| 摘要 |
<p>The propeller has one elliptically shaped blade (13) which has a stiffening bar (14) along one edge. This blade has a propulsive effect. At its inner end the propulsive blade is joined to a balancing blade (12) which is a compact weight of any shape. Its weight is such that the centre of gravity of the assembly is near the inner end of the propulsive blade. When allowed to fall freely the propeller begins to rotate about its centre of gravity and the rate of fall is retarded. It has applications in fireworks and publicity devices and can also be used to propel bodies through fluids.</p> |
