Martin XB-48: Difference between revisions

XB-48
XB-48
General information
Type	Bomber
Manufacturer	Glenn L. Martin Company
Status	Canceled in 1948
Number built	2
History
First flight	22 June 1947

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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.

Design and development

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 history

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)

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 (12,000 m)
Rate of climb: 4,200 ft/min (21 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)

References

Notes

^ "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

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

[1] "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.

[Jones-2] Jones 1969

[3] Mizrahi 1999, pp. 50–52.

[4] 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.

[1]

[2]

[3]

[4]

@@ Line 1: / Line 1: @@
+{{Short description|American bomber prototype}}
 <!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. -->
-{|{{Infobox Aircraft Begin
+{{Infobox aircraft
   |name = XB-48
   |image = File:MartinXB48.jpg
   |caption =
-}}{{Infobox Aircraft Type
   |type = Bomber
   |manufacturer = [[Glenn L. Martin Company]]
   |designer =
-  |first flight = 22 June 1947
+  |first_flight = 22 June 1947
-  |introduced =
+  |introduction =
   |retired =
   |status = Canceled in 1948
-  |primary user =
+  |primary_user =
-  |more users =
+  |more_users =
   |produced =
-  |number built = 2
+  |number_built = 2
-  |unit cost = US$11.5 million for the program<ref name="knaack">Knaack 1988</ref>
+  |unit cost = US$11.5 million for the program<ref name="knaack">Knaack 1988</ref> (equivalent to ${{inflation|US|11.5|1948|r=1|fmt=c}} million today)
-  |variants with their own articles =
+  |variants =
 }}
-|}
 [[File:Martin XB-48 taxiing.jpg|thumb|right|Martin XB-48 prototype taxiing, showing spaces between engines for cooling, tandem main gear, and nacelle outriggers]]
@@ Line 25: / Line 24: @@
 ==Design and development==
-In 1944, the U.S. [[United States Department of War|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&nbsp;lb (36,287&nbsp;kg) to more than 200,000&nbsp;lb (90,718&nbsp;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 [[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 enough "utility" built in to maintain a niche as a reconnaissance aircraft.
+In 1944, the U.S. [[United States Department of War|War Department]] was aware of aviation advances in Germany and issued a requirement for a range of designs for medium bombers weighing from {{convert|80000|lb|||}} to more than {{convert|200000|lb|||}}. 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|date=March 2019}}
-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 showed a distinct influence of Martin's [[Martin B-26 Marauder|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.
+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|reason=does this really apply to the swept-wing B-47?|date=March 2019}} The XB-48 was no exception, as its round fuselage and unswept wings showed a distinct influence of Martin's [[Martin B-26 Marauder|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.
-Although the pictures make it look as if the aircraft had three engine nacelles under each wing, the jet engines were actually clustered in a pair of flat three-engined nacelles with an intricate system of air ducts between the engines, intended to facilitate cooling. At the time of the XB-48's design, jet propulsion was still in its infancy.
 The XB-48 was the first aircraft designed with bicycle-type tandem landing gear, which had previously been tested on a [[Martin B-26 Marauder#Variants|modified B-26]]. The wing airfoil was too thin to house conventional landing gear mechanisms.<ref name="Jones">Jones 1969</ref> The main landing gear was in the fuselage and small outriggers located on each wing were used to balance the aircraft.
@@ Line 35: / Line 34: @@
 ==Operational history==
 The XB-48 made its first flight on 22 June 1947, a 37-minute, 73&nbsp;mi (117&nbsp;km) hop from Martin's Baltimore, Maryland plant to [[NAS Patuxent River]], Maryland, but blew all four tires on its fore-and-aft mounted [[Landing gear|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.<ref>Mizrahi 1999, pp. 50–52.</ref>
-==Video==
-*[https://www.youtube.com/watch?v=DJZwggRWtz8 Film footage of the Martin XB-48]
 ==Specifications (XB-48)==
+[[File:Martin XB-48 3-view line drawing.png|thumb|3-view line drawing of the Martin XB-48]]
-{{Aircraft specifications
+{{Aircraft specs
-<!-- if you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] -->
+|prime units?=kts
-|plane or copter?= plane
-|jet or prop?= jet
 |ref="Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II"<ref>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}}.</ref>
 |crew= three (pilot, co-pilot, and bomber-navigator)
+|length ft= 85
-|capacity=
-|length main= 85 ft 9 in
+|length in= 9
-|length alt= 26.14 m
+|length m= 26.14
-|span main= 108 ft 4 in
+|span ft= 108
-|span alt= 33.02 m
+|span in= 4
+|span m= 33.02
-|height main= 26 ft 6 in
-|height alt= 8.08 m
+|height ft= 26
+|height in= 6
-|area main= 1,330 ft²
-|area alt= 123.5 m²
+|height m= 8.08
+|wing area sqft= 1,330
-|airfoil=
+|wing area sqm= 123.5
-|empty weight main= 58,500 lb
-|empty weight alt= 26,535 kg
+|empty weight lb= 58,500
-|loaded weight main= 92,600 lb
+|empty weight kg= 26,535
-|loaded weight alt= 42,000 kg
+|gross weight lb= 92,600
+|gross weight kg= 42,000
-|useful load main=
+|max takeoff weight lb= 102,600
-|useful load alt=
-|max takeoff weight main= 102,600 lb
+|max takeoff weight kg= 46,540
+|eng1 name= [[General Electric J35]]
-|max takeoff weight alt= 46,540 kg
+|eng1 type= axial flow turbojet
-|more general=
+|eng1 number=6
-|engine (jet)= [[General Electric J35]]
+|eng1 lbf= 3,820
-|type of jet= axial flow gas-turbine
+|eng1 kn=
-|number of jets=6
+|max speed kts= 454
-|thrust main= 3,820 lbf
+|max speed mph= 523
-|thrust alt= 17 kN
+|max speed kmh= 841
-|thrust original=
+|max speed note=at 35,000 ft
-|afterburning thrust main=
+|cruise speed kts= 361
-|afterburning thrust alt=
+|cruise speed mph= 415
-|engine (prop)=
+|cruise speed kmh= 668
-|type of prop=
+|range nmi= 1,566
-|number of props=
-|power main= hp
+|range miles= 1,802
-|power alt= kW
+|range km= 2,900
+|combat range miles= 795
-|power original=
+|combat range km= 1,280
-|max speed main= 454 kn
+|ceiling ft= 39,400
-|max speed alt= 523 mph, 841 km/h
+|ceiling m=
-|max speed more=at 35,000 ft
+|climb rate ftmin= 4,200
-|cruise speed main= 361 kn
+|climb rate ms=
-|cruise speed alt= 415 mph, 668 km/h
+|power/mass= |guns= 2 × .50 in (12.7 mm) M-2 [[machine gun]]s in tail turret (proposed)<ref name="Jones"/>
-|never exceed speed main=
-|never exceed speed alt=
-|stall speed main=
-|stall speed alt=
-|range main= 1,566 nmi
-|range alt= 1,802 mi, 2,900 km
-|combat radius main= 795 mi
-|combat radius alt= 1,280 km
-|ceiling main= 39,400 ft
-|ceiling alt= 12,009 m
-|climb rate main= 4,200 ft/min
-|climb rate alt= 21.3 m/s
-|loading main=
-|loading alt=
-|thrust/weight=
-|power/mass main=
-|power/mass alt=
-|more performance=
-|guns= 2 × .50 in (12.7 mm) M-2 [[machine gun]]s in tail turret (proposed)<ref name="Jones"/>
 |bombs= 1 × 20,000 lb (9,980 kg) or 36 × 250 lb (113 kg)
-|avionics=
 }}
 ==See also==
+[[File:XB-48 342-C-K-004490.jpg|thumb|XB-48 prototype]]
 {{Aircontent
 |similar aircraft=
@@ Line 122: / Line 100: @@
 ==References==
-;Notes
+===Notes===
 {{Reflist}}
-;Bibliography
+===Bibliography===
+* Ginter, Steve. ''Martin XB-48''.Simi Valley, California: Steve Ginter Books, 2022. {{ISBN|979-8-9854726-9-1}}
-{{Refbegin}}
 * 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.
-{{Refend}}
 ==External links==
 {{Commons category}}
-*[http://www.worldcatlibraries.org/wcpa/oclc/3088764?page=frame&url=http%3A%2F%2Fpurl.access.gpo.gov%2FGPO%2FLPS48548&title=&linktype=digitalObject&detail= Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II]
+* [http://www.worldcatlibraries.org/wcpa/oclc/3088764?page=frame&url=http%3A%2F%2Fpurl.access.gpo.gov%2FGPO%2FLPS48548&title=&linktype=digitalObject&detail= Encyclopedia of US Air Force Aircraft and Missile Systems, Volume II] {{Webarchive|url=https://web.archive.org/web/20070929095346/http://www.worldcatlibraries.org/wcpa/oclc/3088764?page=frame&url=http:%2F%2Fpurl.access.gpo.gov%2FGPO%2FLPS48548&title=&linktype=digitalObject&detail= |date=2007-09-29 }}
-*[https://web.archive.org/web/20070629052935/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2661 National Museum of the Air Force]
+* [https://web.archive.org/web/20070629052935/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2661 National Museum of the Air Force]
-*[http://globalsecurity.org/wmd/systems/b-48.htm GlobalSecurity.org]
+* [http://globalsecurity.org/wmd/systems/b-48.htm GlobalSecurity.org]
+* [https://www.youtube.com/watch?v=DJZwggRWtz8 Film footage of the Martin XB-48]
 {{Martin aircraft}}
 {{USAF bomber aircraft}}
+{{Authority control}}
-[[Category:United States bomber aircraft 1940–1949|Martin B-48]]
+[[Category:1940s United States bomber aircraft|Martin B-48]]
 [[Category:Martin aircraft|B-48]]
 [[Category:Six-engined jet aircraft]]
 [[Category:Aircraft first flown in 1947]]
 [[Category:Mid-wing aircraft]]
+[[Category:Aircraft with retractable bicycle landing gear]]

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