Definition
An imaginary straight line drawn from the leading edge to the trailing edge of an airfoil, used as a reference for measuring angles such as the angle of attack and the angle of incidence.
Plain English
A straight reference line running from the front of a wing or propeller blade to the back. It is not a physical line on the wing, just a line used to measure things like how the wing meets the air.
Context Anchor
Seen in airfoil and propeller blade discussions, especially when describing blade angle, pitch, or angle of attack.
Derivation
From geometry, where a 'chord' is a straight line connecting two points on a curve. The chordline does the same thing across the curved shape of an airfoil — front edge to back edge.
Why Pilots Care
The chordline is the reference for angle of attack. Without it, terms like 'angle of attack' and 'angle of incidence' have no anchor. Understanding the chordline is the foundation for understanding lift and stall.
Analogy
Picture laying a straight ruler from the front tip of a curved wing shape to the back tip. The ruler shows the chordline, even though the wing surface itself is curved.
Intuition Check
The chordline is not the curved surface of the wing or blade. It is an imaginary straight line used as a reference.
Example Sentence 1
The angle of attack is measured between the chordline of the wing and the oncoming relative wind.
Example Sentence 2
The technician checked the propeller blade for damage along its chordline during the inspection.