Date:         Tue, 19 Oct 2004 14:37:14 -0400
Reply-To:     Dennis Wood <guskersthecat@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Wood <guskersthecat@YAHOO.COM>
Subject:      Re: aerodynamics, was: 101 MPH Vanagon!

Can anyone decipher the wind speed in the wind tunnel shots?

Given the westy shot, perhaps I shouldn't worry about removing my roof
racks on the poptop...looks like they are sitting in a vaccuum.  For that
matter, a few windsurfers on top would probably help.

The boundary layer effect has been discussed at length I presume in many
disciplines.  My understanding is that it helps in situations where flow
detachment is an issue.  A great example is high end windsurfing fins which
are expected to maintain fluid attachment and generate lift at 35 to 50 mph
in water.  Sanding them in the direction of flow with 600 grit wet/dry
paper is customary.  In doing so, a thin turbulent water layer is
maintained which helps keep non-turbulent flow remain attatched to the
fin.  It's amazing to see what happens when the fin loses attachment
(cavitates)..the board starts sliding sideways at 30mph as if the fin was
knocked off.

At this point the golfers will chime in with the dimpled golf ball thing...

However, with the large difference in density between air and water, I
wouldn't run out with 600 grit paper and start scuffing your van .... any
volunteers to dimple their vans?  Add in some irridescent paint and
you've "Pimp'd your ride"