The Boeing B-52 Stratofortress was originally designed to supercede the B-36 and carry nuclear weapons for the SAC during the coldwar. It never delivered nuclear weapons in combat, but dropped nearly all the weapons tested in the Pacific during the 5060's including the first air-deliverable H-bomb in 1956. The B-52 entered service in 1954 and has served in every major conflict since then. It is not expected to be decomsissioned until at least 2040, an unprecedented service length for a military aircraft.