A boomerang is a thrown tool, typically constructed as a flat aerofoil, that is designed to spin about an axis perpendicular to the direction of its flight.

A returning boomerang is designed to be thrown in a closed arch path, which returns to the thrower.

Boomerangs have been historically used for hunting, as well as sport, and entertainment. They are commonly thought of as an Australian icon.

 

history

The oldest Australian Aboriginal boomerangs are ten thousand years old, but older hunting sticks have been discovered in Europe, where they seem to have formed part of the stone age arsenal of weapons. One boomerang that was discovered in Jaskinia Obłazowa in the Carpathian Mountains in Poland was made of mammoth's tusk and is believed, based on AMS dating of objects found with it, to be about 30,000 years old. King Tutankhamen, the famous Pharaoh of ancient Egypt, who died over 3,300 years ago, owned a collection of boomerangs of both the straight flying (hunting) and returning variety.

No one knows for sure how the returning boomerang was first invented, but some modern boomerang makers speculate that it developed from the flattened throwing stick, still used by the Australian Aborigines and some other tribal people around the world, including the Navajo Indians in America. A hunting boomerang is delicately balanced and much harder to make than a returning one. Probably, the curving flight characteristic of returning boomerangs was first noticed by stone age hunters trying to "tune" their throwing sticks to fly straight.

 

 

Modern use

Today, boomerangs are mostly used as sporting items. There are different types of throwing contests: accuracy of return; Aussie round; trick catch; maximum time aloft; fast catch; and endurance (see below). The modern sport boomerang (often referred to as a 'boom' or 'rang'), is made of Finnish birch plywood, hardwood, plastic or composite materials and comes in many different shapes and colours. Most sport boomerangs typically weigh less than 100 grams (3.5 oz), with MTA boomerangs (boomerangs used for the maximum time aloft event) often under 25 grams (0.9 oz).

Boomerangs have also been suggested as an alternative to clay pigeons in shotgun sports, where the flight of the boomerang better mimics the flight of a bird offering a more challenging target.

The modern boomerang is often CAD designed with precision airfoils. The number of "wings" is often more than 2 as more lift is provided by 3 or 4 wings than by 2.

In 1992 German Astronaut Ulf Merbold performed an experiment aboard Spacelab that established that boomerangs function in zero gravity as they do on Earth. French Astronaut Jean-François Clervoy aboard MIR repeated this in 1997. In 2008, Japanese astronaut Takao Doi again repeated the experiment.

 

 

Modern boomerang construction

The pattern is placed on the plywood so that the wood grain runs across from the tip of one end of the boomerang to the tip of the other end. Try to get the grain of the outer ply running at 45 degrees to the length of the arms. If there is any warp in the wood, make sure that this produces dihedral on the upper side of the boomerang i.e. if the airfoil is uppermost and the boomerang is on a flat surface, then the wingtips are raised slightly above the surface. (Any anhedral and the boomerang won't fly). The pattern is traced on to the boomerang with a pencil. The boomerang shape is cut out of the plywood. This basic cut out is called the blank. An outline is drawn on the top of the blank to show the areas to be shaped for the leading and trailing edges of the wings. The profiles of the wings are shaped. The top of the leading edge of each wing is decreased at a 45° angle, while the rear of the wing is angled down to leave 1–2 mm thick trailing edge. The bottom face of the leading edge is trimmed back slightly. The tips of the wings are shaped down to the same thickness as the trailing edge. The various layers of the plywood serve as an outline that helps the worker achieve equal slopes. A shallow section may also be cut out from the bottom surface of each wing. For example, this might consist of a 5-cm long strip near the wing tip and behind the leading edge. Using progressively finer sandpaper, the surface of the boomerang is smoothed carefully. Check the boomerang for a slight amount of dihedral (2–3 mm) on both wings at this point. If there isn't any, introduce some by heating the boomerang either over a heat source or a brief spell in the microwave (about 30 sec on high) - if the boomerang is just about uncomfortably hot to handle, you've got it just about right. Bend up the tips of the wings and place the boomerang on a flat surface with a coin under each tip and a weight (bag of sugar?) on the elbow of the boomerang. Allow it to cool for twenty minutes or more. After spraying the surface with sanding sealer, the surface is smoothed with fine steel wool. The boomerang is then painted again.