Real-time simulation of Chinese tops using physically-based methods

The Chinese Top is a toy propeller which hovers around through rotating its shaft. Though this toy was created about thousand years ago, it shows exactly the same aero-dynamics behavior to the helicopter rotary wings. Based on the aero-dynamics theories such as Blade Element Theory and Momentum Theory, we analyze all the physical forces causing the dynamic motions of the Chinese tops: the lift, thrust, drag and gravity forces. From the system of force equations, we simplified the final force equations and finally calculated the velocity and angular velocity. Our prototype implementation shows that all the four kinds of forces can be calculated in real time, to finally generate real-time simulation of Chinese tops. Furthermore, since our force equations contain physically-based parameters, we can generate various motions of Chinese tops, through controlling user-controllable parameters. Our works are fundamental steps for the real-time simulation of helicopter or similar objects, and we are now implementing a real-time helicopter simulation system.