Which option correctly labels the drag caused by skin friction on the wing surface?

Which option correctly labels the drag caused by skin friction on the wing surface?

• A. Induced drag
• B. Profile drag
• C. Form drag
• D. Parasite drag

Answer: (B)

The main concept here is how drag is classified by its origin. Drag caused by the friction between the air and the wing surface is the frictional, viscous drag that acts along the surface as air slides past the wing. This boundary-layer shear produces a tangential resistance, known in many glider and aerodynamics texts as profile drag. It’s the specific viscous component of parasite drag, separate from the pressure-based form drag or the lift-related induced drag. Induced drag comes from wingtip vortices produced by generating lift; form drag (pressure drag) comes from the pressure differences around the wing; parasite drag covers all non-lift drag, including profile (skin-friction) drag and form drag. Since the question targets the label for the skin-friction, surface-drag component, profile drag is the best fit.

The main concept here is how drag is classified by its origin. Drag caused by the friction between the air and the wing surface is the frictional, viscous drag that acts along the surface as air slides past the wing. This boundary-layer shear produces a tangential resistance, known in many glider and aerodynamics texts as profile drag. It’s the specific viscous component of parasite drag, separate from the pressure-based form drag or the lift-related induced drag. Induced drag comes from wingtip vortices produced by generating lift; form drag (pressure drag) comes from the pressure differences around the wing; parasite drag covers all non-lift drag, including profile (skin-friction) drag and form drag. Since the question targets the label for the skin-friction, surface-drag component, profile drag is the best fit.