Boomerang

A typical wooden returning boomerang

A boomerang is a simple implement used for various purposes. It is primarily associated with Australian Aborigines, but has been found amongst peoples of North East Africa, Sardinia, Arizona, southern California Native Americans, and in India.^[1][2][3]

Boomerangs come in many shapes and sizes depending on their geographic/tribal origins and intended function. The most recognizable type is the returning boomerang, a kind of throwing stick that, when thrown correctly, travels in a curved path and returns to its point of origin. Other types of boomerang are of the non-returning sort, and indeed, some are not thrown at all but are used in hand-to-hand combat by Aboriginal people.^[4]

Boomerangs can be variously used as hunting weapons, percussive musical instruments, battle clubs, fire-starters, decoys for hunting waterfowl, and as recreational play toys. The smallest boomerang may be less than 10 cm from tip-to-tip, and the largest over 2 meters in length.^[5] Tribal boomerangs may be inscribed and/or painted with designs meaningful to its maker. Most boomerangs seen today are of the tourist or competition sort, and are almost invariably of the returning type.

History

Australian Aboriginal boomerangs

Boomerangs are probably the first heavier-than-air flying machine ever invented by human beings. 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.^[6] One boomerang that was discovered in a cave 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.^[7][8] King Tutankhamun, the famous Pharaoh of ancient Egypt, who died 2,000 years ago, owned a collection of boomerangs of both the straight flying (hunting) and returning variety.^[6]

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 hunting sticks to fly straight.^[6]

The name of the boomerang comes from the language of the Indigenous Australian Turuwal tribe of Aborigines who lived south of Sydney, Australia.^[9] They were also mistakenly referred to as a woomerang, in confusion with the woomera.

Modern sports boomerangs

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 colors. Most sport boomerangs typically weigh less than 100 grams, with MTA boomerangs (boomerangs used for the maximum time aloft event) often under 25 grams.

In 2008, Japanese astronaut Takao Doi verified that boomerangs also function in zero gravity as they do on Earth.^[10][11] He repeated the same experiment that German Astronaut Ulf Meerbold did aboard Spacelab in 1992 and French Astronaut Jean-François Clervoy aboard MIR in 1997.^[12]

Hunting

It is believed that the shape and elliptical flight path of the returning boomerang makes it useful for hunting. Noise generated by the movement of the boomerang through the air, and, by a skilled thrower, lightly clipping leaves of a tree whose branches house birds, would help scare the birds towards the thrower. This was used to frighten flocks or groups of birds into nets that were usually strung up between trees or thrown by hidden hunters.^[13]

Boomerangs (termed "throwsticks") for hunting larger prey, such as kangaroo, were used for small prey as well. These throwsticks fly in a nearly straight path when thrown horizontally and are heavy enough to take down a kangaroo on impact to the legs or knees. For hunting emu, the throwstick is thrown toward the neck, breaking it.

Communication

It has been documented that Western Victorian "aboriginals" used the returnable boomerang, in addition to hunting, as a means of communication over long distances . This visual communication is especially useful when winds or distance make impossible other well known methods of communication such as cooee.

Design

Boomerangs for sale at the 2005 Melbourne Show

A boomerang is an airfoil. Though it is not a requirement that the boomerang be in its traditional shape, it is usually flat. A falling boomerang starts spinning and most then fall in a spiral. When the boomerang is thrown with high spin, the wings produce lift. Larger boomerangs are used in hunting, thus they drop on the ground after striking the target. Smaller ones are used in sport, and are the only boomerangs that return to the thrower. Because of its rapid spinning, a boomerang flies in a curve rather than a straight line. When thrown correctly a boomerang returns to its starting point.

Returning boomerangs consist of two or more arms or wings, connected at an angle. Each wing is shaped as an airfoil, so air travels faster over one side of the wing than the other. This difference in air speed creates suction or lift along what is roughly a plane which intersects the airfoil at a near right angle along the long axis of the wing.

These wings are set so that the lift created by each wing opposes the lift of the other, but at an angle such that the flight pattern is constantly shifted as the forces of lift, drag, speed, rotational inertia etc. 'attempt' to reach equilibrium.

Gyroscopic precession is what makes the boomerang return to the thrower when thrown correctly. This is also what makes the boomerang fly straight up into the air when thrown incorrectly. With the exception of long-distance boomerangs, they should not be thrown sidearm or like a Frisbee, but rather thrown with the long axis of the wings rotating in an almost-vertical plane. When throwing a returning boomerang correctly it is important to follow the correct instructions to achieve a successful return.

Some boomerangs have turbulators—bumps or pits on the top surface that act to make the flight more reliable.

Fast Catch boomerangs usually have three or more symmetrical wings (in the planform view), whereas a Long Distance boomerang is most often shaped similar to a question mark. ^[14] Maximum Time Aloft boomerangs mostly have one wing considerably longer than the other. This feature, along with carefully executed bends and twists in the wings, help to set up an 'auto-rotation' effect to maximize the boomerang's hover-time in descending from the highest point in its flight.

Throwing technique

diagram of the throwing of a boomerang

A right-handed boomerang makes a counter-clockwise flight (as seen from above), while a left-handed boomerang is constructed as a mirror image, and circles clockwise. Most sport boomerangs are in the range of about 2.5 to 4 ounces. The range on most of these is between 25 and 40 yards/metres. A right- or left-handed boomerang can be thrown with either hand, but the flight direction will depend upon the boomerang, not the thrower. Throwing a boomerang with the wrong hand requires a throwing motion that many throwers may find awkward. The wings of the boomerang should be at a 15 degree angle from vertical. The other way also works, but many people find it easier to learn this way. The boomerang should be held by the tip using the thumb and one, two or three fingers, and then launched forward quickly while trying more for spin than for very much force. It should flatten out midflight and arc around, sometimes coming to rest a little in front of the thrower or behind the thrower, but ideally it should hover gently and allow the thrower to catch it as a sort of sandwich between the thrower's hands. Returning boomerangs shouldn't be thrown level like a flying disc, as it will turn in the direction of the top of its airfoils, so if that direction happens to be up rather than to the side it may fly high enough that the landing causes damage to the boomerang or whatever it lands on.

Wind speed and direction are very important for a successful throw. A right-handed boomerang is thrown to the right of the wind. Angle to the wind depends on the boomerang, but starting with a 45 degree angle is recommended. Depending on where the boomerang lands, this angle can be modified so that a closer return is achieved. For example, if the boomerang lands too far on the left, throw more to the right of the wind the next time. As for the wind speed, a light wind is ideal. If the wind is strong enough to fly a kite, that's usually too strong for boomerangs.

Competitions and records

In international competition, a world cup is held every second year, with teams from Germany and the United States dominating international competition. The individual World Champion title was won in 2000, 2002 and 2004 by Swiss thrower Manuel Schütz. In 2006, Fridolin Frost from Germany won the title, with Manuel Schütz finishing third.

Competition disciplines

Modern boomerang tournaments usually involve some or all of the events listed below ^[15] In all disciplines the boomerang must travel at least 20 meters from the thrower. Throwing takes place individually. The thrower stands at the centre of concentric rings marked on an open field.

• Aussie Round: considered by many to be the ultimate test of boomeranging skills. The boomerang should ideally cross the 50 meter circle and come right back to the centre. Each thrower has five attempts. Points are awarded for distance, accuracy and the catch.
• Accuracy: points are awarded according to how close the boomerang lands to the centre of the rings. The thrower must not touch the boomerang after it has been thrown. Each thrower has five attempts. In major competitions there are two accuracy disciplines: Accuracy 100 and Accuracy 50
• Endurance: points are awarded for the number of catches achieved in 5 minutes.
• Fast Catch: the time taken to throw and catch the boomerang five times. The winner has the fastest timed catches.
• Trick Catch/Doubling: points are awarded for trick catches behind the back, between the feet, etc. In Doubling the thrower has to throw two boomerangs at the same time and catch them in sequence in a special way.
• Consecutive Catch: points are awarded for the number of catches achieved before the boomerang is dropped. The event is not timed.
• MTA 100 (Maximal Time Aloft, field size: 100 metres): points are awarded for the length of time spent by the boomerang in the air. The field is normally a circle measuring 100 metres. An alternative to this discipline, without the 100 metre restriction is called MTA unlimited.
• Long Distance: the boomerang is thrown from the middle point of a 40 metre baseline. The furthest distance travelled by the boomerang away from the baseline is measured. On returning the boomerang must cross the baseline again but does not have to be caught. A special section is dedicated to LD below.
• Juggling: as with Consecutive Catch, only with two boomerangs. At any given time one boomerang must be in the air.

There are many other boomerang disciplines, many played just for fun, but most of these are not considered official competition events.

World records

(May 2008)

Non-discipline record: Smallest Boomerang: Sadir Kattan of Australia in 1997 with 48 mm [1.8 in] long and 45 mm [1.77 in] wide. This tiny boomerang flew the required 20 metres, returning to the accuracy circles on 22 March 1997 at the Australian National Championships.^[16]

Long distance boomerangs

Long distance boomerang throwers aim to have the boomerang go the furthest possible while returning close to the throwing point. In competition the boomerang must intersect an imaginary surface defined as an infinite vertical extrude of a 40 m large line centred on the thrower. Outside of competitions the definition is not so strict and the thrower is happy whenever he does not have to travel 50 m after the throw to recover the boomerang.

General properties

Long distance boomerangs are optimized to have minimal drag while still having enough lift to fly and return. For this reason they have a very narrow throwing window which discourages many beginners from continuing with this discipline. For the same reason, the quality of manufactured long distance boomerangs is often non-deterministic.

Today's long distance boomerangs have almost all an S or ? shape and have all a profile on both sides (the profile on the bottom side is sometimes called an undercut). This is to minimzie drag and lower the lift. Lift must be low because the boomerang is thrown with almost total layover (flat). Long distance boomerangs are most frequently made of composite material, mainly glass fiber epoxy composites.

Flight path

The projection of the flight path of long distance boomerang on the ground resembles a water drop. For older types of long distance boomerangs (all types of so called big hooks), the first and last third of the flight path are very low while the middle third is a fast climbing followed by a fast descent. Nowadays boomerangs are made in a way that their whole flight path is almost planar with a constant climbing during the first half of the trajectory and then a rather constant descent during the second half.

From theoretical point of view, long distance boomerangs are interesting also for the following reason: for achieving a different behaviour during different flight phases, the ratio of the rotation frequency to the forward velocity has a U shaped function, i.e. its derivate crosses 0. Practically it means that the boomerang being at the furthest point has a forward velocity very low. The kinetic energy of the forward component is then stored in the potential energy. This is not true for other types of boomerangs where the loss of kinetic energy is non-reversible (the MTAs also store kinetic energy in potential energy during the first half of the flight but then the potential energy is lost directly by the drag).

Interest in the discipline

Long distance boomerang throwing had been considered as the royal competition in the 20th century but with new materials and approach that coincides with the 21st century, throwing 100 m became normal and the interest in this category declined. Following reasons explain the evolution:

• Throwing technique: The throwing technique is slightly different and less natural as the boomerang must be thrown almost horizontally lied down but aiming high yet with maximal power used.
• Deceiving exercising: Long distance boomerangs are more difficult to make or to acquire because they must be much more optimized to achieve good performance which requires more workload. On the other hand they are easy to lose because at 100 m only individuals with good vision still see them clearly and sometimes they do not even make the turn and continue straight forward. It also matters that not all fields are big enough, flat and empty to allow exercising.
• Put apart in tournaments: Due to difficulties to organize competition in this category the events are often separated from the rest of disciplines and scheduled as the last day of the whole tournament, often a Monday.

On the other hand the long distance throwers being very few compared to other disciplines still benefit from a family like spirit present on all LD events.

Related terms

Kylie is one of the Aboriginal words for the hunting stick used in warfare and for hunting animals.^[17] Instead of following a curved flight path, it flies in a straight line from the thrower. They are typically much larger than boomerangs. It can travel very long distances, and due to its size and hook shape can cripple or kill an animal or human opponent. The word is perhaps an English corruption of a word meaning boomerang taken from one of the Western Desert languages, for example, the Warlpiri word karli.

See also

• Batarang
• Roomarang
• Throwing Stick

References

External links

• History of Boomerangs
• Unspinning the Boomerang, The Maths and Physics of a Boomerang
• Boomerang aerodynamics an online dissertation
• Explanation of the origin of the word 'Boomerang'
• How to Throw Boomerangs, a beginner's to advanced guide to throwing boomerangs.