The Tetrahedron Kite

Unique, Spectacular, Mathematical

The tetrahedron kite is rather unique in the kiting world, as you will see. The tetrahedron is a 4-sided 3-dimensional shape, where each side is a triangle. If you make such a rigid structure from sticks or rods, then cover any 2 sides with sail material, you have the basic building block for this type of cellular kite. The photo up there shows a configuration using 64 such building-blocks, or cells. That kite was made and flown by a pair of U.K. enthusiasts known as the The Tetrahedron Flyers.

The smallest practical design uses 4 cells, joined at the corners to form an even bigger tetrahedron. That's only the start of an amazing array of possibilities! But more on that further down this page. Here's a list where I attempt to summarize the tetrahedron kite, compared to all other kites...

• heavier than other kites, per unit of sail area
• despite light and fragile individual spars, the finished kite is very rigid
• traditionally a good strong wind kite, although modern materials allow flying in lighter winds
• stability varies a lot with configuration and number of cells, although tails and special bridling can help
• if you imagine the kite sitting on its base, the towing point is very close to the top tip of the tetrahedron
• traditional construction is laborious, some modern techniques are easier
• setup and breakdown of the larger kites is also laborious
• not the easiest to transport around
• the more complex, the more spectacular and attention-grabbing in the air!
• infinitely scalable as a 'solid' tetrahedron, that is, a larger tetrahedron fully occupied by cells - but there is a practical limit!
• an almost infinite variety of configurations are possible, using such concepts as flat panels of cells, and fractal arrangements

If you think about all that, it becomes clearer why kite shops don't do a roaring trade in these kites! It seems they don't even bother to stock them, although you might find the occasional tetrahedron kite here and there. However, a small but dedicated band of people around the world do make these kites from a range of modern materials. There are even a few designs that use very cheap house-hold materials like plastic straws and elastic. The general public stay away, because it's just too much work!

Tetrahedral Configurations

It's time to make all this a bit clearer! There is one group of configurations that is quite easy to grasp. Here's the idea, just do it in your head, or glue together some match-sticks if you're really keen!

Take 3 tetrahedrons and lay them on the table so their bases form one big triangle. Got it?

Now, add a fourth tetrahedron on top, so the corners of its base triangle touch the upper points of the first 3 tetrahedrons. Stand back a bit, and look. Well, it's just one big tetrahedron now! Just like that kite in the photo on the left.

What if you made 4 such big tetrahedrons, and plugged them together in exactly the same way... Yep, you've just created a 16 cell structure! And again, standing back a bit further this time, it just looks like one even bigger tetrahedron! Can you see where this is going...

Guess what happens when you make 4 of these 16-cell things and join them together. The result looks like that awesome creation in the photo at the top of this page! It's a 64-cell tetrahedron kite!

That little 'thought experiment' is not a set of instructions for building a kite, far from it. It's just a start to getting your head around the idea of making these kites. One day I might do a skewers-and-plastic version of a 16 cell design, with full instructions.

Have you caught the mathematical flavor of all this? Not surprisingly, this kind of cellular kite is used in many educational institutions to illustrate mathematical principles. Like what? Try geometry, measurement, angles, aerodynamics and some basic physics.

Here's a summary of the tetrahedron kite from single-cell to ermmm 256-cells, using the process just described...

• 1-cell: poor flier, very unstable without a long tail, heavy, only practical when made quite large
• 4 cell: most commonly seen configuration, as in the photo, but most still require a tail and plenty of wind
• 16 cell: some time and effort to construct, but flies well without a tail, generally performs well
• 64 cell: very tedious to make all those cells, but this very stable kite will apparently stay 'nailed to the sky' with enough wind!
• 256-cell: yep, 4 of the 64-cells together - I dare you, out of match-sticks and tissue paper! It would be a hit on YouTube ;-) Particularly if you parked it 50 meters up in the air, then guided a powerful R/C model aircraft right through it, creating a cloud of splinters and tissue scraps. Very viral...

Now, are you prepared to be really blown away by the possibilities? Just visit this page on tetrahedron kite variations. You could spend your whole life designing, building and flying these designs!

Alexander Graham Bell's Huge Kites

This page can't finish without at least a brief mention of Mr Bell and his pioneering work with the tetrahedral concept. It was his idea, after all! In the early 1900s, Bell's kites were part of a progression from large kite, to man-carrying towed glider, to man-carrying powered aircraft. Yes, an engine-powered, piloted version actually flew!

The first Bell kite, in 1905, was the Frost King which initially had 256 cells. Later, this was increased to 1300 which was sufficient to carry a man.

The next separate design was the Cygnet I, which had no less than 3393 tetrahedral cells each measuring 25cm along each of the 4 spars. Hey, that's quite close to the spar length of my smallest skewer kites! How about that. The cells on the Cygnet were arranged like a giant beam - 52 x 12 x 12 cells. The overall span was 13 meters (42.5 feet). That's it in the photo, courtesy of the AKA (American Kitefliers Association).

Later development, up to the Cygnet II and III, moved away from the tetrahedron kite and into the world of powered aircraft.

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Last updated: 25 Jun 2008