The topic of balance, pitch rotation and the true center of gravity has an
interesting apppication for a B-ville car. As in drag racing, B-ville is a
straight line sport , but when trouble comes along, far too often we have
ignored basic design rules. Ballast , wheather it is a water tank, fuel tank or
true ballast, mounted too high, or too far to one end , or not taking into
consideration the center of pressure will surely not help a spin condition. In
my mind , I would like to know to true center of gravity of my car before I
started placing ballast anywhere. Tom has outlined how to find the balance
point of a vehicle. The true CG is a point at the balance location but higher
up in the car, somewhere around the cam shaft height( of course, this is
differant on all vehicles). If you could suspened the car from this point , it
would be perfectly balanced.
To find this point requires weighing all four corners of the car then raising
one end of the car up (one foot is recommented) and placing the scales on shim
blocks and reweighing the car. The fun part is the trigonometry reguired to
locate the CG. Do to the need to diagram the process and the required math, I
would be glad to fax or mail this, all I need is to have you e-mail me.
I realize this is a heady process to get the CG, but knowing this info for a
really FAST car may help keep it straight.
>>> "Thomas E. Bryant" <saltracer@awwwsome.com> 06/10 1:31 PM >>>
Gene:
It is easy to find the center of gravity, use two floor jacks, jacking
the car up from the sides, and find the point where it balances. Center
of pressure is a little more evasive. Basically, on most cars it would
be the windshield or cowl area. (Where the frontal area is largest) The
center of gravity needs to be ahead of the center of pressure, so I have
been told.
Wings are allowed on Streamliners, Lakester, Modified Roadsters, and
Production bodies which had the wing as an option. I don't think you
have that choice. Production Spoilers are allowed, and add on spoilers
in some of the coupe & sedan classes. I can't offer too much insight on
spoilers. We have added one to our car it has changed the dust pattern
behind the car. Obviously the vacuum has increased, but, everything has
a cost. Costs and advantages have to be weighed. So far, we think it is
profitable.
There have been some really fast Corvettes on the Salt. I'm sure that
their owners and drivers would be glad to share information they have
gained. That is the great thing about our sport, everyone is willing to
share their knowledge, often gained at great expense. Good Luck with
your project.
Tom
|