Boomerangs at Wilhelm-Ostwald-Gymnasium
there was a boomerang
one wing was to long and then
boomerang just flew its track
but, such is life, it won't come back
by now spectators have to learn
there is no boomerangs return
free after Joachim Ringelnatz
2 kinds of boomerangs
|In opposite to the returning boomerangs kylies are bigger and the angle of their wings is over 150°. The kylie has to be thrown horizontally as shown in the red picture below. That way the lift counters the loss of height due to the gravity. There for the trajectory is rather straight. Finally the energy will be totally converted into rotation and the boomerang will smoothly drop on the ground. This behaviour is typical for some returners as well - we call it autorotation.|
Were boomerangs came from
Australia is not the only place where boomerangs had been found. Findings are spread all over the world.
The oldest find had been made in the polish Carpathians. It's an ivory boomerang made from a mammoth tusk. It has proved to be 23000 years old. Even in Egypt in the tomb of Tut-anch-Amun boomerangs had been discovered.
The culture of Australia only preserved the tradition of boomerang throwing and stick with it until today.
In 1770 captain JAMES COOK rediscovered the boomerang in the botany bay of south-east Australia.
But handling und the physic of flight still kept a mystery for a long time. The illustration of 1922 gives rather a wrong picture of practical use. First scientific works come from antropology by MAX BUCHNER 1910 und JOHANNES LENNOCH 1949.
The first an very succsessful attempt for a mathematical analysis is given by FELIX HESS in 1968.
A brief lesson of physics
can say that two scientific principles can be applied to
the boomerangs flight path
- the principle of aerodynamic lift ( BERNOULLI's principle ) and the gyroscopic precession
thrown, the boomerang is nearly verticaly orientated.
Hence the sum of the lifting forces act sidewards - just
like a drifting boot. The netforce of lift makes the axis
of rotation turning to the left as well. That is
because the upper wing moves faster and tries to tilt.
The top above does not follow the exerted torque, but
turns sidewards by precession. Assuming both angles are
of the same value the boomerang lies in the tangential
plane of the path at any time, therefore the lift has to
be considered as a radial force producing a circular
flight path i. e. the boomerang will come back ...
Altering the angle of attack effects more or less lift to
The simulation seems to prove the theory. Click "Werte"and "ändern" to change angle of height, velocity, tilt, lay down and view - try it:
program by GERHARD BERTLING is rooted in an old source
code written by FELIX HESS - adapted for Pascal and
Delphi by MATTHIAS HAAK and BJÖRN SCHWARZBACH.
The lay-down-effect is no physical routine but a simple loop.
The more of physics supplies FELIX HESS "Boomerangs - Aerodynamics And Motion", Dissertation, Groningen, Niederlande, 1975.
Since 1992, students of our school have been working at boomerangs. We have produced hundreds of different shaped ones, and most of it still come back to the thrower. It works in theory as well as in real - see our video. We participated in three German Competitions (e.g. Bielefeld 2000, Geldern 2002 & Elsfleth/Brake 2006) and we organized numerous school opens by ourselves.
|Andre wirft im kalten März 2000 Andre||Impressionen aus 20 Jahren Bumerang-AG||Schulturnier 2007||Dt. Schülermeisterschaft Brake/Elsfleth 2006|
construction plans have been delivered by GORNY
& SCHLEGEL from Hamburg.
There are no restrictions in having fun - eventually everything behaves like a boomerang, only you have to throw it properly.
We hope the enthusiasm will endure for we want take part at competitions again.
The sporting events are well reported at: http://www.bumerangclub.de/
Boomerangs no limts ...
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