Popular Woodworking 2009-12 № 180, страница 37

Build a

Boomerang

BY TREVOR SMITH

Making a boomerang is simple, fast and will set your head spinning.

I,

f you like a challenge, enjoy having an excuse to be outside and are looking for ideas for practical projects, you'll find that building a boomerang is great fun.

Also, boomerangs are a great project to build with family members you've wanted to introduce to woodworking. And when you are done you get to go to the park and spend time together throwing them.

I have just one warning: Boomerangs will draw a curious crowd of onlookers.

A Little Science of Boomerangs

Here's the first rule of boomerangs: Do not be afraid of trial and error. There are a wide variety of shapes that will work.

Boomerangs operate on the principle of "gyroscopic precession," which is similar to

About to take flight. The students loved watching their classmates throw boomerangs almost as much as they enjoyed throwing them. Above, Jon Roberts throws his "Bat-erang" as his friends observe his effortless (athletic) throwing technique from a safe distance behind. From the look on Jon's face it is easy to see that Troy High School students take boomerangs very seriously.

riding a bike no handed and attempting to initiate a turn. In bike riding, the spinning (gyroscopic) motion of the wheels gives the bike stability. To execute a "no hands" bicycle turn, you simply lean the bike in the direction that you wish to turn. The wheels have a delayed reaction to the force of the leaning action. This way, the wheels actually feel the force a quarter turn from where the force was applied. So instead of falling over, the bicycle turns in the desired direction.

Unlike riding a bicycle with "no hands" while turning, the boomerang experiences a continuous turn as the force is applied for the duration of the flight. The boomerang is thrown with a slight tilt from vertical (more on this later). The gyroscopic nature of a spinning boomerang and the release angle (called the "layover angle") causes the boomerang's flight angle to flatten out as it turns. Thus a well-balanced, well-contoured and well-thrown boomerang will return to the thrower in a horizontal hover. Most people expect that this will take practice though.

The duration of flight is determined by the force with which the boomerang was thrown as well as the spin applied at launch.

52 ■ Popular Woodworking December 2009

PHOTOS BY CHRISTOPHER SCHWARZ