Skin friction on the airfoil is classified as which type of drag?

Skin friction on the airfoil is classified as which type of drag?

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

Answer: (C)

Skin friction on the airfoil comes from viscous shear in the boundary layer as air flows over the surface. This surface-related friction is what we call profile drag—the part of parasite drag tied to the wing’s surface shape and texture. While parasite drag overall includes both skin friction and form drag (pressure drag due to shape), the specific contribution from the surface shear is described as profile drag. Induced drag, by contrast, is produced by lifting the wing and is not related to surface shear. So the best classification for skin friction is profile drag.

Skin friction on the airfoil comes from viscous shear in the boundary layer as air flows over the surface. This surface-related friction is what we call profile drag—the part of parasite drag tied to the wing’s surface shape and texture. While parasite drag overall includes both skin friction and form drag (pressure drag due to shape), the specific contribution from the surface shear is described as profile drag. Induced drag, by contrast, is produced by lifting the wing and is not related to surface shear. So the best classification for skin friction is profile drag.