Bell XP-39 Airacobra: The Army's XP-39 Airacobra in flight over Langley Field, 1943. The pilot of the cobra sat on the front end of the gearbox with the engine behind him and the propeller shaft passing underneath his legs. The P-39 was one of the first military airplanes with tricycle landing gear. Photograph published in Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958 by James R. Hansen. Page 200.