Chord line location question: The chord line of an airfoil is defined as an imaginary straight line drawn from which points?

• A. Leading edge to trailing edge
• B. Leading edge to mid-chord
• C. Root to tip
• D. Nose to tail

Answer: (A)

The line that defines the airfoil’s chord runs straight from the leading edge to the trailing edge of the surface. This is the reference line for the airfoil’s cross-section—the direction of the chord and the baseline for measuring the angle of attack, which is the angle between this chord line and the oncoming airflow. Connecting the line from the leading edge to mid-chord or from root to tip would describe different references (mid-chord line or spanwise direction, respectively), and linking nose to tail describes the aircraft’s longitudinal axis, not the airfoil’s cross-sectional chord. Therefore, the chord line is from the leading edge to the trailing edge.