Which drag component is primarily due to friction of the blade passing through air?

Which drag component is primarily due to friction of the blade passing through air?

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

Answer: (A)

The main idea is that drag can be split into parts that come from different physical causes. The frictional resistance you feel as air shears along the blade’s surface is skin friction drag, and the portion of total drag that represents that surface friction is called profile drag. This is distinct from form drag, which comes from the pressure differences around the blade due to its shape, and from induced drag, which is tied to generating lift. Parasite drag is the total of form drag plus profile drag, but the specific friction-driven component is profile drag. So the blade’s friction with the air, via the boundary layer on its surface, is best described as profile drag.

The main idea is that drag can be split into parts that come from different physical causes. The frictional resistance you feel as air shears along the blade’s surface is skin friction drag, and the portion of total drag that represents that surface friction is called profile drag. This is distinct from form drag, which comes from the pressure differences around the blade due to its shape, and from induced drag, which is tied to generating lift. Parasite drag is the total of form drag plus profile drag, but the specific friction-driven component is profile drag. So the blade’s friction with the air, via the boundary layer on its surface, is best described as profile drag.