| XB-39 Superfortress | |
|---|---|
 Boeing XB-39 serial number: 41-36954 | |
| General information | |
| Type | Heavy bomber |
| Manufacturer | Boeing |
| Primary user | United States Army Air Forces |
| Number built | 1 |
| History | |
| Manufactured | 1944 |
| First flight | 9 December 1944 |
| Developed from | Boeing B-29 Superfortress |
The Boeing XB-39 Superfortress was a United States prototype bomber aircraft, a single example of the B-29 Superfortress converted to fly with alternative powerplants. It was intended to demonstrate that the B-29 could still be put into service even if the first choice of engine, the air-cooled Wright R-3350 radial engine, ran into development or production difficulties.