This paper describes a first attempt to establish the order of magnitude of finite aspect ratio effects for jet-flap wings. Lift, pitching moment, and drag results are presented from pressure-plotting measurements on a jet-flap model of aspect ratio slightly less than three. These experiments were complementary to two-dimensional tests carried out at the National Gas Turbine Establishment.

The aerodynamics of a thin airfoil of arbitrary camber having a porous trailing edge in steady, subsonic, compressible potential flow is investigated. In the special case of a flat plate airfoil with a porous trailing edge, an exact, closed form solution is obtained using complex variable theory. The pressure loading on the airfoil, the lift and pitching moments are exhibited explicitly along with typical numerical results. The corresponding situation in supersonic flow is also considered.

This paper describes rig tests made to evaluate the effectiveness of the cockpit insulation and cooling system of a high-speed aircraft.

The tests showed the dependence of cockpit internal temperature distribution and heat pick-up on the cooling air mass flow and inlet temperature. Analysis of the test data showed that there was considerable heat leakage into the cockpit; the heat leakage increased with cooling air flow and constituted two-thirds of the heat entering the cockpit when the air flow was moderately high (20 lb/min). Some of the leakage heat entered the cockpit through equipment mountings but it was evident that other leakage paths existed. One more obvious heat leakage path, at the canopy, is illustrated.

The tests also showed that the internal heat transfer coefficient increased with air flow, reaching a value of 2·5 C.H.U./hr ft2°C when the flow was 20 lb/min.

Aerodynamics is one of the main fields of application for practical mathematics and the treatment of aerodynamic problems requires a thorough mathematical training. Whoever opens a modern book on aerodynamics will be surprised from the very beginning, that the phenomena within this very fugitive medium air may be expressed by formulas according to mathematical laws.

We must, however, never forget, that before a flow phenomenon can be mathematically analysed, physical reality must be understood by observation and experiment.

The mathematical treatment will always tend towards an approximate solution, as it is much too complicated to analyse a flow process exactly.

We have grown used to the idea that in the Middle Ages inventors produced several forerunners, either real or imaginary, of modern aerodynamic devices. The helicopter was designed, in principle, before Leonardo, while the rigid aerofoil, in the form of the plane-surface kite, achieved a remarkable degree of sophistication before the end of the sixteenth century. It has commonly been assumed that among these mediaeval inventions we should include some sort of three-dimensional kite, a precursor of Hargrave's box-kite, either in the form of a windsock equipped with wings, or in that of a primitive hot-air balloon, with or without additional lifting force provided by wings. I wish to examine the evidence for the existence of these objects, and to make a fresh assessment of the likelihood of their ever having flown.

In 1956 the Defence Research Board of Canada and Canadair Limited (a wholly-owned subsidiary of General Dynamics Corporation), agreed to sponsor jointly a study of V/STOL technology to determine the configuration of aircraft best suited to the support of ground forces. During the following year it was decided that for the transport role the tilt-wing/slipstream-deflection concept promises the best aircraft from the overall point of view. Subsequent analysis and flight experience have confirmed this, and have also demonstrated a high degree of compatibility between aircraft attributes and general requirements for support of surface forces.

The primary object of flying is movement over the surface of the earth in the shortest possible time, and thus it comes about that the performance of an aeroplane is that characteristic which commands greater attention than all others.

This paper is intended to supplement a part of the paper by Mr. F. W. Armstrong on ‘The aero engine and its prospects—fifty years after Griffith’. It deals in more detail with Dr. A. A. Griffith's early ideas on the aerodynamic aspects of turbomachines.

Even with reasonably optimistic use of materials and operating temperatures it was essential in 1926 that very high component efficiencies were obtained to make the gas turbine competitive with the piston engine on fuel consumption. Griffith believed that efficiencies of over 90% could be obtained for the compressor and turbine components, if the correct attention was given to the aerodynamic design of the blades. His 1926 report on ‘An aerodynamic theory of turbine design’ showed how such high efficiency designs should be carried out and gave appropriate formulae for the compressor and turbine efficiencies.

The authors predict that rocket engines will fall into two categories. In both, combustion pressures will approach 200 atmospheres to attain optimum vehicle performance, balancing increased pumping losses and engine mass against increased expansion efficiency and reduced dissociation. For general purposes, engines will be intrinsically convenient: storable propellants will give specific impulses around 270 lb. sec./lb., and engine specific weights will be between 0·02 and 0·03. For exacting applications, the greatest overall convenience may necessitate using unpleasant propellants so as to obtain the highest performance. Immediate research into the use and handling of these is essential if future engine development is not to be hampered.

The CHAIRMAN, in introducing the lecturer, said that they were fortunate in having an extremely topical lecture The subject of gas turbines and their application to helicopters was currently taking a great deal of attention from designers and industry, and the Association were happy to have it in the programme so early in the session

Mr BROWN had been educated at the City Boys Secondary Grammar School, Leicester, and was a State Scholar and a College Exhibitioner at Jesus College, Cambridge He had taken an Honours degree in the Mechamcal Sciences Tripos, and in 1944 joined Power Jets (Research and Development) Ltd, remaining when it became the National Gas Turbine Estabhshment He had been engaged as a research and development engineer on combustion processes and was now employed as a Senior Scientific Officer at the N G T E, being engaged on the examination of gas turbine projects and their thermodynamic performance

There appear in the literature some discrepancies in the various mathematical expressions for the upwash constituting the wall interference on a small lifting wing placed symmetrically in a rectangular tunnel with closed side-walls and open floor and roof. The representation of the interference field as that of a doubly infinite array of image doublets is shown to lead to divergence. An independent calculation by relaxation confirms the correctness of an analytical solution by expansion in Fourier series. The discrepancies are found to arise from incomplete flow conditions at the open boundaries, and it is shown in this paper how the various theories are reconciled.

In parallel with the work undertaken at the University of Southampton on the study of the noise from subsonic jets, a further investigation has been made into the noise from supersonic or choked jets. Whereas in the former case the noise is due to the turbulent velocity fluctuations and thus contains a wide spectrum of random frequencies, the latter case contains, in addition to this wide spectrum, noise caused by turbulence-shock wave inter-action.

Once the critical pressure ratio of a jet has been attained, i.e. that pressure ratio which produces sonic or supersonic flow in the jet pipe just before the orifice, the structure of the jet depends crucially upon the nozzle shape.

Currently there is renewed interest in the evaluation and reduction of steady wind tunnel wall interference, especially for large models.

Evaluation of previous predictions for perforated and slotted tunnels suggests that a hybrid slotted tunnel, ie a slotted tunnel with closed slats and perforated slots) should offer minimum corrections for upwash, flow curvature and solid blockage. This suggestion is confirmed by the present computer studies of a range of rectangular hybrid slotted tunnels.

The computer studies are for tunnel working section height to breadth ratios of 0·835 and 0·600 over the Mach number range from 0 to 0·85. Wings swept at 28° and 50°, with ratios of model span to tunnel breadth varying from 0 to 0·7, are considered. An idealised fuselage shape is used to predict solid and wake blockage corrections for the wall configurations selected on the basis of minimum upwash and curvature interference.

RANS models remain an attractive turbulence simulation method which could provide some open jet aerofoil interaction analysis at a fraction of the cost of a high-fidelity LES approach. The present work explores the potential and limitations of RANS in this context by simulating an open jet aerofoil noise experiment using the aerospace oriented Menter SST RANS model. This model’s tendency to transition at a critical Reynolds number lower than the experimental value was found to impact the boundary layer development. However, the introduction of a low-Re correction improved the prediction of surface pressure and skin friction, enabling the suction surface separation bubble to be captured. The free shear layer’s virtual origin characteristics exhibited sensitivity to the interaction with the aerofoil, which can be developed into a metric of the interaction. The main challenge for RANS was accounting for the rise in background disturbance level in the working section, which is caused by the high-turbulence intensity in the free shear layers.

An improved technique for the use of a five-hole yaw probe has been used in determining velocity, vorticity and pressure distributions over a transverse plane five chords downstream of a lifting wing. A well-defined tip vortex is shown to exist, together with a vortex sheet which contains a significant proportion of the total vorticity. The vorticity distribution is compared with that predicted by the calculation of vortex sheet roll-up using a two-dimensional array of line vortices. Good agreement is obtained, and the validity of using time steps large enough to inhibit the chaotic motion found in some calculations of this type is demonstrated. The structure of the tip vortex is found to be well described by the turbulent vortex model of Hoffman and Joubert.

Major T. M. Barlow : All historical records of aviation from the earliest attempts at flight to our present-day Schneider Trophy and other record flights, show that in common with those nineteenth century experimenters our modern engine and aircraft designers are in one continuous struggle with the physical laws of weight. It is true that the early pioneers were faced with the problem of flying as such to the extent of carrying one man by a heavier than air machine a few hundred yards, but once this was achieved development quickly enlarged, the problem, and weight, with its relationship to power, lifting surface, safety factors, performance, range, and later—with the coming of civil transport—financial weight in the form of pay load, have become the all important item with the aeronautical engineer and constructor.

In May 1966 under threat of USA withdrawal from the 1929 Warsaw Convention, over 30 of the world's leading international airlines agreed to increase the limit of their passenger legal liability from US $8300 (Warsaw) or US $16 600 (Hague) to US $75 000 (inclusive of legal costs) or $58 000 (plus costs) for passengers travelling to, from or via the USA. Today the number of participating airlines is over 90 and there are individual variations, eg (i) BEA has extended the new limits to all its Warsaw or Hague passengers; (ii) Lufthansa and other airlines have adopted the equivalent of a $58 000 limit for domestic passengers within Germany.

In the United Kingdom (including associated overseas territories) on 1st June 1967 the Hague Protocol came into force for the first time and the limit of liability for non-Convention (ie mainly domestic) carriage was raised to the equivalent of approximately £21 000 ($58 000).

The end of the first year of the new limits and the beginning of the new UK limits were marked by the Air Law Group of the Royal Aeronautical Society by an international discussion held at the Society on 1st June 1967. The Chair was taken by Sir William Hildred, CB, OBE, MA, and the principal speakers were: Dr. B. Cheng, University College, London; L. S. Kreindler, Trial Lawyer, New York; A. Goodfellow, Solicitor, London; and M. J. Lester, Secretary and Solicitor, BEA.

The aims of the Discussion were to:–(a) Review the present position nationally and internationally; (b) Discuss possible future developments from the viewpoint both of airlines and their passengers.

Orbiting objects in space are exposed to the risk of collision with space debris over their lifetime. Space debris orbiting in space experiences orbital decay due to various orbital perturbations. This work considers only orbital perturbations due to aerodynamic forces, which spacecraft experience due to the presence of a rarefied atmosphere, causing tumbling motion and orbital decay. Analysis of the orbital decay of a spacecraft is carried out by considering the variation of the drag coefficient as a function of its shape, motion and angle-of-attack. An in-house Direct Simulation Monte Carlo (DSMC) solver is modified for aerodynamic analysis of a spacecraft orbiting in the free molecular regime in low Earth orbit. In addition, an orbital dynamics model is developed to simulate the tumbling motion of a spacecraft and its orbital decay. The orbital decay trajectory is predicted for two sample spacecrafts using the aerodynamic coefficients obtained from the in-house DSMC solver as inputs to the orbital decay model. This study analyses and explores in detail the effects of the aerodynamic coefficients and shape of a spacecraft on its orbital decay.

The title of this paper, “Gas Turbine Accessory Systems,” covers a wide field, and one which is changing all the time. I have known many experimental units devised to perform a certain job, which were discarded almost as soon as they were made for some more up-to-date component and then, after a lapse of months or years, the original units have been dragged out from under the bench or from a museum of relics and pressed into service again with satisfactory results.