chord

An airfoil is a shaped surface, like an airplane wing or propeller blade, designed to create lift and drag when moving through the air. Lift is a force perpendicular to the airstream, while drag is a force parallel to it. High-speed aircraft often use thin, streamlined airfoils for low drag and lift, whereas slower aircraft may use thicker airfoils for higher lift and drag.1

The chord is a straight line segment connecting the leading and trailing edges of an airfoil. In helicopters, rotor blades are airfoils, and their chord line is crucial for understanding flight dynamics, including the angle of attack, which determines lift.23