Contra-Rotating Propeller Model

这是一个演示玩具，展示了如何使用锥齿轮使同轴轴向相反方向旋转。在实际的推进系统中，内轴将由发动机直接驱动，外轴通过齿轮链向相反方向旋转。
This is a demonstration toy to show how bevel gears can be used to make coaxial shafts rotate in opposite directions. In a practical propulsion system, the inner shaft would be driven directly by the engine, and the outer shaft made to rotate in the opposite direction via the gear chain. As a demonstration toy, I made the handle to come out from the "intermediate" gear.