History Of Boomerang

"My boomerang won't come back" goes the song about the disgraced Australian Aborigine.

Figure 1: Traditional boomerangs from Australia.

Well, that's not so bad a thing because boomerangs used for hunting kangaroos aren't meant to come back - they are heavy, hockey-stick-shaped throwing sticks that move in a confusingly wobbly path, and they are designed to break the legs or wings of any 'roo or bird they encounter. So just imagine if that 'rang came back: how would you catch it? It would be as silly as if Robin Hood's deadly arrows came back! The only boomerangs that do come back are those intended to be used as toys and for sport: the Aborigines knew about the fun you can have with boomerangs thousands of years ago.

Figure 2: Some modern sports boomerangs.

Perhaps surprisingly, it's reported that the earliest known users of boomerangs were found in what is now Poland, about twenty thousand years ago (18,000 years BC!). Their boomerangs were the traditional bent-stick variety, like the Australian boomerangs in figure 1.

It wasn't too hard for boomerangs to be discovered by accident because if you were stuck for food you might try throwing a rock, a stick, anything at your prey, and if the stick you found did funny things you might think it was a magic stick and you'd want to keep it for another throw.

These days, we can make boomerangs in many other curious shapes (figure 2), and some of them fly much better than the traditional ones.

In fact, a cross-shaped balsa-wood "boomerang" that looks like a 4-bladed propellor (figure 3) works really well indoors - inside the average-sized living room!

Figure 3: Home-made balsa wood boomerangs, suitable for indoor use.

Why do boomerangs fly?

A boomerang works because it spins as it moves forward and the bit of the boomerang that is at the very top moves forward faster than the bit at the bottom so it generates more lift.

The overall lift force (like a spinning propellor)

Figure 4: Flight path of a boomerang.

points towards the centre of the circular flight path which is necessary for circular motion (centripetal acceleration and all that) but the boomerang has to turn to face forwards all the time as it goes around the circle (figure 4 shows the flight path of a boomerang). This is achieved by the difference in lift force between top and bottom . This difference creates a couple, and this couple causes precession.

A boomerang does funny things because it is in fact a gyroscope. Aerodynamic forces generate a twisting moment which cause the "gyroscope" to precess and to move on a circular path.

How to make a Boomerang

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