B-29 Superfortress "DOC"

One of the most technologically advanced airplanes of World War 2, the B-29 had many new features, including guns that could be fired by remote control. Two crew areas, fore and aft, were pressurized and connected by a long tube over the bomb bays, allowing crew members to crawl between them. The tail gunner had a separate pressurized area that could only be entered or left at altitudes that did not require pressurization.

The B-29 was also the world’s heaviest production plane because of increases in range, bomb load and defensive requirements.