Which of the following is not a parasite drag type?

• A. Skin friction
• B. Induced drag
• C. Form drag
• D. Interference drag

Answer: (B)

Total drag consists of parasite drag and induced drag. Parasite drag includes skin friction, which comes from viscous shear on surfaces; form drag, from pressure differences around the aircraft’s shape; and interference drag, from the interaction of flows around different components. Induced drag, on the other hand, arises from lift production—the wing creates lift by generating circulation and wingtip vortices, which consumes energy as a byproduct of generating lift. It is not caused by surface friction, shape pressure, or flow interference, so it is not a parasite drag type. Its magnitude is linked to lift and tends to be higher at lower speeds and higher angles of attack, decreasing as speed increases. Therefore, the drag type that is not a parasite drag is the induced drag.