North American O-47A

When the North American O-47A appeared in 1935, the U.S. Army Air Corps operated observation squadrons dedicated solely to reconnaissance missions. The O-47A was designed specifically for this role. It had a large cockpit, seating three crew in tandem, and a camera bay with a wide observation window.

The O-47A was the most advanced observation airplane ever delivered to the U.S. Army Air Corps, but on the eve of the United States' entry into the Second World War in 1941, its place was eclipsed by newer and more versatile fighter and bomber aircraft that could also perform the observation role, and were less vulnerable in combat. Thus, the career of the O-47 was short. A few saw limited service in World War II on anti-submarine patrol duty off the U.S. coast, and preformed other mundane tasks. By 1943, most had been sent to military ground schools for training in modern metal construction and engine and airframe maintenance.

In May 1935, General Aviation Manufacturing Corporation of Dundalk, Maryland, a subsidiary of North American Aviation, completed a new design called the GA-15, later designated the XO-47. (The "O" denoted observation. At this time, the U.S. Army Air Corps operated units, called observation squadrons, dedicated solely to reconnaissance missions.) The XO-47 was an all-metal, cantilevered monoplane, with hydraulically-actuated wing flaps and retractable landing gear. The design featured five water-tight compartments that were built into each wing panel. This design feature provided floatation capability in an emergency water landing. The XO-47 had a large cockpit, seating three crew in tandem. The front seat was the pilot's position, the center section was occupied by the copilot/radio operator/cameraman, and the rear area was the gunner's position, equipped with a .30-caliber machine gun. The center seat could be folded to permit the middle crewman to lower himself to a second seat below, giving him access to the camera bay with its wide observation window. In addition to its extensive reconnaissance capabilities, the O-47 was a rugged airplane, flew well, and was very fast for its day, with a maximum speed of 360 kph (225 mph).

In the spring of 1936, the XO-47 was flown to Wright Field, Dayton, Ohio, for evaluation. Strength and flight performance tests met expectations, but design modifications were required in aspects of crew visibility, armament, and propulsion systems. Following these trials, the aircraft was flown to the newly-established North American Aviation plant in Inglewood, California, where it was re-designated the NA-15. A number of further refinements were made by chief engineer and president of N.A.A., James "Dutch" Kindelberger, who had come to North American with the acquisition of the Berliner-Joyce Aircraft Corporation in 1933. The XO-47/NA-15 was accepted by the U.S. Army Air Corps, and on Aug 15, 1936; they ordered 109 aircraft.

The first production model was equipped with a 975-horsepower Wright R-1820-49 Cyclone engine and a three-bladed Hamilton-Standard Hydromatic propeller, and was designated the O-47A. Further tests were conducted at Wright Field. Abnormally high cylinder-head temperatures were noted during full power runs, necessitating modification of the cowling. Rather than undertaking a costly retooling for a complete redesign, small individual air scoops were added to the lip of the cowl on the first production run O-47As. In 1938, the Army Air Corps ordered 55 more O-47As, followed later that year by an order for 74 more, powered by an uprated 1,060-horsepower Wright R-1820-57 engine. This aircraft variant was designated the O-47B.

During the winter of 1937 and 1938, skis were experimentally fitted to an O-47. The Edo Float company also conducted tests with a twin-float installation on an O-47. Both configurations flew, but neither was considered successful.

The O-47 was the most advanced observation airplane ever delivered to the U.S. Army Air Corps, but on the eve of the United States' entry into the Second World War in 1941, its place was eclipsed by newer and more versatile fighter and bomber aircraft that could also perform the observation role, and were less vulnerable in combat. The O-series aircraft were also intended for air-to-ground liaison missions. But light airplanes such as Piper Cubs and Taylorcraft were better suited to this type of flying than the relatively larger and heavier O-47. The new category of L-series, for liaison, using these simpler, light aircraft, was adopted to meet this need, and the O-series designation was phased out.

Thus, the career of the O-47 was short. A few saw limited service in World War II on anti-submarine patrol duty off the U.S. coast, and preformed other mundane tasks. Most had been sent to military ground schools by 1943 for training in modern metal construction and engine and airframe maintenance. By the end of the war only about a dozen O-47s remained intact. A few found their way into civilian hands. One was used to film the final scenes of the movie, Flight of the Phoenix, in 1965, after the famous stunt pilot, Paul Mantz, was killed when flying a specially-built airplane that was the focus of the film. To shoot the last scenes and complete the movie, the O-47 was made to appear like the destroyed airplane.

The NASM O-47A was purchased by the Army Air Corps on October 20, 1938. It was delivered to the Eighth Corps Aero Detachment at Biggs Field, Texas, on October 21, 1938, where it remained until March 3, 1942. After a short stay at March Army Air Force Base, California, it returned to Biggs where it remained until July 12, 1942. It then moved to Salinas AAF Base near Kansas City, where it operated until August 30, 1942, when it went to the Fairfield Air Depot, near Dayton, Ohio. Two months later, it was transferred to the Ames Aeronautical Laboratory at Moffett Field, California, for a tour with the National Advisory Committee for Aeronautics (NACA). On March 17, 1943, it was again transferred to the 4120th AAF unit based at Freeman Field, Seymour, Indiana, and used for instruction. In May 1946, it was sent to the Douglas plant in Orchard Place, Illinois, where it was prepared for museum display. Its engine was replaced at Moffett Field and the airplane was transferred to NASM on January 3, 1949.