Which type of drag on an aircraft increases with airspeed and is caused by the friction of air moving over the aircraft surface?

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

Answer: (C)

As speed increases, drag that doesn’t come from lifting the wing but from the air’s resistance against the aircraft’s surfaces grows. This type of drag arises from the air shearing along the surface, i.e., skin friction, which is a component of parasite drag. Parasite drag covers all drag not directly related to lift, including skin friction plus form and interference drag. So the frictional interaction of air moving over the surface is part of the broader parasite drag category, which increases with airspeed. Induced drag, by contrast, decreases with speed because it’s tied to lift. Skin drag is the frictional part itself, while form/interference drag are other components of parasite drag, but the overall category that best describes the increasing drag with speed due to surface friction is parasite drag.