Boomerang

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 circle back 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.

Description
A boomerang is traditionally a wooden device, although historically boomerang-like devices have also been made from bones. Modern boomerangs used for sport are often made from thin aircraft plywood, plastics such as ABS, polypropylene, phenolic paper, or even high-tech materials such as carbon fibre-reinforced plastics. Boomerangs come in many shapes and sizes depending on their geographic or tribal origins and intended function. Many people think of a boomerang as the Australian type, although today there are many types of easier to use boomerangs, such as the cross-stick; the pinwheel; the tumblestick; the boomabird; and many other less common types.

An important distinction should be made between returning boomerangs and non-returning boomerangs. Returning boomerangs fly and are examples of the earliest heavier-than-air man-made flight. A returning boomerang has two or more airfoil wings arranged so that the spinning creates unbalanced aerodynamic forces that curve its path so that it travels in an elliptical path and returns to its point of origin when thrown correctly. While a throwing stick can also be shaped overall like a returning boomerang, it is designed to travel as straight as possible so that it can be aimed and thrown with great force to bring down game. Its surfaces therefore are symmetrical and not uneven like the aerofoils which give the returning boomerang its characteristic curved flight.

The most recognisable type of boomerang is the returning boomerang; while non-returning boomerangs, throwing sticks (or shaunies) were used as weapons, returning boomerangs have been used primarily for leisure or recreation. Returning boomerangs were also used as decoy birds of prey, thrown above long grass to frighten game birds into flight and into waiting nets. Modern returning boomerangs can be of various shapes or sizes as can be seen in a photo in the Modern use section.

Historical evidence also points to the use of non-returning boomerangs by the ancient Egyptians, Native Americans of California and Arizona, and inhabitants of southern India for killing birds and rabbits. Indeed, some boomerangs were not thrown at all, but were used in hand to hand combat by Indigenous Australians.

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 180 cm in length. Tribal boomerangs may be inscribed and/or painted with designs meaningful to their makers. Most boomerangs seen today are of the tourist or competition sort, and are almost invariably of the returning type.

Etymology
The origin of the term is uncertain, and many researchers have different theories on how the word entered the English vocabulary. One source asserts that the term entered the language in 1827, adapted from an extinct Aboriginal language of New South Wales, Australia, but mentions a variant, wo-mur-rang, which it dates from 1798. The boomerang was first encountered by western people at Farm Cove (Port Jackson), Australia, in December 1804 where its use as a weapon was witnessed during a tribal skirmish:

"...the white spectators were justly astonished at the dexterity and incredible force with which a bent, edged waddy resembling slightly a turkish scimytar, was thrown by Bungary, a native distinguished by his remarkable courtesy. The weapon, thrown at 20 or 30 yards [18 or 27 m] distance, twirled round in the air with astonishing velocity, and alighting on the right arm of one of his opponents, actually rebounded to a distance not less than 70 or 80 yards [64 or 73 m], leaving a horrible contusion behind, and exciting universal admiration."

- final paragraph on page; archaic language reinterpreted here

David Collins listed "Wo-mur-rāng" as one of eight aboriginal "Names of clubs" in 1798. A 1790 anonymous manuscript on aboriginal languages of New South Wales reported "Boo-mer-rit" as "the Scimiter".

In 1822 it was described in detail and recorded as a "bou-mar-rang", in the language of the Turuwal people (a sub-group of the Dharug) of the Georges River near Port Jackson. The Turnawal used other words for their hunting sticks but used "boomerang" to refer to a returning throw-stick. They were also mistakenly referred to as a woomerang, in confusion with the spear-thrower woomera.

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 g, with MTA boomerangs (boomerangs used for the maximum time aloft event) often under 25 g.

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.

Hunting
The shape and elliptical flight path of the returning boomerang makes it useful for hunting birds and small mammals. 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.

Non-returning 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 aimed toward the bird's neck, in an attempt to break it.

Design


A returning boomerang is a rotating wing. 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. 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.

As the wing rotates and the boomerang moves through the air, this creates airflow over the wings and this creates lift on both "wings". However, during one-half of each blade's rotation, it sees a higher airspeed, because the rotation tip-speed and the forward speed add, and when it is in the other half of the rotation, the tip speed subtracts from the forward speed. Thus if thrown nearly upright each blade generates more lift at the top than the bottom.

While it might be expected that this would cause the boomerang to tilt around the axis of travel, because the boomerang has significant angular momentum, gyroscopic effect causes the plane of rotation to tilt about an axis that is 90 degrees to the direction of flight, and this is what curves the flight in such a way that it will tend to return.

Thus 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.

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. 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 maximise the boomerang's hover-time in descending from the highest point in its flight.

Some boomerangs have turbulators—bumps or pits on the top surface that act to increase the lift as boundary layer transition activators (to keep attached turbulent flow instead of laminar separation).

The making of a modern boomerang
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. 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. After spraying the surface with sanding sealer, the surface is smoothed with fine steel wool. The boomerang is then painted again.

Tuning the flight
The boomerang is then thrown several times to check if it works. The extreme subtleties of the aerodynamic forces on the light wooden boomerang make it surprisingly difficult to predict how the finished boomerang will perform. Two apparently identical boomerangs may radically differ in their flight patterns. For example they may climb uncontrollably, they may fall repeatedly into the ground, they may exhibit long narrow pattern non-returning flight, or display other erratic behaviour. The only sure way to know is to flight test them. There are several methods to correct problems, for example the wing profiles might be adjusted by additional sanding. Plywood boomerangs may be heated for a short time in a microwave oven which softens the glue between the layers and then can be carefully intentionally warped. Angle of attack of the leading arm and the dingle arm can be adjusted, as well as the overall dihedral angle of the wings all with some effect. There are many other esoteric tuning techniques as well. Tuning boomerangs is more of a slowly learned art than a science. The quality of the boomerang is also checked throughout this process. A tuned boomerang that flies well should be handled with respect when not in use. It should be stored carefully on a flat surface away from too much humidity, direct sunlight, or heat. These conditions can subtly affect the shape of the boomerang and ruin its flight characteristics, and the boomerang will then need to be re-tuned.

The hunting boomerang is more delicately balanced and is therefore much harder to make than a returning one. When thrown this type of boomerang needs to develop no unbalanced aerodynamic forces that would affect its flight path, so that it will fly true to the target. The curving flight of the returning boomerang was probably first noticed as an undesirable quality when early hunters tried to “tune,” their curved throwing sticks to fly arrow straight.

Art boomerang renaissance
Beginning in the later part of the twentieth century there has been a bloom in the independent creation of unusually designed art boomerangs. These often have little or no resemblance to the traditional historical ones and on first sight some of these objects often do not look like boomerangs at all. The use of modern thin plywoods and synthetic plastics have greatly contributed to their success. As long as there are somewhere in the object several airfoil contoured surfaces, whether wing shaped or not, these boomerangs can be thrown and will return. Designs are amazingly diverse and can range from animal inspired forms, humorous themes, complex calligraphic and symbolic shapes, to the purely abstract. Painted surfaces are similarly richly diverse.

Throwing technique
A right-handed boomerang is thrown with a counter-clockwise spin causing a counter-clockwise flight (as seen from above). Conversely, a left-handed boomerang is constructed as a mirror image with the aerofoils' leading edges on the left side of the wings, as seen from above, causing it to produce lift when circling clockwise. Although appearing symmetrical from a plan view, the leading edges are on opposite edges of the wings (leading and trailing) so as to present the leading edges of the aerofoil to the wind when spinning.

Most sport boomerangs are in the range of about 70 to 110 g. The range on most is between 20 and 40 m. Boomerangs are generally thrown in treeless, large open spaces that are twice as large as the range of the boomerang. 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.

For right-handed boomerangs, throwers first establish the wind and launch direction by first facing into the wind, slowly turning their head left to right. They then turn between thirty to seventy degrees clockwise to the right, depending on wind speed (turning farther for stronger winds). The correct launch orientation makes the boomerang's flight begin by flying into the wind, then having its flight take it through the "eye of the wind" and finally returning downwind using the wind's speed to help complete its flight back to the thrower.

The thrower stands sideways with feet-apart, left foot forward, so as to point in the direction of flight. Holding the right (or left) wing tip, flat side down, using the thumb on top and one to three fingers below, they tilt the boomerang out at a ten to thirty degree angle from vertical. This angle is called "layover." Different boomerangs have different flight characteristics, and the bigger the layover the higher the boomerang will fly.

Cocking the boomerang back to ensure a good spin and stepping sharply forward with the left foot, the thrower follows through with their right arm and leg as they throw the boomerang overhand in a similar way to throwing a spear or pitching a baseball, aiming the boomerang by pointing with their left arm at or just above the horizon. Launching is performed crisply using a whip-like flick with their index finger, at the end of the throw, to cause quick counter-clockwise spin (seen from above). It is the spin that makes the boomerang return. The strength of throw and spin must be varied according to the speed of the wind – the stronger the wind, the less power is required to provide lift enough to make the return journey. In other words, the stronger the wind, the softer the boomerang is thrown.

The boomerang initially should curve around to the left, climb gently, level out in mid-flight, arc around and descend slowly, and then finish by popping up slightly, hovering, then stalling near the thrower. Ideally, it should hover momentarily, to allow the catcher to clamp their hands shut decisively and firmly on the horizontal boomerang from above and below, sandwiching the centre between the catcher's hands. In other words, it is possible to avoid painful wing strikes to the hand by not sticking fingers directly into the edge of the fast-spinning wing rotor.

Contrary to what beginners think, a boomerang should never be thrown level sidearm like a flying disc, as it will turn abruptly upwards in the direction of the top of its airfoils. It will then climb very high vertically and at its highest point will quickly lose all lift and descend accelerating very fast like a dive bomber so that its landing will be vertical and with great force and probably cause damage, especially to wooden boomerangs which may break into pieces.

Wind speed and direction are very important for a successful throw. A right-handed boomerang is thrown with the wind on one's left cheek. The 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, turn to throw more to the right of the wind the next time. If the return goes over one's head, then throw softer. If it falls short, then throw harder. As for the wind speed, a light wind of three to five miles an hour is ideal. If the wind is strong enough to fly a kite, then that is usually too strong for boomerangs.

Throwers can modify various actions to achieve a closer return according to the conditions; the throw angle to the wind, the tilt, the power, the spin, and the inclination can be adjusted to vary the return point so the catch point can be perfected. Facing into the wind, then turning the head slightly to either side to check for the cooling effect, allows one to assess the wind direction, and thus the throwing direction, more accurately. For consistency, return to the same throw point and then use a background target object on the horizon to throw in the same direction relative to the wind each time.

Competitions and records
In international competition, a world cup is held every second year. , teams from Germany and the United States dominated 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 In all disciplines the boomerang must travel at least 20 m from the thrower. Throwing takes place individually. The thrower stands at the centre of concentric rings marked on an open field.

Events include:


 * Aussie Round: considered by many to be the ultimate test of boomeranging skills. The boomerang should ideally cross the 50 m 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, and so on. 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, 100 m): points are awarded for the length of time spent by the boomerang in the air. The field is normally a circle measuring 100 m. An alternative to this discipline, without the 100 m restriction is called MTA unlimited.
 * Long Distance: the boomerang is thrown from the middle point of a 40 m 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.

World records
Non-discipline record: Smallest Returning Boomerang: Sadir Kattan of Australia in 1997 with 1.9 in long and 1.8 in wide. This tiny boomerang flew the required 22 yd, before returning to the accuracy circles on 22 March 1997 at the Australian National Championships.

Guinness world distance record
A boomerang was used to set a Guinness World Record with a throw of 1,401.5 feet (427.2 meters) by David Schummy on 15 March 2005 at Murrarie Recreation Ground, Australia. This broke the previous record set by Erin Hemmings who threw an Aerobie 1,333 feet (406.3 meters) on 14 July 2003 at Fort Funston, San Francisco.

Long distance boomerangs
Long distance boomerang throwers aim to have the boomerang go the furthest possible distance 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 optimised 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 ''? – question mark'' shape and have a beveled edge on both sides (the bevel on the bottom side is sometimes called an undercut). This is to minimise drag and lower the lift. Lift must be low because the boomerang is thrown with an almost total layover (flat). Long distance boomerangs are most frequently made of composite material, mainly fibre glass 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 derivative crosses 0. Practically, it means that the boomerang being at the furthest point has a very low forward velocity. The kinetic energy of the forward component is then stored in the potential energy.TM 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).

Related terms
Kylie is one of the Aboriginal words for the hunting stick used in warfare and for hunting animals. Instead of following curved flight paths, kylies fly in straight lines from the throwers. They are typically much larger than boomerangs, and can travel very long distances; due to their size and hook shapes, they 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.