EDWARDS AIR FORCE BASE, Calif -- Northrop’s YRB-49A made its first flight; Northrop test pilot Fred C. Bretcher flew the aircraft from Hawthorne to Edwards AFB. A final attempt to rescue the ailing Flying Wing concept, the aircraft was a YB‑35 with its troublesome piston engines replaced with six Allison J35-A-19 turbojets. By this date, all of the other B-35 and B-49 airframes had been destroyed or scrapped. The Northrop YB-49 was an American prototype jet-powered heavy bomber developed by Northrop Corporation shortly after World War II for service with the United States Air Force. The YB-49 featured a flying wing design and was a turbojet-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. The YB-49 never entered production, being passed over in favor of the more conventional Convair B-36 piston-driven design. Design work performed in the development of the YB-35 and YB-49 nonetheless proved to be valuable to Northrop decades later in the eventual development of the B-2 stealth bomber, which entered service in the early 1990s. With the XB-35 program seriously behind schedule by 1944, and the end of piston-engined combat aircraft in sight, the production contract for this propeller-driven type was cancelled in May of that year. Nevertheless, the Flying Wing design was still sufficiently interesting to the Air Force that work was continued on testing a single YB-35A production aircraft. Among the aircraft later completed were two airframes that the Air Force ordered be fitted with jet propulsion and designated as YB-49s. The first of these new YB-49 jet-powered aircraft flew on 22 October 1947 (from Northrop airfield in Hawthorne, CA) and immediately proved more promising than its piston engined counterpart. The YB-49 set an unofficial endurance record of staying continually above 40,000 feet for 6.5 hours.
The second YB-49 was lost on 5 June 1948, killing its pilot, Major Daniel Forbes (for whom Forbes Air Force Base was named), co-pilot Captain Glen Edwards (for whom Edwards Air Force Base is named), and three other crew members, one of whom, 1st Lieutenant Edward Lee Swindell, was a crew member on the Boeing B-29 that assisted Chuck Yeager in breaking the sound barrier in the Bell X-1 aircraft. Their aircraft suffered structural failure, with both outer wing sections becoming detached from the center section. Speculation at the time was that the YB-49 was lost due to excessive pullout loads imposed on the heavy airframe when a scheduled flight test of the large bomber's stall recovery resulted in a sudden and dramatic high-speed, nose-over dive. The post-stall high-speed dive resulted from the clean, low-drag, all-wing design, which gave the YB-49 a rapid speed increase in any type of dive. Fellow YB-49 test pilot Robert Cardenas later claimed that the YB-49 rotated backwards in stall, and that he warned Edwards about it. Jack Northrop later countered that such a behavior was impossible for the all-wing design.