Question

The profile drag for a two-dimensional aerofoil is

• A. the pressure drag on the profile
• B. the sum of pressure (or form) drag and skin friction drag caused by the viscosity
• C. the sum of form drag and wave drag
• D. drag due to lift

Hint:

Profile drag = form drag + skin friction drag; it excludes induced drag.

Answer 1

The Correct Option is B

In the context of aerospace engineering, the term "profile drag" refers to the drag experienced by a two-dimensional aerofoil due to aspects of its profile. This type of drag is composed of two primary components:

• Pressure Drag (Form Drag): This occurs due to the pressure differences around the aerofoil.
• Skin Friction Drag: This is caused by the viscosity of the air creating friction against the surface of the aerofoil.

The combination of these two components—pressure drag and skin friction drag—results in the total profile drag of the aerofoil. Therefore, the correct description of profile drag in this scenario is the sum of pressure (or form) drag and skin friction drag caused by the viscosity.