s on its watertight
fuselage with its
hydroplanes submerged beneath it and its wings resting on the water. 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 takeoff runs. 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 . 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 employing 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 takeoff, riding on its submerged hydrofoils until it reached takeoff speed. Without the aerodynamic drag induced by floats or the weight they added to the 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). ==Testing==