RC Slope Soaring in Hong Kong

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 Post subject: 新手CG問題!
PostPosted: Thu Jun 17, 2004 5:48 pm 

Joined: Wed Mar 03, 2004 12:08 am
Posts: 42
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!


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 Post subject:
PostPosted: Thu Jun 17, 2004 5:56 pm 
係,槓桿原理。


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 Post subject:
PostPosted: Thu Jun 17, 2004 6:10 pm 
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Joined: Thu Feb 26, 2004 5:08 pm
Posts: 3081
Location: Hong Kong
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:


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 Post subject:
PostPosted: Thu Jun 17, 2004 6:14 pm 
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Joined: Thu Feb 26, 2004 5:08 pm
Posts: 3081
Location: Hong Kong
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.


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 Post subject:
PostPosted: Thu Jun 17, 2004 6:22 pm 

Joined: Wed Mar 03, 2004 12:08 am
Posts: 42
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?


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 Post subject:
PostPosted: Fri Jun 18, 2004 12:39 pm 

Joined: Sat Apr 03, 2004 10:27 pm
Posts: 44
床板 :roll:


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