| 1938 POUR L AVIAT SOC ET Variable Pitch Airscrew |
| 1938 GEN ELECTRIC Controllable Pitch Propeller Like |
| 1938 PAUL Variable Pitch Airscrew Patent Print |
| 1938 PALMER Controllable Pitch Propeller Patent |
| 1938 PRESTON Controllable Pitch Propeller Patent |
| 1938 BOYD Automatic Variable Pitch Propeller Art |
| 1938 MILDRED M REID Variable Pitch Propeller Art |
| 1938 REID Variable Pitch Propeller Patent Print |
| 1938 MANFRED Variable Pitch Propeller Aircraft |
| 1938 GEN ELECTRIC Controllable Pitch Propeller |
| 1938 GALLAGHER Reverse Variable Pitch Propeller |
| 1938 EDOUARD Airscrew Having A Variable Pitch |
| 1938 LILLEY Automatic Variable Pitch Propeller |
| 1938 EVERTS Variable Pitch Propeller Patent |
| 1938 SMITH Variable Pitch Propeller Patent Print |
| 1938 BENDIX AVIAT CORP Variable Pitch Propeller |
| 1938 EVEREL PROPELLER CORP Variable Pitch Propeller |
| 1938 GROENEVELD Controllable Pitch Propeller Like |
| 1938 BRUNO Variable Pitch Propeller Patent Print |
| 1938 GROENEVELD Controllable Pitch Propeller Art |
| 1938 SMITH Propeller Blade Pitch Regulator Art |
| 1938 ALLRED Variable Pitch Propeller Airplanes Like |
| 1938 AVIAT CORP Controllable Pitch Propeller Art |
| 1938 LAWIEY Variable Controllable Pitch Airscrew |