| Manufacturer | Designation | nickname |
|---|---|---|
| Douglas | R2D | |
| Fairchild | R2K | |
| Lockheed | R2O | |
| Fairchild | R2Q | |
| Consolidated | R2Y | |
| Douglas | R3D | |
| Lockheed | R3O | |
| Stinson | R3Q | Reliant |
| Consolidated | R3Y | Tradewind |
| Curtiss | R4C | |
| Douglas | R4D | Skytrain |
| Lockheed | R4O | |
| Fairchild | R4Q | Flying Boxcar |
| Convair | R4Y | Samaritan |
| Curtiss | R5C | Commando |
| Douglas | R5D | Skymaster |
| Lockheed | R5O | Lodestar |
| Douglas | R6D | Liftmaster |
| Lockheed | R6O | Constitution |
| Lockheed | R6V | Constitution |
| Lockheed | R7V | Constellation |
| Atlantic | RA | |
| Budd | RB | Conestoga |
| Curtiss | RC | Kingbird |
| Douglas | RD | Dolphin |
| Bellanca | RE | |
| Kinner | RK | |
| Lockheed | RO | |
| Fairchild | RQ | |
| Stinson | RQ | Reliant |
| Ford | RR | Tri-motor |
| Sikorsky | RS | |
| Northrop | RT | Delta |
| Consolidated | RY | Liberator Express |