如果真的遇到主伞问题，我们需要切掉主伞，打开备份伞。

If you really have the main umbrella, we need to cut off the main umbrella, open the parachute.

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接着介绍了伞系统的建模方法，重点讨论了主伞衣的模型和降落过程的实现。

Then, it introduces the modeling method of the parachute system, emphasizes the model of the main cloths and the realization of the landing process.

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主伞的顶部开有“天窗”，“天窗”的上端罩有副伞，副伞的上端压有弹簧。

The main umbrella has trap door on the top, the secondary umbrella covers the trap door, and the spring presses the secondary umbrella.

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