Quote:
Originally Posted by freebeard
When I first lurked here, the accepted wisdom was that a 14° angle was all that was required. Pickup aerocaps and such.
Then aerocaps showed up that mimic the GM EV-1 roofline.
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There are almost no numerical rules of thumb in car aerodynamics. As soon as someone - anyone - starts to quote numbers in aero rules of thumb, you can be pretty skeptical.
As for The Template, it's just one of the low drag aero shapes (
shapes, note: not cars) that have developed over the years. No more, no less.
But as I said, this group has been led down a rabbit hole wrt to The Template, and you can see how it has caused all sorts of misapprehensions to (1) develop and (2) then solidify.
To be honest, I think the huge underlying issue - that I am afraid you, Freebeard are a strong part of - is that speculation has become largely the culture of the group. To be blunt, posters just guessing.
That's why, I think, The Template has been grasped by people. Rather than just working by complete guesswork, here was (apparently) a form that could be followed to get best results.
But like any snake oil, it's all too good to be true.
If you are building a car from scratch, pick a template - it matter 4/5ths of stuff-all* which one you pick.
But if you are modifying a car in any way, as soon as someone starts talking about a template, or any other numerical rule of thumb, run a mile. Car aero is simply much too complex to apply that sort of simplistic analysis.
(*Except if you're also interested in minimizing lift. Then it matters!)