In the late 1930s, Vought engineer Rex B. Beisel was tasked with designing an observation monoplane aircraft for the U.S. Navy suitable for a multitude of tasks including directing battleship fire. In replacing the standard biplane observation aircraft with a more modern monoplane design, Beisel incorporated innovations making it the first production type to be assembled with spot welding, a process Vought and the Naval Aircraft Factory jointly developed to create a smooth fuselage that resisted buckling and generated less drag. Beisel also introduced high-lift devices, spoilers and in a unique arrangement, deflector plate flaps and drooping ailerons located on the trailing edge of the wing were deployed to increase the camber of the wing and thus create additional lift. For combat missions, the pilot had a .30-caliber Browning M1919 machine gun, the receiver mounted low in the right front cockpit, firing between the engine cylinder heads, while the radio operator/gunner manned another .30-caliber machine gun (or a pair) on a flexible Scarff ring mount. The aircraft could also carry two 100 lb bombs or two 325 lb depth charges. Additionally, the “Kingfisher”, as it was designated, served as a trainer in both its seaplane and landplane configurations. The first 54 Kingfishers were delivered to the U.S. Navy beginning in August 1940 and six had been assigned to the Pearl Harbor-based Battle Force before the end of the same year.