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mean aerodynamic chord (MAC) — Aviation Definition | Keynomen Aviation

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mean aerodynamic chord (MAC)

MAC is the abbreviation for mean aerodynamic chord.

Plain English Meaning

A real wing usually changes shape from root to tip, which makes it hard to point to one chord line that represents the whole wing. The mean aerodynamic chord is a single calculated chord that stands in for the whole wing for weight and balance and stability calculations.

Full Definition

The chord of an imaginary rectangular wing that would produce the same aerodynamic forces and pitching moment as the actual wing. It is used as the standard reference length for expressing the location of the center of gravity (CG) and aerodynamic center on tapered or swept wings.

mean aerodynamic chord (MAC)

Context Anchor

Seen in weight-and-balance information, aircraft loading data, and center-of-gravity limits, often written as a percent of MAC.

Derivation

‘Mean’ here comes from the Latin sense of ‘average,’ and ‘aerodynamic’ refers to forces produced by air flowing over the wing. So the term literally describes an averaged chord weighted by where the wing actually does its lifting work — not a simple geometric average.

Why Pilots Care

The center of gravity location is expressed as a percentage of MAC to confirm the aircraft stays within its stable and controllable range.

Grounding Statement

MAC gives one usable wing measurement for an airplane whose wing may taper or change shape from root to tip.

Intuition Check

“Mean” does not mean poor or harsh here; it means average. MAC is not the exact chord at every point on the wing—it is one representative chord used for aerodynamic and balance calculations.

Example Sentence 1

The aircraft’s forward CG limit is published as 17 percent of the mean aerodynamic chord.

Example Sentence 2

The pilot checked that the aircraft remained within the forward and aft MAC limits before flight.