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Old 05-06-2009, 03:44 PM   #1 (permalink)
Ernie Rogers
Ernie Rogers
Join Date: Feb 2008
Location: Pleasant Grove, Utah
Posts: 133
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Great forum, asking for help

Well, I just got around to looking in this forum today. You guys are doing great work, and thanks for assembling the drag table.

Today, I am embarking on a great task--beginning of a "white paper" on the potential for greater efficiency in cars. This is for the Sierra Club. I see the matter as logically divided into four or five parts--

1. Aerodynamics
2. Rolling resistance
3. Power plant efficiency
4. Other losses such as accessories, bearings, lubricants, etc.
5. Future prospects outside the paradigm such as pavement
types and modes of car use.

All suggestions are welcome. Citations to similar work would be nice. But, I have a specific request at the moment. There are a few outstanding examples of very low drag in "regular" cars

Aptera...................... 0.15
GM EV1.................... 0.19 (cone mod-- 0.15)
GM Precept 2000....... 0.176 (as I remember).

Those are the "easy" ones. More spectacular numbers have been achieved by SAE Supermileage competitors, close to Cd = 0.10.

I have worked on concepts in the neighborhood of Cd = 0.02, possibly the limit of what can be achieved at very high Reynolds numbers.

My question for today: The lowest documented Cd I have is 0.15. I am looking for published numbers that are lower than that. I know I should do some looking for myself, but I thought it would be nice to check in here first. The next place I would check is the U. of British Columbia Supermileage team, and a few other schools.

Thanks for help and suggestions.

Ernie Rogers

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