Before World War II, aeronautical engineers sought to build an aircraft capable of making short takeoffs and landings. Eventually, their efforts produced the helicopter, but they also pursued a less common design -- the autogiro. Like helicopters, autogiros used a rotary wing to produce lift. However, unlike helicopters, the engine did not power the autogiro's rotor. Instead, aerodynamic forces made the autogiro rotor spin, while the engine propelled the aircraft.
In 1931 the Kellett brothers, Wallace and Rod, manufactured 12 K-2 autogiros. Based on existing Cierva and Pitcairn autogiro designs, the K-2 incorporated a much larger blade area, a simplified landing gear and a wider fuselage to accommodate side-by-side seating. Equipped with a 165-hp Continental A-70 engine, the K-2 could carry a useful load of 609 pounds at a top speed of 100 mph, a cruise speed of 80 mph and a stall speed of 24 mph.
In 1932 Kellett produced an improved model, the K-3. Powered by a 210-hp Kinner C-5 engine, it had a top speed of 110 mph, a cruise speed of 90 mph and a stall speed of only 15 mph. Kellett produced six of these aircraft, with two of them being modified K-2s.
To observe enemy forces and to control artillery fire, the U.S. Army needed an aircraft capable of flying very slowly, and the autogiro seemed to be a perfect solution. Therefore, the U.S. Army Air Corps tested both versions of the Kellett at Wright Field, but these aircraft lacked the performance necessary for military applications.
Later versions of the Kellett autogiro proved more successful, and the Army Air Corps purchased a small number of Kellett YG-1s, the first practical rotorcraft procured by the Army Air Corps, at the end of the 1930s. The Kelletts sold two K-3s to the Japanese War Office in 1932, but the most famous Kellett was the K-3 that Admiral Richard E. Byrd used on his Antarctic Expedition of 1933-1934.
The aircraft on display, a modified K-2, was the first autogiro tested by the Army Air Corps at Wright Field in 1931.
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