Military Factory logo
Icon of F-15 Eagle military combat fighter aircraft
Icon of Abrams Main Battle Tank
Icon of navy warships
Icon of AK-47 assault rifle
HOME
AVIATION
COUNTRIES
MANUFACTURERS
COMPARE
WORLD WAR 2
X-PLANE


Boeing XB-39 (Spirit of Lincoln)


Heavy Strategic Bomber Prototype Aircraft


Intended to test the feasibility of an alternative powerplant, the Allison-powered Boeing XB-39 Superfortress ended its days as a single prototype.
Authored By: Staff Writer | Edited: 9/19/2016
National Flag Graphic

Specifications


Year: 1944
Manufacturer(s): Boeing Company / Fisher (General Motors)
Production: 1
Capabilities: Ground Attack; X-Plane;
Crew: 10
Length: 99.02 ft (30.18 m)
Width: 141.24 ft (43.05 m)
Height: 27.72 ft (8.45 m)
Weight (Empty): 74,516 lb (33,800 kg)
Weight (MTOW): 133,512 lb (60,560 kg)
Power: 4 x Allison V-3420-11 W24 liquid-cooled engines developing 2,100 horsepower each.
Speed: 404 mph (650 kph; 351 kts)
Ceiling: 36,089 feet (11,000 m; 6.84 miles)
Range: 6,251 miles (10,060 km; 5,432 nm)
Rate-of-Climb: 1,000 ft/min (305 m/min)
Operators: United States (cancelled)
Such was the importance of the Boeing B-29 Superfortress to the United States Army Air Forces during the latter stages of World War 2 (1939-1945) that the program was given several fail safes to keep it a viable heavy bomber product moving forwards. This led to a YB-29 developmental machine being set aside by the USAAF for alternative powerplant implementation - assuming that the required stock of problematic Wright R-3350 radial engines would not be available for one reason or another. A modification process was undertaken by Fisher Body (General Motors) in 1944 on the YB-29 aircraft and this went on to produce the XB-39 "Spirit of Lincoln" bomber prototype.

Its basic form and function remained faithful to the original Boeing design but the powerplants in play were now focused on 4 x Allison V-3420-17 series liquid-cooled engine (the original B-29 relied on the aforementioned Wright air-cooled units). Fisher was also using these engines in its (ultimately failed) P-75 "Eagle" long-range escort fighter. Delays in the intended turbosuperchargers dogged the XB-39 project so the first-flight on December 9th, 1944 was had without these installed - though the aircraft provided a successful demonstration nonetheless.

Despite the promising nature of the large aircraft, the Wright air-cooled radials, warts and all, remained the primary focus of the B-29 production campaign, leaving the XB-39 without a battlefield role or notable buyer. Additionally, Fisher was pushed to commit more and more of its resources to the XP-75 fighter prototype which held higher priority for the USAAF at this point in the war. Decisions led to the ultimately abandonment of the XB-39 project with the single prototype being completed and flown (if only for a short time).

As built, the XB-39 held 4 x Allison V-3420-11 liquid-cooled engines of 2,100 horsepower each able to propel the aircraft to speeds of 405 miles per hour out to ranges reaching 6,300 miles and a service ceiling of 35,000 feet. Its crew numbered ten and the armament suite was similar to that of the original B-29 (including remote-controlled turrets and tail cannon). 20,000lb of drop stores could be carried internally.






Armament



STANDARD:
10 x 0.50 cal Browning M2 heavy machine guns in four remote-controlled turrets.
2 x 0.50 cal Browning M2 heavy machine guns and 1 x 20mm M2 cannon in tail unit.

OPTIONAL:
Up to 20,000lb of conventional drop stores held internally.

Graphical image of an aircraft medium machine gun
Graphical image of an aircraft heavy machine gun
Graphical image of an aircrat automatic cannon
Graphical image of an aircraft conventional drop bomb munition

Variants / Models



• XB-39 - Base Project Designation; single, flyable prototype completed.
Site Disclaimer  |  Privacy Policy  |  Cookies  |  Site Map

www.MilitaryFactory.com. Site content ©2003- MilitaryFactory.com, All Rights Reserved.

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.

Part of a network of sites that includes GlobalFirepower, a data-driven property used in ranking the top military powers of the world, and WDMMA.org, the World Directory of Modern Military Aircraft.


Facebook Logo YouTube Logo