Induced drag is best described as what?

• A. It is drag as a byproduct of lift
• B. It increases with speed
• C. It is friction at the surface
• D. It is purely induced by engine

Answer: (A)

Induced drag is the drag that forms as a byproduct of generating lift. When the wing produces lift, air must be deflected downward and rearward, creating wingtip vortices and a downward flow (downwash). This downwash changes the direction of the resultant aerodynamic force, adding a backward component that we experience as drag. It’s more pronounced at lower speeds and higher angles of attack because the wing has to work harder to produce the same lift. It’s not due to skin friction on the surface (that’s a separate, parasite type of drag) and it isn’t caused by the engine. As speed increases for a given weight, the required lift coefficient drops, so induced drag decreases.