If a supersonic nozzle is designed for less than complete expansion of the flow, some lift force can be produced without downwards deflection of the nozzle. A theoretical analysis has been made, by the method of characteristics, for a two-dimensional nozzle consisting of an upper wedge and lower parallel shroud. General trends of lift performance with the main variables have been obtained.

These recollections start a long time after those in the memorable Centenary issue of the JOURNAL, but will add a page in the history of the RAE which I joined in 1939—and found myself in the Engine Research Flight.

Life there was very peaceful before the War and aeroplanes were new and exciting. Looking back now, some of the work done there was very primitive with none of the elaborate test and recording equipment available today. I recall flying for hours in a Harrow, looking for icing conditions to test an automatic carburettor de-icing system; endurance flights on new plug types, high octane fuel and tests of an early Merlin in a very odd aeroplane where the observer sat in a box under the pilot's seat. The pilots then in C Flight are now almost legendary figures—“Spinner” White, killed in the prototype Spitfire K 5054, Rex Hayter, “Tiger” Hawkins, Roly Falk, “Bruin” Purvis, Hubert Broad, Clouston and H. J. Wilson, to name but a few.

Some of my recollections relate to the Aerodynamics Division at the NPL and the ARC, so to refresh my memory of their origin I have referred to the First Report of the Advisory Committee for Aeronautics—later renamed Aeronautical Research Committee—for the year 1909–10. It states there that this Committee was appointed on 30th April 1909, that it was to deal with the scientific study of the problems of flight with a view to their practical solution, and that the NPL was to organise, at Teddington, a special department to research and experiment on problems submitted to it; and further, that the Committee had put themselves in communication with the Aeronautical Society, the Royal Aero Club and the Aerial League with a view to rendering such assistance as might be possible in their work, that arrangements had been made at the Imperial College of Science and Technology for lectures in aeronautics for advanced students, and that two research scholarships in aeronautics had been founded.

Free vibrations of triangular and trapezoidal plates have been analysed recently theoretically and experimentally by many authors. Some of them applied the Rayleigh-Ritz procedure, while others proposed to use the Kantorovich-Vlasov method, reducing the problem to solution of an ordinary differential equation.

In this note, the method developed in ref. 7 on the basis of Reissner’s modified variational theory is extended to include trapezoidal cantilever plates (Fig. 1).

Comparison of theory and experiment shows that, retaining four terms in the deflection function, one obtains three natural frequencies to a high degree of accuracy.

Simple theory for calculating the pressure beneath a hovercraft is well known, see for example ref. 1. Of the two results, and , the former is usually preferred on the grounds of simplicity since over a large range of jet thickness/height ratios the difference between the two results is negligible. For large values of t\h the latter equation is preferred since it tends to a possible limiting value, i.e., whereas in the former equation. This latter is a consequence of one of the basic assumptions, i.e. that and since in the limiting case h=0 there can be no jet, then However, neither equation can be regarded as valid for x > 1 since for this condition a constant jet thickness equal to the slot width t cannot be maintained. In practice what happens in this condition (x > 1) is that the rate of mass flow in the jet is reduced.

Group Captain de la Plain has said that certain defects are reported formally to MoA as the Supply Department. This paper outlines briefly some of the procedures involved in dealing with these reports, particularly those aimed at improving Reliability and mentions some forthcoming changes which have the same aim in view.

In the course of each year some 25 000 of these reports are handled by RDA (Defects) and in spite of “weapon concept” philosophies, some 200 different investigating authorities are involved. Since the capacity for investigation and re-design is limited, and because the traditional system for reporting does not discriminate sufficiently between important and less important defects, this mass of reports may prevent some defects from receiving the urgent attention they deserve. The Services have agreed therefore, to be more selective in their reporting since it is not possible to remedy every defect in existing aircraft and available effort must be directed into areas where the maximum improvement in aircraft safety, availability and reliability will result.

To Enable a Design Authority to act upon User Experience, full and accurate information is required about the defect as soon as possible after it has occurred.

A skin crack in an aircraft structure, the loss of a turbine blade in a jet engine or excessively high brush wear in a generator, are all defects. The reasons for them being defects can be quite different in each case. One can therefore readily see that to solve these defects the designer needs to know not only everything about the failure, but also the environment (in the broadest possible sense) that led to the failure

Some time in the May term in 1914, in my third year, my Supervisor of Studies told me that Mervyn O'Gorman, Head of the Royal Aircraft Factory, as it then was, would be visiting Cambridge and staying with Charles Darwin and might be looking for staff. He offered to arrange a meeting for me if I was interested. I had intended to be a civil engineer, but we agreed that aviation was a coming profession and it would be a good idea to get in more or less on the ground floor.

I went to see O'Gorman, and it was eventually agreed that if I got a good place in the tripos I would be taken on at the Factory at a salary of £1 per week and would report on the 1st August.

Human air transport has beenwith us for centuries— in fact since time immemorial. As in the classical case it is really quite modern in its conception.

There is a partially retractable landing gear. Although there are no seats, there is good leg room and the passenger has his air ticket. Take-off was easy. The flight, being slow, takes anything up to nine months. The landing will be laborious and its successful completion will be accompanied by a fanfare of joyous publicity on the part of the parent company together with the usual noisy complaint from the passenger. Emergency oxygen is occasionally administered.

Consider a lambda matrix F(ƛ, δ). This may, for example, result from the equation of motion of a dynamical system, δ being a measure of the magnitude of some possible modification to the system or some other variable parameter. Let λ be an eigenvalue and p’ and q the corresponding left hand and right hand eigenvectors. Then

One wishes to determine the derivatives of ƛ with respect to δ. Expressions for the first two derivatives will be obtained on the assumptions that F is simply degenerate and that ƛ is not a repeated root.

The success achieved in wing analysis and related problems through the introduction of triangular elements with six nodal points and a prescribed linearly varying strain or stress, naturally raised demands for a further sophistication in the idealisation process by triangularisation. In this context a practically important extension is concerned with the influence of taper in the thickness. We reproduce in what follows the theory for the special case of linear type. The paper may be considered as a generalisation of notes 2 and 3 of this series. However, the analysis is here based on the non-dimensional homogeneous triangular co-ordinates introduced in note 5, which simplify the argument considerably. A significant broadening of the applicability of the new element will be given in notes 9 and 10.

The flow in a two-dimensional plane wall jet with different initial gaps between the nozzle exit and the leading edge of the wall was probed at various stations along the jet. The jet slot thickness and the velocity were kept constant. It was found that the region close to the leading edge of the wall behaved like a transforming region where the type of flow changed from a free jet to a wall jet. The length of this region, which depended directly on the gap size, was so short for small gaps that the gap effects were found to be negligible. In addition, it was found that the inner layer velocity distribution of a wall jet did not follow the classic one-seventh power law.

Recently additional tests have been performed to measure the external pressure necessary to collapse spherical caps. Bellinfante used plastic domes that were machined readily and accurately to final size. The Douglas test data shown in Fig. 1 are considered to be excellent. (2b is the base of the dome).

Thurston used aluminium caps that were chemically etched to final size. However, he intentionally put small dents at the apex. These initial distortions cause wide scatter in the test data as shown in Figs. 2(a) and 2(b). Examination of the recorded waviness reported -by Thurston indicates that the more perfect shells reached higher loads than the others. Note, for example, specimens 1, 6, 11, 16, 28, and 38. Also, usually the more wavy specimens exhibited the lower buckling loads. See specimens 4, 7, 9, 12, 17, 22, 27. Since Thurston's specimens were chemically etched to very thin gauges, the thickness variation could be significant. He does not report actual thickness variation in the shell, but states it could be about 15 per cent at worst.