# Building Tetrahedron Kites

Few things capture the spirit of spring like flying a kite. Watching a kite dance and sail across the sky is not only a visually appealing experience, it also provides a foundation for studies in aerodynamics – a discipline that beautifully integrates science and mathematics.  Building tetrahedron kites combines art and handcrafts as well.

## The Science of Kites

A kite is a tethered aircraft that flies when the forces of lift and thrust are greater than the forces of drag and gravity.  In between flying and crashing to the ground are a variety of swoops, wiggles, pitches, yaws, and rolls that show the kite is seeking a balance among the conflicting forces.

A kite creates a physical obstacle to the normal airflow which causes the air to change direction and speed. The air flows across one surface faster than it moves across the other side of that surface. This difference in speeds results in lift in the direction of the surface with faster moving air. As air pressure can be altered by changing the kite’s angle of attack, the changes in air speed result in changes in air pressure, which cause the kite to produce greater lift.

## Constructing a Kite

Begin by constructing a pyramid composed of equilateral triangles by running string through three straws, arranged in a triangle.  Continue on with the string through two additional straws, forming an additional triangle (the two triangles now share the same base).  Finally, run the string through one more straw and lift the left triangle upward to form a pyramid, tying the the lead end of the strings.

Use the template pictured here to cut out a tissue-paper covering for two sides of the tetrahedron. The template measurements are for standard length drinking straws.  Cover only two sides of the tetrahedron.  Glue the covering over the frame, wrapping the excess materials around the straw frame.  Repeat these steps to create a total of four tetrahedrons.

More detailed instructions for building these kites can be found at Easy Kitemaking: How to Build a Pyramid Kite.

## Designing an Experiment

Now that you have familiarized yourself with the characteristics of the tetrahedron kite, design an experiment to determine how changing one variable in the kite’s design will affect its performance.

For example, you may wish to build a kite using heavier tissue paper or a different kind of covering altogether (newspaper, plastic wrap, or aluminum foil for example).  You may try a kite with a larger number of tetrahedron cells (16 instead of 4).