The Northrop YB-49 was an eight-engine jet-powered flying wing bomber prototype. Two were completed at Northrop's Hawthorne, California facility and flight tested at Muroc. The first YB-49 (42-102367) completed its maiden flight on 21 October 1947.

The second YB-49 airframe, serial number 42-102368, was assigned to the Performance Test phase of the program. Maj. Robert L. Cardenas piloted the first flight of 368 on 13 January 1948. He began performance testing of the aircraft on 19 February. From then until 21 May, Cardenas flew over 14 hours of performance tests in 368 with Maj. Daniel H. Forbes as co-pilot. YB-49 (42-102368) accumulated almost 57 hours of flight time during its 25 flights.