With the introduction of each new generation of combat aircraft it has become popular to assume that they will be operated in a more conservative manner than previously and that less attention, therefore, need be paid to their spinning characteristics. Current experience, however, shows that inadvertent spins will continue to occur, and must be allowed for, if these aircraft are to be operated effectively and to the limit of their capability.

In this connection the Hunter provides an interesting case history, since it has been put to widescale use in a variety of roles and its erect and inverted spinning characteristics have been thoroughly investigated. These characteristics will be described both for their own sake and because of the applicability which they have to current high performance aircraft.

For a number of years it has been the practice at Rolls-Royce to determine the basic aerodynamic characteristics of the turbines of our engines by tests of model turbines. The first model of the single-stage Derwent I turbine was tested In 1945 and a design point efficiency of 75 per cent was measured. Since then over 600 different turbine configurations have been tested and many of the more recent turbines have achieved efficiencies appreciably better than 90 per cent. Typical of modern turbines is the Spey two-shaft turbine in which the four stages reach a design point efficiency of a little over 92 per cent. This paper presents a description of the test techniques which are used in this work and also a simple method of correlation which relates the efficiency of some 70 turbine stages to the velocity triangles and enables the efficiency of those turbines, which fall within the scope of the correlation, to be predicted with an accuracy better than ± 2 per cent. The measured value of turbine efficiency can be markedly influenced by the measurement technique, so the way in which the turbines are manufactured and tested is described in some detail.

The continued expansion of air transport is bound up with its possibility of producing ever lower fares. Thus the future of both sides of industry depends on the success in this field. This paper notes some of the difficulties seen from the manufacturer's side in this rather inexact science. It is essentially a personal view not associated with any one Company's views, but based on some years of experience in the industry. It answers no questions, but is aimed rather at provoking discussions on some of the important issues, particularly those which tend to be taken for granted.

It should be stated also at the outset that this paper is obviously affected by the current beleaguered state of the British airframe industry. There is nothing in it, however, which does not apply to any nation's airframe industry and it is not intended as criticism of the UK one. It is certainly not the intention to add to the volume of anti-British comment which is so valuable to our competition.

Events leading to the inception of the Air Registration Board are described, together with a survey of its make-up. The problem of airworthiness in general is dealt with in broad outline and a variety of problems which have been experienced are dealt with in more detail.

In speaking to the Air Law Group of this Society, I speak as no lawyer and offer no legal profundities. I speak as an airline man, with some experience in bilaterals. I propose to talk upon some practical aspects of bilaterals as they appear to an airline man and to touch little upon “-isms” and “-ologies”. The philosophical profundities matter only if they help an airline to trade where it wishes and to plan ahead with some hope of continuity and flexibility of routeing.

I would like first to pay a tribute to the “only true begetter” of British policy in the bilateral field—Sir George Cribbett. It can have fallen to few Civil Servants to have had such influence on the commercial side of a great industry; it must be unique for such a man never even to have reached the principal post in his own Ministry. The very qualities which made his name so revered in the world at large were probably those which blocked his path at home. Our worldwide networks of today are his memorial. In the civil aviation field his epitaph might well be that on Wren's tomb in St. Paul's Cathedral—“Si monumentum requiris, circumspice”: if you seek his memorial, look around.

The Plowden Committee has been considering ”… the future place and organisation of the Aircraft Industry in relation to the general economy of the country taking into account the demands of national defence, export prospects, the comparable industries of other countries, and the relationship of the Industry with Government activities in the aviation field.” Against this background of inquiry into the future structure of the Industry, it seems opportune to consider in some detail the actual process of mergers and reorganisation which occurred in the Aircraft Industry during the period 1957-60. This paper will attempt to explain the reasons for the mergers, the development of Government policy towards the Industry during this period, and the actual process of events which produced the recent industrial structure.

The title of this lecture is a little misleading in that the intention is to give broad coverage not only to the handling qualities of the aircraft, but also to some of the general information and lessons derived from the flight-testing, some of the background and some of the supporting work. Attempts will be made to correlate some of the characteristics with shapes that are generally regarded as less radical. Only limited attempts will be made to cross-read to larger applications of the slender delta, not because of absence of cross-read, but because this is an activity which must not be undertaken lightly or ill-advisedly, and is within neither the time-scale nor the scope of this lecture.

I hope that I shall be forgiven if I deal only in part with this subject, and also if I approach it from the airline engineer's point of view, although what I have to say is a personal expression of opinion.

Airlines are commercial undertakings and do not welcome change for change's sake. To improve service competitively from the point of view of time, regularity and safety and to encourage the continued growth of traffic through reductions in fares is the broad aim; it is against this background that, for example, the supersonic transport is being considered by the airlines. As you may have gathered, there is no marked enthusiasm. In due course, come it will, and traffic management plans must bear it in mind in considering future developments in Air Traffic Management. I am going to adopt the rather conservative attitude that most air traffic over the next two decades will be in aircraft much as we know them at present, and that if the growth in traffic leads to difficulties in Air Traffic Management then the main source of improvement must be sought in the system of management.

Guderley, Armitage and Valentine have computed the inlet and closed body contours which form the forepart of an axially symmetric body, of given length and fineness ratio, having minimum pressure drag. The solution is not based on a simplified pressure law, such as the Newtonian impact law, because by a suitable choice of control surface for mass flow and momentum they are able to employ the general flow equations. It is clear, however, from an analysis of their tabulated results that their cowl shapes fall on a single curve for a given value of Δ=didt, the ratio of the initial to the final diameter of the cowl, when plotted in terms of a dimensionless length ξ=x/l and thickness η=y/dt, as in Fig. 1. Furthermore Fig. 1 shows that, except for small values of Δ, the Guderley shapes are indistinguishable from the optimum shapes calculated from Newtonian impact theory. The shape and characteristics of the Newtonian duct of given length and thickness, offering minimum drag to the external stream, are derived using the slender-body approximation. Ducts for which Δ > 0.04 are shown to be sufficiently slender. The slopes of those with 0 ≤ Δ < 0.04 are too large only in a small critical region near the nose. Thus slender body theory will give a close approximation to the exact Newtonian solution even in these cases. For the larger values of Δ likely to be used in practice slender body theory is valid everywhere.

Aeronautical research in South Africa probably dates back to a project which is reputed to have culminated in the successful launching of a glider from a hill in Natal, some twenty years before Otto Lilienthal made his first successful flight in 1895. The glider was constructed by two brothers, Archer and Goodman Houshold, its design having been based on a study of bird flight and its design calculations having been verified by Dr. Colenso, at the time Bishop of Natal. Goodman Houshold was at the controls when the glider made its first and last flight from the hill down to a valley below. Further flights were forbidden by an anxious mother.

THE SST project is the largest, most expensive and most dubious project ever undertaken in the development of civil aircraft. It is dubious because of the concern about the side effects of supersonic flying on a regular basis, the main one being the sonic boom. Apparently the more one learns about the sonic boom, the more intractable it appears.

The project is unique in that in Europe it was instigated by, and financed by, the Governments for airlines and not by airlines. A similar, although not exactly the same, pattern is followed in the USA.

Another main characteristic of the SST is that no airline has ever asked for it, but the project existing has tempted a few airlines to put in tentative orders, which has encouraged other airlines out of fear to put in other orders.

The general run of technical unknowns is pretty well-known, one of them being how to get rid of the heat caused by the friction of the air at the high speeds involved. However, probably the greatest doubt lies in the improbability that the SST will be able to be profitable in operation. I agree that it is possible to make any given number of calculations on this matter, all with reasonable degrees of honesty, and half of them will show that airlines will make money and the other half will show the opposite. This is merely a measure of our lack of knowledge of these aircraft.

A surface hot film was used as a boundary layer transition indicator on wind tunnel models at Ifiach numbers from 1·3 to 4·0. The results illustrate the difficulty of fixing transition with distributed roughness on small models at supersonic speeds.

If the thrust line of an aircraft does not pass through the centre of gravity, the offset will introduce a pitching moment whose variation with speed and incidence perturbations will affect the stability characteristics of the aeroplane. Both Duncan and Etkin discussed the influence of the propulsive system on longitudinal static stability, but Duncan's analysis for an offset thrust line is not correct and Etkin restricted consideration of thrust effects on static stability to angle-of-attack disturbances at constant speed. The following remarks have been written, therefore, to clarify the effect of an offset thrust line on an aeroplane's static stability. Consideration is first given to what is meant by static stability, and then the part played by the thrust term is examined.

I took the unusual course of suggesting this lecture because I have something to say. I should have done this ten years ago. Better late than never. The position is that after £20 000 million spent on defence in the past 12 years, of which the air industry has had more than its full share, there is a culmination of industrial mismanagement, a crisis of confidence, a prevailing sense of bewilderment, an air of frustration and, therefore, a craving for new leadership in industry to make a true and worthy partnership of heart and mind with the active new leadership in Government. I sense moreover that behind the shadow boxing lies at this moment a more bi-partisan approach to meeting the future than immediately meets the eye. So this is not an exhortation but a demand to adopt new habits of thought that will lead to evolution of equipment calculated to sell well as a general rule instead of it being more the exception. And this is not a plea, but a demand, for a new resolve and leadership in industry coupled with a determination to make a better export showing in the 1970s on a smaller Government investment. The present Government's actions to promote research mergers and industrial co-operation with other countries seem a logical turning point for a re-start. So why not let us make resurgence date from now ?

The aim of this paper is to show how design improvements may lead to a reduction in direct operating cost, pence per passenger mile. In all the comparisons made it is assumed that equal standards of equipment, accommodation, powerplant efficiency, and so forth, apply and that equal skill and standards apply in manufacturing; differences therefore are due to design features. The paper is in two main sections:

(1) A Satellite's eye-view of the whole design problem of the cheap short-range transport aeroplane.

(2) A more detailed description of two specific examples which illustrate the conclusions drawn from the general survey.

The first part is historically fiction but technically fact; the second part (despite the temptation to interchange the above two nouns and adjectives) is, I claim, fact both historically and technically.

I have departed from the historical sequence of events for the first part because we have now realised that it is possible to present in a comprehensive general argument the rather confused mass of data, ideas, techniques, inspirations and false trails that, in the course of time, led us to an enthusiasm for the all-wing Aerobus.

It is surely of the greatest importance that those engaged on the development of Civil Aircraft should give attention to all aspects of the economic operation of air transport and consider indirect operating costs and revenue, as well as the direct costs. This is no easy field of study and one may be accused of asking questions rather than providing answers. However, no discussion of short-haul transport can be complete without the fullest consideration of all aspects of airline cost.

Although the airframe, engine and accessory manufacturing industries are primarily concerned with the provision of vehicles, systems and equipment for Civil operators, they are also closely concerned with the utilisation of equipment and with the scale and direction of the developments of air transport in the future. We therefore subject to continuous study all areas of potential air transport growth and, of these, the short-haul domain is now of special concern.

Nowhere in the literature of helicopter noise can one find a general understanding; only isolated, inconsistent, and often inadequately documented facts. These could, of course, be reviewed but hardly with profit; it is easier to ask critical questions of nature than of previous investigators.

For fundamental reasons the helicopter in its present state of development is not in fact matched to the bulk, low-cost transport of passengers. But for equally good reasons the phenomena of aerodynamically generated noise now bid fair to banish from inhabited localities all other forms of vertical take-off and landing aircraft so that, if a city-centre to city-centre aircraft transport system is ever to be practicable, it will most probably be based on some metamorphosis of the helicopter.

We have heard that the SST project is the largest and most expensive project ever undertaken. It is fairly large and it is expensive. When making comparisons, however, it is important to remember that major developments in aviation have rarely been cheap. For some civil projects the subsidy has been indirect. For example, the present generation of successful American long range air liners, notably the Boeing 707, has succeeded to a large family of military progenitors and thereby enjoyed its massive inheritance. Even so, funds spent on the 707 development must have been substantial, for many hundreds of aircraft needed to be sold before the break-even point was reached. Those firms in the USA, lacking the advantage of a military ancestor, must have seen the prospect of profitability in the civil field, in straight competition with those better placed, as an illusive difference between two very large sums—launching expenditure and prospective income.

Now, and in the future, all civil projects everywhere must fight for existence without benefit of feed-back from a related defence project.

The question is whether to fight at all in this remorseless arena. Presumably nearly all at a meeting of the Royal Aeronautical Society would not agree that this country should reject the challenge.