B-29A 42-93844 in flight
The B-29 vs. the B-29A
Key differences between the B-29 and the B-29A Superfortress models:
- Wing Construction: The most significant difference between the B-29 and B-29A was the wing construction and how the wing was attached to the fuselage. The B-29 had a two-piece wing center section that was bolted together at the center line and installed as a single unit, passing through the fuselage to support the engine nacelles. In contrast, the B-29A employed a short stub center section that did not extend beyond the fuselage sides. Each pair of engine nacelles was fitted to a separate short section of wing, while the outer wing panels were attached at the same point on both the B-29 and B-29A models.
- Fuel Capacity: Because of the B-29A’s wing construction, it had a reduced fuel load by about 200 gallons compared to the B-29.
- Wingspan: Many aviation publications incorrectly claim that the B-29A’s wingspan was a foot longer than that of the B-29. Official USAAF documentation indicates that both the B-29 and B-29A shared an identical wingspan of 141ft 3in.
- Engine Type: While the B-29 was equipped with Wright R-3350-23, -23A, or -41 engines, the B-29A was powered by four Wright R-3350-57 engines.
- Armament: The B-29A’s forward dorsal turret was up-gunned to four .50-caliber machine guns, and the 20mm cannon was removed from the tail turret.
- Production Location: While B-29 production was split between Boeing, Glenn L. Martin, and Bell Aircraft Corporation, all 1,119 B-29A models were constructed at Boeing’s Renton plant.
In addition to these major differences, it’s important to note that both the B-29 and B-29A models experienced numerous changes throughout their production runs. To manage these modifications, the USAAF implemented a production block system. Airframes within a specific production block were built to the same specifications, allowing for consistent output. Each production block had a code indicating the manufacturing site.