B-17 Flying Fortress

The B-17 Flying Fortress had been designed in response to a United States Army Corps requirement, issued in 1934, for long range, high-altitude daylight bomber. The prototype bearing the company designation Boeing Model 299 was powered by four 750 hp Pratt & Whitney Hornet engines and this flew for the first time on 28th July 1935. Although the prototype was later destroyed in an accident, the cause was attributed to human error and the project went ahead.
Thirteen Y1B-17s and one Y1B-17A were ordered for evaluation and after a trial period, these were designated B-17 and B-17A respectively. The first production batch of 39 B-17s, featuring a modified nose, enlarged rudder and various other mods these were all powered by four Wright 1200hp, Cyclone engines and featured some other minor changes as well. The B-17 continued to improve over the years and by 1942, the RAF took delivery of 42 B-17Es under the designation Fortress llA. A total of 512 B-17Es was produced, this variant being followed by the B17F, which a total of 3400 were made the last 86 B-17Fs were fitted with a chin -mounted power-operated Bendix turret mounting a pair of 0.50in (12.7mm) guns, which proved invaluable as the Luftwaffe increasingly adopted frontal attacks. During World War ll, B-17s flew 219,508 sorties over Europe, dropping 650,000 tonnes (640,036 tons) of bombs