Boeing B-17 Flying Fortress
In response for the Army's request for a large, multiengine bomber, the B-17 (Model 299) prototype, financed by Boeing, went from design board to flight test in less than 12 months. The B-17 was a low-wing monoplane that combined aerodynamic features of the XB-15 bomber, still in the design stage, and the Model 247 transport.[1]
Development
The Flying Fortress was designed for a USAAC competition, announced in 1934, to find a modern replacement for the assorted Keystone biplane bombers. The requirement was for a multi-engined bomber to be used mostly as a coastal-defense aircraft. Specifications required were: a range of at least 1,020 miles (1,641 km), but preferably 2,200 miles (3,540 km); a speed of at least 200 mph (322 km/h), but preferably 250 mph (402 km/h); a capability of carrying a 2,000 lb (907 kg) bomb load.
A Boeing design team began work on the Model 299 prototype in June 1934, and construction began in August of the same year. The Model 299 was make-or-break gamble for Boeing, which first flew on July 28,1935, and later won the competition Boeing built a few preproduction Y1B-17s (later redesignated B-17As), followed by one Y1B-17A, and then followed by thirty-nine B-17Bs. Since funding was lacking at the time, only thirty Flying Fortresses were fully operational when Hitler's forces invaded Poland in September 1939.