Definition
An imaginary line drawn through an airfoil section, equidistant at all points between the upper and lower surfaces, running from the leading edge to the trailing edge. The shape and curvature of this line describe how much the airfoil is curved overall.
Plain English
A line drawn down the middle of a wing's cross-section, exactly halfway between the top and bottom surfaces. Its curvature shows how much the wing is bent or arched from front to back.
Context Anchor
Seen in airfoil, wing, and propeller-blade discussions, especially when describing shape, lift, and aerodynamic performance.
Derivation
"Mean" here means "average" or "middle" -- the line that sits in the middle between the two surfaces. "Camber" comes from the Old French "cambre," meaning "curved" or "arched." Together: the average curve of the airfoil.
Why Pilots Care
The position and shape of this line directly influence the amount of lift an airfoil generates at a given angle of attack.
Grounding Statement
If you sliced through a wing and drew a line halfway between the top and bottom of that slice, that line would show the mean camber.
Intuition Check
Mean does not mean harsh or unkind here; it means middle or average. Mean camber is not the outside surface of the wing—it is an imaginary middle curve used to describe the wing’s shape.
Example Sentence 1
The mean camber line of a training aircraft's wing curves noticeably upward, helping the wing produce lift at lower speeds.
Example Sentence 2
A positive mean camber means the midline sits above the straight reference line running from leading edge to trailing edge.