The New Science of Strong Materials: Or Why You Don't Fall Through the Floor (Penguin Science) by Gordon J E

Author:Gordon, J E [Gordon, J E]
Language: eng
Format: epub
ISBN: 9780140135978
Publisher: Penguin Books Ltd
Published: 1991-03-27T21:00:00+00:00

Figure 2. When an aircraft wing is to be tested, it is mounted by its root fitting in a large steel framework. Many hundreds of attachments, distributed over the wing surface in both dimensions, are used. In this way the effect of aerodynamic pressure is imitated.

As loads increased the general trend of design was however undoubtedly towards monocoque, or hard-skinned, monoplanes in which the loads, as far as possible, were taken in the skin. There is no difficulty about taking tension in a thin membrane, the problem is how to take compression without causing the skin to buckle. In practice this was done by a compromise, the thin skin being stiffened by attaching to it spars and stringers, with which it shared the load, the whole rather elaborate surface forming a shell stiff in bending and therefore unlikely to buckle.

The outstanding early example of this was the D.C.3, later known as the Dakota, and this was followed by the Spitfire and by many of the famous aircraft of the last War. All these were metal aircraft, built of aluminium sheet to which were riveted L-shaped aluminium stringers. This system proved almost exactly equal in structural efficiency, that is in weight, to wood and fabric with the advantage of a smoother outside surface and the almost total elimination of airframe maintenance.

This construction proved very successful and, with minor modifications, is still the standard way of making aeroplanes. By 1939 it was widely believed that no more wooden aeroplanes would be built and this might have come true if the War had not created shortages of aluminium and of the machinery and skilled men for handling it. Furthermore there were furniture firms short of work and again the development time for a wooden aeroplane has always been much shorter than that for a metal one.

One expert achieved unwanted fame by stating, categorically, that it was no longer technically possible to build modern aircraft out of wood. The ink was scarcely dry upon this document when the Mosquito appeared. This wooden aeroplane was one of the most successful aircraft of all time, and 7,781 of them were built. It was probably more detested by the Germans than any other Allied plane.

Besides the Mosquito and a large number of trainers, the other big production of wooden aircraft was of gliders. Most of these were large machines with spans up to 110 feet (33 metres), frequently made to carry tanks and other heavy equipment. The original idea was that the gliders should be built to make one flight only. This turned out to be impracticable, partly because they were needed for training and also had to be moved between aerodromes because of changes in the strategic and tactical situation, but also, more importantly, just how do you build an aeroplane for one flight only? In practice the gliders became much like any other aeroplanes, except that they had no engines.

On the whole the wooden aircraft were extraordinarily successful and I suppose that we could hardly have won the War without them.

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