Northrop YB-49

YB-49
YB-49
Role	Strategic bomber
Manufacturer	Northrop Corporation
Designer	Jack Northrop
First flight	21 October 1947
Status	Prototype only
Primary user	United States Air Force
Number built	3 converted from YB-35 2 YB-49 and one YRB-49A, more incomplete examples scrapped
Developed from	Northrop YB-35

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 XB-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.

The YB-49 never entered production, being passed over in favor of the more conventional Convair B-36 Peacemaker piston-driven design. Design work performed in the development of the YB-35 and YB-49, nonetheless, proved to be valuable to Northrop in the eventual development of the current day B-2 Spirit strategic bomber, which first entered operational service in the 1990s.

Design and development

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.^[1]

Among the aircraft later completed were two airframes that the Air Force ordered be fitted with jet propulsion and designated as YB-49s.^[1] The first of these new YB-49 jet-powered aircraft flew on 21 October 1947 and immediately proved more promising than its piston-engined counterpart. The YB-49 set an unofficial endurance record of staying continually above 40,000 ft (12,200 m) for 6.5 hours.^[2]

The second YB-49 was lost on 5 June 1948, killing its pilot, Major Daniel Forbes for whom Forbes Air Force Base was named, Captain Glen Edwards, co-pilot (after whom Edwards Air Force Base is named), and three other crew members,^[2] one of whom, Lt. 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 airframe when a planned stall recovery resulted in a high speed, nose-over dive. The post-stall high speed dive resulted from the clean, low-drag design, which gave the YB-49 a rapid speed increase in any type of dive.

On 4 February 1949, the first YB-49 flew from Muroc Air Force Base in California to Andrews Air Force Base near Washington, D.C. in 4 hours 25 minutes.^[2] The return flight from Andrews was marred when four of the eight engines had to be shut down for oil starvation. Inspection after a successful emergency landing at Winslow Airport, Arizona revealed no oil had been replaced in these engines at Wright after the Muroc-to-Andrews leg,^[2] raising a suspicion of industrial sabotage.^[1]

The last operational YB-49 prototype was destroyed on March 15, 1950 during high-speed taxi trials at Muroc Field. The nosewheel began to encounter severe vibration problems and finally collapsed.^[2] The aircraft was completely destroyed in the ensuing fire. The taxi trials took place with the YB-49's fuel tanks full, an unusual testing procedure, fanning further speculation of industrial sabotage of the aircraft.^[1]

The Air Force ordered the remaining uncompleted YB-35 piston-engined airframes be completed as production B-35B aircraft.

Bombing target tests showed a tendency of Flying Wings to "hunt" in yaw after turns and when flying in "disturbed" air, degraded bombing accuracy. It was thought that one of the new Honeywell autopilots, with yaw damping, would correct this flaw.

Operational history

One YRB-49A had been completed when, in September 1948, the Air Force ordered the type into full production as the RB-49A reconnaissance aircraft.^[1] It was powered by six jet engines, two of them externally mounted in under wing pods, ruining the aircraft's sleek, aerodynamic lines, but extending its range by carrying additional fuel. The use of jet engines had resulted in considerably increased fuel consumption, and decreased its range significantly below that of the rivaling Convair B-36.^[1]

During early 1950, the remaining YB-35Bs airframes being converted to YRB-49As were scrapped. Flight testing of the sole remaining YB-49 prototype ended 14 March 1950. On 15 March 1950, that program was canceled, and coincidentally, that last YB-49 prototype suffered a high-speed taxiing accident and, as previously noted, was totally destroyed in the ensuing fire.

But only two months later, all Flying Wing contracts were canceled abruptly without explanation by order of Stuart Symington, Secretary of the Air Force. Shortly thereafter, also without explanation, Symington turned down a request from the Smithsonian for the Air Force to donate one of these big wings to its collection of pioneering Northrop aircraft designs.^[3]

All remaining Flying Wing bomber airframes, except for the sole YRB-49A reconnaissance version, were then ordered chopped up by the Air Force, the materials smelted down with portable smelters brought to Northrop's facility, in plain sight of its employees. Jack Northrop retired from both the company he founded and aviation shortly after he saw his dream of a pure, all-wing aircraft destroyed.^[4] His son, John Northrop Jr., later recounted during an interview his father's devastation and life-long suspicion that his Flying Wing project had been sabotaged by political influence and back room wheeling-and-dealing between Convair and the Air Force.^[5]

Northrop YRB-49A with six engines, two of which are mounted externally.

The sole prototype reconnaissance platform, the YRB-49A, first flew on 4 May 1950. After only 13 flights, testing ended abruptly on 26 April 1951. It was then flown back to Northrop's headquarters from Edwards Air Force Base (formally Muroc) on what would be its last flight. There, this remaining Flying Wing sat at edge of Northrop's Ontario airport for more than two years, abandoned. It was finally ordered scrapped on 1 December 1953.^[6]

But in a 1979 videotaped news interview, Jack Northrop broke his long silence and said publicly that all flying wing contracts had been canceled because Northrop Aircraft Corporation had refused to merge with competitor Convair at Stuart Symington's strong suggestion, because according to Jack Northrop, Convair's merger demands were "grossly unfair to Northrop.".^[7] A short while later, Symington became president of Convair upon leaving his post as Secretary of the Air Force.^[3] Allegations of political influences in the cancellation of the Flying Wing were investigated by the House Armed Services Committee, where Symington publicly denied exerting pressure on Northrup to merge.^[3]

Northrop's entire Flying Wing program may have been terminated due to its technical difficulties and the program being behind schedule and over budget. Another possible contributing factor to the program's cancellation may have been the tendency of Northrop to become engaged in other experimental programs, which spread its small engineering staff too wide. While the competing propeller-driven Convair B-36 "Peacemaker" was an obsolete World War II-era design by this time, and had been having just as many or even more development problems, the Air Force seemed to have greater confidence that its more conventional design and "teething" problems could be overcome, when compared to those of the more radical Flying Wing. While the YB-49 had well-documented performance and design issues, the B-36 program needed more development money.^[8]At one time, it appeared the B-36 program might be canceled as well. But the Air Force and the Texas Congressional delegation desired to have a production program for their large Fort Worth aircraft production factory, and Convair had much more effective lobbyists in Washington DC. The Northrop Corporation was always a technological trailblazer, but the independent nature of Jack Northrop often collided with the political wheeling-and-dealing in Washington, which gravitated to massive military appropriations; consequently, the Convair B-36 prevailed. When the YB-49 jet bomber was canceled, Northrop received a much smaller production contract for its F-89 Scorpion fighter as compensation for the lost Flying Wing contract.^[9][10]

The YB-49 and its modern counterpart, the B-2 Spirit, both built by Northrop, have the same wingspan: 172.0 ft (52.4 m). Flight test data collected from the original YB-49 test flights, including the aircraft's (then) undervalued invisibility to early radar systems, was used in the development of the B-2 bomber.

Thirty years later, in April 1980, Jack Northrop, now quite elderly and wheel chair bound, was taken back to the company he founded. There, he was ushered into a classified area and shown a scale model of the Air Force's forthcoming but still highly classified Advanced Technology Bomber, which would eventually become known as the B-2A; it was a sleek, all-black Flying Wing. Looking over its all-wing design, Northrop, unable to speak due to various illnesses, was reported to have written on a pad: "I know why God has kept me alive for the past 25 years." Jack Northrop died 10 months later, in February 1981, eight years before the first B-2A became the Air Force's most advanced bomber aircraft. ^[11]

Notable appearances in media

Main article: Aircraft in fiction#Northrop YB-49

Paramount Studios' 1953 film, The War of the Worlds incorporates color footage of a YB-49 test flight, originally used in Paramount's Popular Science theatrical shorts; in the film the Flying Wing is used to drop an atomic bomb on the invading Martians.

Specifications (YB-49)

YB-49 takes to the air for the first time.

Partially completed YB-35B airframes lined up for completion or conversion to YRB-49As.

Data from National Museum of the United States Air Force ^[6]

General characteristics

• Crew: 7
• Length: 53 ft 1 in (16.0 m)
• Wingspan: 172 ft 0 in (52.4 m)
• Height: 20 ft 3 in (6.2 m)
• Wing area: 4,000 ft² (371.6 m²)
• Airfoil: NACA 65-019 root, NACA 65-018 tip
• Empty weight: 88,442 lb (40,116 kg)
• Loaded weight: 133,559 lb (60,581 kg)
• Max takeoff weight: 193,938 lb (87,969 kg)
• Powerplant: 8 (6 J35-A-19 on the YRB-49A) × Allison/General Electric J35-A-5 turbojets, 4,000 (5,000 for J35-A-19) lbf (17 kN) each

Performance

• Maximum speed: 495 mph (793 km/h)
• Range: 9,978 mi (16,057 km) Maximum^[12]
• Combat radius: 1,615 mi (2,599 km)
• Service ceiling: 45,700 ft (13,900 m)
• Rate of climb: 3,758 ft/min (19.1 m/s)
• Wing loading: 33 lb/ft² (163 kg/m²)
• Thrust/weight: 0.23

Armament

• Guns: 4 × .50 in (12.7 mm) machine guns
• Bombs: 32,000 lb (14,500 kg)

See also

	Military of the United States portal
	Aviation portal

Related development

• Northrop N-1M
• Northrop N-9M
• Northrop YB-35
• Northrop Grumman B-2 Spirit
  

Aircraft of comparable role, configuration and era

• Horten Ho 229
  

Related lists

• List of bomber aircraft
• List of flying wings
• List of military aircraft of the United States
  

References

Notes

1. ^ ^{a b c d e f} Pattillo 2001, p. 185.
2. ^ ^{a b c d e} Wooldridge, E.T. "The Northrop bombers." Century of Flight, 2003. Retrieved: 22 October 2010.
3. ^ ^{a b c} Pattillo 2001, p. 153.
4. ^ Pattillo 2001, p. 186.
5. ^ Honey, John. "The Wing Will Fly." Broadcast on The Discovery Channel: 1991.
6. ^ ^{a b} "Fact sheet: Northrop YRB-49A." National Museum of the United States Air Force. Retrieved: 29 October 2010.
7. ^ Fitzsimons 1978, p. 2282.
8. ^ Donald 1997, p. 709.
9. ^ Donald 1997, p. 708.
10. ^ Jones 1975, p. 238.
11. ^ Withington and Davey 2006, p. 12.
12. ^ Winchester 2005, p. 193.

Bibliography

• Coleman, Ted. Jack Northrop and the Flying Wing: The Real Story Behind the Stealth Bomber. New York: Paragon House, 1988. ISBN 1-55778-079-X.
• Donald, David, editor. "Northrop Flying Wings". Encyclopedia of World Aircraft. Etobicoke, Ontario: Prospero Books, 1997. ISBN 1-85605-375-X.
• Fitzsimons, Bernard, ed. "Scorpion, Northrop F-89." Illustrated Encyclopedia of 20th Century Weapons and Warfare, Volume 21. London: Phoebus, 1978. ISBN 0-83936-175-0.
• Maloney, Edward T. Northrop Flying Wings. Corona del Mar, California: World War II Publications, 1988. ISBN 0-915464-00-4.
• O'Leary, Michael. "Wings of Northrop, Conclusion". Air Classics, Volume 44, Number 3, March 2008, Challenge Publications, Inc. ISSN 0002-2241. (Heavily illustrated, authoritative YB-49 article)
• Pape, Garry and John Campbell. Northrop Flying Wings: A History of Jack Northrop's Visionary Aircraft. Atglen, Pennsylvania: Schiffer Publishing, Ltd., 1995. ISBN 0-88740-689-0.
• Pattillo, Donald M. "Pushing the Envelope: The American Aircraft Industry". Ann Arbor, Michigan: University of Michigan Press, 2001. ISBN 0-47208-671-5.
• Winchester, Jim. "Northrop XB-35/YB-49" Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. Kent, UK: Grange Books plc., 2005. ISBN 1-84013-309-2.
• Withington, Thomas and Chris Davey. B-2A Spirit Units in Combat. Oxford, UK: Osprey Publishing, 2006. ISBN 1-84176-993-2.
• Wooldridge, E. T. Winged Wonders: The Story of the Flying Wings. Washington, D.C.: Smithsonian Institution Press, 1983. ISBN 0-87474-966-2.

External links

• The Crash of the YB-49 - Flying Wing
• History of the Flying Wing.
• Northrop Claims AF scuttled "flying wing"