The Convair B-36 "Peacemaker" was a strategic bomber built by Convair and operated solely by the United States Air Force (USAF) from 1949 to 1959. The B-36 was the largest mass-produced piston engine aircraft ever made. It had the longest wingspan of any combat aircraft ever built (230 ft, 70.1 m), although there have been larger military transports. The B-36 was the first bomber capable of delivering any of the nuclear weapons in the US arsenal from inside its two bomb bays without aircraft modifications. With a range greater than 9,700 km (6,000 mi) and a maximum payload of 33,000 kg (73,000 lb), the B-36 was the world's first manned bomber with an unrefueled intercontinental range.