09-16-2010, 04:33 PM
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#11 (permalink)
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Left Lane Ecodriver
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XPRT/Neil: Can you get Cd and A values, or coefficients of rolling resistance, for ANY of the vehicles participating in the Validation phase? Hopefully these values are exemplary, and of interest to folks contemplating their own extreme mpg project vehicles.
All I've got so far are Cd without A on the Edison2 and Aptera entries. 
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09-16-2010, 05:16 PM
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#12 (permalink)
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needs more cowbell
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or can someone take some stylish shots of them like in the em banner? and a reference length? Is coastdown data available?
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WINDMILLS DO NOT WORK THAT WAY!!!
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09-16-2010, 08:25 PM
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#13 (permalink)
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Master EcoModder
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The Edison2 VLC 4 seat car has a frontal area of 1.7082 square meters. The "old" method Cd is 0.145, and the new SAE method Cd is 0.161.
No other Cd's or areas are available. :-(
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The Following User Says Thank You to NeilBlanchard For This Useful Post:
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09-16-2010, 09:28 PM
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#14 (permalink)
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...beats walking...
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Quote:
Originally Posted by NeilBlanchard
The Edison2 VLC 4 seat car has a frontal area of 1.7082 square meters. The "old" method Cd is 0.145, and the new SAE method Cd is 0.161.
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...what's the +11% difference between 'old' and 'new' SAE methods...different 'corner' coefficients, ground-effect, or what? |
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09-16-2010, 10:00 PM
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#15 (permalink)
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Left Lane Ecodriver
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Quote:
Originally Posted by NeilBlanchard
No other Cd's or areas are available. :-(
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Thanks for the bad news. Let's see what I can do with a few letters to the X-Prize Foundation and finalist teams. |
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09-16-2010, 11:01 PM
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#16 (permalink)
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(:
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Just saw on Yahoo that 3 cars are splitting the 10M; one got 5M, the other two 2.5M each. No Aptera.
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09-16-2010, 11:10 PM
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#17 (permalink)
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needs more cowbell
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__________________
WINDMILLS DO NOT WORK THAT WAY!!!
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09-16-2010, 11:29 PM
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#18 (permalink)
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Left Lane Ecodriver
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I found this gem in the comments over at the Edison2 blog. Coastdown data were published, but they fit the curve F=A+Bx+Cx²...
Quote:
So that CoastDown data has this A, B, C format which is great but does not match the simplified model of a car that has no B term. So I resampled the data to and refit it to F = A1 + C1 v^2 type of curve fit. The fit is not as good, but it allows calculations of a few key items.
Crr = 0.012
CdA = 0.244 m^2
CD = 0.143 (assuming 1.702 m^2 area)
The numbers seem pretty reasonable and most impressive.
John C. Briggs
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Does anyone else think that CRR number is unimpressive? |
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09-17-2010, 12:14 AM
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#19 (permalink)
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...beats walking...
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Quote:
Originally Posted by RobertSmalls
Does anyone else think that CRR number is unimpressive?
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...well, my OEM Goodyear Eagles are listed as CRR = 0.0092, so maybe yes...or, maybe no.
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