Luke Scharf via EV wrote:
We need a way to rate the trailer's drag, as well as its weight.
One possibility is a roll-down test. Accellerate the vehicle to speed,
put it in neutral, and measure the time and/or distance to coast down to
a lower speed.
Obviously, do it on flat ground when there is no wind. It's best to
repeat the test in both directions to cancel out any effects of wind or
incline.
If you want more data, you could record the speed and distance every
second or so right down to a standstill. The drag of a vehicle has 3
factors: friction (constant), rolling (proportional to speed), and
aerodynamic (proportional to speed squared). With some math, the 3
factors can be separated out. This can give you the actual aerodynamic
drag coefficient.
Lee Hart
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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