The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Air Force (USAF) since the 1950s. The bomber is capable of carrying up to 70,000 pounds (32,000 kg) of weapons. 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. Built to carry nuclear weapons for Cold War-era deterrence missions, the B-52 Stratofortress replaced the Convair B-36. A veteran of several wars, the B-52 has dropped only conventional munitions in combat. The B-52's official name Stratofortress is rarely used; informally, the aircraft has become commonly referred to as the BUFF The B-52 has been in active service with the USAF since 1955. As of 2012, 85 were in active service with nine in reserve. The bombers flew under the Strategic Air Command (SAC) until it was inactivated in 1992 and its aircraft absorbed into the Air Combat Command (ACC); in 2010 all B-52 Stratofortresses were transferred from the ACC to the new Air Force Global Strike Command (AFGSC). Superior performance at high subsonic speeds and relatively low operating costs have kept the B-52 in service despite the advent of later, more advanced aircraft, including the canceled Mach 3 B-70 Valkyrie, the variable-geometry B-1 Lancer, and the stealth B-2 Spirit. The B-52 completed fifty years of continuous service with its original operator in 2005; after being upgraded between 2013 and 2015, it is expected to serve into the 2040s. A Day in the Life of the B-52. Takes a look at what it takes to get a B-52 from the ground to the air. Stringer has Air Traffic Control and B-52 Takeoff. The 96th Bomb Squadron takes flight during a B-52 training mission at Barksdale Air Force Base, La. Scenes include aerial refueling, low level flying and aircraft ops. Produced by Tech. Sgt. Rebecca Zannetti. Utah Air National Guard members from the 191st Air Refueling Squadron maintain proficiency. The crewmembers of the KC-135 Stratotanker refuel a B-52 Stratofortress from Barksdale Air Force Base, Louisiana. Imagery of B-52's landing and taking off during EXERCISE VIGILANT SHIELD FTX 2014. B-roll footage of B-52 crew inspects the bomb bay prior to take off at Barksdale Air Force Base, La. Produced by Airman 1st Class Antonio Gonzalez. This compilation contains imager protected by US copyright.