The maximum lift-to-drag ratio depends only on the drag coefficient at zero lift, which is a measure of the parasitic drag or skin friction of the airfoil. The lower the drag coefficient at zero lift, the higher the maximum lift-to-drag ratio. The maximum coefficient of lift to drag ratio is a measure of the maximum aerodynamic efficiency of an airfoil or an aircraft. It is the ratio of the lift force to the drag force when they are both at their maximum values for a given flight condition. The higher the maximum coefficient of lift to drag ratio, the less drag the airfoil or aircraft experiences for a given amount of lift, and the more fuel-efficient and long-range it is.
- Maximum coefficient of lift to drag ratio (cl/cd)max
- Zero lift drag coefficient (cd,0)