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Old 11-28-2019, 11:24 PM   #85 (permalink)
The Armadillo
EcoModding Lurker
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Originally Posted by freebeard View Post
That seems like a reasonable analysis. It shows no separation at the top. I believe that max angle per Coanda or somebody is 45° and it's much less than that. The surprise is the top of the nose, but as I suspected, the chamfered front reduces the stagnation area.

The analysis of the tow I saw said the Ford's front wheel spin clockwise and the rear wheel spins counterclockwise ((two wheel drive)). And the German Expressionist camera angle made it look uphill.

I think the aero or towing capacity are beside the point. It initiates a new era of manufacturability. Six pasengers 500 miles for $70K. The aero will be fine on Mars. Isn't that the point anyway?

The Motortrend article mentions using "active suction" at the roof peak to reduce separation:

"But the aerodynamics of that peaky profile?

It almost looks like a deliberate, suicidal attempt to trigger boundary separation—a potential drag-raising catastrophe for limited-energy EVs. And an odd 180 turn from the Model X and Y, which have such delicately arched profiles precisely to avoid drag-raising trip wires like this.

Tesla might have erased the problem with active suction to bend the boundary-layer downward just aft of that peak. Gordon Murray's McLaren F1 used this trick, and SpaceX has plenty of expertise in active measures to manipulate airflow around its re-entering Falcon 9 first stages. However, with the bed cover deployed, the angle of its vast descending surface is evidently shallow enough for the flow to naturally reattach. The benefit being that it harvests a useful fraction of the air pressure that blocky, open-bed trucks almost entirely forfeit. Actually, the tougher aerodynamic trick has been coaxing the temperamental flow around those sharp A-pillars.
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