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XB-48
Role Bomber
Manufacturer Glenn L. Martin Company
First flight 1947-06-22
Status Cancelled in 1948
Number built 2
Unit cost US$11.5 million for the program[1]
Martin XB-48 prototype taxiing, showing spaces between engines for cooling, tandem main gear, & nacelle outriggers.

The Martin XB-48 was a medium jet bomber developed in the mid-1940s. It never saw production or active duty, and only two prototypes, serial numbers 45-59585 and 45-59586[2], were built.

In 1944 the U.S. War Department was aware of aviation advances in Germany and issued a requirement for a range of designs for medium bombers weighing from 80,000 lb (36,287 kg) to more than 200,000 lb (90,718 kg). Other designs resulting from this competition, sometimes named the class of '45, included the North American XB-45 and the Convair XB-46. Production orders finally went to the B-45 Tornado and even this airplane only served for a couple of years before again being replaced by the much more modern B-47 Stratojet.

In retrospect, the class of '45 were transitional aircraft combining the power of turbojets with the aeronautical knowledge of World War II. The XB-48 was no exception, as its round fuselage and unswept wings show a distinct patronage from the earlier Martin B-26 medium bomber. Still, where the B-26 had enough thrust with two massive 18-cylinder radial engines, the XB-48 needed no less than six of the new jet engines. Although the pictures make it look like the aircraft has three engine gondolas under each wing, the jet engines were actually clustered in a pair of flat three-engined gondolas with an intricate system of air canals between the engines providing cooling. At the time of the XB-48's design, jet propulsion was clearly still in its infancy.

The XB-48 was the first aircraft designed with bicycle type landing gear. The wing airfoil was too thin to house conventional land gear mechanisms.[3] The main landing gear was in the fuselage and small outriggers located on each wing were used to balance the aircraft.

The XB-48 made its first flight on 22 June 1947, a 37-minute, 73 mi (117 km) hop from Martin's Baltimore, Maryland plant to NAS Patuxent River, Maryland, but blew all four tires on its fore-and-aft mounted undercarriage on landing when pilot Pat Tibbs applied heavy pressure to the specially-designed, but very slow to respond, insensitive air-braking lever. Tibbs and co-pilot Dutch Gelvin were uninjured. [4]

Contents

Specifications (XB-48)

Data from "Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II" by Knaack, Marcelle Size (Washington: Office of Air Force History, ISBN 0-16-002260-6), 1988.

General characteristics

  • Crew: 3 (pilot, co-pilot, and bomber-navigator)
  • Length: 85 ft 9 in (26 m)
  • Wingspan: 108 ft 4 in (33 m)
  • Height: 26 ft 6 in (8 m)
  • Wing area: 1,330 ft² (123.5 m²)
  • Empty weight: 58,500 lb (26,535 kg)
  • Loaded weight: 92,600 lb (42,000 kg)
  • Max takeoff weight: 102,600 lb (46,540 kg)
  • Powerplant:General Electric J35 axial flow gas-turbine, 3,820 lbf (17 kN) each

Performance

Armament

  • Guns: 2 × .50 in (12.7 mm) M7 machine guns in tail turret (proposed)[3]
  • Bombs: 1 × 20,000 lb (9,980 kg) or 36 × 250 lb (113 kg)

See also

Comparable aircraft

Related lists

References

Notes

  1. ^ "Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II" by Knaack, Marcelle Size (Washington: Office of Air Force History, ISBN 0-16-002260-6), 1988.
  2. ^ http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2661
  3. ^ a b Jones, Lloyd S.: U.S. Bombers: B-1 - B-70, Aero Publishers, Inc., 1969. LCCN 62-15969
  4. ^ Mizrahi, Joe, "The Last Great Bomber Fly Off", Wings, Granada Hills, California, June 1999, Volume 29, Number 3, pages 50-52.

Bibliography

  • Jones, Lloyd S. U.S. Bombers, B-1 1928 to B-1 1980s. Fallbrook, CA: Aero Publishers, 1962, second edition 1974. ISBN 0-8168-9126-5.

External links








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