Northrop YB-49
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| YB-49 | |
|---|---|
 YB-49 in color |
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| Type | Strategic bomber |
| Manufacturer | Northrop Corporation |
| Designed by | Jack Northrop |
| Maiden 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 flying wing medium bomber aircraft developed by Northrop for the United States Air Force shortly after World War II. It was a development of the piston-engined YB-35, and the two YB-49s actually built were both converted YB-35 test aircraft. The aircraft was never to enter production, however, being passed over in favor of the more conventional Convair B-36 in service.
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[edit] Design and development
With the B-35 program seriously behind schedule by 1944, and the end of the piston-engined combat aircraft in sight, the production contract for the type was cancelled in May. Nevertheless, the design was still sufficiently interesting to the Air Force that work on the pre-production aircraft was ordered to continue for testing purposes. Among the aircraft to be completed were two that the Air Force required to be fitted with jet propulsion.
The first aircraft flew on 21 October 1947 and immediately proved more promising than its piston-engined counterpart. The YB-49 set both an unofficial endurance record of staying continually above 40,000 ft (12,200 m) for six hours, and a trans-continental speed record, flying from Muroc Air Force Base in California to Andrews Air Force Base near Washington, D.C. in 4 hours 20 minutes. The program nevertheless experienced a number of serious problems including the low reliability of the Allison J35 engines and the auxiliary power unit. 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, copilot (after whom Edwards Air Force Base is named), and three other crew. The aircraft suffered structural failure, with both outer wing sections becoming detached from the center section. Speculation at the time was that the aircraft was lost due to loads imposed when a spin recovery resulted in a high speed dive. The Northrop flying wings required an unconventional spin recovery technique which involved the use of no rudder input and aileron input against the spin.
The Air Force ordered the remaining uncompleted YB-35 aircraft completed as B-35Bs, which were essentially identical to the YRB-49A mentioned below.
The YB-49 had several severe design limitations which doomed it. It retained the B-35's very thick airfoil section designed for cruising at 240 mph. This wing gave the aircraft a low Mach limit. Thick as the wing was, its bomb cells were incapable of holding the first generations of American atomic weapons (Mk III, IV and VI). Bombing tests showed that the tendency of flying wings to "hunt" in yaw when in "disturbed" air tended to degrade bombing accuracy unless an autopilot or yaw damper was used.
[edit] Operational history
In September 1948, the Air Force ordered the type into production as the RB-49A reconnaissance aircraft, which was powered by six engines, two externally mounted in pods. This contract was cancelled two months later. By this time it was clear other aircraft could handle the job, including the upcoming B-52 and the advanced B-47 which had entered Phase II testing. The main strategic bomber contracts fell to the Convair B-36 Peacemaker and the importance that the USAF placed on this program, effectively doomed the Northrop flying wings. [1]
During early 1950 the remaining YB-35B jet conversions of the B-35 aircraft were scrapped.
Flight testing of the remaining YB-49 prototype ended 14 March 1950. On 15 March 1950, the program was cancelled completely, and coincidentally, the prototype suffered a high speed taxiing accident and was totally destroyed in the fire that ensued.
The prototype reconnaissance platform, the YRB-49A first flew on 4 May 1950, and testing ended 26 April 1951. The YRB-49A was scrapped 1 December 1953.[2]The YB-49 and its modern counterpart, the B-2, both built by Northrop, have the same exact wingspan: 172.0 ft (52.40 m).
[edit] Popular culture
Stock footage of a YB-49 in flight appeared in The War of the Worlds. Ironically, the Flying Wing was tasked with dropping an atomic bomb on the invading Martians, although in reality the aircraft could not carry the devices of the time, and the last airworthy Flying Wing was scrapped within months of the film's release.
[edit] Specifications (YB-49)
Data from[citation needed]
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[1]
- 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 x .50 in (12.7 mm) machine guns
- Bombs: 32,000 lb (14,500 kg)
[edit] See also
Related development
Comparable aircraft
Related lists
[edit] References
[edit] Notes
- ^ a b Winchester 2005, p. 193.
- ^ Northrop YRB-49A
[edit] 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, ed. "Northrop Flying Wings." Encyclopedia of World Aircraft. Etobicoke, Ontario: Prospero Books, 1997. ISBN 1-85605-375-X.
- Maloney, Edward T. Northrop Flying Wings. Corona del Mar, California: World War II Publications, 1988. ISBN 0-915464-00-4.
- Pape, Garry and Campbell, John. Northrop Flying Wings: A History of Jack Northrop's Visionary Aircraft. Atglen, PA: Schiffer Publishing, Ltd., 1995. ISBN 0-88740-689-0.
- 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.
[edit] External links
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