Lift-to-drag ratio

In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the amount of lift generated by a wing or vehicle, divided by the aerodynamic drag it creates by moving through air. A greater or more favorable L/D ratio is typically one of the major goals of aircraft design; since a particular aircraft's required lift is set by its weight, delivering that lift with lower drag results directly in better fuel economy in aircraft, climb performance, and glide ratio. The term is calculated for any particular airspeed by measuring the lift generated, then dividing by the drag at that speed. These vary with speed, so the results are typically plotted on a 2 dimensional graph. In almost all cases the graph forms a U-shape, due to the two main components of drag.