The Martin XB-48 was an American medium jet bomber developed in the mid-1940s. It competed with the Boeing B-47 Stratojet, which proved to be a superior design, and was largely considered as a backup plan in case the B-47 ran into development problems. It never saw production or active duty, and only two prototypes, serial numbers 45-59585 and 45-59586,[1] 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 pounds (36,000 kg) to more than 200,000 pounds (91,000 kg). Other designs resulting from this competition, sometimes nicknamed "The Class of '45", included the North American XB-45 and the Convair XB-46. Production orders finally went to the North American B-45 Tornado, and even this airplane served only for a couple of years before again being replaced by the much more modern Boeing B-47 Stratojet, although the B-45 had the inherent performance – especially if it was not burdened with a payload – for it to then serve as a reconnaissance aircraft.[citation needed]
All of the bombers comprising the Class of '45 were transitional aircraft, which combined the power of turbojets with the aeronautical knowledge of World War II.[citation needed] The XB-48 was no exception, as its round fuselage and unswept wings showed a distinct influence of Martin's B-26 Marauder 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.
At the time of the XB-48's design, jet propulsion was still in its infancy. And, although it appeared superficially to have six separate engine nacelles – that is, three under each wing – the XB-48 actually had only two, unusually wide, three-engined nacelles. Each of these large nacelles also contained an intricate set of air ducts that constituted the engines' cooling system.
The XB-48 was the first aircraft designed with bicycle-type tandem landing gear, which had previously been tested on a modified B-26. The wing airfoil was too thin to house conventional landing gear mechanisms.[2] The main landing gear was in the fuselage and small outriggers located on each wing were used to balance the aircraft.
Operational historyEdit
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.[3]
Specifications (XB-48)Edit
3-view line drawing of the Martin XB-48
Data from "Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II"[4]
General characteristics
Crew: three (pilot, co-pilot, and bomber-navigator)
Length: 85 ft 9 in (26.14 m)
Wingspan: 108 ft 4 in (33.02 m)
Height: 26 ft 6 in (8.08 m)
Wing area: 1,330 sq ft (123.5 m2)
Empty weight: 58,500 lb (26,535 kg)
Gross weight: 92,600 lb (42,000 kg)
Max takeoff weight: 102,600 lb (46,540 kg)
Powerplant: 6 × General Electric J35 axial flow turbojet, 3,820 lbf (17.0 kN) thrust each
Performance
Maximum speed: 454 kn (523 mph, 841 km/h) at 35,000 ft
Cruise speed: 361 kn (415 mph, 668 km/h)
Range: 1,566 nmi (1,802 mi, 2,900 km)
Combat range: 691 nmi (795 mi, 1,280 km)
Service ceiling: 39,400 ft (12,009 m)
Rate of climb: 4,200 ft/min (21.3 m/s)
Armament
Guns: 2 × .50 in (12.7 mm) M-2 machine guns in tail turret (proposed)[2]
Bombs: 1 × 20,000 lb (9,980 kg) or 36 × 250 lb (113 kg)
See alsoEdit
Aircraft of comparable role, configuration, and era
^Knaack, Marcelle Size. Encyclopedia of U.S. Air Force Aircraft and Missile Systems: Volume II: Post-World War II Bombers, 1945–1973. Washington, DC: Office of Air Force History, 1988. ISBN0-16-002260-6.
BibliographyEdit
Ginter, Steve. Martin XB-48.Simi Valley, California: Steve Ginter Books, 2022. ISBN979-8-9854726-9-1
Jones, Lloyd S. U.S. Bombers, B-1 1928 to B-1 1980s. Fallbrook, CA: Aero Publishers, 1962, second edition 1974. ISBN0-8168-9126-5.
Mizrahi, Joe. "The Last Great Bomber Fly Off". Wings, Volume 29, Number 3, June 1999.
External linksEdit
Wikimedia Commons has media related to Martin XB-48.
Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II
GlobalSecurity.org
Film footage of the Martin XB-48
October 15, 2023
martin, american, medium, bomber, developed, 1940s, competed, with, boeing, stratojet, which, proved, superior, design, largely, considered, backup, plan, case, into, development, problems, never, production, active, duty, only, prototypes, serial, numbers, 59. The Martin XB 48 was an American medium jet bomber developed in the mid 1940s It competed with the Boeing B 47 Stratojet which proved to be a superior design and was largely considered as a backup plan in case the B 47 ran into development problems It never saw production or active duty and only two prototypes serial numbers 45 59585 and 45 59586 1 were built XB 48Role BomberManufacturer Glenn L Martin CompanyFirst flight 22 June 1947Status Canceled in 1948Number built 2Martin XB 48 prototype taxiing showing spaces between engines for cooling tandem main gear and nacelle outriggers Contents 1 Design and development 2 Operational history 3 Specifications XB 48 4 See also 5 References 5 1 Notes 5 2 Bibliography 6 External linksDesign and development EditIn 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 pounds 36 000 kg to more than 200 000 pounds 91 000 kg Other designs resulting from this competition sometimes nicknamed The Class of 45 included the North American XB 45 and the Convair XB 46 Production orders finally went to the North American B 45 Tornado and even this airplane served only for a couple of years before again being replaced by the much more modern Boeing B 47 Stratojet although the B 45 had the inherent performance especially if it was not burdened with a payload for it to then serve as a reconnaissance aircraft citation needed All of the bombers comprising the Class of 45 were transitional aircraft which combined the power of turbojets with the aeronautical knowledge of World War II citation needed The XB 48 was no exception as its round fuselage and unswept wings showed a distinct influence of Martin s B 26 Marauder 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 At the time of the XB 48 s design jet propulsion was still in its infancy And although it appeared superficially to have six separate engine nacelles that is three under each wing the XB 48 actually had only two unusually wide three engined nacelles Each of these large nacelles also contained an intricate set of air ducts that constituted the engines cooling system The XB 48 was the first aircraft designed with bicycle type tandem landing gear which had previously been tested on a modified B 26 The wing airfoil was too thin to house conventional landing gear mechanisms 2 The main landing gear was in the fuselage and small outriggers located on each wing were used to balance the aircraft Operational history EditThe 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 3 Specifications XB 48 Edit nbsp 3 view line drawing of the Martin XB 48Data from Encyclopedia of US Air Force Aircraft and Missile Systems Volume II 4 General characteristicsCrew three pilot co pilot and bomber navigator Length 85 ft 9 in 26 14 m Wingspan 108 ft 4 in 33 02 m Height 26 ft 6 in 8 08 m Wing area 1 330 sq ft 123 5 m2 Empty weight 58 500 lb 26 535 kg Gross weight 92 600 lb 42 000 kg Max takeoff weight 102 600 lb 46 540 kg Powerplant 6 General Electric J35 axial flow turbojet 3 820 lbf 17 0 kN thrust eachPerformance Maximum speed 454 kn 523 mph 841 km h at 35 000 ft Cruise speed 361 kn 415 mph 668 km h Range 1 566 nmi 1 802 mi 2 900 km Combat range 691 nmi 795 mi 1 280 km Service ceiling 39 400 ft 12 009 m Rate of climb 4 200 ft min 21 3 m s Armament Guns 2 50 in 12 7 mm M 2 machine guns in tail turret proposed 2 Bombs 1 20 000 lb 9 980 kg or 36 250 lb 113 kg See also EditAircraft of comparable role configuration and era Boeing B 47 Stratojet Convair XB 46 English Electric Canberra Ilyushin Il 22 Ilyushin Il 28 North American B 45 TornadoRelated lists List of bomber aircraft List of military aircraft of the United StatesReferences EditNotes Edit Fact Sheet Martin XB 48 Archived 2007 06 29 at the Wayback Machine National Museum of the United States Air Force Retrieved 5 July 2010 a b Jones 1969 Mizrahi 1999 pp 50 52 Knaack Marcelle Size Encyclopedia of U S Air Force Aircraft and Missile Systems Volume II Post World War II Bombers 1945 1973 Washington DC Office of Air Force History 1988 ISBN 0 16 002260 6 Bibliography Edit Ginter Steve Martin XB 48 Simi Valley California Steve Ginter Books 2022 ISBN 979 8 9854726 9 1 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 Mizrahi Joe The Last Great Bomber Fly Off Wings Volume 29 Number 3 June 1999 External links Edit nbsp Wikimedia Commons has media related to Martin XB 48 Encyclopedia of US Air Force Aircraft and Missile Systems Volume II National Museum of the Air Force GlobalSecurity org Film footage of the Martin XB 48 Retrieved from https en wikipedia org w index php title Martin XB 48 amp oldid 1142144406, wikipedia, wiki, book, books, library,
