Boeing B-17 Flying Fortress NAN10-50.jpg|thumb|B-17 modified for testing of the [[Pratt & Whitney T34|XT-34 turboprop]]. When testing concluded, the aircraft was restored to stock configuration as the "[[Liberty Belle (B-17)|Liberty Belle]]", but was lost in a post-forced-landing fire near [[Oswego, Illinois]] on 13 June 2011.]] [[Category:Boeing aircraft|B-17 Flying Fortress]] [[Category:United States bomber aircraft 1930–1939]] [[Category:Four-engined tractor aircraft]] [[Category:Low-wing aircraft]] [[Category:World War II bombers of the United States]] [[Category:Boeing B-17 Flying Fortress| ]] [[Category:Aircraft first flown in 1935]] Boeing B-17 Flying Fortress The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Competing
RAF Bomber Command aircrew of World War II air gunner to man the mid-upper gun turret although sometimes the gunners would agree to exchange turrets. At the outbreak of war in September 1939 operational Royal Air Force bomber squadrons in Europe were equipped with two main categories of bombers, single-engined Fairey Battle and twin-engined Bristol Blenheim light bombers and Armstrong Whitworth Whitley, Vickers Wellington and Handley Page Hampden medium bombers. Bomber Command aircrew "trades" flying operationally in the early stages of the war were: Pilot – A qualified pilot flew the aircraft and in the Royal Air Force was usually the captain (function not rank) of the crew,