The Hyperlogos

A Monocoque (MOW-no-coke) structure is one which uses its outer skin as a structural member to bear shear or load forces due to bending, which is accomplished through the distribution of these forces. They can be divided into three groups - monocoque, semi-monocoque, and reinforced shell. Monocoque comes from a French word meaning "single shell". These designs first came into vogue in aircraft, as a way to save weight by transferring load from a heavy frame to the skin of the craft, which is after all a required component.

Monocoque design is primarily facilitated by placing planes perpendicular to the direction of load. This translates load into shear, which is distributed fairly evenly throughout the structural member. It allows a very lightweight and low-volume piece to handle a great deal of load.

Any material can be used to create monocoque structures - A cardboard box is actually an excellent example of monocoque design; both in the corrugated structure of the walls and in the fact that its skin bears all the load it has to accept. The honeycomb structure used in many lightweight materials, including the skins of modern military aircraft and the interior of wakeboards used for aquatic recreation, is also an application of monocoque technology. The box frames used in [[motorcycle]]s, and the combination chassis/body of the [[McLaren F1 Road Car]] are also semi-monocoque designs. The [[Opel Aero]] ("poor man's [[Corvette]]) is also monocoque, and the [[Ford GT40]] is a partial monocoque with a curved sheet on the bottom of a tubular steel chassis.

While monocoque design has seen limited use over the years in favor of more widely used designs like the ladder chassis and tubular steel frames, a resurgence in interest has come with the development of (relatively) inexpensive [[carbon fiber]]. Carbon fiber is especially well-suited for monocoque designs because it can be designed for distributing shearing loads in specific directions, and be made semi-flexible in others, while it has an extremely light weight. This fits in with the design goals of monocoque systems nicely. Monocoque designs also require somewhat arbitrarily shaped pieces to be used for optimum redistribution of force, and it is easier to craft carbon fiber into odd shapes than it is steel.

References:

1. Mossman, Ralph W. and Russell G. Robinson. Bending tests of metal monocoque fuselage construction. NACA TN 357, Nov 1930. (http://naca.larc.nasa.gov/reports/1930/naca-tn-357/)
2. Monocoque. Harcourt Academic Press Dictionary of Science and Technology, (http://www.harcourt.com/dictionary/def/6/6/3/8/6638900.html)