Sixty-three years ago this month, the USAF/Northrop YB-49 Flying Wing came apart during a test flight that originated at Muroc Air Force Base. Among the five crew members who perished in the aviation mishap was famed test pilot USAF Captain Glen W. Edwards.
The USAF/Northrop YB-49 heavy bomber prototype first flew in October of 1947. The aircraft was a jet-powered derivative of the propeller-driven XB-35. Both of these legendary aircraft were flying wing designs pioneered by visionary aircraft designer Jack Northrop.
Traditionally, interest in a flying wing aircraft stems from its inherently-high lift, low drag and hence high lift-to-drag ratio characteristics. These attributes make a flying wing ideal for the strategic bombing mission where large payloads must be carried long distances to the target. In addition, the type’s low profile and swept wings contributed to its low radar cross-section.
The same configurational features that give flying wing aircraft favorable performance also present stability and control issues and adverse handling qualities. The lack of a traditional empenage requires that all flight controls be placed on the wing itself. This leads to significant aerodynamic coupling that affects aircraft pitch, yaw and roll motion.
The YB-49 had a wing span of 172 feet, a length of 53 feet and a height of 15 feet. Gross take-off weight was approximately 194,000 lbs. Fuel accounted for roughly 106,000 lbs of that total. Power was supplied by eight (8) Allison/General Electric J35-A-5 turbojets. Each of these early-generation powerplants was rated at a mere 4,000 lbs of sea level thrust.
The YB-49 design performance included a maximum speed of 495 mph, a service ceiling of 45,700 feet and a maximum range of 8,668 nautical miles. The aircraft was designed to carry a maximum bomb load of 32,000 lbs. The strategic bombing mission would be flown by a crew of seven (7) including pilot, co-pilot, navigator, bombardier and gunners.
A pair of XB-35 airframes were modified to the YB-49 configuration. Ship No. 1 (S/N 42-102367) first took to the air on Tuesday, 21 October 1947. The maiden flight of Ship No. 2 (S/N 42-102368) occurred on Tuesday, 13 January 1948. Both flights originated from Hawthorne Airport and recovered at Muroc Air Force Base.
Flight testing of the YB-49 quickly confirmed the type’s performance promise. Demonstrated performance included a top speed of 520 mph and a maximum altitude of 42,000 feet. On Monday, April 26, 1948. On that date, the aircraft remained aloft for 9.5 hours, of which 6.5 hours were flown at an altitude of 40,000 feet.
The low point in YB-49 flight testing came on Saturday, 05 June 1948. On that fateful day, YB-49 Ship No. 2 crashed to destruction in the Mojave Desert northwest of Muroc Air Force Base. The entire crew of five (5) perished in the mishap. These crew members included Major Daniel N. Forbes (pilot), Captain Glen W. Edwards (co-pilot), Lt. Edward L. Swindell (flight engineer), Clare E. Lesser (observer) and Charles H. LaFountain (observer).
The cause of the YB-49 mishap was never fully determined. In descending from 40,000 feet following a test mission, the aircraft somehow exceeded its structural limit. The outer wing panels failed and the rest of the aircraft tumbled out of control, struck the ground inverted and immediately fireballed. Whether the incident was related to wing stall, spin or some such other flight control issue will never be definitively known.
YB-49 Ship No. 1 continued to fly after the loss of its stable mate. However, it too met an unkind fate. On Wednesday, 15 March 1950, the aircraft was declared a total loss following a non-fatal high-speed taxiing mishap. Several months later, all of Northrop’s flying wing contracts with the government were unexpectedly cancelled. Incredibly, the Wizards of the Beltway ultimately ordered that all Northrop-produced flying wing variants be cut-up for scrap.
Despite its performance, the YB-49 was too far ahead of its time. The aircraft did not exhibit good handling qualities and thus was not a good bombing platform. It needed the type of computer-based, multiply-redundant autopilot that is standard equipment on today’s aircraft.
Happily, the performance merits of the flying wing concept would be fully exploited with the introduction of the USAF/Northrop B-2 Advanced Technology Bomber (ATB). This aircraft first flew on Monday, 17 July 1989. Its subsequent success is now history. A host of new technologies converged to finally made the flying wing concept viable. Not the least of which is the aircraft’s multiply-redundant flight control system.
Finally, we note that 30-year old Captain Glen W. Edwards was a rising star in military flight test circles at the time of his death. In tribute to his aviation skills and in memory of a life cut short, Muroc Air Force Base was officially renamed on Tuesday, 05 December 1950. Since that day, it has been known as Edwards Air Force Base.
Posted in Aerospace, History
