The B-36 Peacemaker had six piston engines, four jet engines, and the longest wingspan of any combat aircraft. It was only in service for 11 years. The Boeing B-47 Stratojet (Boeing company designation Model 450) is a retired American long- range, six-engined, turbojet -powered strategic bomber designed to fly at high subsonic speed and at high altitude to avoid enemy interceptor aircraft. The primary mission of the B-47 was as a nuclear bomber capable of striking targets within the Soviet .