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A lower number of inflection points relates to a smoother shape function curve, translating to a more aerodynamically efficient shape. So an aerodynamically efficient shape would have a shape function curve with low number of inflection points and gradual rate of change in area.
How to create a Shape Function Graph of a Car Design
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The smaller the Cd the lesser the power loss. The power loss induced by aerodynamic drag increases at a cubic rate of the velocity variable:
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