Cant get CG on my plane
02-16-2010, 09:21 PM
#27
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RE: Cant get CG on my plane
I don't know how scale the KMP AT6 is but working from a scale drawing and info 30% of the MAC would be almost exactly in line with the windscreen frame. Where are you measuring from ?
02-16-2010, 09:29 PM
#29
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RE: Cant get CG on my plane
Make 9 measurements with a yardstick, plug them into this online application and you'll have an excellent idea where the CG range should be for a reliable, stable 1st flight http://www.geistware.com/rcmodeling/cg_super_calc.htm
It takes about 15 minutes to make the measurements and no time to use the app. Do the 1st run with 15% static margin and the 2nd run with 5%. That'll give you a completely reliable range.
It takes about 15 minutes to make the measurements and no time to use the app. Do the 1st run with 15% static margin and the 2nd run with 5%. That'll give you a completely reliable range.
02-16-2010, 10:26 PM
#32
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RE: Cant get CG on my plane
DaRock is right , that's a very good calculator , you have to just realise that you have a parallel section of wing at the root which will alter it slightly , but not enough to worry about . When you say 1/8 to a 1/4 before the windscreen , is that the front of the screen or at the frame where the canopy would slide from ? The correct position on a true scale would be right at the windscreen frame /sliding canopy joint , that's at about 30% MAC
02-16-2010, 11:41 PM
#34
RE: Cant get CG on my plane
A graphic calculation, based on the full scale airplane, locates the CG of this model of 61.4" wing span at 3.76" behind the leading edge, measured to the wing root (25% of MAC).
02-18-2010, 08:38 PM
#35
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RE: Cant get CG on my plane
WOW! I feel like a real dummy when I read and see the calculations everyone comes up with! Im still fairly new to this, but the help has been great. Im finally getting the CG where it needs to be. Had to move servos and batteries forward some, but the factory CG was also incorect. This will make you laugh. Last nite I called KMP about their crappy plane, and told them about my problems I've been having with the plane. First off, the guy I spoke with was not familiar with the plane. Then he told me it was not uncommon for a composite fusalage to be tail heavy. Then he told me to just keep adding weight to the nose untill it balances out. He said the this plane would fly just fine all the way up to 10lbs. This is a plane that only weighs 6.5lbs. Can anyone say customer service, or product support? This will be my last KMP product.
