Advertisements

Aviation / Aerospace

Boeing XB-55

Strategic Bomber Proposal [ 1947 ]

The proposed Boeing XB-55 strategic bomber was being developed to succeed the in-development Boeing B-47 Stratojet - it was commissioned before the B-47 had even flown.

Authored By: Staff Writer | Last Edited: 04/25/2016 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

Image from the Public Domain; Artist impression of the XB-55 bomber proposal.

GO TO SPECIFICATIONS [+]

Advertisements

Not convinced of the reliability of, and promised performance from, early turbojet engines, the United States Air Force (USAF) looked beyond all-jet-powered forms in-development after the close of World War 2 (1939-1945). The Boeing B-47 "Stratojet" swept-wing strategic jet bomber was selected by the USAF to fulfill an earlier specification and was a product of the period - it eventually went on to find success as over 2,000 of the type were built and flown until the late-1970s.

However, even before the B-47 prototype went airborne in 1947, USAF authorities penciled out a new request in October of that year for an insurance-minded strategic bombing platform relying on more conventional propulsion power. The usual participants responded and this crop included Boeing whose submission was selected for further development under the designation of "XB-55" (Company Model 474).

Boeing engineers elected for a form that was not unlike their B-47 proposal save for the use of Allison T40-A-2 turboprop engines over turbojets. These systems would be underslung at the wings in the usual way (the wing mainplanes being of reduced sweepback when compared to the B-47) and drive three-bladed contra-rotating propeller units. Four engines would be used to power the large bomber and output up to 5,600 horsepower. Estimated performance included a maximum speed of 490 miles per hour (cruising at about 450 mph), a range out to 5,000 miles and a ceiling of 42,000 feet. In comparison, the B-47 (B-47E) managed a maximum speed of 607mph, cruised at 557mph, flew out to 4,650 miles and reached up to 33,100 feet of altitude.

The XB-55 would be crewed by ten personnel and the airframe was to hold an overall length of 119 feet, a wingspan of 135 feet and a height of 33.7 feet. Maximum Take-Off Weight (MTOW) was listed at 168,000lb. As in the B-47, the XB-55 was to feature a "bicycle" undercarriage arrangement in which the main legs were held inline under the mass of the body and outrigger legs were used to support the wings. Standard, defensive armament was to include 10 x 20mm cannons while the bomb load reached 24,000lb of stores. The B-47 was defensed by 2 x 20mm cannons and carried around 25,000lb of stores.©MilitaryFactory.com

Advertisements

In many ways the XB-55 was an insurance policy against the B-47 - it was far more conventional in design and held qualities for a bomber influenced by the recent World War but the USAF could at least understand what it was getting without pinning all their hope on the success (or failure) of unreliable, underpowered and thirsty turbojet engines of the time.

Eventually there proved delays with the expected Allison engines which prompted a look into an all-turbojet-powered form by way of the "XB-52" initiative - this design promised considerably better performance figures from the impending arrival of the Pratt & Whitney J57 turbojet engine. Couple this with waning interest on the part of the USAF over the XB-55 (the B-47 was seeing success in service by this point) and the XB-55 project contract was terminated in 1949. It, too, dawned on the USAF that it required a fleet of fast bombers and turboprop-powered forms were not going to be sufficient.

The XB0-55 endeavor lived a short time longer as "Model 479" which studied the use of 6 x Westinghouse J40 turbojet engines along a revised wing element and this data then served the upcoming Boeing B-52 "Stratofortress" strategic heavy bomber program. Leftover funding for the XB-55 went into pursuit of a supersonic strategic bomber under the Boeing "XB-59" designation (Model 701).

As no functional prototype of the XB-55 was ever completed, specifications reported in this article and on this page are purely estimates based on engineering data.©MilitaryFactory.com

Note: The above text is EXCLUSIVE to the site www.MilitaryFactory.com. It is the product of many hours of research and work made possible with the help of contributors, veterans, insiders, and topic specialists. If you happen upon this text anywhere else on the internet or in print, please let us know at MilitaryFactory AT gmail DOT com so that we may take appropriate action against the offender / offending site and continue to protect this original work.

Specifications

Service Year

1947

Origin

United States

Crew

10

Production

0
UNITS

Boeing - USA

(View other Aviaton-Related Manufacturers)

United States (cancelled)

(OPERATORS list includes past, present, and future operators when applicable)

✓ Ground Attack (Bombing, Strafing)
Ability to conduct aerial bombing of ground targets by way of (but not limited to) guns, bombs, missiles, rockets, and the like.

✓ X-Plane (Developmental, Prototype, Technology Demonstrator)
Aircraft developed for the role of prototyping, technology demonstration, or research / data collection.

Length

118.9 ft
(36.25 m)

Width/Span

135.0 ft
(41.15 m)

Height

33.6 ft
(10.25 m)

Empty Wgt

99,208 lb
(45,000 kg)

MTOW

167,992 lb
(76,200 kg)

Wgt Diff

+68,784 lb
(+31,200 kg)

(Showcased structural values pertain to the base Boeing XB-55 production variant)

Installed: 4 x Allison T40-A-2 turboprop engines developing 5,600 horsepower each and driving three-bladed propellers in contra-rotating fashion.

Max Speed

491 mph
(790 kph | 427 kts)

Ceiling

42,651 ft
(13,000 m | 8 mi)

Range

5,005 mi
(8,055 km | 14,918 nm)

♦ MACH Regime (Sonic)

Sub

Trans

Super

Hyper

HiHyper

ReEntry

♦

(Showcased performance specifications pertain to the base Boeing XB-55 production variant. Performance specifications showcased above are subject to environmental factors as well as aircraft configuration. Estimates are made when Real Data not available. Compare this aircraft entry against any other in our database or View aircraft by powerplant type)

STANDARD:
10 x 20mm cannons

OPTIONAL:
Up to 24,000lb of drop stores.

Supported Types

Graphical image of an aircraft automatic cannon

Graphical image of an aircraft conventional drop bomb munition

(Not all ordnance types may be represented in the showcase above)

Hardpoint Mountings: 0

XB-55 - Base Series Designation

Military lapel ribbon for Operation Allied Force

Military lapel ribbon for the Arab-Israeli War

Military lapel ribbon for the Battle of Britain

Military lapel ribbon for the Battle of Midway

Military lapel ribbon for the Berlin Airlift

Military lapel ribbon for the Cuban Missile Crisis

Military lapel ribbon for pioneering aircraft

Military lapel ribbon for the Falklands War

Military lapel ribbon for the French-Indochina War

Military lapel ribbon for the Golden Age of Flight

Military lapel ribbon for the 1991 Gulf War

Military lapel ribbon for the Indo-Pak Wars

Military lapel ribbon for the Iran-Iraq War

Military lapel ribbon for the Korean War

Military lapel ribbon for the 1982 Lebanon War

Military lapel ribbon for the Malayan Emergency

Military lapel ribbon representing modern aircraft

Military lapel ribbon for the attack on Pearl Harbor

Military lapel ribbon for the Six Day War

Military lapel ribbon for the Soviet-Afghan War

Military lapel ribbon for the Spanish Civil War

Military lapel ribbon for the Suez Crisis

Military lapel ribbon for the Ukranian-Russian War

Military lapel ribbon for the Vietnam War

Military lapel ribbon for Warsaw Pact of the Cold War-era

Military lapel ribbon for the WASP (WW2)

Military lapel ribbon for the World War 1

Military lapel ribbon for the World War 2

Military lapel ribbon for the Yom Kippur War

Military lapel ribbon for experimental x-plane aircraft

Ribbon graphics not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective aerial campaigns / operations / aviation periods.

Images Gallery

1 / 1

Image from the Public Domain; Artist impression of the XB-55 bomber proposal.

Advertisements

Disclaimer | Privacy Policy | Cookies

2023 Military Pay Chart Military Ranks DoD Dictionary Conversion Calculators Military Alphabet Code Military Map Symbols

The "Military Factory" name and MilitaryFactory.com logo are registered ® U.S. trademarks protected by all applicable domestic and international intellectual property laws. All written content, illustrations, and photography are unique to this website (unless where indicated) and not for reuse/reproduction in any form. Material presented throughout this website is for historical and entertainment value only and should not to be construed as usable for hardware restoration, maintenance, or general operation. We do not sell any of the items showcased on this site. Please direct all other inquiries to militaryfactory AT gmail.com. No A.I. was used in the generation of this content; site is 100% curated by humans.

Part of a network of sites that includes GlobalFirepower, a data-driven property used in ranking the top military powers of the world, WDMMA.org (World Directory of Modern Military Aircraft), WDMMW.org (World Directory of Modern Military Warships), SR71blackbird.org, detailing the history of the world's most iconic spyplane, and MilitaryRibbons.info, cataloguing military medals and ribbons.

View day-by-day actions of the American Civil War with CivilWarTimeline.net. View day-by-day actions of World War II with SecondWorldWarHistory.com.

©2023 www.MilitaryFactory.com • All Rights Reserved • Content ©2003-2023 (20yrs)