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Boeing XB-39 (Spirit of Lincoln)

United States (1944)
Picture of Boeing XB-39 (Spirit of Lincoln) Heavy Strategic Bomber Prototype Aircraft
Picture of 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.


Detailing the development and operational history of the Boeing XB-39 (Spirit of Lincoln) Heavy Strategic Bomber Prototype Aircraft.  Entry last updated on 9/19/2016. Authored by Staff Writer. Content ©www.MilitaryFactory.com

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.

Any available statistics for the Boeing XB-39 (Spirit of Lincoln) Heavy Strategic Bomber Prototype Aircraft are showcased in the areas immediately below. Categories include basic specifications covering country-of-origin, operational status, manufacture(s) and total quantitative production. Other qualities showcased are related to structural values (namely dimensions), installed power and standard day performance figures, installed or proposed armament and mission equipment (if any), global users (from A-to-Z) and series model variants (if any).






Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

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Relative Maximum Speed Rating
Hi: 500mph
Lo: 250mph
    This entry's maximum listed speed (404mph).

    Graph average of 375 miles-per-hour.
City-to-City Ranges
NYC
 
  LON
LON
 
  PAR
PAR
 
  BER
BER
 
  MOS
MOS
 
  TOK
TOK
 
  SYD
SYD
 
  LAX
LAX
 
  NYC
Graph showcases the Boeing XB-39's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era
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Pie graph section
Pie graph section
Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
1
1


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
Small airplane graphic
  Compare this entry against other aircraft using our Comparison Tool  
National Flag Graphic
Origin: United States
Year: 1944
Type: Heavy Strategic Bomber Prototype Aircraft
Manufacturer(s): Boeing Company / Fisher (General Motors)
Production: 1
Global Operators:
United States (cancelled)
Historical Commitments / Honors:

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 Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
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 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 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
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.
Measurements and Weights icon
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Boeing XB-39 model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
10


Dimension
LENGTH


Feet
99.02 ft


Meters
30.18 m


Dimension
WIDTH


Feet
141.24 ft


Meters
43.05 m


Dimension
HEIGHT


Feet
27.72 ft


Meters
8.45 m


Weight
EMPTY


Pounds
74,516 lb


Kilograms
33,800 kg


Weight
LOADED


Pounds
133,512 lb


Kilograms
60,560 kg

Engine icon
Installed Power - Standard Day Performance:
4 x Allison V-3420-11 W24 liquid-cooled engines developing 2,100 horsepower each.

Performance
SPEED


Miles-per-Hour
404 mph


Kilometers-per-Hour
650 kph


Knots
351 kts


Performance
RANGE


Miles
6,251 mi


Kilometers
10,060 km


Nautical Miles
5,432 nm


Performance
CEILING


Feet
36,089 ft


Meters
11,000 m


Miles
6.84 mi


Performance
CLIMB RATE


Feet-per-Minute
1,000 ft/min


Meters-per-Minute
305 m/min

Supported Weapon Systems:

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
Armament - Hardpoints (0):

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.
Variants: Series Model Variants
• XB-39 - Base Project Designation; single, flyable prototype completed.