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Old 12-29-2020, 01:23 PM   #62 (permalink)
Vman455
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Quote:
Originally Posted by orange4boy View Post
I didn't mean that as a conclusion. Should have added an /s. It was meant to jokingly prove a point about semantics and pedantry. I'm poking fun in both directions. A fixed template that claims to solve all problems is obviously not practical or efficacious (not that I ever thought the template was) but output from applied knowledge meant to modify a vehicle can be a template.

(Also, the "context from the experts" you posted refers to the Ahmed body and SAE body, not the DrivAer models. It isn't clear in your subsequent posts that you understood that).

I did and I'm glad the piece was posted.
Thanks for the clarification; it's very hard to read intention in text. These days I end up editing my replies 4-5 times before I post anything just to try and make sure I'm not coming across as confrontational (hopefully I'm successful!).

Quote:
Originally Posted by orange4boy View Post
I agree. I have personally never expected "thee holy template" to do anything more than exemplify one possible low drag shape and, in the absence of something better, ie: CFD and an accurate model of my personal vehicle, to give one a very basic principal shape to keep in your head. At the time I was active, I understood the 22 degree taper to be a rough guide for mods which would then require tuft testing and evidence of mpg improvement.
That may have been your understanding, but I'm afraid it wasn't--and isn't--universal. I've linked before to a thread from 2010 wherein several posters speculate on how to "cure" the flow separation over the rear window of a Prius when no such separation exists, a fact revealed by a simple tuft test. They reached that conclusion based solely on visual comparison to the template profile! And that's just one of many examples of the template being used here as the arbiter of aerodynamic performance.

I agree that tuft testing is important. But I disagree that there is nothing between that and CFD modeling that is useful--pressure measurement, direct measurement of lift, throttle-stop testing, etc. can all give us a better picture than intuition, which is unreliable and often wrong.
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