Using a small scale wind tunnel just triggered an idea. How hard would
it be to make a 3D printed model of your car ? (Pretty hard when you
have to consider that it's every tiny bump that makes a difference in
wind, but doable.)
Anyway, having a scale model would allow inexpensive wind tunnel
testing. You could test, for example, the effect of a trailer. Or
raising the suspension of your vehicle a bit. Or adding an air dam in
the front. Or adding roof racks.
Peri
<< Want to know about the effects of leaf blowers ?
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------ Original Message ------
From: "Lee Hart via EV" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Cc: "Lee Hart" <[email protected]>
Sent: 12-Jul-20 2:26:39 PM
Subject: Re: [EVDL] Solar powered vehicle panel requirements.
When I put a small flat 4'x6' utility trailer on my Prius, the
mileage went from 55 down to 40! And that was with no load or added
wind drag other than the trailer. So it is quite silly to think one
can add a trailer to get SOlar without losing more in the trade!
Aerodynamics is funny stuff. It's not at all intuitive, unless you've studied
aeronautical engineering.
A flat trailer might seem like it would have low wind resistance; but a square
front edge and rough surface can create a considerable amount of drag. Open
tires without fenders or wheel wells also have a lot of wind resistance;
especially at the top of the tire, which is moving forward at *double* the
speed of the vehicle. The bottom of a trailer is also rarely flat or smooth; it
will have lots of projections.
Some museums have little wind tunnel setups, where you can insert verious
shapes, and read the drag and lift on meters. Some include little smoke
generators, so you can see where laminar flow breaks into turbulence, and the
big increase in drag it causes.
Lee Hart
-- If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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