Why Winglets Reduce Drag?

By significantly reducing the size of the wingtip vortex, winglets reduce induced drag—the aerodynamic drag created by an airfoil when it is producing lift. ... This airflow forms a vortex that causes induced drag, reducing the wing's aerodynamic efficiency.

How does wingtip reduce drag?

Wingtip devices increase the lift generated at the wingtip (by smoothing the airflow across the upper wing near the tip) and reduce the lift-induced drag caused by wingtip vortices, improving lift-to-drag ratio.

Do winglets make a difference?

Winglets produce an especially good performance boost for jets by reducing drag, and that reduction could translate into marginally higher cruise speed. But most operators take advantage of the drag reduction by throttling back to normal speed and pocketing the fuel savings. Several airliners use them.