How To Make A Boomerang

Part 1

A simple boomerang that is safe to fly indoors can be made with balsa wood, a rubber band, some blutack and a matchstick.

The only tools that are required are some sandpaper and a sharp knife. A true-blue boomerang is boomerang-shaped because bent bits of wood are easy to find in outback Australia, but the aerodynamic and gyrodynamic efficiency of such a shape is not good. You need wide open spaces to fly them. Small cross-shaped boomerangs have such good gyroscopic and aerodynamic properties that they can fly indoors.

You will need:
- two bits of balsa wood, 200 x 25 x 3 mm approx;
- some sand paper (not too coarse);
- a match stick;
- some blutack;
- a small rubber band.

Figure 1: A right handed boomerang

Step 1:

Decide if you want a right- or left-handed boomerang. They're each as easy to throw with either hand. Instructions here are for right-handers. Use the mirror image of all constructions to make a left-hander.

Step 2:

Figure 2: Mark sanding lines

Mark the centre of the two pieces of balsa and draw two lines in pencil near one edge of each piece as shown (about 1|6 the width from one edge). These lines must never be touched with sand paper!

Step 3:

Figure 3: Sand to this section

With sandpaper wrapped around a sanding block (a ruler will do), create airfoil shapes as shown leaving the bottom absolutely flat. Use the edge of a plank of wood as a firm base to get a good angle on the trailing edge. Don't make the trailing edge too `sharp' as it will be easily damaged in flight. When you have finished sanding the four airfoils, the pencil lines should still be visible.

Step 4:

Figure 4: Fasten together

Carefully press a matchstick through the centre of the two wings and join them together. Secure with a rubber band as shown.

Step 5:

Figure 5: Add weights

Add four small blobs of blutack (each about the size of a pea) to the flat side of each wing at about 3/4 the radius from the centre. This should roughly double the weight of the boomerang. You are now ready for a test flight!

The Test Flight

You will notice that good flight can only be obtained if the boomerang has just the right spin and just the right forward velocity. In fact the ratio of these two parameters is what counts and this comes from boomerang theory too. For a cross-shaped boomerang, we find that the `flick-of-the-wrist' needed is aw = Ö2V. You can experiment with different values of velocity and spin to verify that this is true.

Make Your Own Kite (Sled, Diamond, Delta, Box, Parafoil, Dragon). How to guide.