What is meant by the mean camber line of a wing?

The mean camber line of a wing refers to the line that runs along the length of the wing and represents the average curvature. It is situated halfway between the upper and lower surfaces of the airfoil and provides an indication of the overall shape of the wing. This concept is critical in aerodynamics, as it directly influences the lift characteristics and flight performance of the airfoil. By understanding the mean camber line, one can analyze how the air flows over the wing, which affects the lift generated during flight.

The other options do not accurately capture the essence of the mean camber line. A line that runs outside the wing's structure does not represent the internal aerodynamic characteristics that the mean camber line embodies. A line of equal thickness would imply a uniformity that doesn't account for varying curvature, and a line indicating wing stress points is unrelated to the wing shape and mostly concerns structural analysis rather than aerodynamic performance. Thus, the mean camber line is specifically focused on defining the curvature of the wing itself.