Date:         Sat, 5 Feb 2005 07:13:20 -0800
Reply-To:     mark drillock <drillock@EARTHLINK.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         mark drillock <drillock@EARTHLINK.NET>
Subject:      Re: Adventurewagon high top molds -  wind tunnel tests
In-Reply-To:  <20050205004943.1989.qmail@web52508.mail.yahoo.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

The drag coefficient is not the same as the drag. A vehicle with a lower
coefficient does not also have to have less drag. The coefficient is a
measurement of the efficiency of the shape for the objects frontal size.
If you made a Vanagon to exact scale that was 20 feet tall it would
still have about the same .44 CD but the actual drag would be 10 times
greater or something. The hightop model may be more efficient for it's
frontal size but it is still larger. Just because a modification reduces
the drag coefficient does not mean it will also reduce the total drag if
in the process the modification also increases the effective size. The
Dehler top may well make enough of an improvement in the coefficient to
overcome the increase in size. The Adventurewagwen top is quite
different from the Dehler top that was tested in any case. I would still
be interested in one if they were available.

Mark

 value.Chris S. wrote

>I FOUND IT!
>
>http://www.farrside.net/vanagon/windtests.jpg
>
>Regular Vanagon Carat - CD .44
>Westfalia - CD .51
>Dehler High-top - CD .40
>
>Yes.  I was surprised too when I first saw it.  The high top
>should give better fuel mileage on the highway as well.
>
>
>
>
>
>=====
>Chris S.
>
>'84 Westy -> http://www.knology.net/~vwghost/hershey/
>'01 NB TDI -> http://www.knology.net/~vw/Beetle.jpg
>
>
>