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新手CG問題!
http://www.rcsail.com/forum/viewtopic.php?f=3&t=160
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Author:  Henry Chan [ 17 Jun 2004 05:48 pm ]
Post subject:  新手CG問題!

可能係一個好簡單既CG問題.
好多機都要放好多鉛係機頭個CG先正確, 如果D機設計既時候做到個頭長D, 咁咪可以落小D鉛黎戥CG?

Thanks!

Author:  Willy (as guest) [ 17 Jun 2004 05:56 pm ]
Post subject: 

係,槓桿原理。

Author:  CM Cheng [ 17 Jun 2004 06:10 pm ]
Post subject: 

Yes, but there is a side effect. The moment of inertia is proportional to the square of the distance. This means if you double the length of the nose, yes you can save half of the nose weight. But at the same time the moment of inertia is four times of the original. This makes the plane difficult to control.

So better makes the tail lighter! :wink:

Author:  CM Cheng [ 17 Jun 2004 06:14 pm ]
Post subject: 

CM Cheng wrote:
. . . But at the same time the moment of inertia is four times of the original. . . .


Sorry, should be TWO times as the mass is half of the original now.

Author:  Henry Chan [ 17 Jun 2004 06:22 pm ]
Post subject: 

Thanks CM, your Physics is really great!
So there should be a balance point between moment of inertia and nose distance? If weight is not an issue, an ideal plane should have no nose, and vice versa?

Author:  rocky [ 18 Jun 2004 12:39 pm ]
Post subject: 

床板 :roll:

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