High Quality Content by WIKIPEDIA articles! The Northrop YB-49 was a prototype jet-powered heavy bomber aircraft developed by Northrop shortly after World War II. Intended for service with the U.S. Air Force, the YB-49 featured a flying wing design. It was a jet-powered development of the earlier, piston-engined Northrop XB-35 and YB-35; the two YB-49s actually built were both converted YB-35 test aircraft.