The Royal Aeronautical Society and the Weybridge Branch have given me a great honour in inviting me to deliver this unique lecture in memory of one of its distinguished Honorary Fellows.

The life and achievements of Sir Barnes Wallis (Fig. 1) have been well chronicled and broadcast. It is with some trepidation, therefore that I make this contribution, but as one of many at Weybridge who worked directly under his authority, I would like in paying this tribute to feel that I am representing all of them. In a lecture of about 75 minutes it is not possible to give proper justice to the work of a man who devoted something like 70 years to engineering design. He was already 16 years old and in his last year at school when the Wright Brothers were the first to fly, in 1903; he was still in full-time employment when Concorde flew in 1969. Although not involved in either of these epics, his own career was studded with many achievements, and even after his retirement he continued to work on visionary projects.

In recent years the advances in materials technology, coupled with the rising operating costs of conventional aircraft, have led to renewed interest in the airship as a means of fulfilling certain transportation requirements.

This brief paper does not attempt to retell the story of the airship or to try and justify its present day use, this being far better left to the experts in this field, but considers the requirements and considerations to be taken into account when selecting a propulsion device. The propulsion devices considered are limited to open propellers and very low pressure ratio ducted fans.

Hydrogen is the medium of the past and helium is the hope of the future. I do not intend, in this paper to go into the relevant merits of helium over hydrogen and vice versa for its uses in the airship industry, for the obvious reason that most of you here today will be more knowledgeable on this particular aspect than I. What I will try and do in this paper is to give a brief background on the interesting aspects of helium and its unique characteristics.

There is currently some interest in supersonic sea-skimming as a possible terminal phase for anti-ship guided weapons. The flight of a supersonic vehicle, close to a density interface, will produce an additional series of shock waves from the reflection of the shock waves generated by the vehicle from the interface. The angle of reflection of these shock waves will depend, interalia,on the slope of the surface upon which they are incident. Given a surface with a periodic positional displacement, such as would be produced by a train of surface waves, the variation in position of the reflected shocks, in relation to the generating vehicle, will also be periodic in nature. This coherent motion could produce periodically fluctuating forces and moments on the vehicle generating the incident shocks and these, in turn, could cause stability or control problems for the missile autopilot.

It has long been recognised that in moving vehicles, if an observer wishes to study a distant object with any accuracy, the sightline along which he is looking must be stabilised against the vehicle motion. There are various ways by which a sightline may be stabilised, and for several years now the Aircraft Equipment Department of Ferranti Instrumentation Limited have been producing stabilised sighting systems for helicopters and tanks using a directly coupled gyro/mirror technique. At present we are developing systems for use in RPVs, one of which will be flown for evaluation in a fixed wing RPV research vehicle, the other under a tethered parachute.

The memory of the early Comet tragedies lives on as a reminder that aircraft structures must be damage tolerant. Aircraft structures may be cracked in manufacture or in service as a result of fatigue, corrosion, incorrect maintenance, the impact of ground handling equipment or accidents such as a turbine disc break-up. A damage tolerant structure should retain adequate residual strength until any cracks are detected and repaired.

In the spring of 1980, a long range derivative of the L-1011 TriStar entered commercial airline service with an extended wing span and a digital Active Control System (ACS). The extended wing span improves fuel efficiency by 3 to 3½ % due to a higher wing aspect ratio and lower induced drag. The digital ACS provides load alleviation functions by symmetric motions of the outboard ailerons which relieve the loads induced by the increased wing span. This load relief minimises the amount of structural modifications required to the basic L-1011 wing to accommodate the increased wing span.

It is not always possible for a designer to accommodate a conical diffuser giving the greatest possible pressure recovery for a given area ratio because this usually involves a long version with a total conical angle of about 7 degrees. Considerable efforts have therefore been made to improve the performance of diffusers with total conical angles up to at least 30 degrees by adopting various techniques listed in Ref. 1. One suggestion was the addition of whirl to the flow in the inlet pipe; that is, to superimpose a vortex coaxial with the pipe and diffuser axis. However, Refs. 1 and 2 show the amount of published research on this topic to have been meagre.

A previous paper has dealt with the case of adding a forced vortex whirl velocity distribution to the incoming flow and showed that improvements were possible, certainly in static pressure recovery and even in so-called efficiency, using a restricted definition of the latter. Because of mechanical vibration problems, the maximum swirl angle that could be added to the flow was about 15 degrees, corresponding to a forced vortex rotation rate of about 28 rad/s. This led to a beneficial redistribution of axial velocity components and a diminished tendency for flow separation from the walls.

The lessons learnt in the design and manufacture of a non-rigid airship in 1979 have been put to good use in the development of a new range of airships. The first of these is now nearing completion. Its potential for a variety of tasks, both civilian and military, is discussed as are other non-rigid designs.

For the heavier payloads the rigid airship has greater potential. Detail design work against an option demand is described. At the other end of the scale the hot-air airship continues to be developed and sold successfully.

In this paper I do not intend to make a comparison between British designs. I merely list the companies in alphabetical order and discuss the designs each is working on. Those requiring further information will find the list of references and company addresses at the end of the paper.

The serious mathematical complications of the kinetics of the aeroplane spin have given birth to methods of explanation based on assumptions and simplifications, the application of which, not unfrequently, has led to confusion and misunderstanding on the part of the student, let alone error on the part of the initiator of the method.

One of the problems, is the selection of the geometric parameters that have to be introduced as opposed to those which may be left out of the picture. Obviously, in such complex movement as the spin, the most obscure parameters are the angles of the motion. Unfortunately, there is a minimum number of such angles which is necessary and if one, hopefully, begins with a lesser number, one soon finds that the rest have to be put in place, even tardily, if the puzzle is to be completed.

If the comparisons on productivity made by Mr. Harvey for the United Kingdom and other countries are accepted the question to be considered is why there should be any difference.

In particular I would like to identify some of the reasons for making comparisons with a principal competitor — the USA industry.

While the comments made reflect experience on airframe manufacture there is little doubt that the situation is no different in the rest of the aerospace industry or for that matter the UK engineering industry in general.

A little time ago Peter Martin suggested that it would be of some interest to airlines and others if someone from the CAA were to come along tonight and talk about the Civil Aviation Authority's future policy. We had to reply that this was something we could not usefully do at a time when we would be in the middle of our consultations with the industry about what that future policy should be. There the matter rested until July when I was discussing another matter with Peter Martin. I happened to say, in response to an observation of his, that I had in my mind a clear picture of where the industry had been, where it stands now and — perhaps rather less clearly — what the options were for its future development. Mr Martin seized upon this, believing that it would not only be interesting but even helpful to the industry and others if I were to share this personal vision with you. He may be right.

In any event that is how I come to be standing here before you tonight, in essence to talk about my own view of the industry as it was and as it is, together perhaps with a few glimpses of the way things might develop in future.

This paper deals, in the main, with aluminium alloys and steels that are currently available on a commercial basis or are likely to become available in the near future. It highlights the more significant improvements made during the past two decades.

Aircraft structures have been built predominantly of aluminium alloys since the Second World War and, although certain improvements have been made over this period, the alloy systems used have changed little essentially because the alloys available have been limited by the solid solubilities of the selected solute elements at safe solution temperatures. The slow but certain development of novel production routes including fibre and whisker reinforcement of metals, powder production and rapid solidification techniques will circumvent this limitation by the turn of the century.

Two philosophies for the attitude control of space vehicles with flexible appendages have appeared in the literature, these are:

1. (i) control of the rigid centre body to lie within some bounded region while the flexural vibrations are allowed to behave in an uncontrolled manner;

2. (ii) control of all plant states to some finite value as time tends to infinity.

The former method does not require flexural information and therefore avoids the on-board computational burden associated with state estimation, or the cost of additional instrumentation. However, attitude degradation has been observed and reported indicating a clear need to compensate for structural vibrations.

The ‘universal’ Strouhal number, SB, which was derived by Bearman using the Kronauer vortex stability criterion is presented for two-dimensional rectangular-section prisms of depth to width ratio, d/h, from 1 to 5, for a flat plate with and without splitter plates, for a circular cylinder with splitter plates and for a circular cylinder with two blowing slots to control its wake width. A value of SB close to Bearman's value of 0·181 is obtained for the prisms of small d/h, for the plate without a splitter plate, for the cylinder with small splitter plates and for the cylinder for low blowing rates. For the other cases, however, SB is found to vary within the range 0·137 to 0·208 which is an indication that the general application of this concept to two-dimensional bluff bodies is superficial.

In considering the subject of this Symposium I was somewhat encouraged by a reminder of my company's first memorandum of association, written back in 1946. It is: to send and receive signals, messages and communications to and from aircraft, dirigibles and all other vehicles propelled in the air. How far-sighted those solicitors and recently demobilised airmen must have been! For although it has been the brief privilege of but very few of my air traffic control colleagues to have worked a non-dirigible a few years ago, I cannot honestly feel certain that they seriously believed that the age of the airship would dawn again. (Or did they?)

In the current issue of Jane's All the World's Aircraft, J. W. R. Taylor states that ‘It would be pleasing to see in the development of programmes like Airbus and Tornado the seeds of increasingly successful European collaboration in the aerospace business … ‘

The Management Studies Group of the Royal Aeronautical Society have, for many years, been concerned with improving the effectiveness of the aerospace industry, and saw in European collaboration great opportunities as well as problems to be overcome. It was felt that the time was right for a review which could indicate the way forward, and identify the best growing conditions for the seeds of successful European collaboration.

This paper was commissioned by the Management Studies Group to review published papers for quantitative data in order to help set the scene for the talks and discussion to follow.

Lift and drag measurements were made to determine the effects of vertical flaps when positioned along a ray on the upper surface of a sharp-edged, flat, 60° delta wing. Six flap heights were tested at each of four semi-span positions.

Results showed that all configurations gave improved lift-drag ratios. The maximum improvement was 33% using a flap of height 6·1% of the local semi-span placed at the 84% semi-span station. The flaps did not affect the lift but reduced the drag by generating a thrust force on the vertical flap surfaces.

Flaps at the 84% position were modified to investigate the possibility of obtaining further increases in lift-drag ratio. In practice these modifications, inward inclination of the flaps, and fairing the inboard side of the vertical flaps, slightly reduced the flap effectiveness and were hot pursued further. Part chord flaps were also tried and showed that the reduction in benefit was roughly proportional to the length of flap removed.

A practical application of two-dimensional subsonic bluff body flow research can be seen in the design, construction and positioning of tall slender buildings. Similarly, from a three-dimensional viewpoint, drag reduction and vortex control is an important factor in the latest road vehicle designs. From just these two examples it can be seen that the problem of flow about a bluff body is one of major practical importance, while at the same time being of great theoretical interest. However, despite many years of extensive testing, there has been little progress made on the theoretical investigation of turbulent base flows since the foundations laid down by Kirchhoff and von Karman. The non-steady processes in the wake, in particular the complex dynamics of vortex formation, have proved to be problems of formidable size.