Panel 4: History of Boomerangs (Here it comes again!)

Dr. Mike Larson, at the Aviation Institute, University of Nebraska-Omaha shows his collection of boomerangs in the background.   

Someone once said that if you understand the principles       governing the flight of boomerangs, there is nothing about aeronautics you won't understand. The Australian Aborigines 10,000 years ago   created an incredibly complex flying device that operates because of the interaction of many scientific principles and laws. Bernoulli's Principle The pressure of a fluid, such as air, decreases as its velocity over a surface increases. ( Generates lift from curved upper surface of boomerang .) Newton 's First Law of Motion An object continues in a state of rest or in motion in a straight line unless it is acted upon by an unbalanced force. ( Describes flight of non-returning boomerangs and why gyroscopic precession is necessary for returning boomerangs .) Newton 's Second Law of Motion The acceleration of an object is directly proportional to the force acting upon it and inversely proportional to the object's mass. ( Describes the amount of lift produced from the underside of a boomerang .) Newton 's Third Law of Motion -For every action force there is an opposite and equal reaction force. ( Produces lift from the underside of the boomerang. )

National Engineers Week Foundation

http:// www.eweek.org/site/DiscoverE/PDFs/middle/Here%20It%20Comes%20Again.pdf

Boomerangs, or "booms", as enthusiasts call them, are curved sticks of wood or plastic that either return to the thrower or travel in straight paths for long distances. Although the Australian Aborigines are generally credited with inventing the returning kind of boomerang more than 10,000 years ago, many cultures, including Egyptians, Hopi Indians, people in southern India , and people in Africa , Polynesia , and northern Europe , have used the non-returning kind as hunting sticks and as combat weapons.

For thousands of years boomerang design and performance have remained relatively constant. Recently, however, modern aerodynamics research, engineering studies, and computer simulation technology have led to design changes that have increased boomerang performance dramatically. While conventional boomerangs may

return in flight for 10-15 seconds, new boomerangs have remained aloft for nearly three minutes. Drawing upon existing NASA low-speed airfoil research, designers have employed computers to subtly alter airfoil cross-sections to maximize lift while minimizing drag. Performance improvements have led to the creation of international boomerang flight competitions that include events in accuracy, distance, catching, two-boomerang juggling, and maximum time aloft (MTA).

As a chance to see some of these principles in a different context many middle and secondary schools have bicycle wheel gyroscopes for use in physical science and physics classes. Inquire if one is available for your use, if not, a small gyroscope can be substituted. Small gyroscopes can be obtained at toy and museum shops.

This activity was provided by NASA Johnson Space Center Houston, Houston , Texas 77058

For more detailed information on this activity and other lessons: http://www.aeroi.org/aia/