Built by the US company Convair, the B-36 Peacemaker was the largest, mass produced, piston-engine aircraft ever made, having six Pratt & Whitney B4360s supplemented by four General Electric J47 jet engines. It was the first manned bomber with an unrefuellled intercontinental range capability and also had the longest wingspan of any combat aircraft ever built at 230 feet (70.1 metres). It was operational from 1949 to 1959 and was capable of carrying strategic nuclear weapons.