B-50 Superfortress operations continued until November 1953, when the 2 BW began receiving jet-powered B-47E Stratojet medium bombers. The B-47 was a fast bomber that relied on speed to penetrate the air defenses of the Soviet Union. Produced in large numbers, it became the SAC's main medium bomber throughout the 1950s. The wing participated in SAC REFLEX deployments to North Africa and England. Beginning in 1958, the B-47 was becoming obsolete, as the air defenses of the Soviet Union improved. The Stratojet was phased out of SAC beginning in 1960.