Profile Drag

•Profile Drag- is due to the rotor blade passing through the air

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     –It does not change significantly with the airfoil’s angle of attack

     –It increases moderately when airspeed increases

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•Profile drag, like parasite drag has 2 sub categories form drag and skin friction

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     –Form drag results from the wake caused by the separation of airflow from the               surface of a structure

     –The amount of drag is related to the size and shape of the structure that                       protrudes into the relative wind

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     –Skin friction is caused by surface roughness. Even though the surface appears             smooth, it may be rough when viewed under a microscope. A thin layer of air clings       to the rough surface, creates small eddies