What is the term for the line drawn from the leading to trailing edge of an airfoil, halfway between the upper and lower surface?

The term that refers to the line drawn from the leading edge to the trailing edge of an airfoil, positioned halfway between the upper and lower surfaces, is the Mean Camber Line. This line indicates the average curve of the airfoil and is crucial for understanding the airfoil's performance characteristics, such as lift and drag. The mean camber line is indicative of how the airfoil shape is designed to affect airflow over the surfaces, thereby influencing the aerodynamic properties.

In contrast, the Chordline typically refers to a straight line connecting the leading edge to the trailing edge of the airfoil itself, rather than being positioned between the upper and lower surfaces. The Reference Line could be a more generic term but does not specifically define the mean curvature at half the airfoil's height. The Center of Pressure is a point where the total aerodynamic force is considered to act; it does not describe a line or curve relating to the airfoil's shape. Understanding these distinctions helps clarify why the Mean Camber Line is the correct choice.