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COG seems well out using cog tool. NEED HELP!!!!!

Old 10-15-2012, 07:46 PM
  #1  
npowell28
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Default COG seems well out using cog tool. NEED HELP!!!!!

Attached is a picture of my 54 Inch cargo type plane. I've just used the COG tool at this page



http://adamone.rchomepage.com/cg_calc.htm

Using this tool puts the COG about an inch behind the leading edge. This seems mad to me. I'm having to put the batterys about 4-5 inches behind the leading edge to just get the balance. From what i've experienced and read in the past the COG is normally 1/4 to 1/3 of the Root chord measured from the leading edge.

What do you guys think?

Cheers

Neil
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Old 10-15-2012, 08:04 PM
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npowell28
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Forget this one guys. I've sorted it. I won't embarass myself too much other than to say i really should check my measurements.

Thanks all the same
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Old 10-15-2012, 08:12 PM
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JetPlaneFlyer
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I'm confused as to the problem.
1" behind the LE would appear to be further forward that the 1/4-1/3 rule of thumb predicts (I assume the wing chord is more than 4"). And I cant understand how the plane could be balancing that far forward if the battery was installed 5" back from the LE Do you have a big heavy piece of kit in the nose?

It may be helpful if you posted all the necessary dimensions to plug into the calculator.

Steve

PS.. I take it that you know that the flaps and ailerons need to be included in the wing chord dimensions?
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Old 10-15-2012, 08:14 PM
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Sorry, i was typing when you posted your follow up...
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Old 10-15-2012, 08:20 PM
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npowell28
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no probs. I did mean 1 inch behind the TE not the LE. I'd made a mistake in my measurements. I did all the measurements in mm but did the stab measurement in cm's e.g 30 in stead of 300. I've adjusted it now and it comes back fine.
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Old 10-18-2012, 03:14 PM
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Right thats that sorted. Nicely balanced now.

Mental note. Check measurements in future
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Old 10-18-2012, 09:21 PM
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Yakfishingfool
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damn metric system....
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