A curved, multiwinged projectile which, when properly thrown, returns near the original starting point.
The boomerang originated in Australia and was used as a hunting tool by the Aborigines. Although the boomerang is often thought of as a weapon, it has primarily served as a recreational and sport toy.
The killer-stick, believed to be the predecessor of the boomerang, was used for both hunting and fighting. The killer-stick has a similar shape and shares many of the boomerang’s properties with one important difference: the killer-stick does not return to the thrower. The stick was smoothed, sanded, and shaped to provide an airfoil cross-section like a wing and could be thrown fast, far, and with great accuracy. Like many other sports projectiles, such as the discus, the killer-stick was thrown with rotational spin stabilizing its flight path.
The boomerang, which is smaller, lighter and has a more pronounced separation of wings than the killer-stick, was not used to kill game, but to trap birds. An Aboriginal hunter would imitate a hawk’s call and throw the boomerang over a flying bird flock. To evade the hawk, the flock would swoop down into the hunter’s waiting nets.
The boomerang is composed of two connected wings. The point of connection is called the elbow. There is a front, or leading, wing and a rear, or trailing, wing. The elbow separates the two wings at an angle generally ranging between 105 and 110 degrees.
Each of the boomerang’s wings has a traditional airfoil cross-sectional shape with a leading and trailing edge. As with any other flight vehicle, the leading edge strikes the air first and the air flows over the top and bottom of the wing, past the trailing edge.
Unlike a bird’s or aircraft’s wings, the two boomerang wings are not mirror images of one another. Thus, there are right-handed and left-handed boomerangs. When thrown vertically into the wind, the upper wing’s leading edge is located on the inner concave portion of the boomerang. The lower wing’s leading edge is on the outer convex portion. Air first strikes the upper leading edge. As the boomerang rotates, this allows the lower wing’s leading edge to meet and strike the air.
Common to all sports projectiles, the aerodynamic forces acting on the boomerang are lift, drag, and gravity, or the boomerang’s own weight. The spin imparted to the boomerang stabilizes the flight path. When a boomerang is thrown correctly, these forces cause the boomerang to circle around and return.
As the boomerang flies through the air, each wing produces lift. Although the shape of the wing generates lift, the lifting force is not enough to sustain the boomerang’s flight. A boomerang is thrown with a spin similar to that of a discus. Without spin, a boomerang will wobble and fall to the ground; the boomerang’s flight is not stable. Airplanes and birds have tail configurations that provide stability, while the rotational spin of a boomerang stabilizes its flight and produces a curved flight path. Stabilizing effects of spinning also are observed in a toy top and a bicycle wheel.
The turning force produced is a result of the unequal airspeeds over the spinning wings. The wings of a stationary, spinning boomerang produce the same amount of lift. When launched with a forward velocity, the forward-moving wing experiences more lift than the retreating wing. The net result is a force which turns the boomerang.
As with anything flying through the air, a boomerang is subject to drag and its own weight. The drag slows the boomerang down, limiting the flight time. However, given enough spin and initial velocity, the boomerang might circle above the thrower’s head a few times before landing.
A boomerang is launched almost vertically, based on the speed of the wind. The boomerang incurs a continuous turn throughout the duration of its flight, which causes the boomerang to lay down as it turns. Thus, the boomerang returns to the thrower in a horizontal hover. If a boomerang were thrown horizontally, it would climb until the wings stalled and simply fall to the ground.
The boomerang is launched at an angle to the wind. The thrower faces the wind and turns approximately 50 degrees to the right or left, depending on whether the person is right handed or left handed. Thrown at the proper angle, the boomerang will return.
Simple and sleek in design, the boomerang’s unique motion utilizes complex aerodynamics and physics. Based on these same scientific principles, some modern boomerangs have advanced technical or artistic designs. Several wings may be joined at a centralized hub. Modern boomerangs may be constructed to resemble letters of the alphabet or birds, for example. Some boomerangs are constructed so that the wings’ tips are slower, making the boomerang easier to catch. All boomerangs use the same basic aerodynamic and physical principles to return to the thrower at the end of their flight.
Hess, Felix. “Aerodynamics of Boomerangs.” Scientific American 219 (1968): 123-136. A classic and comprehensive technical work on the aerodynamics and basic science concepts related to the boomerang. Mason, Bernard S. Boomerangs: How to Make and Throw Them. Mineola, N.Y.: Dover, 1974. Comprehensive information on the boomerang design, construction, and throwing techniques. Ruhe, Benjamin, and Eric Darnell. Boomerangs: How to Throw, Catch, and Make Them. New York: Workman, 1985. A nicely illustrated book on the technical and athletic aspects of boomerangs. Walker, Pearl. “Boomerangs! How to Make Them and Also How They Fly.” Scientific American 240 (1979): 130-135. A technical overview of the construction and aerodynamics of boomerangs.
Forces of flight