Definition
An imaginary straight line drawn from the leading edge of an airfoil to the trailing edge. It serves as the reference line used to measure the angle of attack (the angle between the chord line and the relative wind).
Plain English
A straight line running from the front of the wing to the back. It's the reference line pilots and engineers use when talking about how the wing meets the oncoming air.
Context Anchor
Seen in stall training and basic aerodynamics, especially when explaining angle of attack.
Derivation
From the Latin chorda, meaning 'string' or 'cord.' In geometry, a chord is a straight line connecting two points on a curve. Since an airfoil has a curved shape, the line connecting its front and back points is its chord.
Why Pilots Care
The chord line lets pilots and designers measure angle of attack accurately, which determines lift, stall onset, and safe operating limits.
Analogy
Imagine laying a straight ruler across the side view of a wing shape from the front point to the back point. That ruler is like the chord line.
Intuition Check
Do not think of the chord line as the curved top or bottom surface of the wing. It is an imaginary straight line from the wing shape’s front edge to its back edge.
Example Sentence 1
The angle of attack is measured between the chord line of the wing and the relative wind.
Example Sentence 2
Camber is measured as the maximum distance from the chord line to the upper or lower surface of the wing.