth Lecture”. Sir Hudson chose as his subject “Australia in Empire Air Transport”.

I feel deeply honoured to have this opportunity to contribute to the very considerable accumulation of knowledge which this series of lectures represents. My topic, despite the difference in title, is really a continuation of Sir Hudson's theme, with the advantage of an additional twenty-five years of hindsight.

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.

Flying locust swarms have already been found to provide particularly efficient three-dimensional targets for ultra-low-volume aircraft spraying. An exceptionally large proportion of the total insecticide applied can be picked up on the insects themselves, and kills exceeding one tonne of locusts per litre of insecticide have been assessed in the course of such operations. There is reason to believe that it was by aircraft spraying of swarms, often in flight, in Morocco during 1960, that locust control operations may for the first time have had a significant impact on the overall Desert Locust situation. Similar operations during 1968, in Ethiopia (with an outstanding Ethiopian senior pilot, Ato Abebe Wordofa) and again in Morocco, appear to have played a considerable part in suppressing the unusually short-lived recent upsurge of the Desert Locust, Schistocerca gregaria Forskal.