MBK Skewer Tetrahedral (4-cell)
MBK Skewer Tetrahedral (4-cell)
If you want to just get started in this direction, without having to take too many pain-killers ;-) a good design to try is the 4-cell tetra. See the photo. One of these can be made small enough so it fits neatly inside the boot of a modern car, fully ready-to-fly.
This kite likes Gentle-strength winds, but is still light enough to be affected by thermals.
If made lightly enough, a 4-cell design is just stable enough to fly tail-less. But generally, tetras need more cells to become stable over a wide range of wind speeds. Even our 10-cell skewer design benefits from some added tail. We also have a rather heavy dowel version of the 10-cell. This kite has plenty of tail but can take a ton of wind. At the other end of the scale, it won't even stay clear of the ground at anything less than about 25kph!
Although time-consuming, constructing tetrahedral kites is fairly easy to understand and carry out.
A triangular base of spars comes first. From each corner, another
spar is attached, with all 3 of these coming together at the top. All
spars are of exactly the same length.
Skewer tetra flying in thermals
When all 4 vertices are securely joined, a sail is attached to 2
sides. Any 2 sides will do, due to the symmetry of the shape! This whole
thing is 1 cell.
See if you can pick out the 4 individual cells of my skewer-and-plastic tetra in the photo up there on the right.
Oh, by the way, don't try flying a single cell - it simply will not be stable. 4 cells is the minimum!
In general, a 4 cell tetra is easily constructed by following these steps...
- Make a single tetrahedral cell as described above.
- Copy it to make 3 more cells.
- Put 3 cells on a flat surface, in a triangular arrangement, so there
are 3 points of contact between them. The sails should all be oriented
the same way, and none of them should be lying flat on the flat surface!
- Fasten the cells together at their points of contact.
- Add the remaining cell to the top of the 3 connected
ones, arranging the sail in the same direction as the others, and
fastening the 3 points of contact.
Lastly, attach a flying line and bridle so the arrangement looks like the photo. Then go out to fly! However, unless the kite is super-light, it might need a fair amount of breeze to fly successfully.
A very high proportion of the weight of tetrahedral kites
is in the spars. Wait for a windy day, or put your running shoes on and
tow it like an exuberant kid!
You might first have to settle on the exact materials and techniques you wish to use.
All sounds a bit hard?
Guess what, I'm going to show you the relatively quick and easy way to make a 4-cell tetra that loves light-to-moderate winds!
Tetras In Skewers And Plastic
Bamboo BBQ skewers are a great spar material for small tetrahedral kites, being very stiff and strong for their weight.
A cheap sail material is garden bag plastic. The thinnest,
cheapest ones can be used, or you can use thicker brighter-looking
plastic for more durability and perhaps better looks!
I decided to whip together a 4 cell tetra just for readers of this page! Using the cheapest bamboo skewers and garden plastic.
Here's step-by-step instructions on how to do it...
Making A 4-Cell Tetra
Step By Step...
Compared to most methods for making tetrahedral kites, the following method is relatively quick and easy...
Take a 30 cm (12") bamboo BBQ skewer, and attach a length of clear
sticky tape to one end as in the photo. The tape should be about as long
as an average adult middle finger. The skewer is sitting on half the
length of the tape.
Carefully roll the skewer in your fingers, attaching the width
of the tape to it as you go. Then, keep rolling the skewer while
drawing your fingers away from the tip, so the free length of tape spins
itself into a tight cord. It should be pretty clear in the photo.
Attach tape to the other end of the skewer in the same way. Then do both ends of another 5 skewers!
Arrange all 6 skewers as in the photo, and note how the little cords of
rolled-up tape overlap each other at the 3 corners of the large triangle
Here's a close-up of one of those corners. The 3 little cords have
been twisted together, then another short length of tape has been
wrapped around the 3 cords several times. The 3 skewers are now joined
securely at the tips.
Do the other 2 corners too!
Finally, draw those 3 free skewers up away from the floor, and secure the 3 tips together in the same way as all the others.
(Cue trumpet flourish...) Tada! A tetrahedron.
Take your tetrahedron and lay it on a sheet of plastic that you would
like to use as sail material. Trace around the inside of the triangle
that is in contact with the plastic. Use a black permanent marker pen.
Flip the tetrahedron over, along one side, without letting that side slip or change position. Now trace around the inside of the new triangle which is in contact with the plastic.
Finally, draw tabs in, next to 4 of the sides of the diamond
shape you have drawn. See the photo. I was in a hurry, so just
eye-balled it apart from ruling the longest straight lines in with a
ruler! Just allow plenty of width to fold each tab over a skewer.
Next, cut all around the tabbed diamond shape with scissors.
The photo also shows a couple of the tabs folded over and stuck
down with sticky tape. The tetrahedron has been flipped back to its
Look at that! A complete cell, where the remaining 2 tabs have been folded over and stuck down.
Now make another 3 complete cells. Whew. I'll wait here while you create them all...
OK, now arrange them as in the photo. All the sails should be
facing the same way. At every corner point where the tetrahedrons touch,
there should be 2 short sticks of tape. One coming from each
Here's a close-up of one join between tetrahedrons. See how the sticky
tape sticks point in opposite directions. Lay them side by side and wrap
more sticky tape around the whole lot, using several wraps to make it
Take a length of 20 pound flying line, about 2 skewer-lengths long,
and attach it to the kite as shown in the photo. I just used Half-Hitches around the sticky tape at both points. Small tetrahedral kites such as this one do not require more than 20 pound line.
Also tie a small Loop Knot
into the bridle, so the line angles are approximately as shown. The
exact position is not as critical as for other types of kites. It should
Here's the Skewer tetrahedral kite in flight...
Tetrahedral Kites From Straws
Yes, ordinary drinking straws, in either paper or plastic. Now that you know all about the details of construction, you should also be able to whip up a 4-cell tetra using straws instead.
One quite popular method is to feed a line through each of the 6 straws, leaving an ample amount hanging out each end of the straw. A simple 3-strand knot at each vertex keeps the whole structure rigid. Well, rigid enough for the purpose. The extra lengths of line at each vertex can be used to tie the vertices of several completed cells together.
Here's some ideas for those threaded lines:
- polyester sewing thread
- embroidery cotton
- light fishing line - could be fiddly!
- 10 or 20 pound kite line of any type
With use, the line can tend to cut into the ends of the straws and shorten the life of the kite.
One proven idea for plastic straws is to carefully melt each end
of each straw, by touching it to a hot plate. Just enough to soften and
thicken the wall of the straw a little, right on the end!
For paper straws, you could try a single wrap of narrow sticky
tape around each end of each straw, for reinforcement. This would also
increase the weight of the kite a little, but it's worth a try.
Regarding sail materials for tetrahedral kites, there are many options...
- wrapping paper
- rip-stop nylon (spinnaker cloth)
- rice paper
- plastic bags
- builder's drop-sheet plastic
Tetrahedral Kites - General Points
One thing to try, if you have the patience, is to connect four 4-cell
tetrahedral kites together to form a 16 cell! It will fly more stable
than the 4-cell, so should have a better wind range.
Out In The Field
Box kite stories of my real-life flying experiences are worth checking out!
Illustrated with photos and videos, of course.
This page hardly scratches the surface of this fascinating corner
of the kiting world. Tetras can be tied together in an infinite variety
of configurations, requiring complex bridles to match.
More durable tetras can be constructed from fiberglass or graphite spars and covered with rip-stop nylon sails like most retail kites. With sufficient spar thickness and stiffness, these kites don't need the full 6-stick tetrahedron cell construction. Instead, other forms of bracing can be used, which use far less spar material.
Making tetrahedral kites is an area that remains wide open to experimentation and new ideas! Perhaps you might end up inventing your own method. As I did, with .... skewers and plastic. In fact, a couple of my smaller box kite designs use bamboo skewers...