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Old 05-16-2022, 02:01 PM   #295 (permalink)
Phase
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Join Date: Mar 2022
Location: oregon
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Black Bullet - '19 Hyundai Ioniq Hybrid Blue
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Quote:
Originally Posted by aerohead View Post
1) Decades-old mirrors would ( have been reported at ) delta-Cd 0.015. Giving you Cd 0.225.
2) TESLA-quality mirrors would be delta-Cd 0.010, giving you Cd 0.23.
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' With a long diffuser, a notable reduction in drag can be achieved with a very small angle... However, this effect is only assured with a very smooth underside.' Dr.-Ing. Wolf Heinrich Hucho, 2nd-Edition, page-144
3) No belly-pan, no diffuser, and lose 30-counts.
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Belly pan with diffuser, rear skirts, and mirror delete: Cd 0.19-to- Cd 0.195.
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The 2012 Coventry University testing of the Audi A2 box-cavity showed a 2% delta Cd, from a car with Cd 0.288.
2% from a Cd 0.24 car would be 0.0048, yielding Cd 0.1852-to- Cd 0.1902
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I taped all the seams on SPIRIT and it showed zero difference in the wind tunnel. General Motors allowed 0.007 for these 'features'.
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' Qualitatively, the effect of the length upon the aerodynamic drag is similar to that for the ( streamline ) body of rotation.' W.H. Hucho, 2nd-Ed., pg 142
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' the drag reduction from an elongated tail varies almost linearly with the reduction in cross section area.' Jeff Howell et al.,' Streamlined Tails- The Effects of Truncation on Aerodynamic Drag,' Loughborough University, 2020, Abstract, SAE Paper 2020-01-0673
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' base pressure also depends upon the angle at which the flow separates from the contour.' W.H. Hucho, 2nd-Ed, page- 141
I wonder how much wiper blade delete affects drag. Lots of people do it for racing or hypermiling.

Wonder what my highway mpg at 59 EPA rating would be by dropping the drag from 24 down to cd 19. Seems realistic.

I wish I could shave weight in the car for city driving, but removing rear seats or changing front seats to light weight racing seats seems like it wouldn’t even make much of a difference.
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