Boeing B-29 Superfortress variants

The Boeing B-29 Superfortress is a United States Army Air Forces long range, strategic heavy bomber that was produced in many experimental and production models from 1943 to 1946. == XB-29 == Section source: Baugher The XB-29, Boeing Model 345, was the first accepted prototype or experimental model delivered to the Army Air Corps, incorporating a number of improvements on the design originally submitted, including more and larger guns and self-sealing fuel tanks.

Source: Wikipedia — Boeing B-29 Superfortress variants (CC BY-SA 4.0)