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Fairings that are completely rigid can be designed to mount onto a curve surface, but fairings that move are better mounted on flat surfaces and it can be worth it to flatten surfaces to get ease of manufacturability even at the cost of aerodynamics.

Body Drag

Reynold’s Number

Reynold’s number is a dimensionless quantity that gives information on turbulent flow.

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The definition is above. D is the characteristic length. The Reynold’s number ranges that describe flow type are below.

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This is an important constant as laminar vs turbulent flow comes with implications for drag. A streamlined body that maintains laminar flow for as long as possible is desirable, because it minimizes the pressure drag by delaying flow seperation.