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Boeing B-50A "Superfortress" “B” Listings Boeing KB-50J "Superfortress"

Boeing WB-50D "Superfortress"
United States — USAF four-engine medium bomber

Archive Photos

Boeing WB-50D "Superfortress" (AF 49-0310) at the National Museum of the United States Air Force, WPAFB, Dayton, OH (Photos by John Shupek)

Boeing WB-50D "Superfortress - Flight of the Phoenix" (AF 49-0351) at the Castle Air Museum, Atwater, CA (Photos by John Shupek)

Design and Development

Boeing B-50 "Superfortress"
Role:Strategic bomber
First flight:25 June 1947
Primary user:United States Air Force
Number built:371
Unit costUS $1,144,296
Developed from:B-29 Superfortress
Variants:• Boeing C-97
• Stratofreighter
• Boeing KB-50
The Boeing B-50 Superfortress was a post-World War II revision of the wartime United States B-29 Superfortress with larger Pratt & Whitney R-4360 radial engines, a taller vertical stabilizer, and other improvements.

The B-50 program began life as the XB-44 Superfortress. One B-29A-5-BN (s/n 42-93845) was modified by Pratt & Whitney in 1944 to accept the larger engines; the resulting engine testbed first flew in May 1945. If the engine modification had been included in the B-29 program, the resulting model was to have been known as the B-29D. However, due to other structural changes that would also be necessary to address the increased power, weight and fuel consumption, it was decided to change its military designation to a new model. Since the B-44 program was only for the engine modification, that designation was not considered, and in December 1945 the program was named B-50 Superfortress. Officially, the aircraft's new designation was justified by the changes incorporated into the revised aircraft, but according to Peter M. Bowers, a long-time Boeing employee and aircraft designer, and a well-known authority on Boeing aircraft, "the redesignation was an outright military ruse to win appropriations for the procurement of an airplane that by its designation appeared to be merely a later version of an existing model that was being canceled wholesale, with many existing examples being put into dead storage." Revisions to the Boeing B-50 (from its predecessor Boeing B-29) would result in a top speed just short of 400 mph (644 km/h), faster than many World War II propeller-powered fighters.

Changes included:

  • Larger engines

  • Redesigned engine nacelles and engine mounts

  • Enlarged vertical tail and rudder (to maintain adequate yaw control during engine-out conditions)

  • Reinforced wing structure (required due to increased engine mass, larger gyroscopic forces from larger propeller, greater fuel load, and revised landing gear loading)

  • Revised routing for engine gases (cooling, intake, exhaust and intercooler ducts; also oil lines)

  • Upgraded fire-control equipment (to control remote turrets)

  • Landing gear strengthening (takeoff weight increased from 133,500 lb/60,555 kg to 173,000 lb/78,471 kg)

  • Increased fuel capacity (this was largely addressed by adding underwing fuel tanks).

  • Revisions to flight control systems (the B-29 was already difficult to fly; with its increased weight the B-50 would have been much harder to hand-fly).

  • Redesigned with a larger upper fuselage, the B-50 design would form the basis for the Boeing 377 series of airliners and C-97/KC-97 military transports, with 816 of the KC-97 built. The B-29 and B-50's would be phased out with introduction of the jet powered B-47 Stratojet.

  • The B-50 was nicknamed "Andy Gump" because the redesigned engine nacelles reminded aircrew of the chinless newspaper comic character popular at the time.

Operational History

  • Boeing built 371 of the various B-50 models and variants between 1947 and 1953, the tanker versions serving until 1965.

  • A reconnaissance variant, the RB-50B (a B-50B conversion) played an important role in Cold War espionage.

  • An aerial refueling tanker conversion designated KB-50 was used in the Vietnam War.

  • In 1949, The “Lucky Lady II”, commanded by Captain James Gallagher, became the first airplane to circle the world nonstop. This was achieved by refueling the plane in flight.

  • Although constructed in relatively small numbers, the B-50 was the last member of the B-29 family and was one of the last piston-engined bombers built. The B-50 was retired from its main role as atomic bomber in 1955. A number were converted into KB-50 tankers and lasted long enough to be deployed to Southeast Asia in support of tactical operations.

  • B-50's were grounded and removed completely from inventory when wreckage of a KB-50 that broke up in flight in 1965 revealed corrosion problems in the fleet.

  • No flying examples exist today, although several can be found in various air museums.

  • The USAF Strategic Air Command had B-50 Superfortresses (B-50's and RB-50's) in service from 1948 through 1954.


  • XB-44: One B-29A was handed over to Pratt & Whitney to be fitted with the new Wasp Major 28-cylinder engines. Initially designated B-29D, this was eventually changed to B-50A in December 1945. (x1, converted)

  • B-50A—First production version of the B-50. It had new wings that were stronger and lighter than the units on the B-29. It also had taller vertical tail than the B-29. (x60)

  • B-50B—Increase in gross weight over the A model, from 168,480 lb (76,420 kg) to 170,400 lb (77,290 kg). Also included a new type of lightweight fuel cell. (x45)

  • B-50D—Definitive production version of the B-50. The 7-piece nose cone window was replaced by a single plastic cone and a flat bomb-aimer's window. Many included the new boom-type refueling system. (x222)

  • DB-50D—Drone director conversion of a B-50D, to be used with the GAM-63 RASCAL missile. (x1, converted)

  • EB-50B—Single conversion of a B-50B to be fitted with a track-tread undercarriage. (x1, converted)

  • KB-50—Air to air refueling tanker conversions of the bomber. (x134, converted)

  • KB-50J—Tanker B-50's with improved performance, via two extra General Electric J47 turbojets under the outer wings. (x112, converted)

  • KB-50K—Tanker conversions of the TB-50H trainer aircraft. (x24, converted)

  • RB-50B—All but one of the B-50B's were converted into the recon role. These were fitted with nine cameras in four stations, weather instruments, and a bomb bay capsule holding the extra crew members. (x44, converted)

  • RB-50E—Special photographic conversions of the RB-50B, modified at Wichita. (x14, converted)

  • RB-50F—Conversions of the RB-50B, fitted with SHORAN navigation radar for special missions. (x14, converted)

  • RB-50G—Conversions of the RB-50B, fitted with electronics countermeasures stations along with the SHORAN radar. (x15, converted)

  • TB-50A—Trainer conversion of the B-50A. (x11, converted)

  • TB-50D—Trainer conversion of the B-50D. (x11, converted)

  • TB-50H—Newly built trainer planes. (x24)

  • WB-50 —Weather reconnaissance conversion of the B-50.

  • WB-50D—Weather reconnaissance conversions of outdated B-50D's, fitted with meteorological equipment. (x36, converted). Some of these flew highly classified missions for atmospheric sampling between 1953 and 1955 to detect Soviet detonation of atomic weapons.

  • YB-50C—Version to be fitted with the Variable Discharge Turbine version of the R-4360 engine. None were built.

  • B-54A—Proposed version of the YB-50C.

  • RB-54A—Proposed reconnaissance version of the YB-50C.


  • Boeing B-50A-5-BO "Superfortress" (AF 46-0010) on display at the Planes Of Fame, Chino, California

  • Boeing B-50D-115-BO "Superfortress" (AF 49-310) on display at the National Museum of the United States Air Force, Wright-Patterson AFB, Dayton, Ohio

  • Boeing B-50D-120-BO "Superfortress" (AF 49-0351) on display at the Castle Air Museum, Castle Airport, Atwater, California

  • Boeing B-50D-125-BO "Superfortress" (AF 49-0372) on display at the Pima Air and Space Museum, Tucson, Arizona

  • Boeing B-50D-125-BO "Superfortress" (AF 49-0389) on display at MacDill AFB, Tampa, Florida



  • United States: United States Air Force

Specifications (Boeing B-50D "Superfortress")

General Characteristics

  • Crew: 8: Pilot, co-pilot, flight engineer, radio/electronic countermeasures operator, two side gunners, top gunner and tail gunner
  • Length: 99 ft 0 in (30.2 m)
  • Wingspan: 141 ft 3 in (43.1 m)
  • Height: 32 ft 8 in (10.0 m)
  • Wing area: 1736 ft² (161.3 m²)
  • Empty weight: 80,610 lb (36,560 kg)
  • Loaded weight: 121,850 lb (55,270 kg)
  • Max takeoff weight: 173,000 lb (78,470 kg)
  • Powerplant: 4 × Pratt & Whitney R-4360 radial engines, 3,500 hp (2,600 kW) each


  • Maximum speed: 395 mph (343 kn, 636 km/h)
  • Cruise speed: 244 mph (212 kn, 393 km/h)
  • Combat radius: 2,100 NM (2,400 mi, 3,860 km)
  • Ferry range: 5,000 NM (5,760 mi, 9,270 km)
  • Service ceiling: 36,650 ft (11,170 m)
  • Rate of climb: 2,225 ft/min (11.3 m/s)
  • Wing loading: 70.19 lb/ft² (343 kg/m²)
  • Power/mass: 0.115 hp/lb (193 W/kg)


  • Guns: 12× .50 in (12.7 mm) M2 Browning machine guns in remote controlled turrets
  • Guns: 1× 20 mm (0.787 in) cannon in tail
  • Bombs: 20,000 lb (9,100 kg) internally
  • Bombs: 8,000 lb (3,600 kg) on external hardpoints


  1. Photos: John Shupek, Copyright © 2009 Skytamer Images. All Rights Reserved
  2. Wikepedia. "B-50 Superfortress." [Online] Available, 8 December 2009

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