Welcome to Heathcote Soaring League

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.

Enter Root Cord (A):
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**

C.G. Calculator

This form will calculate the position of a Center of Gravity (CG) on a model airplane wing as measured from the leading edge of the Root Chord.

Enter Root Chord (A):
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**

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