Luigi Stipa

Luigi Stipa
Luigi Stipa, probably sometime in the 1920s or 1930s
Born	1900 Italy
Died	1992
Occupation	Aeronautical engineer, hydraulic engineer, civil engineer
Years active	fl. ca. 1920s–1930s

Luigi Stipa (1900–1992) was an Italian aeronautical, hydraulic, and civil engineer and aircraft designer who invented the "intubed propeller" for aircraft, a concept that some aviation historians view as the predecessor of the turbofan engine.

Stipa was born in Ascoli Piceno, Italy in 1900. He left school to serve in the Italian Army's Bersaglieri Corps during World War I. After the war, he earned academic degrees in aeronautical engineering, hydraulic engineering and civil engineering. He went to work for the Italian Air Ministry, where he rose to the position of general inspector of the Engineering Division of the Regia Aeronautica (Italian Royal Air Force).

In the 1920s, Stipa applied his study of hydraulic engineering to develop a theory of how to make aircraft more efficient as they traveled through the air. Noting that in fluid dynamics—in accordance with Bernoulli's principle—a fluid's velocity increases as the diameter of a tube it is passing through decreases, Stipa believed that the same principle could be applied to air flow to make an aircraft's engine more efficient by directing its propeller wash through a venturi tube in a design he termed an "intubed propeller". In his concept, the fuselage of a single-engined airplane designed around an intubed propeller would be constructed as a tube, with the propeller and engine nacelle inside the tube, and therefore within the fuselage. The propeller would be of the same diameter as the tube, and its slipstream would exit the tube via the opening at the tube's trailing edge at the rear of the fuselage.