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Old 11-12-2010, 09:04 PM   #288 (permalink)
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Originally Posted by wyatt View Post
Not to get picky on you Jim, but your graph should say FE increase on the y-axis, not Drag Reduction (%). The % Drag should be approximately 2 times as much as the FE increase (maybe 21% drag reduction at 56 mph), and would be measured by coast down testing. With that being said, very impressive! I was guessing 12% myself, just based on the SedanKamm I had built earlier this year, and figuring you would get double the results (yours is both top and bottom, and tapers on the sides)

EDIT: I retract my previous statement, I see what you were doing, your posting showed the first picture twice, and I never got to see the second one.
Hi Wyatt,

Actually I have to say a big thanks for you getting "picky"!


Because you just reminded me that a 10% increase in gas mileage is really due to roughly a 20% increase in body shape aero efficiency.

I had forgotten about this "little" detail in my attempt to qualify this effect more succinctly in the table and graph above.

I will try to rectify the current situation in a further post, and hopefully make it more clear on how the aero drag reduction interacts with the rolling resistance and yields total vehicle drag.

Thanks again Wyatt.

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