The 1,186th Lecture to be given before the Society—and the 40th Main Lecture to be held at a Branch centre—“ Trends in Aircraft Propulsion” by H. Pearson, B.A., F.R.Ae.S., Chief Engineer (Performance & Research), Rolls-Royce Ltd., was given under the auspices of the Southampton Branch on 19th January 1961. Professor A. R. Collar, M.A., D.Sc., F.R.Ae.S., F.I.A.S., Vice-President of the Society, presided. A message specially recorded on tape by the President, Dr. E. S. Moult, C.B.E., B.Sc.(Eng.), F.R.Ae.S., M.I.Mech.E., was broadcast. The President said how much he regretted missing Mr. Pearson's lecture and the meeting at the Southampton Branch. He had looked forward to the occasion but he and Dr. Ballantyne, Secretary of the Society, were attending an international congress in Detroit. He was grateful to Professor Collar for deputising for him and sent his best wishes to the Southampton Branch and to everyone present on the occasion.

Professor Collar, introducing the Lecturer, said that Mr. Pearson graduated in Physics from Christ Church. Oxford, and since 1940 he had been with Rolls-Royce, working first at Hucknall on problems connected with exhaust systems. In 1943 he had joined the Rolls- Royce team at Barnoldswick under Dr. S. G. Hooker, now of Bristol Siddeley Engines Ltd. Mr. Pearson had returned to Derby in 1946 as Chief Performance Engineer on turbine engines and three years later was appointed Chief Research Engineer. He was now a Director of the Aero Division of Rolls-Royce, and Chief Engineer (Performance and Research).

I shall try to set the Air Traffic Control scene by describing how the responsibilities of States to provide Air Traffic Services are currently exercised in the United Kingdom, and by indicating some of the measures being taken to ensure that these services keep pace with the increasing demands of the air space users. Any opinions I may express are, of course, my own, and do not necessarily reflect the views of the Ministry of Aviation.

The Oxford Dictionary defines the word responsible as, “liable to be called to account; of good credit or position; trustworthy;” this you will agree is quite a formidable definition.

Therefore, I have assumed the title of this paper to indicate that I should try to explain the abstract effects of this definition upon the individual Air Traffic Control Officer, rather than detail a list of the many and varied duties for which he is responsible.

This paper deals primarily with Air Traffic Control in the European region and does not refer to problems specific to other areas. Nevertheless, most of these problems are common to all regions and differ only in degree. Their solution depends upon the existence of a properly organised and equipped Air Traffic Control Service and there is now world-wide recognition by users and providers alike that such a service is an essential element in the ordered development of aviation.

The basic objective of air traffic control in military flying is, of course, the same as in any other flying; to enable all aircraft to fly safely throughout each flight with the maximum freedom to attain their purpose efficiently. In practice, this necessarily involves the imposition of conditions and restrictions, and it is one of the main aims in the development of air traffic services to increase both the safety and flexibility of aircraft operation with the minimum restrictions. In progressing this we fully recognise the needs of civil aviation and, contrary to some public misconceptions of civil/military conflict in air traffic control, a joint approach is made at all levels to resolve A.T.C. requirements.

The words “automatic techniques” used in the title of this paper are interpreted as applying to all aspects of the Air Traffic Control complex, in which the latest electronic and electromechanical developments and techniques might prove beneficial. Navigational capability, communications efficiency, data processing, planning and dynamic displays, and conflict detection can all be improved, for example, by equipment incorporating various degrees of automation. While it is easy to list such improvements, it is much more difficult to relate their value specifically to a particular Air Traffic Control problem at a particular centre, and to recommend in which respects money or effort expended by the Government responsible would bring them the greatest or most immediate benefit. In fact, experience shows that each case differs and requires special study and consideration so that any difficulties currently existing or foreseen can be expressed in terms that facilitate rational engineering solutions.

The application of automatic data processing techniques to air traffic control has been espoused by both operational and research and development groups dealing in air traffic control throughout the world. As far back as 1947, in the U.S.A., the Special Study Group, SC-31 of the Radio Technical Commission for Aeronautics suggested that a high degree of automation be applied—including rigid control of all flights and their times of arrival.

The use of primary pulsed radar as a surveillance instrument in Air Traffic Control is familiar to most, and is a direct development of the various ground radars current in the last war. The wavelengths generally employed are 10 cms. for more local control, and 50 cms. for long range and high coverage. The primary radar depends for its information on reflection from the target aircraft of sequences of pulses of electromagnetic energy radiated by the aerial, and displays this information as a “paint” on a P.P.I. (Plan-Position Indicator) cathode ray tube giving range and bearing relative to the radar site. The radar beam is fan-shaped, narrow in the horizontal plane to a few degrees, and wide in the vertical plane to provide adequate vertical cover. The beam is made to scan through the target by a rotation of the aerial about a vertical axis up to a rate of 14 r.p.m. The beam width in the horizontal plane is necessarily kept narrow to provide adequate discrimination between targets at the same range but different bearings. The primary radar is frequently associated with a height-finding radar in which the beam shape is reversed, having a narrow angular cross section in the vertical plane. In this case the aerial is made to nod up and down along an appropriate azimuth selected by the controller, and the height of an aircraft is displayed on a height-range cathode ray tube.

The purpose of this contribution is to draw attention to some of the major areas in A.T.C. where there are difficulties and to outline the steps that are being taken to surmount them.

Before looking quickly at some of the technical problems I think it might be worth taking a brief look at two important aspects which surmount the whole scene: namely the Civil/Military situation and the birth of Eurocontrol.

The relationship between service and civil authorities on A.T.C. matters springs directly from the differing requirements of the two sides for air space. The increasing use of jets by civil operators has made this problem more acute because now the Service aircraft not only have to be shepherded up through the commercial traffic, but also protected from them in the upper levels. The requirements of research aircraft are also stringent and yet again, different.

To avoid any misunderstandings, it should be made clear that in the author's opinion the techniques of Air Traffic Control are not likely to be significantly affected by the future advent of an air-to-air collision avoidance system. This is admittedly a contentious view and this paper is a brief survey of some of the factors which lead the author to hold this opinion. After clarifying what is meant by an air-to-air collision avoidance system, the paper deals first with some of the operational problems, then with some of the technical problems and concludes with general comments.

To provide a basis for discussion of air traffic control problems some of the operating characteristics of long haul subsonic and supersonic jet transport aircraft are examined. Two trans-Atlantic aircraft are compared, one designed to cruise at 500 knots (Mach 0·85) and the other at 1,250 knots (Mach 2·2).

The title of this paper is “V.T.OX. and S.T.O.L. Aircraft and Helicopters and the System of Air Traffic Control they will require,” but it does not set out to give an audience of Air Traffic Control experts a lecture on how they will have to run their business in the future. What it does do is to make a few remarks on how the operators will wish to run these types of aircraft, when they have them, and to draw some inferences about the new problems in Air Traffic Control which will have to be solved as a result.

It was nearly a year after the holding of the Aeronautical Exhibition, before the next meeting of the Society was held on 20th May 1869.

Despite the fact that in the first three years of the Society's life much attention had been paid to heavier-than-air ideas, the Chairman, Glaisher, had lost none of his enthusiasm for balloons for certain purposes.

“They met that night under peculiar circumstances,” he said, “there being in London at this time the largest balloon yet made.“

Glaisher referred to Henri Giffard's captive balloon, capable of lifting twenty people at a time. In a calm it could be held captive at 2,000 ft., and was exhibited at Ashburnham Park. Giffard placed the balloon at the disposal of Glaisher for taking meteorological observations, and he made close on 30 ascents in it on behalf of the British Association, in whose transactions the results are reported.

Lower bounds for the intensity of the sonic bang of a slender aircraft configuration with various constraints are given in this note which is a condensed version of Ref. 1. Although these lower bounds cannot be achieved in practice the method of obtaining them demonstrates how low values can be obtained. Special emphasis is given to a possible supersonic transport.

The ecliptic plane is the plane of the orbit of the Earth round the Sun. In a previous note the velocity requirements were examined for conventional rocket vehicles to enter reconnaissance orbits around the Sun in this plane.

Departure from the ecliptic plane obviously involves an increase in the velocity requirement. To some extent, all interplanetry voyages necessitate such motion, as the planets lie in planes inclined to the ecliptic. In this note, the extreme case of entry into orbits normal to the ecliptic will be considered.