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Old 04-29-2013, 07:16 AM   #1 (permalink)
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Automobile drag coefficient article on Wikipedia

As usual, I was trying to study, while my mind tried to think of anything more interesting. Specifically, the absurdity of creating a boat tail for my Forester. It seems like a lot of work for something that increases MPGs by ten percent or slightly more--but that is for a 0.25 Cd Insight!

My car is 0.405!

However, I submit that a boattail equal in length to the car itself is impractical, that is why it is funny!

Good news! I have a point!

Please look at that definition and see if we can make it meet standards. Kammbacks make the world a better place!

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Old 04-29-2013, 08:34 AM   #2 (permalink)
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Using the Template is not always easy. I put more effort into it here: http://ecomodder.com/forum/showthrea...tml#post368673
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Old 04-29-2013, 03:03 PM   #3 (permalink)
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The Kamm-back is a truncated boat tail--the same shape to start, but chopped off partway back. It gives you most of the benefit of the full tail, but without the full length. The two are not equivalent.

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Old 04-30-2013, 04:33 PM   #4 (permalink)
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tail

A full boat tail would drop the Subie's drag from Cd 0.405,to 0.12.At 55 mph you'd be looking at a 35% mpg increase.
Baron Reinhard von Fachsenfeld/Professor Wunibald I.Kamm both knew the value of a full boat tail and these are included in all their published research.The K-form was just a compromise and concession to length issues during urban driving.
A 50% truncation will not give the drag reduction of a full tail but it is certainly easier to 'park,' and get into a garage.
To address the length issue of a full tail,Fachsenfeld patented the inflatable boat tail which you can see in Hucho's book back in the commercial vehicle section.
NASA's boat tail helped reduce the drag of their Ford Econoline from Cd 0.48,to Cd 0.235.Which leaves half the drag still on the table.
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Old 05-18-2013, 05:19 PM   #5 (permalink)
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Shouldn't you be studying?

Your Forester's utility would be less compromised with a box cavity or retractable base plate. Look at the Coventry sessions:
http://ecomodder.com/forum/showthrea...tml#post296613
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Old 06-12-2013, 09:20 PM   #6 (permalink)
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Quote:
Originally Posted by freebeard View Post
Shouldn't you be studying?
Now that you mention it, I do have a test tomorrow!

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Old 06-13-2013, 12:50 AM   #7 (permalink)
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Happy to help.
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Old 06-13-2013, 01:23 AM   #8 (permalink)
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Good luck on the test Xist.


This thread leaves me wondering if there are any wikipedia articles we should be building or updating with the research that's been happening here. It's great having our own wiki, but it would be more accessible if there were an official wikipedia summary of best ways to improve mpg and whatnot. I will keep this in mind for a while and see if I find the inspiration to start organizing some content for this...
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Old 06-13-2013, 03:38 AM   #9 (permalink)
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Quote:
Originally Posted by a8ksh4 View Post
Good luck on the test Xist.


This thread leaves me wondering if there are any wikipedia articles we should be building or updating with the research that's been happening here. It's great having our own wiki, but it would be more accessible if there were an official wikipedia summary of best ways to improve mpg and whatnot. I will keep this in mind for a while and see if I find the inspiration to start organizing some content for this...
Thanks!

How would people find those entries?
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Old 06-13-2013, 03:53 PM   #10 (permalink)
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Quote:
How would people find those entries?
One way might be to have general articles created or amplified on Wikipedia, and then an article on Wikipedia about the Main Page of the EcoModder Wiki.

Then add that back into the External Links on the general article pages.

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