Date:         Fri, 13 Jun 2008 10:24:21 -0700
Reply-To:     Randy Bergum <organslave@EARTHLINK.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Randy Bergum <organslave@EARTHLINK.NET>
Subject:      Re: re  Aerodynamics for MPG - 1971 Bay air dam
In-Reply-To:  <061320081543.16002.485295A9000EEC9600003E822207020953979A09019B0E0D9A9D@comcast.net>
Content-Type: text/plain; charset=us-ascii

Hi All:
      During my senior year in college, I focused on fuel economy
      improvements for my 1971 bay window.   Built a wrap around air dam that
      dropped to about 4" above the ground on the front end.  We
      covered the bus with red yarn streamlines and went at it, before
      and after.

      Results of the coastdown tests showed that the center of
      pressure was lowered about 6" and there was a 3% reduction in
      drag (which was within the noise of testing!)...... BUT the penalty of scraping the dam on the slightest
      driveway apron was horrendous - it was simply unworkable.  Even
      with rubber, you'd be a-scrapin' away every trip.

      Perhaps a better way to improve mileage would be to install
      "Rounders" at all the sharp edges - the roof could stand to have
      something there to ease the wind around the top instead of
      letting it separate from the beginning.  A-pillar gutters don't
      help things, but keep the wet off of you.  It's all compromise.

      I recall that early on, VW put a slight curve on the front of
      the bus, and that cut drag down something like an astounding 30% from a bluff
      squared box shape.  To get more, you have to manage the air
      carefully - flush windows, pressure recovery, and so on.

      Maybe what we need is someone to replicate the Vanagon shape in
      a fiberglass body with all the improvements outside for
      slipperyness-osity.

      I'm just sayin'........

Randy Bergum
1990 Carat
Fullerton, CA
************************

How many people recall the air dams that used to be for sale during the first energy crisis in the '70's?
Fiberglass with a rubber lip for the last few inches near the pavement. (see example)
http://i.pbase.com/g3/81/39681/2/89377443.k2jmfbT1.jpg

How about attaching a large lenght of thin sheet steel to the undercarrage of the van, so it has a smooth surface and an air dam at the front?
How about a roof spoiler at the rear to direct air behind the van?
Remember the old spoilers they used to put on the roof of stationwagons to keep the dirt off the rear windows?
Installing more aerodynamic side mirrors would help as well.
I agree with the idea that all the little bits add up.
Someone might want to check the Car and Driver or Motor trend magazines of the mid '70s. They did a story where they took a Vega and did as many mods as possible to increase fuel economy.
Todd
'88 Westy