In the period since the inception of civil jet transport, during which a dramatic increase in travel and commerce by air has taken place, the research and development directed towards the containment and reduction of aircraft noise has spread across a steadily broadening front. The noise of the simple jet engines which propelled the first civil transport aircraft was almost entirely due to the high exhaust jet velocities that were used to obtain thrust from comparatively small mass flows. This is illustrated in Fig. 1(a), where it is seen that noise from other sources, such as the compressor and turbine, is comparatively insignificant. Thus aero engine noise research in the late fifties and early sixties was concentrated mainly on the prediction of jet noise and the development of noise-reducing propelling nozzles. It was not until bypass engines began to appear, with higher propulsive efficiencies resulting from lower exhaust jet velocities and higher mass flows, that the noise of their larger compressors drew attention to the turbomachinery as an additional source requiring investigation.

At last year’s Symposium ‘Designing from the inside out’ the keynote address made a strong case for improved matching of the machine to the man, starting with an understanding at the project stage of the optimum way that systems should be designed to achieve integration between man and machine. This year, we are discussing one aspect of human engineering—the presentation of information to the pilot.

Britten-Norman started out as converters of Tiger Moths for export to New Zealand as top-dressers. As new aircraft came into that particular scene (Cessna 180s) we turned our attention to spray equipment. As luck would have it during our researches into available ground spraying techniques, I ran into Edward Bals who had perfected some very simple rotating gauze atomisers to make possible ultra low volume spraying applications upon, for example, orchards.

Thanks to the efficiency of his rotary atomiser he was able to dispense with almost all the carrier liquid of which hundreds of gallons were used on each acre to secure proper coverage by substituting a mist of small uniform sized droplets carried in a dratt (not a blast) of air.

Problems of noise at airports have now been with us for over a quarter of a century and in many ways the situation seems to be more acute than ever before. The promise of new and better sited national airports has receded to such an extent that all that remains is a vague threat of the need to find a cheaper but less environmentally suitable site, and an exhortation to permit added traffic to operate from existing airports, even though the local communities have expressed their displeasure most forcefully. The introduction of the Concorde, unlikely as it is to always meet the old noise rules, let alone the new ones, makes a mockery of those operators who are willing and have striven to accept a policy of progressive reductions of noise limits, and the present governmental tardiness to proceed with plans for retrofit will add to this unwillingness.

The idea of this pair of lectures is to give some idea of the problems which face an official organisation when it is given the task and the responsibility of making recommendations to allow a helicopter to operate in icing conditions. The principles of the problems are not new— they will be recognised by all quality assurance people, from those who have to vet the design of the Severn Bridge to those who have to certify the safety of a new dog food. We are engaged on another chapter of the everlasting question: how do we define the environment; how do we find the test condition; and, how do we interpolate or extrapolate from what we have tested to what will be found by the operator?

As the result of over a decade of intensive Anglo-French effort on both the airframe and the powerplant, the Concorde supersonic transport has completed its development and has convincingly demonstrated its ability to cross the Atlantic non-stop at Mach 2·0 with a full payload.

This represents a major milestone in the evolution of aviation where increases in speed and reduction of journey times have always attracted traffic. It also represents a major break-through in reducing passenger travel fatigue as has been demonstrated to a large number of people during the recent route-proving trials.

The pay-off, in the final analysis needs to be a better air transport system for the traveller. This will, in turn, generate more traffic for the airline and hence more business for the aircraft manufacturer. To achieve a substantial and profitable share of the available market for new aircraft the manufacturer's product must be produced at the right time, meet the requirements of the airlines, and be competitive in terms of price and capability with the products, both new and existing, of his competitors. Advanced technology, applied in a cost effective manner, can be one of the ways of achieving this competitiveness and of improving the air transport system.

The operation of civil aircraft in the Terminal Movement Area is a very complex subject. Many disciplines are involved and, certainly in Europe, there are problems of international agreements on standards and procedures for the various airline operators, airport authorities and regulatory bodies. For this reason there has been a tendency for certain aspects of the Operational System to be studied and improved without fully evaluating the interactions and hence overall effectiveness of new technological developments.

The powerplant has always played a vital role in the development of aviation. In the beginning, the crucial need was for an engine of high enough power-to-weight ratio to enable the aircraft to fly at all. The Wright brothers had to build their own, and they took to the air with a four cylinder petrol engine having a specific weight of around 15 lb/hp. Much progress was made over the next two decades, and by the mid-nineteen twenties this figure was down to about 2 lb/hp. The aeroplane was now emerging from its infancy; the Atlantic had been flown, and the Otto cycle engine had established itself as successfully in the air as on the road.

It may be asked why I have chosen the subject of instrumentation for this Folland Memorial Lecture, rather than one more closely allied to that of aircraft design— the craft of which we remember Henry Folland as a master. In part I believe the two subjects are closely related, and that a study of the way in which instrumentation has developed indicates many respects in which this development has paralleled, or depended upon, the various developments which have occurred in airframe design.

There is no indication in the admirable biographical lecture on H. P. Folland presented to this Society by his son, as to any special views he may have held on the subject of flight instrumentation. One thing is sure, however : his working life spanned the era in which there was a fundamental change in the views held by aviators about instruments.

This Convention poses a challenge to the lecturers. It asks us to gaze into a crystal ball and to forecast the future on the basis of the research of today. My contribution is to review the aerodynamics scene. I am the first specialist lecturer; this is perhaps a recognition that many of the significant advances of the past have been aerodynamically inspired. It is natural to start by thinking back 20 years and asking whether we would then have predicted what has come true today. In aerodynamics, there is obviously a clear answer to this question.

It is now some 20 years since aircraft noise became a significant public nuisance and every conceivable aspect of the problem has been scrutinised and discussed in a vast literature. The scope of the present paper, in relation to this broad canvas, will appear extremely narrow. Nothing will be found herein about such important questions as the influence of noise on the development of aviation, engine technology, operational procedures, reduction of noise by acoustical means, the economics of air transport, regulatory action, or the planning of airports. It is only necessary to make slight reference to these matters to sketch the framework within which a system of measurement and assessment of noise has developed. The circumscribed nature of these aspects, unfortunately, does not mean that they can be dealt with briefly or summarised easily.

A comprehensive survey of advanced materials for civil aircraft structures from the research point of view would of course include new aluminium alloys, titanium alloys, steels, composites, transparency materials and adhesives. Such a survey is, however, out of the question within the scope of this part of the paper and attention will therefore be concentrated on fibre-reinforced composite materials, partly because as a primary structural material they are now widely recognised to offer much the greatest prospect for really substantial improvements in structural efficiency (weight saving of the order of 30%, for example Fig. 1.1 shows comparative specific properties of various structural materials) and for lower costs, and partly because to realise these improvements a wide and in many ways novel range of research problems throughout the whole spectrum of material development and characterisation, design, fabrication and testing needs to be solved. It will nevertheless be possible, even with this limitation, to do no more than to give a brief sketch of the present position in some of the main research areas, primarily from the UK point of view.

The first part of this paper was concerned with the evaluation of the now classic form of low noise, single stage front fan engine as used on all contemporary designs of large subsonic civil aircraft.

This second part deals with other forms of the aircraft gas turbine which we have categorised as unconventional in the sense that they seek to achieve one or more of the following objectives:

1. (a) a superior performance by moving towards more extreme constant pressure gas turbine cycles;

2. (b) a superior performance by use of a different thermo-dynamic/propulsive system;

3. (c) a performance which requires an ability to modify the thermodynamic cycle at different flight conditions;

4. (d) uses for the engine which are additional to the normal propulsive role.

In the main, these engines are, as their title suggests, not generally adopted as powerplants for production aircraft and their often specialist role must detract from their wide use in a range of aircraft. However, it could be argued that the classic design of engine will soon be approaching a plateau of achievement and therefore some degree of unconventional form will be required in future to advance aircraft performance.

This paper is on the practical experience in British Airways on civil helicopters during the past 29 years, and my recommendation for the continued expansion and success in the vertical flight field of which the present day helicopter is the first example.

I still believe that open rotors, because of their low noise and low speed control aspects, will certainly have a future as far as we can see on short stage lengths up to the end of the century; and by short stage lengths I mean up to 4/500 miles.

Noise and economics are major interlinking factors which are likely to have an impact on the whole future pattern of civil air transport development. In the past decade environmental pressures increased the need to design for low community noise levels; however, the fuel crisis and inflation have now shifted emphasis back towards fuel economy and lower operating costs.

The rate of growth achieved by air transport during the past three decades far exceeds that of any other transport system; this considerable rate of growth is clearly illustrated by, for example, the overall increase in total annual passenger movements at London's Heathrow airport, as shown in Fig. 1. It will be further noted that, despite the tendency for aircraft size to increase, the total annual aircraft movements at the same airport also show an overall growth pattern.

A paper was read to the Test Pilots’ Group of the Royal Aeronautical Society in 1974 some months before the first Hawk flew in August of that year. On that occasion the paper consisted of some background information on how the aircraft came about, followed by a technical description and outline of the projected flight test programme. Now, some two years later, it is intended to describe the flight test programme in general terms from first flight up to the end of 1975. It is hoped that in due course some detailed aspects of this programme will be presented as a separate paper to the Test Pilots’ Group. Before starting on the flight test programme I intend to give a brief description of the aircraft for those who have not seen it before, and to refresh the memories of those who have.

In the past thirty years the exploration and exploitation of space has been one of the few new eras into which man has penetrated and opened a new frontier. Naturally, this drive was made by the two world powers which possess the resources and which are pushed by their competitive fight for public prestige and world-wide admiration. Once again Europe supplied many of the ideas and many of the leading people. And what did we do for ourselves?

In the beginning of post Second World War space activities we missed the start. The first satellites were already in orbit when the first space activities in Europe were proposed. But when we began to move in 1961 we began to move in the right direction. For our purpose the essential factor was the creation of the European agencies—ELDO and ESRO at that time—in which the national efforts of the member states were combined and co-ordinated towards the common goal.

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.

It is now 72 years since the Wright Brothers made the first controlled flights with a manned heavier-than-air machine, and I am deeply conscious of the great honour conveyed by the invitation to deliver this 64th Memorial Lecture commemorating their great achievement.

Their research and development work provides a classic model of a combination of the scientific and practical approaches to the solution of a major problem. However, it is fascinating to look back to those very different days at the turn of the century, and see how incompletely they foresaw all the consequences of their own efforts. Contemporary evidence suggests that their vision was confined to certain secondary uses of the aeroplane, such as military reconnaissance, sport and exploration.