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Mean Aerodynamic Chord (MAC)
The Mean Aerodynamic Chord (MAC) is the average chord length of a wing, used as a reference datum for calculating and expressing the aircraft's centre of gravity (CG) limits. The CG position can be expressed as a percentage of MAC for comparison purposes.
Key Points
- •MAC is the chord of an equivalent rectangular wing with the same aerodynamic characteristics as the actual wing.
- •CG position can be expressed as a percentage of MAC for comparison purposes.
- •In CASA workbooks, CG limits are typically expressed in millimetres aft of the datum, not as positions along the MAC directly.
- •MAC data (chord length and leading edge location) can be used to convert a CG position into % MAC.
Exam Relevance
Pilots operating complex or larger aircraft must understand how CG relates to the MAC to ensure the aircraft is loaded within safe limits.
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