I greatly appreciate the invitation to give the Handley Page Memorial Lecture. It has not been easy to select a reasonably suitable subject not already covered by some distinguished lecturer and I hope you will not think the subject I have chosen is too far removed from HP's interests.

I do not think it is: for he was a great practical engineer and a keen supporter of Cranfield in its early days. I doubt whether he had much time for academics except at Cranfield and maybe not for graduates even of engineering, for he had learnt his trade in a hard school and was justly proud of it. But times have changed, and just as the aircraft he designed changed to meet new markets and take advantage of advancing technology, so I think he would have approved of the new Cranfield Institute of Technology which has developed out of the old Cranfield College of Aeronautics, and particularly the Institute's very practical approach to teaching and research, and its close ties with industry from which it draws over 60% of its income.

It is surprising that, in a country with long and strong traditions in aeronautical engineering and naval architecture, the interactions between these two professions have only been sporadic and largely informal. There have been some notable exceptions, of course, such as the airship story of the 1920s (and its revival of interest in very recent times); hovercraft development; and on the educational front events such as the creation of a Ship Science group within the Department of Aeronautics and Astronautics at Southampton University in 1968. But unlike France, with its Association Technique Maritime et Aéronautique, and USA, with its regular joint meetings of the Society of Naval Architects and Marine Engineers with the American Institute of Aeronautics and Astronautics, collaboration between our two ‘Royal’ institutions has been negligible.

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.

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.

In the design of contraction cones for wind tunnels little account appears to have been taken of the influence of compressibility on the performance; the rules of thumb resulting from experience in low-speed wind tunnels are applied regardless of the speed range being considered. This is not surprising in view of the lack of understanding of the complex processes in the development of the stream turbulence through a contraction cone. In addition to the dominant process of the distortion of the vortex lines, the flow is influenced by decay, by the interchange of energy between components both because of the tendency to isotropy and because of the curvature of the flow, and by the apparent turbulence created by turbulent wall boundary layers. Eventually methods of turbulence modelling should be able to calculate the flow but meanwhile it is worth examining the predictions of rapid distortion theory.