

| Subject: | Re: How much fuel efficiency gained by shedding 300 lbs? |
| From: | John Bange |
| Date: | Thu, 18 Aug 2005 07:57:58 -0700 |
> > Vanagon body is 0.75, and the rolling coefficient is 0.014. See > > http://www.goshen.edu/physics/horsepower/1998_LabReport-87Vanagon.gif ) > > 0.75??! i kinda don't think so. perhaps for the entire bus ... Looking at the methodology used to arrive at that .75 number leaves me with serious doubts. It was a physics project where the students had to collect data on their own vehicles following a specific protocol of acceleration, coasting, downshifting, and braking. Too much room for "pilot error", both in driving and measuring the constants. > but > that calculator > > http://www.bgsoflex.com/aero.html > only wants the FRONTAL drag coefficient. which vw was giving out to > the magazines > as 0.44 when the vanagon first appeared in 1979. That's about right. I poked around the archives and found a post from Frank Grunthaner wherein he passes on the actual VW wind tunnel test numbers: > Some numbers! The drag coefficient (Cd) and frontal area (A) for the regular > Vanagon are 0.45 and 3.06 m2; > > for the later Vanagon with front spoiler lip,the values are: 0.44 and 3.08 > m2; > > for the Westfalia, the numbers are 0.52 and 3.17 m2; > > the later Westfalia with spoiler drops the drag coefficient to 0.51. > > The European hightop camper (Dehler profile) takes the drag coefficient to > 0.40 with a frontal area of 3.61 m2. > > So highest drag for the Westfalia and the Euro hightop has essentially the > same drag as the regular passenger version. > > BTW, I have info somewhere that the drag coefficient for the syncros is > higher by about 0.03 but I can't place my hands on those notes just now. > > > Frank (Grunthaner) > > This data comes from VW factory wind tunnel tests, conducted as they worked > out the optimal gearing for the various powerplant combinations.
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