| Model 299: Boeing model number |
| B-17: U.S. Army bomber version |
| B-40: U.S. Army bomber escort. Carried
extra turret and ammo in lieu of bombs |
| BQ-7: U.S. Army pilotless flying bomb |
| CB-17: U.S. Army staff transport |
| DB-17: U.S. Army drone director |
| F-9: U.S. Army photo reconnaissance
version |
| PB-1: U.S. Navy ASW/AEW version/U.S.
Coast Guard SAR |
| QB-17: target drones |
| SR-17: U.S. Air Force SAR version |
| VB-17: U.S. Army VIP transport |
| Y1B-17: U.S. Army service test version |
| Fortress: Royal Air Force designation |