If a CG is located at 24% of MAC, this percentage expresses distance from which reference?

If a CG is located at 24% of MAC, this percentage expresses distance from which reference?

• A. The datum
• B. The LEMAC
• C. The leading edge
• D. The trailing edge

Answer: (B)

The distance expressed as a percent of MAC is measured from the leading edge of the mean aerodynamic chord, the LEMAC. This reference is used because the MAC represents the wing’s average chord for aerodynamic behavior, and expressing CG location relative to its leading edge provides a consistent, normalized way to compare aircraft regardless of wing shape. So a CG at 24% of MAC means it lies 0.24 times the MAC length aft of the leading edge of the MAC. The datum or the outer leading/trailing edges aren’t the standard reference for this particular percentage, which is why the correct reference is the LEMAC.

The distance expressed as a percent of MAC is measured from the leading edge of the mean aerodynamic chord, the LEMAC. This reference is used because the MAC represents the wing’s average chord for aerodynamic behavior, and expressing CG location relative to its leading edge provides a consistent, normalized way to compare aircraft regardless of wing shape. So a CG at 24% of MAC means it lies 0.24 times the MAC length aft of the leading edge of the MAC. The datum or the outer leading/trailing edges aren’t the standard reference for this particular percentage, which is why the correct reference is the LEMAC.