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B-47 Stratojet Boeing
B-47 Stratojet
Medium Strategic Bomber

DESCRIPTION:
As the first jet-powered fighters began entering service during World War II, the US Army Air Force soon realized that a jet-powered bomber would also be needed. Boeing originally entered the B-47 bomber competition with a straight-wing design, but after learning of Germany's research on swept-wings (see the Bell X-5), Boeing engineers quickly adopted such a configuration for their proposal. Boeing also planned to mount six turbojet engines in the fuselage, but this design was rejected by the USAAF citing maintainability and safety concerns. Boeing then unveiled its fourth proposal, still featuring swept-wings but now with the six engines mounted in underwing pods. This approach was accepted by the USAAF, and Boeing was awarded a contract for production of the B-47.

The B-47 design featured a high-mounted, high aspect ratio, laminar-flow wing with a very thin cross-section. The wing was indeed so thin that it flexed as much as 5 ft (1.5 m) up or down in flight. Beneath each wing were mounted three engines, two in an inboard nacelle and the other near the wing tip. The landing gear layout was composed of twin bicycle gear on the centerline and two outrigger units that retracted into the inboard engine pods. The large fuselage of the B-47 was equipped with a single bomb bay able to carry the large nuclear weapons of the day or some 20,000 lb (9,070 kg) of conventional bombs. In addition, the fuselage provided room for the three-man crew, a tail gun turret that could be controlled manually by the gunner or automatically by radar, and mountings for jet-assisted takeoff (JATO) or rocket packs to shorten the takeoff run.

After the United States entered the Korean War, demand for the new B-47 became urgent and production was split between Boeing, Lockheed, and Douglas. The first production model, the B-47B, was later eclipsed by the improved B-47E, and both saw extensive service with the new US Air Force Strategic Air Command (SAC). Numerous reconnaissance models were also developed.

Although the Air Force had planned to replace the B-47 by 1957, a suitable replacement was not yet available, and the B-47 was forced to remain in service well into the 1960s. Unfortunately, this demand and the adoption of a low-level bombing strategy to avoid Soviet surface-to-air missiles resulted in severe structural fatigue problems. Update programs were instituted to upgrade many aircraft with wing structural reinforcements. These updates were referred to as the B-47B-II and B-47E-II variants. These aircraft continued in front-line service until 1966, and weather reconnaissance models were flown until 1969. The US Navy also acquired EB-47E electronics countermeasures aircraft that remained in use until 1977.

Data below for B-47E-II
Last modified 17 March 2012

HISTORY:
First Flight (XB-47) 17 December 1947
(B-47A) 25 June 1950
(B-47B) 26 April 1951
(B-47E) 30 January 1953
Service Entry (B-47B) June 1951
Retirement

(B-47E-II) 1966
(EB-47E) 1977

CREW: three: pilot, co-pilot/gunner, navigator/bombardier

ESTIMATED COST:

$1,887,770

AIRFOIL SECTIONS:
Wing Root NACA 64A(.225)12 mod
Wing Tip

NACA 64A(.225)12 mod

DIMENSIONS:
Length 109.83 ft (33.48 m)
Wingspan 116.00 ft (35.36 m)
Height 27.92 ft (8.51 m)
Wing Area 1,428 ft (132.66 m)
Canard Area

not applicable

WEIGHTS:
Empty 80,755 lb (36,630 kg)
Normal Takeoff 133,030 lb (60,340 kg)
Max Takeoff 198,180 lb (89,895 kg)
Fuel Capacity internal: unknown
external: unknown
Max Payload

20,000 lb (9,070 kg)

PROPULSION:
Powerplant six General Electric J47-25 turbojets with water injection plus
up to 33 auxiliary rocket motors jettisoned after takeoff
Thrust (J47) 43,200 lb (192.17 kN)
(rockets) 1,000 lb (4.45 kN) each

PERFORMANCE:
Max Level Speed at altitude: 605 mph (975 km/h) at 16,300 ft (4,970 m)
at sea level: unknown
cruise speed: 555 mph (895 km/h) at 38,500 ft (11,735 m)
Initial Climb Rate at sea level: 1,850 ft (565 m) / min
combat rate (at max power): 4,350 ft (1,325 m) / min
Service Ceiling 40,500 ft (12,345 m)
Range typical: 3,475 nm (6,435 km)
ferry: unknown
g-Limits unknown

ARMAMENT:
Gun two 20-mm cannons in a remotely-controlled tail turret
Stations one internal bomb bay
Air-to-Air Missile none
Air-to-Surface Missile none
Bomb various nuclear or conventional bombs
Other none

KNOWN VARIANTS:
XB-47 Prototype equipped with GE J35 engines; 2 built
B-47A Model built for service testing and familiarization, used primarily to test different tail armaments and fire-control systems, featured improved GE J47-11 engines; 10 built
B-47B First production model with structural modifications for higher gross takeoff weight, in-flight refueling capability, and the ability to carry underwing fuel tanks; 399 built
B-47B-II Extensively modified B-47B airframes brought up to the B-47E standard plus incorporating wing structural modifications for low-altitude flight
DB-47B B-47B airframes converted to drone control aircraft with tail armaments removed
RB-47B
YRB-47B
B-47B airframes modified for reconnaissance missions and equipped with eight cameras and other surveillance equipment placed in the bomb bay; 24 converted
TB-47B B-47B airframes modified with a fourth seat in the cockpit for an instructor and used for pilot and navigator training; 66 converted
WB-47B B-47B modified for weather reconnaissance missions; 1 converted
YDB-47B B-47B modified to conduct trials of the Bell XGAM-63 Rascal missile; 1 converted
YB-47C or YB-56 Proposal for a new B-47 model to be equipped with only four Allison J71-5 or Pratt & Whitney YJ57 turbojets; cancelled
XB-47D B-47B airframes modifed to test Wright YT49-1 turboprop engines, two such engines replacing the inboard pairs of turbojets; 2 converted
B-47E Major production version with strengthened landing gear, a new fuselage nose with an in-flight refueling receptacle, ejection seats, drag parachute, revised tail turret, updated GE J47-25 engines, and a new external rack for jettisonable rocket packs; over 1,600 built
B-47E-II B-47E airframes modified with a strengthened wing structure for low-altitude flight
DB-47E
YDB-47E
B-47E airframes modified to conduct trials of the Bell XGAM-63 Rascal missile; 4 converted
EB-47E B-47E aircraft modified for electronic countermeasures missions and used by the US Navy; 2 converted
ETB-47E B-47E aircraft modified as four-seat trainers similar to the TB-47B
QB-47E B-47E aircraft modified as radio-controlled drones and used as targets; 14 converted
RB-47E Strategic reconnaissance model based on he B-47E and equipped with up to 11 cameras and night photography equipment; 240 built
WB-47E B-47E airframes modified to conduct weather reconnaissance duties; 24 converted
YB-47F B-47B airframes modified with an in-flight refueling probe and used to conduct refueling tests; 1 converted
KB-47G B-47B modified as an in-flight refueling tanker and used for refueling tests with the YB-47F; 1 converted
RB-47H Electronic reconnaissance model equipped with nose, fuselage, and wing radomes plus the bomb bay was converted to house three operators; 32 built
ERB-47H B-47E aircraft modified to the RB-47H standard but with a total crew of only five; 3 converted
YB-47J B-47 modified to test a new radar navigation and bombing system; 1 converted
RB-47K Photo and weather reconnaissance model similar to the RB-47E; 15 built
EB-47L B-47E aircraft modified as communications relay stations; 35 converted
MB-47 Proposed unmanned test aircraft to explore dropping hydrogen bombs without a crew
CL-52 B-47B transferred to the Royal Canadian Air Force and used to test the Orenda Iroquois turbojet mounted in a pod on the starboard side of the aft fuselage; 1 converted

KNOWN COMBAT RECORD:

Korean War (USAF, 1951-1953)
Vietnam War (USAF, 1965-1966)

KNOWN OPERATORS:

United States (US Air Force)
United States (US Navy)

3-VIEW SCHEMATIC:

B-47 Stratojet


SOURCES:
  • B-47 Stratojet Association
  • Chant, Christopher and Taylor, Michael J.H. The World's Greatest Aircraft. Edison, NJ: Chartwell Books, 2006, p. 111, Boeing B-47 Stratojet.
  • Donald, David, ed. The Complete Encyclopedia of World Aircraft. NY: Barnes & Noble, 1997, p. 160-161, Boeing Model 450 (B-47 Stratojet).
  • Jackson, Robert. The Encyclopedia of Military Aircraft. London: Paragon Books, 2002, p. 54-55, Boeing B-47 Stratojet.
  • Military.cz B-47 site
  • Pima Air & Space Museum B-47 site
  • Winchester, Jim. Military Aircraft of the Cold War. San Diego, CA: Thunder Bay Press, 2006, p. 36-37, Boeing B-47 Stratojet.





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