On This Day in History / April 15, 2024 1952: Boeing pilot A. M. “Tex” Johnston flew the YB-52 prototype for the first time at Seattle. Beginning with the successful contract bid in June 1946, the B-52 design evolved from a straight wing aircraft powered by six turboprop engines to the final prototype YB-52 with eight turbojet engines and swept wings. The B-52 took its maiden flight in April 1952. The B-52 has been in service with the USAF since 1955, and NASA from 1959 to 2007. Built to carry nuclear weapons for Cold War–era deterrence missions, the B-52 Stratofortress replaced the Convair B-36 Peacemaker. The BUFF remains the “heavy lifter” for the USAF bomber force carrying a wide range of weapons—from nuclear to conventional cruise missiles.