Space frame

[1][2] Bell's interest was primarily in using them to make rigid frames for nautical and aeronautical engineering, with the tetrahedral truss being one of his inventions.

Gilman was an admirer of Buckminster Fuller's architectural trusses, and developed a stronger matrix, in part by rotating an alignment of tetrahedral nodes in relation to each other.

The simplest form of space frame is a horizontal slab of interlocking square pyramids and tetrahedra built from Aluminium or tubular steel struts.

More technically this is referred to as an isotropic vector matrix or in a single unit width an octet truss.

More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes.

The CAC CA-6 Wackett and Yeoman YA-1 Cropmaster 250R aircraft were built using roughly the same welded steel tube fuselage frame.

Although many tubular chassis developed additional tubes and were even described as "space frames", their design was rarely correctly stressed as a space frame and they behaved mechanically as a tube ladder chassis, with additional brackets to support the attached components, suspension, engine etc.

As this included diagonal tubes, it can be considered a true space frame and arguable the first mid-rear engined design.

Later, TVR, the small British car manufacturers developed the concept and produced an alloy-bodied two seater on a multi tubular chassis, which appeared in 1949.

A drawback of the space frame chassis is that it encloses much of the working volume of the car and can make access for both the driver and to the engine difficult.