| 摘要 |
PURPOSE:To avoid making the diameter of screw propeller blades larger, by attaching rotary blades 14 like turbine blades and thrust blades in the rear of the former on a propeller cap body which is arranged rotatably in the rear of a screw propeller. CONSTITUTION:A plurality of rotary blades 14 like turbine blades, having a diameter less than of a screw propeller 12 are radially attached to a propeller cap body 13 which is rotatably arranged in the rear of the screw propeller 12 driven by a propeller shaft 11. These blades 14 are adapted to retrieve rotating energy in the back wash of the propeller 12. Further, a plurality of thrust blades 15 like turbine blades having a diameter less than that of the propeller 12 are radially attached to the propeller cap body 13 in the rear of the blades 14. When the blades 15 are rotated, thrust is produced. As a result it is possible to avoid making the diameter of the proper larger, and to make the blades lightweight and to reduce the cost of blade materials.
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