Reconnaissance bomber proposal by Boeing
B-56
|
Role
|
Jet reconnaissance bomber
Type of aircraft
|
National origin
|
United States
|
Manufacturer
|
Boeing
|
Status
|
Canceled
|
Number built
|
None (not converted)
|
Developed from
|
Boeing B-47 Stratojet
|
The
Boeing XB-56
was a proposal by
Boeing
for a re-engined version of the American jet-powered medium
bomber
aircraft, the
B-47 Stratojet
. The original designation for this modification was
YB-47C
.
Design and development
[
edit
]
The B-47 was equipped with six
General Electric J47
turbojets, each rated at 5,200
pounds-force
(23
kN
)
thrust
. The engines were mounted in four
nacelles
slung from the high wing, with two engines in the inboard pod and one engine in the outboard nacelle. To reduce complexity and increase commonality, it was proposed that a higher-rated engine be selected such that one engine could be mounted in each nacelle.
The
Allison J35
turbojet engine was being developed during the late 1940s, and it was provisionally rated at 8,500 lb
f
(38 kN) or 9,700 lb
f
(43 kN) with
afterburner
. Thus 4 × 8500 lb
f
= 34,000 lb
f
(150 kN) using that engine, as compared to 6 × 5,200 lb
f
= 31,200 lb
f
(139 kN) in the production B-47. Thus the conversion would be lighter, simpler and more powerful.
[1]
A contract was signed with Boeing in January 1950, calling for rework of one aircraft. A B-47B-20-BW (s/n 50-082) was earmarked for the conversion. The date for first flight was projected as April 1951.
[2]
A combination of delays and less-than-expected performance of the J35 led to the consideration of other engines. The
Allison J71
was proposed,
[1]
however problems with this engine meant that this was not feasible for the by-then redesignated B-56A. The
Pratt & Whitney J57
, eventually rated at 17,000 lb
f
(76 kN) thrust, was also considered, but that engine was still in development, and the
Boeing B-52 Stratofortress
, which was being concurrently developed (first flight was April 1952), had priority for this engine.
The B-56 program was canceled in December 1952 before conversion of the prototype was started. The unconverted B-47 was relegated to a ground instructional airframe and in the late 1960s was in use at the
Naval Air Facility El Centro
as an egress trainer.
[
citation needed
]
Variants
[
edit
]
- XB-56
- Designation for a single B-47 to be re-engined with four YJ71-A-5 engines, later re-designated YB-56 and YB-47C but was not converted.
[3]
- RB-56A
- Designation for production variant, cancelled and not built.
[3]
Specifications (XB-56)
[
edit
]
General characteristics
- Crew:
3
- Length:
107 ft 1 in (32.64 m)
- Wingspan:
116 ft 0 in (35.36 m)
- Height:
28 ft 0 in (8.53 m)
- Wing area:
1,428 sq ft (132.7 m
2
)
- Powerplant:
4 ×
Allison YJ71-A-5
turbojet
See also
[
edit
]
Related development
Related lists
References
[
edit
]
Notes
[
edit
]
Bibliography
[
edit
]
- Andrade, John (1979).
U.S.Military Aircraft Designations and Serials since 1909
. Midland Counties Publications.
ISBN
0-904597-22-9
.
External links
[
edit
]
Media related to
Boeing XB-56
at Wikimedia Commons
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Original sequences
(1924?1930)
| Light Bomber
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Medium Bomber
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Heavy Bomber
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Main sequence
(1930?1962)
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Long-range Bomber
(1935?1936)
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Tri-Service sequence
(1962?current)
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Non-sequential
| Redesignated A-series
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Fighter-bomber, in F-series
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Other
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Fighters/attack aircraft
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Bombers
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Piston-engined transports
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Jet transports
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Tanker-transports
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Trainers
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Patrol and surveillance
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Reconnaissance
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Drones/UAVs
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Experimental/prototypes
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