This is a B-52 Stratofortress. According to the Air Force museum, the B-52 became operational in 1955 and for years was the Air Force's main long-range heavy bomber, especially during the Cold War. Indeed, the plane is still operational today with some potentially flying until 2040. Nearly 750 were built, with production ending in 1962. A B-52 dropped the first airborne hydrogen bomb on May 21, 1956, over Bikini Atoll, and in 1965, the planes entered combat in Southeast Asia. "By August 1973, they had flown 126,615 combat sorties with 17 B-52s lost to enemy action," according to the museum.