Boeing XB-39 (Spirit of Lincoln)

History

The importance of the Boeing B-29 Superfortress to the U.S. Army Air Force in the late WW2 period (1939-1945) was that the program received multiple fail-safes to maintain its viability as a heavy bomber product moving forward . This led the USAF to shelve a YB-29 development machine to implement a replacement engine - believing that for some reason the required inventory of problematic Wright R-3350 radial engines would not be available.

In 1944, Fisher Body (General Motors) modified the YB-29 aircraft to produce the XB-39 "Lincoln Spirit" prototype bomber.

Its basic form and function remain the same as the original Boeing design, but the engines are now centered around 4 x Allison V-3420-17 series liquid-cooled engines (the original B-29 relied on the aforementioned Wright air-cooled engines). refrigerated equipment). Fisher also used these engines in his (eventually unsuccessful) long-range P-75 Eagle escort fighter.

Delays in ordering the turbochargers hampered the XB-39 program, so the first flight on December 9, 1944, did not have them installed - although the aircraft still made a successful demonstration.

Despite the promise of the large aircraft, Wright's air-cooled Meridian, warts and all components remained the primary focus of B-29 production activity, leaving the XB-39 with no battlefield role or significant buyer. Additionally, Fisher was forced to devote more and more resources to the XP-75 prototype fighter, which was a higher priority for the Air Force at this stage of the war.

The decision eventually led to the abandonment of the XB-39 project, and the only prototype was completed and flown (albeit for a short time).

As shipped, the XB-39 contains 4 Allison V-3420-11 liquid-cooled engines, each producing 2,100 horsepower, propelling the aircraft to a speed of 405 mph, with a range of 6,300 miles and a service limit of 100 kilometers /h can bring 35,000 feet. Crew of 10, armament similar to the original B-29 (including remote control turret and tail gun).

20,000 lbs can be transported internally.

Specification

Basic

Production

Roles

Dimensions

Weight

Performance

Performance

Armor

Changes