Today we are going to investigate how boomerangs work. A boomerang is a flying wing used as  
tool, toy, or weapon used for a variety of things from fun to hunting. Usually made of wood or
plastic, but ours in made of foam. Our foam boomerang is called a Roomerang because it can be
thrown and used indoors without breaking anything. Boomerangs fly in a circle and come back to
you. We will learn about wings, airfoils, lift, rotational inertia and gyroscopic precession.


Watch The Roomerang Video:




























The Science Behind Boomerangs

A 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. 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 aerofoil 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, rotational inertia
(etc.) 'attempt' to reach equilibrium. In simple terms, this means that one side of the boomerang is
different from the other. If both wings were identical, then the boomerang would spin, but fly in a
straight line.

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 increase the lift
as boundary layer transition activators (to keep attached turbulent flow instead of laminar
separation).

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.


A boomerang is a flying tool with a curved shape used as a weapon or for sport. Although it is
usually thought of as a wooden device, modern boomerangs used for sport are often made from
carbon fibre-reinforced plastics or other high-tech materials. Historically, boomerang-like devices
have also been made from bones. Boomerangs come in many shapes and sizes depending on
their geographic or tribal origins and intended function. The most recognisable type is the
returning boomerang, which is a throwing stick that travels in an elliptical path and returns to its
point of origin when thrown correctly. A returning boomerang has uneven arms or wings, so that
the spinning is lopsided to curve the path. Although non-returning boomerangs throw sticks (or
kylies) 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 in order to frighten game birds into flight and into waiting nets. Modern returning
boomerangs can be of various sizes or shapes and are made from a variety of materials.

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 centimetres (4 in) from tip to tip, and the largest over 180
centimetres (6 ft) 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.

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 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. King Tutankhamen, the famous Pharaoh of ancient Egypt, who died over
3,000 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. In 1909 the Ngarrindjeri inventor
David Unaipon patented an invention for a rotary wing aircraft based on his study of boomerang
aerodynamics.

Modern Use

Modern sports boomerangsToday, 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).

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

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 [citation needed] 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.

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 victim's neck, in an attempt to break it.


Source: Wikipedia
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