As individuals, those who have been born and bred and nurtured in the long, unique and formative tradition of the British people may justly claim a pride in their scientific and technical achievements over the years which cannot be claimed in such measure by any other nation. It is a claim they can make as proudly this very day as they could have done over the past three hundred years.

In the main, this paper is concerned with but a small, although not unimportant, part of the scientific achievement of the Seventeenth, Eighteenth and Nineteenth centuries. It was a period, in Great Britain, of such giants as Isaac Newton, James Watt, John Dalton, Robert Boyle, Henry Cavendish, Michael Faraday, Charles Darwin, Clerk Maxwell, W. J. M. Rankine, Lord Kelvin, Lord Rayleigh, Sir Charles Parsons, Prescott Joule, C. G. Stokes, Osborne Reynolds, Sir J. J. Thomson, C. Babbage, F. W. Lanchester, and so many others whose ideas and achievements have changed the face of the world in this Twentieth century of application.

The 1,000th Lecture to be given before the Society and the 27th Main Lecture to be held at a Branch of the Society was held under the auspices of the Henlow Branch. The lecture, “Rocket Engines,” was given by Mr. S. Allen, F.R.Ae.S., on 11th October 1956. Professor A. J. Murphy, A.F.R.Ae.S., President of the Henlow Branch, opened the meeting, and Mr. E. T. Jones, C.B., O.B.E., F.R.Ae.S., President of the Society, presided for the rest of the meeting.

Professor A. J. Murphy: Tonight they had the great honour of welcoming to Henlow for the first time the parent body of the Royal Aeronautical Society for a Main Society Lecture. On behalf of the Branch he welcomed the President, Mr. E. T. Jones, several Members of Council and other members of the Royal Aeronautical Society.

He had been asked to introduce Mr. Jones, and of all the redundant things that he had been called upon to do, that was the most unnecessary. All of them were aware of Mr. Jones' distinguished career in aeronautics and would forgive him, as he knew Mr. Jones would, if he did not enlarge on that aspect. However, there were a large number of people both from the Royal Air Force and the Ministry of Supply present and it seemed appropriate to recall that Mr. Jones served as a pilot and flying instructor in the Royal Flying Corps and Royal Air Force until 1919. Thereafter he joined the Aerodynamics Department of the R.A.E. at Farnborough and since then, as they knew well, he had played an increasingly distinguished part in the experimental establishments connected with the Aircraft Industry and the Royal Air Force and in the field of Aircraft Research and Development. This year, in addition to being elected President of the Royal Aeronautical Society, Mr. Jones became the Director-General of Technical Development (Air) in the Ministry of Supply.

Mr. E. T. Jones: This was the first Main Lecture of the Society to be held at the Henlow Branch and in that respect the evening was an historical one.

The practice of holding Main Lectures of the Society at Branches was started in 1948 and the underlying idea was to take the Society to the Branches.

In all, some two dozen Main Lectures had now been given at one or other of the twenty-four Branches of the Society and it gave him much pleasure to see such a large attendance.

This was but the second Main Lecture of the season and curiously enough it was the second to be held at a Branch, This fact caused him to look more closely at the lecture programme and he found that four Main Lectures out of a total of nine this season would be held at the Branches. Thus the Council was doing its best to bring the Society more and more into contact with the Branches and this must surely be a good thing for all those who were interested in aeronautics.

He hoped, too. that it would encourage more of the aeronautically minded to attend those of the Main Lectures which were to be held in London.

Now it was his pleasant duty to introduce the lecturer.

Mr. Sidney Allen was a Fellow of the Society and had had thirty years' continuous experience in the design, research and development of all forms of internal combustion engines for aircraft. For twenty years he had been with Armstrong Siddeley Motors and over the past seven years he had been Chief Engineer of their Rocket Engine Division.

He thought he would be right in saying that few people could have more experience in the United Kingdom of rocket engines and he had much pleasure in calling on Mr. Sidney Allen to give his paper.

Relatively simple theoretical procedures enable the pressure loss of the simpler forms of baffle used for flame stabilisation in combustion chambers to be computed, while tests made under non-burning conditions are available for ad hoc testing of the geometrically more complicated forms. Both these methods, with the appropriate corrections for the momentum changes due to burning, have in the past proved suitable for the prediction of the drag of aero-engine combustion chambers under operating conditions. Recently, however, it has been found that under certain conditions, associated especially with very high rates of heat release, the drag of combustion systems can become very much greater than would be predicted either from simple theoretical considerations or from conventional “cold” tests, and vary in an unexpected manner with the normal flow parameters.

While congratulating F. H. Robertson on his technical note in the January 1957 JOURNAL (page 52) on “short cut” methods of estimating aircraft direct operating costs, which certainly give a very rapid approximate answer, I am somewhat uncertain as to its practical value. In the analysis of possible projects, having established the general range of operating costs, which can usually be done by a combination of experience and inspection, interest lies primarily in the effect on cost of operation of such factors as change of type of power plant, fuel used, what complexity of structural designs is permissible from a cost aspect, how much is desirable from a weight saving aspect and so on. Unfortunately, Mr. Robertson's formulae do not allow such comparisons to be made primarily because of the assumptions made.