| 1 | For the next 20 years, various propeller driven aircraft served the President. | |
| 2 | "We saw the helicopter propellers fly all over, " she said. | |
| 3 | The first aeroplanes were driven by propellers and they flew slowly by present day standards. | |
| 4 | His jet needed no propellers. It was a tube, open at both ends. | |
| 5 | He conducted tests to show that they could recognize different vessels by the sounds of their propellers. |