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Kite mayhem

By Pat, 10 July 2013 Activity

Diagram of the sled kite.

Use this diagram to help make your kite.

Kites are a great way to combine science, playfulness, patience and imagination. So grab a some simple household items and start building!

Written by Beth Askham

You will need

  • Plastic or a large garbage bag
  • Skewers (without pointy ends), or dowel (thin wooden rods)
  • Tape
  • Scissors
    Sled kite made from clear plastic lying on a table.

    Your kite should look something like this.

  • Ruler
  • String or fishing line
  • Marking pens, felt tip pens or paints (optional)

What to do

  1. Flatten the plastic out on a table and cut out a rectangle approximately 40 cm by 50 cm.
  2. Cut two triangles away from the short sides of the rectangle (see diagram).
  3. Tape the skewers or the dowel to the plastic down the length of the shape, starting at the top corner of each triangle as indicated by the diagram.
  4. Cut a piece of string 1 m long, and firmly tape each end to one of the triangular points on the sides of the kite.
  5. Now all you need is the kite’s bridle. Tie a small loop with a diameter of around 2 cm around the 1 m string loop. The loop needs to be able move along the long string freely.
    Hand holding the string of a kite as it flies in the air.

    A kite cannot produce its own thrust and relies on being held in place while the wind moves past it.

  6. Tie your kite string to the loop bridle.
  7. If you wish, decorate your kite with marking pens, felt tip pens or paints.
  8. You are now ready to look to the sky, test the wind and fly your kite!

What’s happening?

The science behind flying a kite is actually quite similar to aeroplane flight. They are both affected by the movement of air and the forces of gravity, lift, thrust, and drag.

Kites achieve lift because of the angle they fly into the wind. As air hits the kite it is deflected downwards. If air is being pushed downwards, according to Newton’s third law where every action has an equal and opposite reaction, the kite is pushed upwards. This upwards lift is able to overcome gravity.

A kite cannot produce its own thrust and relies on being held in place while the wind moves past it. In some cases this is helped by running into the wind with the kite. As you hold onto the kite string, this allows the wind to move over the kite and in effect, generate thrust.

Any kite will have friction with the air – known as drag. Drag can be created by giving a kite a tail. Air flows through the kite tail, pulling the bottom of the kite into the wind. This helps the kite continue to point into the wind and continue flying.

Applications

Humans have been flying kites for a very long time. The ancient Chinese were great kite builders. Legend has it that lightning was discovered to be electric during a do-it-yourself science experiment by Benjamin Franklin holding a kite in a storm — not one to try at home though.

Test out different kite designs and materials to see how this affects your kite flying success! Tell us about your designs below.

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