Induced drag is primarily caused by which aerodynamic effect?

Induced drag is primarily caused by which aerodynamic effect?

• A. Induced drag is primarily caused by lift
• B. Induced drag is caused by surface friction
• C. Induced drag is independent of lift
• D. Induced drag only occurs at stall

Answer: (A)

Induced drag appears when a wing produces lift. To generate lift, air must circulate around the wing and accelerate downward in the wake, creating wingtip vortices. That downward flow (downwash) tilts the lift vector aft, so part of the energy goes into pushing air backward rather than purely upward. The result is a backward force on the wing—a drag component that grows as the amount of lift increases. This is why induced drag is directly linked to lift: stronger lift requires stronger downwash and stronger vortices, increasing the drag produced by the lifting process. It’s not due to surface friction—that’s parasite drag from skin, roughness, and shape. Induced drag isn’t independent of lift; it rises with the lift coefficient and is influenced by wing aspect ratio (higher AR reduces it). And while stall can complicate the flow and add other drag sources, induced drag is present whenever lift is being produced, not only at stall.

Induced drag appears when a wing produces lift. To generate lift, air must circulate around the wing and accelerate downward in the wake, creating wingtip vortices. That downward flow (downwash) tilts the lift vector aft, so part of the energy goes into pushing air backward rather than purely upward. The result is a backward force on the wing—a drag component that grows as the amount of lift increases. This is why induced drag is directly linked to lift: stronger lift requires stronger downwash and stronger vortices, increasing the drag produced by the lifting process.

It’s not due to surface friction—that’s parasite drag from skin, roughness, and shape. Induced drag isn’t independent of lift; it rises with the lift coefficient and is influenced by wing aspect ratio (higher AR reduces it). And while stall can complicate the flow and add other drag sources, induced drag is present whenever lift is being produced, not only at stall.