Boeing XB-47

B-47 Stratojet
Boeing B-47 Stratojet in flight.
Role	Strategic bomber/Aerial reconnaissance
National origin	United States
Manufacturer	Boeing
First flight	17 December 1947
Introduction	June 1951
Retired	1969, B-47E 1977, EB-47E
Primary user	U.S. Air Force
Number built	2,032
Unit cost	US$1.9 million (B-47E) equivalent to $20.4 million in current value

The Boeing B-47 Stratojet (company Model 450) was an American long range, six-engine, turbojet-powered strategic bomber designed to fly at high subsonic speed and at high altitude to avoid enemy interceptor aircraft. The B-47's primary mission was to drop nuclear bombs on the Soviet Union. With its engines carried in nacelles under the swept wing, the B-47 was a major innovation in post-World War II combat jet design, and contributed to the development of modern jet airliners.

The B-47 entered service with the United States Air Force's Strategic Air Command (SAC) in 1951. It never saw combat as a bomber, but was a mainstay of SAC's bomber strength during the late 1950s and early 1960s, and remained in use as a bomber until 1965. It was also adapted to a number of other missions, including photographic reconnaissance, electronic intelligence and weather reconnaissance, remaining in service as a reconnaissance aircraft until 1969 and as a testbed until 1977.

The B-47 arose from an informal 1943 requirement for a jet-powered reconnaissance bomber, drawn up by the U.S. Army Air Forces (USAAF) to prompt manufacturers to start research into jet bombers. Boeing was among several companies that responded to this request; its initial design, the Model 424, was basically a scaled-down version of the piston-engined B-29 Superfortress equipped with four jet engines.