Many may have asked the questions ‘Why are boomerangs crescent-shaped?’ and ‘Why do boomerangs come back?’ – but few, however, are in a position to provide scientific explanations – aside, that is, from Prof. Yutaka Nishiyama of the Osaka University of Economics, Japan. In his article ‘Why Do Boomerangs Come Back?’ (Bulletin of Science, Technology & Society, Vol.22, No.1, 13-20，Feb 2002.) he answers both, with references to Bernoulli’s Principle, gyroscopes, inertial moments, the ‘right-hand-rule’, and more. Noting, for example :
“A boomerang, along with making a left turn when thrown vertically, also makes a sideways fall and returns in a horizontal position. Difference in the lift force between the top and bottom of the wing forms the force to left-turn the boomerang, whereas the difference in the lift force between front and back of the wings forms the force to make a boomerang fall sideward”
The professor also provides (via the Kansai Boomerang Network) a comprehensive set of instructions on how to construct and operate a three-bladed boomerang made out of cardboard – which he has personally translated into 70 different languages.
“Recommend this boomerang to your friends, or neighbors for world peace!”
Note: Professor Nishiyama is Honored Director of the Japan Boomerang Association.
Also see: Boomerangs, the aerodynamics of – regarding work by Alexander S. Kuleshov, at the Department of Mechanics and Mathematics, of Московского государственного университета.
Also see as well: Previous Improbable notes regarding professor Nishiyama : Here, Here, Here and Here.