The engineer William Bushnell Stout originated many of the concepts that went into the building of the triple-engine Ford Trimotors. Stout designed one of the first all metal military aircraft -- a torpedo bomber -- for the United States Navy in the 1920s. At the time, metal aircraft construction was a revolutionary idea. With the help of Henry Ford, Stout built one of the first metal civil aircraft. After Ford bought out his company, Stout's design was developed into the aluminum-alloy covered Ford Trimotor.
The initial generation of Ford Trimotors were designated the 3-AT. The letters AT stood for Air Transport. The first three featured open cockpits so pilots could get a "feel for the wind." Enclosed cabins and other comfort features were soon added. A nose-mounted engine and two engines integrated into the wing powered the 3-AT. The plane's wings and fuselage were covered with thin-gauge corrugated sheets of Duralumin, a high-tensile-strength aluminum alloy. The pilot's seat was located above the passenger section of the plane.
The next model, the 49-feet, 10-inch-long Trimotor 4-AT was redesigned to mount two of the engines on struts beneath the wings. The triple Pratt & Whitney engines allowed the aircraft to cruise at 90 mph with a range of 500 miles. The reengineered plane was easier to fly and maintain, but the extra drag from the lowered engines diminished the cruising speed by 10 mph. Henry Ford wanted to cut the landing speed of the 4-AT for safer landings on unpaved strips.
In 1928, the aircraft division of Ford Motor Company enlarged the Trimotor and called it the 5-AT. More powerful Pratt & Whitney Wasp engines were installed in the new models. The 5-AT planes were built until 1932, with 116 units produced. Many of them saw service as mail planes. By this time, Ford Trimotors were the most common transport planes in the air. Manufacturing the planes became unprofitable during the Great Depression years, and in 1933 Ford ceased production of the Trimotor.
