What is the infinite line drawn directly from the leading to trailing edge of an airfoil called?

The infinite line drawn directly from the leading edge to the trailing edge of an airfoil is referred to as the chordline. This line represents the straight distance between these two points on the airfoil and serves as a reference line for various aerodynamic calculations.

The chordline is particularly important in defining the airfoil's geometry and is utilized to determine the angle of attack, which is a crucial factor in understanding lift and drag characteristics. It provides a baseline for measuring camber and other significant properties of the airfoil's shape. Understanding the role of the chordline helps in analyzing how the airfoil interacts with airflow, ultimately influencing its performance.

Other terms like "mean camber line" and "camber axis" relate to the airfoil's curvature and are defined differently. The mean camber line represents the centerline of the airfoil's shape, while "flow line" pertains to the path fluid particles take as they flow around the airfoil, which is not the same as the physical line from leading to trailing edge.