The ratio of lift to drag l / d for a wing or airfoil is an important aerodynamic parameter; indeed, it is a direct measure of the aerodynamic effi ciency of the wing.
If a wing is pitched through a range of angle of attack, l / d fi rst increases, then goes through a maximum, and then decreases.
Consider an infi nite wing with an naca 2412 airfoil. estimate the maximum value of l / d . assume that the reynolds number is 9 × 10⁶ .