The M.A.C. Calculator

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

Enter Root Cord (A):  MAC Graphic
Enter Tip Cord (B): 
Enter Sweep Distance (S):
Enter Half Span (Y):
Enter Center of Gravity (CG):
Sweep Distance @ MAC (C) =
Mean Aerodynamic Cord (MAC) =
MAC Distance from Root (d) =
% Mean Aerodynamic Cord (%MAC) =
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))
%MAC B.P.  = ((CG-C) / MAC)*100

Reposted with permission from the Palos R/C Flying Club.