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Old 02-03-2010, 11:40 PM   #2 (permalink)
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Originally Posted by RobertSmalls View Post
...Here's a picture where I extended the roof at 18 and the bottom of the rear bumper at 7, and truncated where it is 15.5cm tall for the license plate....
Hi Robert,

It's funny, but I have that same sketch from Honda, and was going to use it in a similar manner...

The 7 from the underside of the car might be more of an issue.

For this large of a taper, there has to be a large amount of air entering the stream under car, and then expand to fill the void created by the 7 degree taper. I hope your model shows that you have enough air volume to play with there.

The stagnation point at the front of the car typically does not let that volume of air underneath, and thus could "starve" the taper and not expand fully, thus causing a partial vacuum and resultantly cause unwanted turbulence there.

Hopefully the model will show if can expand at that rate on the bottom side or not.

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I also wrote an email to my DOT safety inspector, and asked if there are any either State or Federal restrictions for the extended length of the tail on the back side of the car.

If I spend that much time planning and building an extension, I want to be darn sure that all bases are covered legally, and not get a big surprise if I am pulled over for an adhoc inspection.

I know for Class II motorcycles (3-wheeler's), there are very specific requirements for tail lights, reflectors, running lights, etc.

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