What does MAC stand for in CG calculations?

• A. Mean Aerodynamic Chord
• B. Mean Axial Chord
• C. Maximum Aerodynamic Coordinate
• D. Mean Airspeed Constant

Answer: (A)

Mean Aerodynamic Chord is the reference length used in center of gravity calculations because it represents a single chord length that corresponds to the wing’s actual lift distribution. The MAC is defined as the chord length of a hypothetical wing segment that would produce the same total lift distribution as the real wing; it’s computed from the wing’s chord variation across the span (often shown as MAC = (2/S) ∫ c^2 dy). In CG work, the aircraft’s CG is commonly expressed as a percentage of the MAC, providing a consistent way to compare different wing geometries. The other terms aren’t standard in this context and don’t relate to how CG is tied to the wing’s lift characteristics.