Following the cancellation of the B-49 project, the Air Force still decided to fund the conversion of the tenth YB-35 (42-102376) as a testbed for an unarmed, long-range photographic reconnaissance aircraft. The designation YRB-49A was assigned to the conversion, with the company designation being Model NS-41. It was powered by four 5000 lb.s.t. Allison J35-A-19 engines mounted in the wings, two on each side, plus two more J35s suspended in pods below the wing leading edge. The placement of two engines in nacelles allowed more room for fuel in the wings, the additional fuel being necessary for the long-range reconnaissance mission. In addition, the engine pylons acted as vertical stabilizers which would supposedly help to correct the yaw-axis stability problems that had been encounted during YB-49A testing.
The crew was six--pilot, copilot, flight engineer, photo navigator, radar navigator, and photo technician. Photographic equipment was installed in the tail cone bay just below the center section.
The company designation N-37 was used for the planned RB-49. The N-38 designation was alllocated to the planned modification of the YB-49s to carry equipment planned for the RB-49.
Northrop received a letter contract on June 12, 1948 for preliminary engineering work leading perhaps to an eventual production contract for 30 aircraft. Serials were 49-200/229. This contract was signed on August 12, 1948. The Air Force believed that the nation would benefit from the pooling of Northrop's engineering skill and Convair's experience in quantity production of large aircraft, and the contract stipulated that only one of the aircraft was to be built by Northrop, with the remaining 29 to be built by Convair at its government-leased plant in Fort Worth, Texas.
However, it soon became apparent that the proposed six-jet RB-49A would be much slower than the B-47, and the Air Force Board recommended immediate termination of the RB-49A. This was done formally in late December of 1948. The funds that had been allocated to the RB-49A were then re-allocated to more B-36s. The cancellation became official in mid-January of 1949, and Northrop was directed to stop all work on the project except for completion and test of a single YRB-49A as part of a proof-of concept research and development program.
The YRB-49A took off on its first test flight on May 4, 1950. Its first flight was from Hawthorne to Edwards AFB. Tests were conducted at Edwards AFB for a period of time. On August 10, 1950, during its tenth test flight, the cockpit canopy blew off, tearing away the pilot's oxygen mask and injuring him slightly. Fortunately, the flight engineer was able to supply enough emergency oxygen to the pilot so that he was able to land the aircraft safely.
A short period of only 13 test flights took place until the aircraft was placed in storage in late 1950. In early 1952, the YRB-49A was flown to Northrop's Ontario International Airport facility (in California) for the installation of a device that would improve the stability. However, at this time the Air Force had cut off further funding for the YRB-49A project, and the aircraft remained sitting out in the open in dead storage for a period of time. It was finally scrapped by the Air Force in November of 1953.
N-40 was assigned to one RB-49 on order for conversion to a prototype of the production B-49 bomber variant. Engine options investigated for the N-40/production B-49 included eight J47s (six in the trailing edge of the wing between the fins and two in individual pods under the wings), six J40s, a combination of two T37s and 2 or 4 J40s, and six J48s (Rolls-Royce Tays built under license by Pratt & Whitney). The company designations N-46 and N-47 were allocated to advanced design studies for the RB-49 featuring T37 turboprops. N-50 was assigned to Northrop’s plan for modifications to the sole remaining YB-49 prototype to improve stability (which never materialized because 42-102367 was destroyed during taxiing. N-52 was the Northrop company designation for the planned Air Force test phase involving the YRB-49A (which did not materialize)
Sources:
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Northrop's Big Wing--The B-2, David Baker, Air International, June
1993.
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Northrop Flying Wings, Edward T. Maloney, World War II Publications,
1988.
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B-2 Intrigue, Graham Stallard, Air International, August 1993, p117.
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American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
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Chong, Tony, 2016. Flying Wings & Radical Things: Northrop’s Secret Aerospace Projects & Concepts 1939-1994. Forest Lake,
Minnesota: Specialty Press.
- Pape, G. and Campbell, J., 1995. Northrop Flying Wings: A History of Jack Northrop's Visionary Aircraft. Atglen, PS: Schiffer Publishing.
