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A boomerang is a thrown tool, typically constructed as a flat aero foil, that is designed to spin about an axis perpendicular to the direction of its flight. A returning boomerang is designed to return to the thrower. It is well known as a weapon used by Indigenous Australians for hunting. Boomerangs have been historically used for hunting, as well as a sport, and entertainment. They are commonly thought of as an Australian icon. == Description == A boomerang is traditionally a long wooden device, although historically boomerang-like devices have also been made from bones. Modern boomerangs used for sport are often made from thin aircraft plywood, plastics such as ABS, polypropylene, phenolic paper, or even high-tech materials such as carbon fibre-reinforced plastics. Boomerangs come in many shapes and sizes depending on their geographic or tribal origins and intended function. Many people think of a boomerang as the Australian type, although today there are many types of easier to use boomerangs, such as the cross-stick; the pinwheel; the tumblestick; the boomabird; and many other less common types. An important distinction should be made between returning boomerangs and non-returning boomerangs. Returning boomerangs fly and are examples of the earliest heavier-than-air man-made flight. A returning boomerang has two or more airfoil wings arranged so that the spinning creates unbalanced aerodynamic forces that curve its path so that it travels in an elliptical path and returns to its point of origin when thrown correctly. While a throwing stick can also be shaped overall like a returning boomerang, it is designed to travel as straight as possible so that it can be aimed and thrown with great force to bring down game. Its surfaces therefore are symmetrical and not uneven like the aerofoils which give the returning boomerang its characteristic curved flight. The most recognisable type of the boomerang is the returning boomerang; while non-returning boomerangs, throwing sticks (or shaunies) were used as weapons, returning boomerangs have been used primarily for leisure or recreation. Returning boomerangs were also used to decoy birds of prey, thrown above long grass to frighten game birds into flight and into waiting nets. Modern returning boomerangs can be of various shapes or sizes as can be seen in a photo in the ''Modern use'' section. Historical evidence also points to the use of non-returning boomerangs by the Native Americans of California and Arizona, and inhabitants of southern India for killing birds and rabbits. Indeed, some boomerangs were not thrown at all, but were used in hand to hand combat by Indigenous Australians. Ancient Egyptian examples, however, have been recovered and experiments have shown that they functioned as returning boomerangs.〔Rivers, Pitt "On the Egyptian Boomerang and its Affinities" The journal of the Anthropological Institute of Great Britain and Ireland, 1883 12: 454–463〕 Boomerangs can be variously used as hunting weapons, percussive musical instruments, battle clubs, fire-starters, decoys for hunting waterfowl, and as recreational play toys. The smallest boomerang may be less than from tip to tip, and the largest over in length. Tribal boomerangs may be inscribed and/or painted with designs meaningful to their makers. Most boomerangs seen today are of the tourist or competition sort, and are almost invariably of the returning type. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「boomerang」の詳細全文を読む スポンサード リンク
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