What is chord line?

The chord line is a straight line drawn between two points on the curve of an airfoil. It can be any straight line that connects any two points on the upper and lower surfaces of the airfoil, but it is usually drawn between the leading edge and the trailing edge. The chord line is an important reference line in aerodynamics because it is used to determine the angle of attack and the lift and drag characteristics of the airfoil. It is also used to calculate the geometric properties of the airfoil, such as the mean camber line and the thickness distribution. The length of the chord line is called the chord length, and it is usually expressed as a percentage of the wing span. For example, a wing with a chord length of 10 feet and a span of 50 feet would have a chord length of 20%.