Date:         Mon, 18 Oct 2004 12:32:02 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re:       Re: aerodynamics, was
              : 101 MPH Vanagon!
Comments: To: motorbruce@HOTMAIL.COM
Content-Type: text/plain; charset="ISO-8859-1"

In a message dated 10/18/04 8:17:12 AM, motorbruce@HOTMAIL.COM writes:


> O.K., I've seen all sorts of formulas and explanations for aerodynamics and
> drag. What I haven't seen is actual numbers for a Vanagon. Does anyone know
> the actual coefficient of drag for a Vanagon? Does anyone know what frontal
> area of a Vanagon is? Without this  information, all the formulas in the
> world are pretty useless for us.
> 
> Inquiring minds want to know.
> 

Gentlemen, ladies and specifically inquiring minds,

About a year ago, when this topic was visited at some length, I posted the 
numbers reproduced in the following from the archives. I will soon (hopefully 
within the next week) send Alistair an extensive series of plots detailing 
different powertrain combinations and the residual power and torque to the road for 
the Westfalia camper. These are both calculations and measurements taking 
into account aerodynamic drag and rolling resistance. TheFor the calculations, I 
have used measured torque curves for a variety of I4 combinations including 
the 1.8L 8V Digifant, the 2.0L Audi 3A, the Turbocharged Audi 3A, the 1Z TDi and 
a chipped version of the 1Z TDi with 0.205 injectors and VNT 15 turbo. For 
argumentative purposes, I have included tthe DK and DZ transmissions, running 
either 27-8.50x14 or 215/65x15 tires (either 802 or 755 revs/mile). The top 
speed and passing reserve numbers are readily seen. If time permits, I'll run the c
urves for the waterboxer engines and the 1.6L NA diesel for completeness.

In a message dated 6/10/03 11:50:23 AM, albell@UVIC.CA writes:

<< Drag = 1/2 A * Cd * rho *vsquared

 = frontal area (any one know this for Vanagon/Westy?)
Cd = drag coefficient, I have seen 0.44 stated for Vanagon
rho = density of air
 >>

Alistair,

Greetings from Yungay Station, Antofagasta, Chile with relative humidity of
1.1 to 4.2%!

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.

Pleased to see some technical discussion on the list!


Frank Grunthaner