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Old 03-25-2010, 05:21 PM   #7 (permalink)
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Join Date: Oct 2008
Location: Warsaw, Poland
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Svietlana II - '13 Peugeot 308SW e-HDI 6sp
90 day: 58.1 mpg (US)
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Originally Posted by NeilBlanchard View Post
I thought that the new Bug had a Cd of 0.45? The curve in the rear is way too steep. I doubt it has attached flow as far down the back as the picture shows...
In this case, the sooner the airflow detaches the better.

EDIT: The following in red isn't exactly true, see post #10 for details.

I saw a chart somewhere (can't find it right now, grrrr). Pretty much it showed that as the rear angle gets steeper (starting from 0°=flat) lift decreases until 12°-14°, then it increases again until 26°-28° when airflow detaches and lift goes down again.

So, if you can find the spot where the tangent is 12° and make a small "step", then the airflow will detach there, reducing lift at the best point. Many new cars already have this small "step" around the top of the rear window.

Originally Posted by aerohead View Post
While it has good penetration,once it gets to the frontal area cross-section,the curves rapidly approach those that cannot support attached flow,creating a significantly large wake,'poison of mpg'.
If you extend this "step" into a Kammback, you keep the angle right while reducing wake area, and keeping Aerohead happy at the same time
e·co·mod·ding: the art of turning vehicles into what they should be

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[Old] Piwoslaw's Peugeot 307sw modding thread

Last edited by Piwoslaw; 03-26-2010 at 12:36 PM..
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