The effect of backlash and trailing-edge strips on the flutter speed of a two-dimensional model of a tailplane with tab has been investigated in a series of wind tunnel tests. When backlash is present, a change in preload, which is achieved by varying the incidence of the tab, can dramatically alter the flutter speed. The addition of trailing-edge strips to the tab lowered the flutter speed.

This paper discusses some of the factors that need to be taken into consideration if other services are to be included within a satellite that provides direct TV broadcasting to the UK. The main reason for considering such an approach is that the inclusion of other services may improve the overall economics.

It should be recognised that the requirements of the DBS services will impose certain constraints, in particular on the orbit location. Also there is less flexibility in the choice of frequencies for the DBS services than there may be for other services.

The study of powerplant control systems is often carried out in isolation from the requirements of the aircraft. In this collaborative study a Systems approach has been adopted to ensure that the results obtained for an integrated control system are truly applicable to the combined system: airframe, avionics and powerplant with particular regard to the next generation of aircraft employing high technology in methods of data transmission, system integration and crew-system interfaces.

The procedure described applies to aerofoils or cascades with circulation controlled by tangential blowing jets and provides a complete numerical solution for aerodynamic performance in incompressible flow conditions.

The pressure distribution over the blade surface is predicted by a potential flow model in which the region of separated flow is represented by an appropriated source distribution. Boundary layer development is calculated by a finite-difference solution of the parabolic boundary layer momentum equation: the development of the blowing jet and its mixing with the boundary layer over the curved trailing edge is predicted by the same procedure applied to an angular momentum equation, using an intermittency representation of the eddy viscosity distribution.

Predictions are compared with experimentally measured lift coefficients for an isolated aerofoil, with turning angles for a cascade tested by other workers and with experimental turning angles for a cascade tested by the authors. The agreement between theory and experiment is good.

Ever since I was a young boy I have been fascinated by aviation. While a mixture of pedagogical advice and lack of mechanical aptitude steered me away from a flying career I am delighted to say that it has been almost as satisfying providing credit to the industry over the past six years since I joined Bank of America in London. It is therefore with great pleasure that I will attempt (in the august environment of this society) to clear some of the mystery that shrouds the commercial banking world’s assessment of the underlying value of an airline. At the same time I am conscious that bank finance has only been one way of funding capital equipment costs, even though it has grown disproportionately as a source of funds in the past five years. I will then, as John Prothero Thomas (of Caledonian Airways) has already anticipated, attempt to tell you why the financial community has begun to retreat into its shell when asked to stretch even more to accommodate deficient cash flows in the industry.

Of all the factors taken into account when justifying the use of flight simulators cost is most important. As one airline administrator put the case in 1970, ‘If simulators did not save the airlines money they would not exist however valid the other reasons are, we would have no difficulty in convincing ourselves that training in the air was better in every way’. In their 1977 study of the cost effectiveness of flight simulators for military training Orlansky and String could find only 30 studies between 1950-1977 which attempted to measure training effectiveness in a controlled and effective manner. This paper directs attention to one particular method of measuring training effectiveness, namely, the Incremental Transfer Effectiveness Function (ITEF).

The technique of geometric programming is applied to the design of optimum aircraft wings in the multi-spar monolithic skin configuration. Both flat and corrugated web systems are considered and design examples are given based on contemporary wing data. The present report is confined to the consideration of minimum weight design of metallic structure and the constraints are those which arise naturally from consideration of allowable stress, buckling and in some instances geometric limitations on the layout. Most of the problems solved give rise to closed form solutions while more complex problems are readily solved by computer program.

In the aeronautical field, there has been from time to time an interest in inflatable structures, ranging from their consideration for use in space to the design and manufacture of an inflatable wing for a man-powered aircraft and their use in remotely piloted vehicles . This interest stems from the fact that such structures have relatively low weight; are suitable for reacting light loads and can be packed into a small volume.

One particularly useful structural component is the inflated circular cylinder acting as a cantilever and a number of such cylinders are used in Ref. 3 to form the main load carrying structure of a wing. In Ref. 1 an expression is derived for the collapse load of a single cylinder with the assumption that the root behaves like a plastic hinge, and in Ref. 5, Comer and Levy go on to consider the beam deflections and stresses between incipient wrinkling and final collapse.

The paper reviews the development of amphibious hovercraft and considers the noise emission levels of current types of in-service craft. A brief reference is also made to side wall hovercraft and hover barges.

An outline of suggested methods for quantitative measurement of noise level and format is given, should legislation be deemed necessary at some future date.

Finally recommendations are made for further research and development programmes aimed at achieving significant improvement in the next generation of hovercraft.

What is the record of the airlines over the past two decades? Is it a performance of which we can be proud? Have accidents occurred that could have been avoided? Are we becoming complacent? What may be the consequences of the present airline economic situation with regard to airworthiness? Are our staff adequately trained and will they continue to be so?

These are just a few of the questions we must keep asking ourselves if we are to improve our airworthiness and safety records.

The current debate on the level of air fares must at the moment look more than usually odd to people outside the industry, and indeed to many people within it. The prospectus for this seminar refers to current accusations that the travelling public is being ‘ripped off and to comparisons between Europe and the USA. Yet we have only to look at the classified advertisements in the evening newspaper to see that we can buy a week’s inclusive tour to Majorca in early December for £60. The airlines tell us not only that they are making losses in Europe, but that even in good years profitability is never more than modest. They point to the high level of costs in Europe relative to the USA — the price of fuel, airport charges, the indirectness of many European routeings, the costs of a multi-country operation and to the more favourable operating conditions in the US, particularly the route density, the long sector distances and the greater flexibility in the hiring, firing and use of labour. The present period of recession, with its combination of high inflation and weak demand is making life even more difficult. Yet users call for lower fares in Europe and the CAA and the Department of Trade are also identified with the cause. What is going on?

Whilst I doubt my experience is unique, it is a fact of life that I have never enjoyed the sort of back up one expects as a customer who has bought an aircraft from a factory which built it and which contracted to support it.

Starting in 1949 with very much used DC-3’s, then on to ex BEA Vikings and Ambassadors, ex Canadair Argonauts and ex Pan Am DC-4’s and DC-7DF’s, with ex Flying Tiger CL-44’s and ex KLM DC-8’s, the entire story has been one of secondhand hand-me-downs, but with a factory still in operation to which as a several times removed customer, one could always turn to for help. On my acquisition of Carvairs in 1971 when I bought BAF, the same situation applied, and having a much modified obsolete aircraft did not exactly enhance the ease of maintenance.

Ventilated wall jets have recently received the attention of some investigators, motivated by its important applications in aircraft industry. In practice, the boundaries of the flow are more apt to be rough than smooth. The purpose of the present work is to study the effect of surface roughness on the mean and turbulence characteristics of ventilated wall jets. Experiments were performed with a two-dimensional turbulent jet flow over a smooth surface and over rough surfaces at different grades of sand roughness.

The aviation fuel market is one of the few areas in the petroleum industry where an increase in future demand can be predicted with a reasonable degree of certainty. However, this growth in demand is likely to be influenced by two major constraints, price and availability. At present aviation fuel represents only a relatively small portion of the barrel, but any increase in this fraction is limited by the need to meet specification requirements and competition from other products. The changing pattern in product demand is focusing attention on secondary refinery processes to maximise output of distillate fractions and on the use of alternative non-petroleum sources of fuel. In both of these approaches, significant upgrading of the initial product, involving both large capital outlay and high operating costs, may be necessary to produce final products within current specification limits. Under these conditions it is desirable to identify ways of easing specification requirements that will increase flexibility, but at the same time maintain product quality.

The first major step in the L-SAT programme was the publication by ESA in 1979 of the report ESA/EXEC (79) 3, (known as the ‘Blue Book’) which identified the market potential for a ‘large’ communication spacecraft and many of the essential features required to service the market needs. One of these features was the desirability for a multi-purpose platform which is now the basis of the overall L-SAT programme and the prime objective of the L-SAT 1 mission.

An informal Working Party was set up in October 1980 to review the present state-of-the-art in turbulence modelling for aeronautical applications and to make recommendations for future progress in this field. The report assesses the extent to which further developments in design and prediction methods for both external and internal flow are dependent on achieving advances in turbulence modelling and considers how these improvements realistically could be obtained. Reference is made to the conclusions from an international symposium on the same topic held at Stanford University, California in 1980-81.

The requirements of the first engine controllers were primarily to satisfy the needs of the engine and, almost as an afterthought, to consider interface with the aircraft and the pilot.

The latter resulted in the overwhelming plethora of ‘essential’ ground test-sets and cockpit instruments that we see today. In a performance and integrity conscious world, beset with ever increasing costs and sometimes decreasing maintenance personnel skills, the engine controller can no longer be considered in isolation from the rest of the system that it serves. The obvious ability of a digital system to self-check and diagnose itself, its interface with the real world, and to make intelligent decisions based on those tests, has enhanced the case for digital engine control.

In the few moments that I have, I would like to discuss in very general terms the role of information feedback in aircrew training and make the case that there is a need for improved computer-based debriefing aids. I am sure that there is little disagreement today that flight simulators offer a range of benefits. Such things as cost savings, reduced energy expenditure, safety and availability have been mentioned again and again. However, the most important benefit to be derived, namely training, is often-times overlooked. The assumption is often made that a good simulator, in terms of its fidelity, will lead to good training. While there are certainly examples of this, there are also cases of good simulators providing poor training because of improper utilisation, and cases of poor simulators providing very good training. The key appears to be in the proper utilisation of the simulator as a trainer, which in turn, is partially based on the simulators instructional features.