Lift-induced drag

Lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, in aerodynamics, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars with airfoil wings that redirect air to cause a downforce. It is symbolized as ${\textstyle D_{\text{i}}}$, and the lift-induced drag coefficient as ${\textstyle C_{D,i}}$.

For a constant amount of lift, induced drag can be reduced by increasing airspeed. A counter-intuitive effect of this is that, up to the speed-for-minimum-drag, aircraft need less power to fly faster.^[1] Induced drag is also reduced when the wingspan is higher,^[2] or for wings with wingtip devices.