Which type of drag is induced by lift generation and wingtip vortices?

• A. Skin Friction Drag
• B. Wave Drag
• C. Induced Drag
• D. Parasite Drag

Answer: (C)

Induced drag is the drag that arises specifically from generating lift. When a wing produces lift, air streams from the high-pressure bottom over the top surface and around the wingtips, creating wingtip vortices. These vortices carry energy away from the wing and cause a downward component of flow behind the wing (downwash). This downwash tilts the lift vector aft, so part of the lift acts in the drag direction. The result is a distinct drag component that increases with the amount of lift produced (and decreases with higher aspect ratio and winglets that mitigate the wingtip vortices).

In contrast, skin friction drag comes from viscous shear on the surface, wave drag from shock waves at high speeds, and parasite drag from components not producing lift. The link between lift generation, wingtip vortices, and the resulting backward tilt of the lift vector is what makes induced drag the correct description.