A Bell Tetrahedron!

Back at the end of the 19th Century there was a competition to build the first man carrying powered aircraft.  We all know who the eventual winner was, but less known is that Alexander Graham Bell (yes, the telephone man) was also in the race for this prize.

One of the major problems encountered when building this sort of device is how to make it rigid and strong enough to carry the weight of a person.  Bell realised that the strongest, most rigid shape he could use was a triangle, and that if you put four triangles together you form a tetrahedron. 

One further advantage of Tetrahedra is that you can join them together, again using only triangles, to form bigger rigid shapes.

By covering two sides of the Tetrahedron with fabric and leaving the other two open a good shape is formed for making kites - in the case of powered flight, put an engine on the front of a big enough structure, and you have a plane

When Bell was making his kites, the materials he had available were timber and silk.  Nowadays with materials such as Carbon Fibre and Ripstop Nylon teh kite can be made much lighter and stronger, allowing more flexibility in the assembly

Using the standard accepted methods of construction, this kite has several problems, no least is the fact that the shape is constrained, the assembly and transportation is difficult and the original construction is tedious and laborious.