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Old Dec 15, 2012, 07:26 PM
Red Beard
United States, PA
Joined Jun 2007
48 Posts
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fun cub centre of gravity is way off

the book says 80mm back should be the centre of gravity. even if i put my battery almost all the way back it is still way to front heavy. has anyone else had this problem?? what should i do??
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Old Dec 15, 2012, 10:42 PM
Registered User
Livermore, CA
Joined Sep 2004
8,577 Posts
Are you using the recommended battery and motor?

I've had to carve out some foam to move the batt.
I've had to add some weight to the tip of the tail or nose, to get the C/G.
I've moved the esc, servos, rx and what ever I could.

It may be best to weight the tail, test fly it and see if it really is that far off.
A nose heavy plane is more controllable than a tail heavy one.
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Old Dec 15, 2012, 10:52 PM
Red Beard
United States, PA
Joined Jun 2007
48 Posts
Quote:
Originally Posted by Butch777 View Post
Are you using the recommended battery and motor?

I've had to carve out some foam to move the batt.
I've had to add some weight to the tip of the tail or nose, to get the C/G.
I've moved the esc, servos, rx and what ever I could.

It may be best to weight the tail, test fly it and see if it really is that far off.
A nose heavy plane is more controllable than a tail heavy one.
I'm using the recommended battery and the plane came rtf from multiplex. I guess I'll add weight to the tail
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Old Dec 16, 2012, 01:11 AM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by redbearddebspike View Post
the book says 80mm back should be the centre of gravity. even if i put my battery almost all the way back it is still way to front heavy. has anyone else had this problem?? what should i do??
CG is also a matter of personal preference. Some FunCub pilots prefer the CG at 65-70mm. So how far off are you really?

Jürgen
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Old Dec 16, 2012, 08:02 AM
ltc
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United States, MA, Mendon
Joined Mar 2010
2,257 Posts
When you say "way too front heavy", exactly where the is CG?

Did you do anything else different compared to stock? Larger servos, paint, landing gear, spinner...anything that might affect balance?
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Old Dec 16, 2012, 01:10 PM
Registered User
Huesca, Spain
Joined Aug 2009
510 Posts
The FC is very tolerant when it comes to the CofG.

As Jurgen said, it's often a matter of personal preference which is also related to how you want to fly the model.

When I built my FC I stuffed a 2200mah lipo as far back as it would go. My CofG worked out at 73mm from the LE of the wing which was within the range that many others were recommending.

I have flown the FC from day one with this setting and haven't felt the need to change it. In fact I've found that at this setting the model will fly inverted with no elevator required to mainmtain level flight.

Steve.
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