# 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.

64-cell tetrahedral kite

The photo on the right 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

Despite the construction challenges, a small but dedicated band of people around the world enjoy making these kites from a range of modern materials.

If you are a teacher, this Paper 4-Cell Tetrahedron Kite Kit (For 30 Students) from Amazon could be of interest.

## 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!

4-cell tetra - simple but barely stable

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 colorful tetrahedron kite in the photo up there.

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. Could be very viral, don't you think?

Like to see what a tetrahedral looks like in flight? This is our MBK Skewer tetra in flight, a simple 4 cell design. Thanks to the lightness and strength of bamboo, it doesn't require a lot of wind to fly...

Here's another relatively simple and cheap tetrahedron kite... Make a 4-cell tetrahedral from straws, cellophane and a few other bits and pieces!

For a class situation, this Paper 4-Cell Tetrahedron Kite Kit (For 30 Students) from Amazon provides a proven approach which works out to around \$3 per kite.

## 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 tetrahedron 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.

Bell's Cygnet I with 3393 cells

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 over there on the right, 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.

## What's New!

1. ### Flight Report:Paper Sled Logs Flying Time

Sep 21, 17 11:36 PM

That 's what it was all about this morning. Edging towards the 3 hours of total flying time required for certification... Why 3 hours? All to expose the design to several separate flights, manual hand…

Plenty of fun kite info, photos and videos - there's definitely too much here for only one visit! Feel free to leave your impressions of this site or just this page, below...

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"Making Skewer Kites"

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Wind Speeds

Light air
1-5 km/h
1-3 mph
1-3 knots
Beaufort 1

Light breeze
6–11 km/h
4–7 mph
4–6 knots
Beaufort 2

Gentle breeze
12–19 km/h
8–12 mph
7–10 knots
Beaufort 3

Moderate breeze
20–28 km/h
13–18 mph
11–16 knots
Beaufort 4

Fresh breeze
29–38 km/h
19–24 mph
17–21 knots
Beaufort 5

Strong breeze
39–49 km/h
25–31 mph
22–27 knots
Beaufort 6

High Wind
50-61 km/h
32-38 mph
28-33 knots
Beaufort 7