The
Boeing B-17 Flying Fortress is a four-engine
heavy bomber aircraft developed in the 1930s for the
United States Army Air Corps (USAAC). Competing against
Douglas and
Martin for a contract to build 200 bombers, the
Boeing entry outperformed both competitors and exceeded the air corps' expectations. Although Boeing lost the contract because the prototype crashed, the air corps was so impressed with Boeing's design that it ordered 13 more B-17s for further evaluation. From its introduction in 1938, the B-17 Flying Fortress evolved through numerous
design advances.