The C.G. Calculator

The form shown below will calculate the position of the Center of Gravity (CG) of a model airplane wing as measured from the leading edge of the Root Chord. If you would like to know the percentage of the Mean Aerodynamic Chord (MAC) for a given position of the CG you should use the form on The Mean Aerodynamic Chord Page.
 

Enter Root Chord (A):  cg.gif
Enter Tip Chord (B): 
Enter Sweep Distance (S):
Enter Half Span (Y):
Enter %MAC Balance Point:
Sweep Distance @ MAC (C) =
Mean Aerodynamic Chord (MAC) =
MAC Distance from Root (d) =
Balance Point @ Root Chord (CG) =
The Equations
C = (S(A+2B)) / (3(A+B))
MAC = A-(2(A-B)(0.5A+B) / (3(A+B)))
d = (2Y(0.5A+B)) / (3(A+B))
CG = %MAC B.P.*(MAC) + C

A good starting point for the %MAC  is about 25-35 percent.

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