Find Your Model's Center of Gravity (CG) You can use this method.
At the wing root, draw a reference line that extends after from the trailing edge that's parallel to the fuselage centerline. This line should be the same length as the tip chord. see reference (a) = (a)
At the wingtip, draw another reference line forward of the tip that's the same length as the root chord. see reference (b) = (b)
Now find the center of the root chord and tip chord and connect the points with centerline.
Draw a diagonal line between the ends of the two entension reference lines at the tip and the root chord.
To Find Mean Aerodynamic Chord (MAC) Located
The point at which the diagonal line and the centerline interset is spanwise location of the MAC. At this location, draw the MAC reference line parallel to the root and tip chord line
To determine the CG location, measure the required % or distance from the leading edge back along the MAC Where should your CG fall ?
Generally, CG should fall somewhere in the MAC's 25% to 30% range. For example, on the a 12" constant chord wing, the 28% MAC is 3 3/8" back from the leading edge (0.28 x 12 = 3 3/8" )
Balance Your Model Once you have found the correct CG, balance your model accordingly. For low-wing models, balance them upside-down
For high-wing models, can be balance right-side-up. You should also balance your model laterally (wingtip to wingtip). Loop a piece of string around the fuselage just ahead of the stabilizer, grab it and the prop shaft, and lift. Add weight to the high wing until the model balances with its wing level.
For easy..please check this link for auto calculation on CG http://sky.prohosting.com/air2/cg_calc.htm
p/s these calculations are based on the real aircraft calculation on determining the CG for a level flight and fuel consumptions.
by
ash ketchum
got the let them go ooo
How To Find Air Craft Centre of Gravity (CG)
