No one who has served in the Royal Air Force for any length of time can be anything but vividly aware of the intimate connection of Sir Sydney Camm with the Service, and the profound effect that he and his aircraft have had upon us. The list of military aircraft for which he was responsible from 1925 onwards reads almost like a history of the Royal Air Force: Hornbill, Hart, Fury, Hurricane, Typhoon, Tempest, Hunter, P.1127 and the Hawk.

After the merging of the British helicopter industry under the Westland banner in early 1960, the three larger constituent parts continued on a semi-autonomous basis putting into service such aircraft as the Wessex, Belvedere and Wasp. Future thinking was still contained within the separate groups with activities related principally to the Westminster, Bristol 194 and the Rotodyne. All three of these projects had merit but were in competition and obviously could not all continue. In the event, however, all were unfortunately abandoned and in 1963 the Group's project activities were centralised at Yeovil. The first task of this new Project Group was to attempt to make proposals for a rational range of future products particularly with respect to the future requirements of our major customer—the British Armed Forces.

As described in Mr. Austin's paper “The Concept of the WG-13”, the Lynx stems from a series of project studies for a small tactical twin-engined helicopter, begun as long ago as 1963.

In 1967, an agreement was reached between the French and British Governments to produce, jointly, three helicopter types as a package for service with the Armed Forces of both nations. The package consisted of the Puma (SA.330-14000 lb auw) the Gazelle (SA.341-3500 lb auw) and the Lynx (WG-13 basic aircraft-8000 lb auw).

This paper deals with the conception of the initial programme, the management and development of this programme up to its present philosophy and how this programme is now being managed to meet the future of the Lynx in relation to the current development knowledge. Some aspects of the development manufacture are also covered.

Any duplication from the preceding papers given by Messrs. Austin and Rogers is considered to be given as reiteration of points necessary for completeness of this paper in its own right.

The natural frequencies of a plate or a shell can be changed by altering its stiffness. This can be achieved by appropriately varying the mass or curvature, by introducing initial stresses or by attaching stiffeners to the system. The last method has obvious advantages over the other methods. The natural frequencies are thus raised, lowered or remain unchanged depending on (i) the dimensions of the stiffener relative to the plate or shell dimensions, and (ii) its position.

It has been known for some time that when a cylinder spans a wind tunnel the boundary layers on the walls of the tunnel may have important effects, especially on the pressure in the base region. By making the boundary layers thin by the use of end plates, it may be possible to approach a complete elimination of the effects of these layers on the central part of the span and obtain a flow that is very nearly two-dimensional. Most of the published pressure distributions for circular cylinders were obtained without end plates and this probably explains their inconsistency. Gerrard has described experiments in which the addition of end plates caused a substantial change of base pressure coefficient but he did not attempt to design an optimum end plate to give nearly two-dimensional flow.

It is an honour which I greatly appreciate to be invited to give the 19th Barnwell Memorial Lecture and I value the invitation all the more after noting that all previous lecturers have been distinguished aeronautical engineers, or at the least specialists, very experienced in air transportation.

It has always been a matter of regret to me that I never knew Frank Barnwell at work. When I went to Filton in October 1938 it was a few weeks after the flying accident in which he lost his life, so I cannot add from personal experience to the comprehensive account of his career compiled by Major Bulman for the first Barnwell Lecture in 1954, supplemented by the reminiscences of Captain Cyril Uwins and others.