Stipa-Caproni

The Stipa-Caproni, nicknamed the Flying Barrel, was an experimental Italian aircraft designed by Luigi Stipa and built by the Caproni company to test his idea of the intubed propeller. Its fuselage was a short, wide, hollow barrel-shaped tube that enclosed the engine and propeller, so that the airframe worked like a ducted fan. Stipa reasoned from Bernoulli's principle that squeezing the airflow through a venturi would raise propeller efficiency, engine performance and lift. The aircraft accommodated one or two crew and was powered by a 120-horsepower de Havilland Gipsy III four-cylinder inverted inline piston engine. Caproni test pilot Domenico Antonini made the first flight on 7 October 1932. Trials showed only a modest gain in climb rate, but the machine proved very stable and easy to handle, with a landing speed of 42 mph and a takeoff and landing run of 590 feet. The Regia Aeronautica chose not to develop it further, although the concept is seen as foreshadowing the modern turbofan, and a three-fifths scale replica was later built in Australia.