Before we begin, let me say that this paper is not a catalogue of engines, their bores and strokes, their output and weight. These aspects have been well covered before and are well recorded.

However, engines will figure prominently because that was the business of de Havilland Engines and our fortunes or misfortunes followed their pattern. However, instead of rigorously following the historic trail I prefer to pick out some of the landmarks and to outline some of the problems we met on the way. There may be a few anecdotes and something about the people who took part.

To begin at the beginning, we must start with Geoffrey de Havilland, who wanted to fly.

Before getting to the heart of the matter as it were, it would seem to be sensible to sketch in some of the background to the whole project.

One of the teaching methods used at Cranfield relating to aircraft design students, is to enforce on them the discipline of a design project study undertaken within a group, to be completed within a given timescale and within defined specifications. Many an interesting paper aeroplane has evolved which, for obvious reasons, never progresses beyond model stage.

About a decade ago Nick Carter, the then manager of the British Aerobatic Team and Peter Little an ex-student of the College of Aeronautics asked Cranfield if they would consider the use of student effort to design an aerobatic aircraft for competitive work. On investigation it was discovered that such a task was sufficiently demanding to prove a challenge.

With the increasing need for fuel economy all possible areas of drag reduction need investigating. One form which offers considerable promise is lift-dependent drag which for most transport aircraft is approximately 30% of the total drag in the cruise and more at lower speeds. A reduction in lift-dependent drag at a given flight speed would directly reduce the operating costs of existing aircraft. Even greater savings might be obtained for twin-engined airliners where the wing loading is fixed by the high lift-dependent drag at climb-out from the airfield. A method of increasing the effective aspect ratio of a wing would allow new aircraft of this type to have lower wing areas and weights in addition to higher cruise lift-drag ratios.

Previous attempts to analyse clamped skew plates by Galerkin's variational procedure have resulted in discrepancy occurring for rhombic plates. Iyenger and Srinivasan employed along both of the skew axis of the plates the characteristic displacement functions for the normal modes of vibration of a clamped-clamped beam. Their results compared well with those of other investigators but not with Kennedy which differed significantly from the others for rhombic plates.

Many methods and computer programs, e.g. those listed in reference 1, give ‘exact’ initial buckling loads for prismatic structures which consist of thin, rectangular plates which are rigidly connected together along their longitudinal edges. The component plates can be flat or curved, isotropic or anisotropic and can carry any combination of longitudinally invariant in-plane stresses, i.e. longitudinal, transverse and shear stresses. The working which follows can be extended to cover all such plate assemblies, but for simplicity attention is confined to assemblies of uniformly longitudinally compressed, isotropic, flat plates with simply supported ends. The stiffened panel of Fig. 1 is typical of such assemblies, and hence is used to represent them below, because the extrapolation from this particular assembly to the general is obvious.