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BOEING XB-39 SUPERFORTRESS
Operational History

Fisher finally focused again on the B-39. The first flight of the B-39 was made on 9 December 1944 at Cleveland, Ohio. The initial flight tests of the B-39, without turbosuperchargers installed, were impressive. However, the B-39 program was by now seriously delayed, and the flawed R-3350 B-29s had already been rushed into combat in June 1944.


Boeing-GM XB-39 Superfortress/41-36954.
[Source: Unknown]

Despite continuing problems with the B-29s, the aircraft was functioning well enough in combat that it no longer made any sense to shift resources in the manufacturing base to a new engine for the B-29 and so the B-39 was not ordered into production.

Sources:
Wikipedia
U.S.A.A.F. RESOURCE CENTER > EXPERIMENTAL > PREVIOUS PAGE