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Old 12-16-2014, 02:26 PM   #386 (permalink)
aerohead
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tufts/cavity

Quote:
Originally Posted by Cd View Post
This is a question for Aerohead : If BamZipPow did indeed drive around for the next week or two with tufts stuck to his truck, what effect would this present aero wise ?

I'm guessing it would cause so little drag as to be unnoticeable.

And for BamZipPow, how about adding an extra inch or two of lip around the edges at the rear ? Tests have shown that an open cavity - a box cavity- to sometimes be beneficial.

It would be super easy to do !
*Yes,the drag of the tufts would be statistically meaningless.
*And as to the cavity,at least one investigator has published that trailer vans which have a recessed door cavity DO show a small drag advantage,as this separation void partially isolated the door face from the base pressure of the wake.
*Hucho's research demonstrated a drag minimum when the length of the cavity was around 42% body length,giving a 7.9% drag reduction to a Volkswagen Transporter.
*Hucho recommended a practical length of 19% body length which yielded a 6% drag reduction.
*So you can see that these things have to be pretty long to show up at the pump.
*Something like a 42% boat tail has demonstrated a 26% drag reduction on a GM SUV scale wind tunnel model.
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