The Boeing B-47 Stratojet jet bomber was a medium-range and -size bomber capable of flying at high subsonic speeds and primarily designed for penetrating the the airspace of the Soviet Union. A major innovation in post-World War II combat jet design, it helped lead to the development of modern jet airliners. While the B-47 never saw major combat use, the United States Air Force, Strategic Air Command, had B-47 Stratojets (B-47s, EB-47s, RB-47s and YRB-47s) in service from 1951 through 1965.
When B-47s began to be delivered to the Air Force, most crews were excited about getting their hands on the hot new bomber. The bomber was so fast that in the early days, the B-47 set records with ease. However, it took the US Air Force until 1953 to turn the B-47 into an operational aircraft. The aircraft was sluggish on takeoff and too fast on landings. Improved training led to a good safety record. By 1956, the U.S. Air Force had 28 wings of B-47 bombers and five wings of RB-47 reconnaissance aircraft. B-47 production ceased in 1957, though modifications and rebuilds continued after that. The B-47 would be the backbone of SAC into 1959, when the B-52 began to take assume nuclear alert duties and the B-47 wings started to be cut back.