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]
The first B-17s saw combat in 1941, when the British Royal Air Force took delivery of several B-17s for high-altitude missions. As World War II intensified, the bombers needed additional armament and armor. The B-17E, the first mass-produced model Flying Fortress, carried nine machine guns and a 4,000-pound bomb load. It was several tons heavier than the prototypes and bristled with armament. It was the first Boeing airplane with the distinctive -- and enormous -- tail for improved control and stability during high-altitude bombing. Each version was more heavily armed. In the Pacific, the planes earned a deadly reputation with the Japanese, who dubbed them "four-engine fighters." The Fortresses were also legendary for their ability to stay in the air after taking brutal poundings. They sometimes limped back to their bases with large chunks of the fuselage shot off. Boeing plants built a total of 6,981 B-17s in various models, and another 5,745 were built under a nationwide collaborative effort by Douglas and Lockheed (Vega), only a few B-17s survive today.