BOOMERANGS Magic or Science ? * 07/16/96 BOOMERANGS Magic or Science ? By Tom Conally Flying Frog Boomerangs eclecticartsandcrafts.com *

Boomerangs 1 Magic or Science * 07/16/96 Boomerangs 1 Magic or Science Technology For many years children of all ages have marveled at the mysterious returning stick called a Boomerang. You can fly a boomerang without knowing anything about the sophisticated physics of flight. Some people equate technology to magic! *

Boomerangs 2 Magic or Science * 07/16/96 Boomerangs 2 Magic or Science Science With a little study, you can learn the rudiments of what makes a boomerang return to the thrower with an accurate throw. *

Boomerangs 3 Definitions * 07/16/96 Boomerangs 3 Definitions Boomerang A curved, aerodynamically styled article made of wood, bone, or other materials that will return to the thrower when thrown properly. There is some controversy over their use as hunting implements and weapons. More than likely, throw sticks were the hunting implements and weapons. *

Boomerangs 4 Definitions * 07/16/96 Boomerangs 4 Definitions Modern Boomerang The modern boomerang is a sporting object, made of strong plywood, plastic, fiberglass, carbon fiber, paxolin, aluminum, and other modern materials. They are used for games and pleasure. The United States Boomerang Association has rules for competition in tournaments. *

Boomerangs 5 Definitions * 07/16/96 Boomerangs 5 Definitions Throw-stick The throw-stick or kylie as it is known in Australia, was probably the precursor of the boomerang. They were aerodynamically shaped with a small hook shape. They were thrown horizontal with the ground and traveled long distances straight and true. An airfoil provided lift to keep in the air. A non returning implement. *

History 1 Origin of Boomerangs and Throw-sticks * 07/16/96 History 1 Origin of Boomerangs and Throw-sticks Australia ? Aborigines were actively using boomerangs when Captain Cook discovered Australia in April of 1770. Poland ? Returning boomerang-like sticks and throwing sticks were found in ancient burial grounds. *

* 07/16/96 History 2 Egypt ? Beautiful boomerangs and boomerang- like like artifacts and throw-sticks were found in Egyptian tombs. There are magnificent displays of those artifacts in Egyptian museums. The American West ? Boomerang-like sticks and throw-sticks were found in Indian burial mounds in the American west. Even in our times they are known as rabbit sticks. *

* 07/16/96 History 3 What about other countries ? Many different countries have divulged their early secrets through the study of their burial grounds, mounds, and other tombs. Boomerangs or whatever were the indigenous names for those aerodynamically shaped sticks, have been found in burial and other significant archaeological sites all over the world. *

What’s in a name ? Boomerang ! * 07/16/96 What’s in a name ? Boomerang ! What does the name Boomerang mean? Come Back Stick One theory is that when Captain Cook’s men asked what it was, the answer was “Boomerang” signifying a stick that returns. Unknown “Boomerang” may have meant “What stick ?” We don’t really know ! History has not recorded for us the true meaning of Boomerang as the Aborigines did not have a written language. *

How does a boomerang fly? 1 * 07/16/96 How does a boomerang fly? 1 What does it need to fly? It has wings like an airplane Each wing has airfoils like any airplane. Lift The airfoil provides lift just as an airplane wing. Energy When you throw the boomerang, you provide rotational and linear kinetic energy. *

* 07/16/96 Airfoil Mechanics 1 (1)Air molecules acting as a support for the airfoil traveling over them (2) The air molecules in the upper layer move up and over the airfoil when disturbed by the airfoil. (3) When the top layer of air molecules are redirected by the air foil, they flow up and along the surface of the air foil with the exception of a few molecules which travel up and away as in (4), their momentum *

* 07/16/96 Airfoil Mechanics 2 being too great to be influenced by the laminar forces. Laminar forces tend to keep the air molecules close to the airfoil surface. This leaves fewer molecules to flow along the airfoil lessening the number of molecules on the top surface. *

* 07/16/96 Airfoil Mechanics 3 (5)As the airfoil begins to slope away, two things are happening. Some molecules tend to travel in a straight line and some tend to follow laminar flow leaving an area with less molecules per square unit as in (6) than underneath the airfoil as in (7) the straight line laminar flow beneath the airfoil. *

* 07/16/96 Airfoil Mechanics 4 More molecules under the airfoil (7) support the structure with more pressure Where the smaller number of molecules on the top surface (5, 6) push down with less pressure therefore the net pressure is pushing the airfoil upwards. *

* 07/16/96 Airfoil Mechanics 5 The curved area of an airfoil serves to increase the distance molecules travel, disperse some of those molecules, and to lessen the number of molecules of air per square unit relative to the straight area of the airfoil. This ratio of air molecules on each side of the airfoil is what causes the airfoil to move in the direction of fewer molecules. This is the classic Bernoulli Principle. *

How does a boomerang fly? 2 * 07/16/96 How does a boomerang fly? 2 What is rotational energy ? As the boomerang spins, it acts as a gyroscope. The combination of lift from the wings and a force called gyroscopic precession which is an effect of rotational kinetic energy along with the linear kinetic energy causes the boomerang to follow a circular or elliptical path hopefully terminating at the thrower. *

How does a boomerang fly? 3 * 07/16/96 How does a boomerang fly? 3 *

Precession The path of the boomerang follows the direction of the * 07/16/96 Precession The path of the boomerang follows the direction of the revolution of the axis of precession *

How to throw a Boomerang 1 * 07/16/96 How to throw a Boomerang 1 The correct way to throw Overhand like a baseball. If you throw it side arm or like a Frisbee, it will climb straight up and crash to the ground Grip Pinch grip: pinch the end wing between your forefinger and thumb. Cradle grip: grip the end of the wing with your forefinger wrapped around the front of the wing. *

How to throw a Boomerang 2 * 07/16/96 How to throw a Boomerang 2 Spin The objective of the throw is to provide forward momentum and spin (rotational energy). This will cause the boomerang to precess and therefore begin its circular trip. Snap your wrist at the end of the throw to impart more spin. Remember: spin not power! Layover The angle of the boomerang to the vertical: the more layover, the more lift. Use more layover in calm conditions and less in windy conditions. *

How to throw a Boomerang 3 * 07/16/96 How to throw a Boomerang 3 Angle of throw The Angle from the horizontal or elevation with which one throws the boomerang. It is dependent on each boomerang. Wind effects The wind is the second most important factor in throwing a boomerang. The first? Making sure that your boomerang is positioned with the airfoils on the side toward you and that you have chosen the correct handed boomerang. *

How to throw a Boomerang 4 * 07/16/96 How to throw a Boomerang 4 Wind effects continued: The wind will aid or hinder the forces bringing your boomerang back to you. Be sure that you throw your boomerang into and a little right of the wind. (Left handers reverse of this: into and a little left of the wind. ) *

How to throw a Boomerang 5 * 07/16/96 How to throw a Boomerang 5 Wind effects continued: Again the angle depends on the Particular characteristics of the boomerang and the wind speed. If the boomerang lands to your left and behind you, turn more away from the wind. If it lands to your right and in front, turn more into the wind. ( Lefties reverse of this.) When the wind is greater than 10 or 12 MPH, go fly a kite. You’ll have more fun. *

How to throw a Boomerang 6 * 07/16/96 How to throw a Boomerang 6 *

How to throw a Boomerang 7 * 07/16/96 How to throw a Boomerang 7 Practice Now you can see that the main ingredients in throwing a boomerang are learning the proper throwing techniques and practice, practice, practice. It never hurts to find someone who knows proper throwing techniques and ask for a few lessons. *

How to throw a Boomerang 8 * 07/16/96 How to throw a Boomerang 8 Don’t give up You must realize that when you start a new sport, there is a learning curve and you must pay your dues first. The likely hood of getting your first few throws to come back and land in your hand is as likely as getting a hole in one in your first round of golf or a home run in your very first at bat. Stick with it and you will reap many rewards. *

* 07/16/96 Boomerang Safety 1 How much Area do you need Always choose an area at least twice as large as the expected range of your boomerang. Warn onlookers Make sure that onlookers realize that the boomerang, while usually under some control, is at the mercy of the wind or a bad throw and may go way off course. *

* 07/16/96 Boomerang Safety 2 Always announce when you are throwing Never throw while another thrower is retrieving an errant throw and is unaware of your intention to throw. Watch out for “non-lookers” Be extremely careful of throwing near a road or people who aren't involved in your activity or who just aren’t paying attention. *

* 07/16/96 Boomerang Safety 3 Eye protection Always wear some type of eye protection. Your eyes are extremely vulnerable to a spinning object approaching you at eye level. Sun glasses are needed for UV protection Skin protection. Use suntan lotion to keep from getting a sunburn. *

* 07/16/96 Boomerang Safety 4 Catching your boomerang A boomerang is easy to catch if you use reasonable care. Use the Sandwich catch. Holding your hands horizontally, slap them together as the boomerang flies between them Never catch at eye level. You may deflect it into your eye. Catch either above your head or below the shoulder. *

Boomerang Safety 5 Warn a “Non-looker” of an errant throw * 07/16/96 Boomerang Safety 5 Warn a “Non-looker” of an errant throw Let “Non-lookers” know that an errant throw might hit them by loudly announcing “INCOMING” or ”DUCK” If you hear those calls Assume the caller meant you and bend down with your arms thrown over your head to protect it. *

Science or Magic Now you have the facts * 07/16/96 Science or Magic Now you have the facts You can decide for yourself, science or magic. Maybe you would like to try to throw a boomerang and experience the thrill of seeing a small curved stick leaving your hand and rising into the air, curving and returning to you like magic. *

Boomerang Philosophy In every boomerang there is a perfect throw * 07/16/96 Boomerang Philosophy In every boomerang there is a perfect throw Your mission is to practice till you become one with the boomerang. Only then will you find that perfect throw. May you have many happy returns. The End. *