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   Date: Mon, 4 Jan 1999 08:23:23 -0800
   From: Alistair Bell <albell@uvic.ca>
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   Martin, John

   thanks for all of the info regarding power, torque and drag. I was
   especially interested in the drag data. Just a minor quibble, drag probably
   should be expressed as a force.

True.

   Anyway, relating power to speed is more useful, i regraphed your data and
   had the computer fit an exponential curve (a cube function, if I remember
   correctly, the power required to propel an object varies as a cube function
   of velocity, the drag force varies as a square function, thats right isn't
   it? ).

You would actually need all terms in the polynomial.
Contributiong to the force is:
0th order: static friction.
1st: surface friction in laminar flow, tire and bearing friction etc.
2nd: Turbulent flow.
The "fitted curve" on my graph is done this way.

   The resulting graph shows how dramtically the power requirements rise at
   the higher velocities. (try finding the power required to push a vanagon at
   133mph/60m/s!).

I don't think the data will extrapolate that well.

/Martin
--
Westy 1.9l Turbo Diesel
Quantum 1.6l Turbo Diesel

Martin Jagersand                 email: jag@cs.yale.edu
Computer Science Department             jag@cs.rochester.edu
Yale University

        Slow down and visit the VW diesel Westy page:
          WWW: http://www.cs.rochester.edu/u/jag/vw
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