AEROBATICS

the sport of flying an airplane through such unusual maneuvers as rolls, loops, stalls, and spins. The term, derived in imitation of acrobatics, came into use during World War I to describe what had earlier been called stunt flying (q.v.). As an organized sport, rather than as an air show attraction or a part of military aviation training, aerobatics began international competition in 1964. A plane used to perform aerobatics needs extra strength in construction, low weight, a wing that will develop lift in either upright or inverted flight, and fuel and oil systems that will operate in both kinds of flight. The U.S. Champion Aircraft Corporation in the early 1960s produced the first post-World War II plane specifically for aerobatics. Other notable aerobatic planes were the Yak (developed in the U.S.S.R.), the Zlin (Czechoslovakia), and the Akro Star (developed in West Germany). Many planes in American competition are antiques or modified trainers, but the Pitts Special, a sports and aerobatic homebuilt plane, produced from 1948, is also popular. Competition is at three levels: primary, advanced, and unlimited, the latter two flying more and more difficult maneuvers and at lower altitudes. World competition is supervised by the Fdration Aronautique Internationale (FAI), and world championships were held from 1960 (except for 1974). The annual contest of the Experimental Aircraft Association (U.S.) is one of the largest. Aerobatic contests are held in a zone from 100 to 1,000 m (328 to 3,280 feet) in altitude, 1,000 m long and 800 m (2,600 feet) wide. Teams have three to five pilots. Planes are piston-engined with from 150 to 350 horsepower. Judging is based on methods introduced by the Spanish aerobatic flyer Jos L. Aresti.