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Piaggio P.7
The Piaggio P.7, also known as the Piaggio-Pegna P.c.7, was an Italian racing seaplane designed and built by Piaggio for the 1929 Schneider Trophy race.
==Design and development==
Seeking to avoid the aerodynamic drag induced by floats in seaplanes of floatplane design, Ing Giovanni Pegna of the Piaggio company designed a very unusual seaplane to represent Italy in the 1929 Schneider Trophy race. A cantilever shoulder-wing monoplane, known both as the Piaggio P.7 and the Piaggio-Pegna P.c.7, his design floated up to its wings on its long, slender, watertight fuselage with the wings resting on the water, and employed twin high-incidence hydrofoils to get itself off the water during take-off runs.〔Vašiček, Per. ''Aviation History'', September 2002, p. 35.〕
Sources differ on the P.7s engine; it is described both as an Isotta-Fraschini Special V6 rated at and as an Isotta-Fraschini AS-5 of .〔Vašiček, p. 35.〕 The engine was connected both to a two-bladed automatic variable-pitch tractor propeller by a long metal shaft and by another shaft to a smaller marine propeller, similar to those used on motorboats, mounted beneath the aircraft's tail. To take off, the pilot would start the engine with the flight propeller feathered and the normal carburettor air intake closed and use a clutch to engage the tail propeller and get the aircraft moving through the water. The two hydrofoils, mounted beneath the fuselage on struts just forward of the wings similar to the way in which floats were mounted on floatplanes, would cause the P.7 to rise out of the water almost immediately. After the aircraft had risen on its hydrofoils and the flight propeller had cleared the water, the pilot would open the carburettor air intake, again employ the clutch to disengage the marine propeller, and use another clutch to engage the flight propeller, which automatically would switch from feathered to flight pitch. Driven by its flight propeller, the aircraft then would engage in a conventional take-off, riding on its submerged hydrofoils until it reached take-off speed.〔
Without the aerodynamic drag induced by floats or the weight they added to an aircraft, Pegna projected that the P.7 would reach high speeds. Sources differ on the speeds he predicted, claiming both 580 km/h (360 mph) and 700 km/h (434.7 mph).〔Vašiček, p. 35.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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