Stipa-Caproni
One of the oddest looking aircraft ever built, and slightly out of strict alphabetical order,the Stipa-Caproni, also generally called the Caproni Stipa, was an experimental Italian aircraft designed in 1932.
It featured a barrel-shaped fuselage with the engine and propeller completely enclosed by the fuselage, the entire fuselage was a single ducted fan. The Regia Aeronautica (Italian Royal Air Force) was not interested in pursuing development of the Stipa-Caproni, its design influenced the development of jet propulsion.
Designer Luigi Stipa's basic idea, which he called the "intubed propeller", was to mount the engine and propeller inside a fuselage that formed a tapered duct, or venturi tube, and compressed the propeller's airflow and engine exhaust before it exited the duct at the trailing edge of the aircraft.This is a similar principle as used in turbofan engines, but used a piston engine to drive the compressor/propeller rather than a jet engine.
Stipa spent years studying the idea whilst working in the Engineering Division of the Italian Air Ministry. He determined that the venturi tube's inner surface needed to be shaped like an airfoil in order to achieve the greatest efficiency. He also determined the optimum shape of the propeller, the most efficient distance between the leading edge of the tube and the propeller, and the best rate of revolution of the propeller. He petitioned the Italian Fascist government to produce a prototype aircraft, seeking to showcase Italian technological achievement in aviation,they contracted the Caproni company to construct the aircraft in 1932.
The fuselage was a short barrel-like tube, open at both ends to form the tapered duct, with twin open cockpits in tandem mounted in a bulge on top. The wings were elliptical and passed through the duct and the engine nacelle inside it. The propeller was mounted inside the fuselage tube, flush with the leading edge of the fuselage, and the 120-horsepower de Havilland Gipsy III engine that powered it was mounted within the duct behind it at the midpoint of the fuselage. The aircraft had low, fixed, spatted main landing gear and a tailwheel.
Testing showed that the design did increase the engine's efficiency as Stipa had calculated, and additional lift provided by the shape of the interior of the duct itself allowed a very low landing speed of only 42 mph and assisted the Stipa-Caproni in achieving a higher rate of climb than other aircraft with similar power and wing loading. The placement of the rudder and elevators in the exhaust from the propeller wash at the trailing edge of the tube gave the aircraft handling characteristics that made it very stable in flight, although they later were enlarged to further improve the plane's handling.
As the aircraft did not perform noticeably better than conventional designs, the Regia Aeronautica decided to cancel further development. No further prototypes were built.
https://www.youtube.com/watch?v=c_FH7wsugIg[attachment deleted by admin]