Since becoming operational in 1955, the B-52 has served as the Strategic Air Command’s main long-range heavy bomber. It first flew on Apr. 15, 1952, and nearly 750 B-52s were built before production ended in Oct. 1963, including 170 D models. The D models were modified to carry conventional bombs externally, and later series could carry Hound Dog air-to-surface missiles and Quail decoy missiles. The B-52 set numerous records during more than 45 years of service, including the world’s first non-stop around-the-world flight by jet aircraft on Jan. 18, 1957, when three B-52Bs completed the journey in 45 hrs. and 19 min. with only three aerial refuelings, and the first airborne hydrogen bomb drop over Bikini Atoll on May 21, 1956. In June 1965, B-52s entered combat in support of operations in Southeast Asia, and by Aug. 1973 they had flown 126,615 combat sorties, losing 17 to enemy action. The aircraft identified as tail # 56-0629 was the first B-52D modified as the test bed bomber for the Big Belly modification at Boeing Wichita, later flew more than 400 combat sorties in Southeast Asia, was severely damaged by an enemy surface-to-air missile on December 27, 1972 during Operation Linebacker II, then returned to the United States, served with the 22d Bomb Wing at March Air Force Base in California, became the last B-52D retired from March AFB, and was flown to Barksdale AFB in 1983.