Keystone Y1B-4 (S/N 30-281). The first B-3A was converted to Y1B-4 configuration with the addition of R-1860-7 radial engines and low pressure tires. ( Air Force photo)

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Size: 1929px × 1296px
Photo credit: © PJF Military Collection / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: air, airforce, force, military, states, united, usa