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Old 07-24-2019, 11:39 PM   #73 (permalink)
Master EcoModder
Join Date: Dec 2008
Location: Eugene, OR, USA
Posts: 290

Lord Vader - '15 BMW i3 REx
90 day: 35.06 mpg (US)
Thanks: 61
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Did some more 'dust-up' testing this evening to examine skirt performance and I think it's encouraging. I ended up not testing a full skirt because I just couldn't come up with an attachment method for the rear of it that didn't either rub on the tire or not reduce the wake area down lower.

I think it exceeded the benefit seen with the rear disc which is not surprising.

I also think it is interesting how the holes I left in the skirt show a pressure difference within the wheel well. Looking at the dust pattern on the wheel as well, it is clear that air is moving in toward underneath the car where they are exposed to the exterior flow. Many race cars can be seen utilizing vertical venting over the wheels to deal with this. This flow pattern has me wondering if that pressure behind the upper area of the skirt couldn't be effectively redirected back into the side airflow with side louvers or something.

And yes, I included the rear shot because it appears to be slightly less dusty on the skirted side. Whether that result would hold with both sides faired may be questionable however.
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2015 BMW i3 REx
2011 Ford Flex SEL AWD
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