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Old 11-10-2020, 06:05 PM   #7 (permalink)
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Originally Posted by kach22i View Post
In short, most aero in this forum deals with drag, drag forms on the aft part of the car after the highest part of the roof.
kachi22, I don't mean to single you out here, but at the same time this needs to be addressed: This is way too simplistic, but it's one of those "rules of thumb" that get thrown around here constantly. Drag is one of the three components of the aerodynamic force resultant that forms from pressures acting on the entire surface of a car.

As I posted about in another thread recently, a well-shaped car can have a lot of forward-facing surface area subject to negative pressure differential from atmospheric--the implications of which (that this reduces overall drag because of the contribution of thrust) appeared to go over the heads of nearly everyone who subsequently commented in the thread.

Incidentally, Julian Edgar later told me that Rob Palin, former Tesla aerodynamicist, said that lowering pressures on forward-facing surfaces by careful shaping was a key strategy for reducing drag in the development of the Model S. This runs counter to the prevailing wisdom here that beyond a certain amount of rounding--just enough to support attached flow--shaping of the front of a car has little to no effect on drag and everything important happens at the back because the prevailing wisdom is overly simplistic to the point that it is not true.

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