| Manufacturer | Designation | nickname |
|---|---|---|
| Elias | EO | |
| Huff-Daland | HO | |
| Martin | M2O | |
| Martin | MO | |
| Naval Aircraft Factory | NO | |
| Boeing | O2B | |
| Curtiss | O2C | Helldiver |
| Douglas | O2D | |
| Loening | O2L | |
| Naval Aircraft Factory | O2N | |
| Vought | O2U | Corasir |
| Curtiss | O3C | Seagull |
| Vought | O3U | Corsair |
| Vought | O4U | |
| Vought | O5U | |
| Boeing | OB | |
| Curtiss | OC | Falcon |
| Douglas | OD | |
| Cessna | OE | Bird Dog |
| Berliner-Joyce | OJ | |
| Keystone | OK | |
| Loening | OL | |
| Viking (Lockheed) | OO | |
| Pitcairn | OP | |
| Convair | OY | Sentinel |
| Vought | UO | |