Quote:
Originally Posted by Frank Lee
I think complications come from having a 2D template with only a side view trying to define an optimal 3D form.
Just about every vehicle on that template pic is very aerodynamically efficient, yet just about every vehicle has a backlight that is steeper than the template. I don't think they'd have the low Cds if they suffered separation at the top of the backlight.
And then there are those like the Rumpler and the Boxfish that are aero but don't conform to the template very well at all.
Still, I like the template because if one uses it they won't go way wrong.
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If I remember correctly (and please do correct me if I am wrong), Aerohead has designed the template to provide a combination of low drag, and zero lift. The other vehicles may not have been as concerned with lift, or may have used other means of overcoming/compensating. For example, the Prius has a "steeper than the template" rear windshield, and to compensate for the lift being generated, there is a flat spoiler on the back. I suspect that the
SedanKamm that I put on my car also generated a fair amount of lift, but I wasn't worried about losing control, because the duct tape holding it in place would have given way long before the rear tires came off the ground!