The O-47 was a single-engine, mid-wing observation monoplane developed to meet U.S. Army Air Force requirements. It was of all-metal construction with retractable landing gear. The subsequent production model O-47s were built with the North American Aviation designation of NA-25 at the Inglewood, Calif., plant. The O-47As were powered by a 975-horsepower engine, while the subsequent O-47Bs carried more fuel and were powered by a 1,060-horsepower engine. The O-47 used a downward firing gun, and because the observer was stationed in a special compartment in the lower fuselage, the airplane had a swollen appearance. North American produced 238 O-47s between 1936 and 1939. They saw little operational service, however, after America entered World War II. During the war, O-47s were used mainly as trainers and target tugs. After the war, a few O-47Bs were modified as single-seat commercial airplanes with the center and rear seats removed so they could carry cargo.