Tetrahedron Box Kite
The Tetrahedron Box Kite was originally designed by Alexander Graham Bell. It has a beautiful geometric structure made up of identical tetrahedron pyramids. It can be made of four, sixteen cells or MORE! With sixteen cells it is a very stable flyer. This design can be collapsed down to an easy to transport, flat triangle. Note to educators: One tetrahedron per student can then be combined to make a fantastic kite which then becomes a great geometric sculpture. Click on the link to view as a PDF Tetra Kite Instructions.pdf
16 Cell Tetra Kite Instructions
Difficulty to make: 9+ years old
bamboo skewers, vinyl tube to snugly fit over skewers, sail material, sticky-tape, pva glue, hot glue
coarse sandpaper, bradawls or nail, pliers
Make a single Tetra
1 Sharpen 6 skewers at both ends
2 Pierce through middle of 4x 2.5cm tube segments
3 Push 3 Skewers through the middle hole in 3 tube segments, front spar goes through middle of the tube top and bottom
4 Connect the bottom of vertical spars with 3 horizontal spars.
5 The backspar right joint is not to be glued. Mark with permanent marker on tube and skewer. You can remove this spar end from the tube to dismantle the tetra flat
6 Glue all joints except dismantling joint, with the spar ends dipped in PVA glue.
7 Draw around tetra on one side of front spar on your sail material. Roll tetra over frontspar and draw around other side. Add 15mm wide tabs the length of each 4 sides. Cut out with scissors.
Or make a template of the shape and make many sails at the same time by cutting through multiple layers of sail material with a sharp blade.
8 Tape sail over spars at center point of sail edge to establish tightness. Then tape from the ends.
The front spar is the spar over which the two sided sail goes over! it is the only spar which goes through the middle of a tube at the top and bottom. The back spar lies perpendicular to front spar. It is glued at only one end so as to be able to dismantle the tetra and flatten it. The tetra has 3 feet (pointy spar ends) facing down like a moon lander. Spars need to protrude from middle hole in tube by at least 8mm. So as to make connections easy with other tetra.
Tube needs to be only slightly smaller than spar width to make assembling easy. If tube is tight, make spar tapers longer and more gradual and tube segments shorter. Poke nail awl fully through tube.
Assembling four and 16 Cell Tetra
9 On the ground face three tetra with front spars in the same direction, making a triangle.
10 Connect 6 adjacent spar points with 3x 2cm tubes and hotglue.
11 Place 4th tetra on top with front spar facing in the same direction as bottom tetra's. Join bottom 3 spar points of the forth tetra to the top spar points of the bottom 3 tetra.
12 Join the 4 cell tetra kites together in the same way you joined 4 single tetra.
13 Tie bridal string to top and bottom of the front edge. The bridle string should be about 1.5 times the length of the leading edge.
14 Tie tow point in bridle at a height equal to the middle of top tetra. Tie tow point with overhand knot or use larks head knot onto a ring.
Set tetra on feet, roll out 10+ meters of flying line into the wind and tug.
4 cell tetra flies with a tail
16 cell tetra flies without a tail, may have slight wobble
64 cell tetra flies rock still
• If making with a group of children, get each child to make one tetra then join them together to make a four or 16 cell tetra.• Sail material could be a strong plastic bag film, silver mylar or gift wrapping foil
• Colour code unglued joins, so it is easy to see which spars need inserting into which tubes when dismantled.
• Widening dihedral A longer spar at the back of a single tetra, widens the sail, creating a larger sail area, more lift, but possibly less stability. You will need a bigger sail pattern if back spar is more than 10% longer.
• Bridling Can tie an alternative loop in bridle towards zenith of kite, for higher winds.
• Alternate bridling from the top tetra only, four legs, one from each corner meeting in the middle of the top cell a small distance from the sail.
• Tetra kites can also be made by joining spars with sticky-tape or joining straws with