A combined experimental and theoretical study has been made of radial compressible flow without swirl between parallel discs when the fluid velocity is everywhere subsonic. It constitutes an extension of a previous analysis, wherein the flow was considered to be incompressible.

A similarity solution for the radial pressure distribution is shown to be possible only in special cases where certain terms in the equations of motion can be neglected. Approximate solutions are obtained for the laminar and the turbulent radial pressure distributions, using an integral momentum method. Both theories agree well with experiment. The critical Reynolds number for reverse transition is found to be approximately the same as that for incompressible flow in radial channels and circular pipes. The radial pressure level for compressible radial flow between parallel discs is found to be less than that for incompressible flow at the same mass-flow rate. The non-linear form, in pressure, of the compressible solution can be shown to account for this result.

Safety regulation usually has some direct impact on airline costs. All operators aim to operate safely - some more than others - and one might ask, should safety be left to manufacturers and operators, all of whom have a real vested interest in high standards, including the added spur of potential litigation? However, there is, I believe, a clear wish in the minds of the public, and hence governments, for independent and positive regulation. Major fatal accidents frequently cause a clamour of demands for higher safety, and governments, through their appointed bodies, are expected to act. Airlines broadly accept such pressures but wish to see common and consistent standards applied so that the economic burden is spread equally - preferably internationally.

ICAO requires all aircraft involved in international navigation to conform to ‘a detailed and comprehensive code’, but the detailed provisions and their interpretation may vary from country to country.

For the engineer, the “Concorde challenge” could be defined as follows:

A passenger carrying aircraft twice as fast as the existing aircraft and at least as safe.

When the jets came out 20 years ago, there was a sudden increase of the speeds used up to then, but their envelope stopped at the limit where the difficulties associated with very high speeds start

Consideration is given to the relationship H1 = f(H) linking the common shape factor H and the mass-flow shape parameter H1 which is used in entrainment models of boundary-layer development. A formula suggested by Green et al is found to be most nearly consistent with the measurements presented. However, a more exact prediction of H1 is obtained by introducing a factor involving the Reynolds number based on the local momentum thickness θ; thus H1 = f(H, Reθ). Predictions obtained by incorporating the appropriately modified entrainment equation into the well-known method of Green et al prove not to give an improved representation of the development of boundary layers studied experimentally by the authors and others. It is concluded that the modified formula for H1 is primarily useful in giving an improved specification of the overall boundary layer thickness δ = θ(H1 + H), and hence of other features of the developing profile.

The paper reproduces the results of an earlier report on the vortex theory of windmills and follows that theory through to establish the aerodynamic design procedure for a horizontal axis windmill. The results are shown to differ considerably from those given in a recent paper by Griffith and the differences are explained. The main conclusion is that, when full allowance is made for the drag of the blades, hub and tip losses, and losses due to interference with the support tower, the power output coefficient or efficiency of a horizontal axis windmill cannot exceed 30 to 35 per cent, as compared to an ideal efficiency of 59 per cent.

Earlier analysis, Middleton, of the laminar discharge of a ‘strong’ incompressible jet, due to a line or point source of momentum, into an unbounded co-flowing stream of the same density, is extended to the case of plane and round ‘weak’ jets the velocity in which only slightly exceeds the ambient velocity. In addition to recovering Goldstein’s solutions for ‘wake-like’ flows, use of the momentum integral equation provides approximate relationships for the decay of the centre velocities from the strong to the weak situations. Comparison is made with Wygnanski’s perturbation approach, suitably extended, and it is concluded that for the plane jet case, for which the agreement is better, the curve for the centre-plane velocity is correct to within about 12% throughout its range. The present approach is applicable to any flow for which a similarity solution exists as a first order solution, and is especially suitable when two such solutions exist for large and small values of an appropriate parameter. Its use also throws light on the form to be adopted for a perturbation expansion.

Recent studies of the performance of high-speed aircraft have emphasised the importance of engine-airframe integration. For example, Probert and Mallinson, and Bragg have pointed out the advantages of jet deflection in producing extra lift with little penalty in decreased thrust. Townend has drawn attention to producing thrust or lift on high-speed aircraft by external heat addition, and has calculated the effects on the range of the aircraft.

This Account of Flying-Boats will deal mainly with British craft, and must necessarily have a personal approach from one who has been involved in flyingboat development over nearly the whole of its life history.

The prehistoric giant amphibians suffered eclipse through changing environment; similarly changed conditions in Aviation caused the still-evolving flying-boat to come to the end of its economic life. Probably concrete runways were the basic reason for the disappearance of flying-boats for both civil and military use, since landplanes were then no longer restricted either in size of efficiency or aerodrome conditions.

To the practical designer the cumulative knowledge on airscrews seems at present to be in an unsatisfactory state of disorder. He wants to get reasonably accurate estimates reasonably quickly, without taking the time to become a specialist.

Several airscrew theories exist, but they either give wrong answers or take too long to work out, or both.

The great mass of test data that have been accumulated is so confused in a tangle of variables that the practical designer is often forced to select a test report almost at random and use it as if it applied to his particular problem; usually it does not and the calculation is seriously in error.

The present study attempts to clarify airscrew practical knowledge by coordinating data in a form suitable for use in performance calculations. It embraces the whole body of test data, but places particular reliance upon large scale wind tunnel results.

The arrangement of the analysis is such as to permit quick estimates to be made, the degree of accuracy obtained being a function of the amount of time available to the calculator. It is also designed to be as foolproof as possible so that it may be readily applied by inexperienced calculators.

It is especially adapted to calculations of the performance of aluminium alloy variable pitch airscrews.

One of the points brought out in the paper is the need for more data on certain subjects. They are specifically designated, and suggestions are made for carrying out research.

A choked nozzle installation suitable tor the absolute calibration of air flowmeters over a limited flow range is described. An entry package is prescribed to ensure that near ideal flow conditions are presented to the nozzle. This package should remove swirl and flow distortions from most entry flows.

Provided that the instructions given in this note are followed meticulously then the quoted discharge coefficients for the nozzle may be guaranteed to better than ±0-25% at Reynolds numbers greater than 106. The overall accuracy of flow calibrations are then dependent only on the accuracy with which the mean gas thermodynamic properties and condition of state at the nozzle entry can be determined.

The approach taken by this examination of flight simulation in the RAF in the Second World War reflects the fact that one author is an engineer and the other a psychologist. As a consequence the paper not only attempts to examine the technology that was established to create the training devices but also something of the personalities who created the simulators and the applications to which they were applied.

In the space available it will only be possible to skim the surface of a topic which has been relatively undisturbed for some thirty years. The authors hope is that the paper will stimulate interest and admiration for the dedicated and ingenious innovators who set out to create the devices which enabled the Royal Air Force to learn new skills safely and apply them effectively.

The long-running debate between the US and the EU over government supports for large commercial aircraft has recently boiled over into a major dispute involving the World Trade Organisation (WTO). While the two sides have currently backed off from what could be a very damaging WTO outcome, there are still wide differences over the legitimacy of government supports (direct or indirect) for Airbus and Boeing airliners. This paper:

1. • Describes the background to the current dispute.

2. • Analyses the 1992 US–EU Agreement on Large Aircraft Subsidies.

3. • Outlines the WTO Agreement on Subsidies and Countervailing Measures and the decision by the US to mount an action under the WTO complaints procedures against launch investment for Airbus and the EU’s counter claim against Boeing.

4. • Considers the precedents set by the WTO rulings on the Brazilian–Canadian dispute over regional jet supports.

5. • Summarises the US–EU complaints to the WTO.

6. • Considers potential outcomes and the implications for the civil aerospace industry on both sides of the Atlantic.

7. • Analyses the wider issues surrounding government intervention in the aerospace sector.

The paper views the dispute as a reflection of fundamental differences, based primarily on divergent economic doctrines and values, between the US and the EU states. There could be especially damaging consequences for the EU should the WTO rule against the systems of repayable launch investment used by the Airbus governments. But both sides could lose heavily from the affair and there is a good case for maintaining some form of direct government intervention in civil aerospace technology acquisition, even near market research, in support of environmental sustainability objectives.

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).

Routine periodic audiometry performed as part of the statutory medical examination of flight crew employed by a major international airline indicated that up to 27–5% may suffer noise induced hearing loss, with 10-8% showing unilateral hearing loss. This was considered to result from the practice of listening to radio communications through a headset covering one ear only, leaving the other ear uncovered to allow direct conversation between crew members on the flightdeck. Ambient noise levels at the crew seats and noise levels from crew headsets were measured on a sample of aircraft and routes using a Kemar acoustic manikin. Noise levels on the flightdecks were 70-79dB(A) Leqaveraged over a flight of typically seven to ten hours duration. Noise levels from headsets were 77-89dB(A) Leq being 80dB(A) or higher on 80% of flights, and 85dB(A) or higher on 40% of flights. Five prototype or production active noise reducing (ANR) headsets were evaluated in flight and in the laboratory. It was shown that the better examples, worn to cover both ears, would allow flight crew to reduce headset volumes so reducing risk to their hearing.

The structural problems introduced by the kinetic heating of high speed aircraft require a radical extension of what has hitherto been regarded as the normal domain of structural theory. Aerodynamics, for example, cannot be regarded as a self-contained subject which merely provides basic data for the structural worker. Certain aspects of aerodynamic theory, particularly the mode of heat generation, have to be considered simultaneously with the structural problem. Thermodynamics and metallurgy are still more closely integrated with structural theory. The laws of heat transfer, and the variation of material properties with temperature, are both essential factors in the structural analysis.

The average orthodox mathematician who writes or reads books about hydrodynamics is so keen about getting a peg on which he can hang what he calls examples that he quite forgets to apply his formulae to compressible fluids. It appeared to me on reading Colonel De Villamil's letter that a useful purpose would be served by writing the present note; it contains nothing but what anyone could write out for himself, but it was only recently that I made the attempt myself and I should be surprised if many readers have seen the same thing before. We know that in the irrotational motion of an incompressible fluid the velocity potential satisfies Laplace's equation, the present object is to find the corresponding equation for a compressible fluid, to grind it out at full length, and (what is more important than grinding it out) to interpret the result.

The aeroelastic phenomenon of limit-cycle oscillations (LCOs) is analysed using a projection-based reduced-order model (PROM) and Navier–Stokes computational fluid dynamics (CFD) in the time domain. The proposed approach employs incompressible Navier–Stokes CFD to construct the full-order model flow field. A proper orthogonal decomposition (POD) of the snapshot matrix is conducted to extract the POD modes and corresponding temporal coefficients. The POD modes are directly projected to the incompressible Navier–Stokes equation to reconstruct the flow field efficiently. The methodology is applied to a plunging cylinder and an aerofoil undergoing LCOs. This scheme decreases the computational time while preserving the capability to predict the flow field accurately. The ROM is capable of reducing the computational time by at least 70% while maintaining the discrepancy within 0.1%. The causes of LCOs are also investigated. The scheme can be used to analyse non-linear aeroelastic phenomena in the time domain with reduced computational time.

The slender-body theory of Ward is applied to a configuration consisting of a slender, pointed wing, carrying directly beneath it a pointed half-body of revolution divided along a meridian plane.

Expressions for lift and drag due to incidence are found which are valid in both subsonic and supersonic flow if the flow is attached. The lift result can be used to find pitching moment. For the supersonic case the drag at zero incidence is also found and the expressions for a conical configuration are developed so that a limiting form of these can be compared with the results of ref. 3.