The Short brothers were pioneers in the true sense of the word. They were inspired by the vision of flight and had the driving force while still in their early twenties to build and fly their own balloons (Refs. 1, 2). Through their practical skill and thoroughness they were soon making balloons for other enthusiasts, including the Hon. C. S. Rolls, a co-founder of my Company. Horace Short, the Hon. C. S. Rolls and Griffith Brewer are seen with the Wright brothers in the Rolls-Royce Silver Ghost in 1908 (Fig. 1).

For centuries man had dreamed of flying. Kites, gliders, balloons and ornithopters were built but none achieved sustained controlled flight until the brilliant practical experimental work of the Wright brothers brought success in 1903. Some gloomy predictions of eminent academics were thus confounded.

In terms of world scheduled passenger traffic, Europe accounts for:

• (a) 35% of passenger journeys;

• (b) 10% of passenger kilometres;

• (c) 40% of aircraft movements.

This traffic has shown sustained growth at about twice the rate of general economic expansion.

Rapid growth of trade and discretionary income explains a substantial proportion of this growth, but the efforts of the airline industry itself, which have resulted in improvements in speed and comfort and a persistent fall in real fares, are equally important.

Since the early 1960s the air travel market has broadened considerably. The scheduled industry no longer caters solely for business and wealthy leisure travellers. Increasingly, in a consumerist world, it caters for travellers with modest incomes. Consumerism is not the only external force to be reckoned with. The environmental lobby is strong and demands attention.

The local buckling of structural sections composed of isotropic plate elements is well documented. It is the purpose of this paper to extend this work to include sections composed of orthotropic plates. It has been shown that the buckling behaviour of single orthotropic plates with certain boundary conditions can be related to that of an equivalent isotropic plate in terms of a single parameter involving the principal plate rigidities. It is proposed to investigate whether this principle may also be applied to the structural buckling problem.

It has been shown that simple approximations to the deflected form of buckled plates can be used to give fast and reasonably accurate results for the plate buckling problem using an energy method. If these simple deflection functions are used in an energy analysis for structural sections then large errors may be introduced.