On Sep 27, 2008, at 12:49 AM, Mike S wrote:

> At 10:04 PM 9/26/2008, Chris S wrote...
>> The front luggage rack creates a LOT of turbulence and drag.  Yes,
>> frontal area is the same but with the rack the drag is much higher.
>>
>> <http://i16.photobucket.com/albums/b7/misterpolak/Misc%20VW%20nuttiness/windtests.jpg
>> >http://i16.photobucket.com/albums/b7/misterpolak/Misc%20VW%20nuttiness/windtests.jpg
>
> That shows 5 different configurations, none of which is the oddball in
> question. What makes you think #3 is significantly different than that
> one?

On that page the first van is a passenger Vanagon. Note how the smoke
trails over the top are fairly still laminar?

The 3rd one down is a traditional US Westy. Notice that the how the
extra height of the luggage rack really blows the smoke and destroys
the laminar flow.

The 4th one down is closest to the Atlantic poptop. Due to the low
area of the top right above the windshield, the laminar flow is able
to be preserved further down the body of the vehicle.

Short of the behemoth at the bottom, the Westy air flow is just about
the worst possible. It may only seem to be a couple of inches of
difference, but that's all it takes. That's why aircraft designs were
as much art as science in the beginning, and why they use computers to
map the air flow now. Little tiny differences can make a huge
difference in turbulence.