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help with finding c.g Point on some planes

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help with finding c.g Point on some planes

Old 03-26-2015, 01:07 PM
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rcworld2000
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Default help with finding c.g Point on some planes

Ok guys I bought a delta wing this weekend as well as a plane that is like a high but not a trainer not sure of maker on it. The delta was a scratch built.

What I need to know is how to find the cg points for these plans?
Old 03-26-2015, 05:04 PM
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GSXR1000
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Originally Posted by rcworld2000 View Post
Ok guys I bought a delta wing this weekend as well as a plane that is like a high but not a trainer not sure of maker on it. The delta was a scratch built.

What I need to know is how to find the cg points for these plans?
Here you go my friend

http://fwcg.3dzone.dk/
for delta wing use this site, while following these guidelines.

Delta wings have no horizontal stabilizer so in a way they are a flying wing with an extremely low aspect ratio... so they must follow some of the same airfoil and CG layouts of the flying wing. This means that it must be set up slightly nose heavy, and have an airfoil with a Positive pitching moment. You can use the WebPages way of finding the location if the wing has a tip chord, if it tapers all the way to the tip, just go to the point halfway between the tip and the Centerline of the fuselage. At this point draw a straight line from trailing edge to leading edge. Measure 15-20% back from the leading edge and draw a perpendicular line to the fuselage... that is where the CG will go. If it has a tip chord, use the method in the WebPages and substitute 80-85% in for the 75%... It will need to have an aerodynamic force behind the CG pushing down to counter the weight in the nose so you either need to plan on having extra up elevator throw and always flying with it trimmed up a little. You can use an airfoil with a Positive pitching moment like flying wing airfoils. You can try moving the CG farther back and using less elevator to counter it and see what happens... but start off with a little room to work with.

http://adamone.rchomepage.com/cg_calc.htm
for regular aircraft

Last edited by GSXR1000; 03-26-2015 at 08:25 PM.
Old 03-27-2015, 04:09 AM
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rcworld2000
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Thank you very helpful.

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