How to build A Bell Tetrahedron Kite

Method designed by:

Materials

Method

Into each end of the 6 carbon fibre tubes glue a screw eye; four of the pieces need the screw eyes at right angles to each other (edge poles), the other two need them aligned the same (cross poles).

The shape of the fabric is based on two 50cm triangles.  It needs to be cut to leave enough on each side for a hem to hold the poles.  We recommend that you leave at least 2cm, but it is easier with 3.

Sew the four edges allowing a hem on each side to hold the edge poles.  Cut enough from each corner to allow the poles to poke through.

Insert the four edge poles, one into each hemmed edge.

where the three poles join at each corner there are various methods we have tried to fasten the eyes together.  The three favorite methods are shown below:  These are, in order, opening one of the eyes out and interlinking, joining using an angling Split ring and joining with a cable tie.  In our experience all these methods have merits and downsides, and the choice is one for personal preference.

when assembled the cell should look like this (the first image has no fabric to show the frame clearly)

Flying

To link the cells together we have been using 3.5 to 4mm cable ties, any smaller tends to be too weak for larger assemblies.

The basic assembly consists of four blocks.  To go to a 4-cell kite a pyramid is built by joining at six points.

Taking an assembly of four cells to be a building block, four of these blocks can be joined in the same way to make a 16-cell tetrahedron – four of those to make a 64.  By that time you have a 4m high kite and further building gets difficult.

4 cell kites will fly with a tail, 16 cell kites fly well with no help and 64 cell kites appear to be glued in position when flying

Our experience with bridles for the kite is that it flies best from a point very close to the peak.  When tying on the bridle tie the string to the top and bottom of the top cell.  The flying point on the bridle can be roughly found as being just higher than the peak when the kite is sat as in the picture

The cells can be joined in other ways to form beams and panels