Monocoque

Monocoque is a construction technique that utilizes the external skinning of an object to form most of the structure. This is as opposed to using an internal framework that is then covered with a non-structural skinning.

Monocoque construction was first widely used in aircraft construction, starting in the 1930's. At that point the price of aluminum had dropped to the point where it was becoming the preferred material for building planes. Prior to this the main materials were wood framing with fabric covering, although some of the wood was being replaced by steel. At first the aluminum was often used in the same systems as the earlier materials, replacing either the wood or fabric, and sometimes both.

However it was realized that the skinning itself had significant structural properties of its own, at least for certain loads. Specifically the skinning could easily provide the structure for tension loads (pulling), and if it was bent into a curve or pipe, it became quite strong against bending loads as well. The only loading it could not handle on its own - at least in thin "skins" is compression - which required a series of bulkheads inside the plane.

The result was a structure that was just as strong as ones made with older methods, but weighing considerably less. For aircraft consistruction this is a very important consideration.

In the post-war period the technique became more widely used in other areas. It is now used quite commonly in automobile construction as well.