John;
The flaw in that argument is that tire traction is non-linear; bounce &
rebound do not average to 1 G.
Think of what happens to an early Mustang off the line at the drag strip.
Lots of tire smoke as the rear end chatters up and down. They were notorious
for wheel hop and it really hurt traction off the line. I've seen a VW beat
an early Mustang off the line; of course, a hundred feet off the line, the
VW got blown into the weeds.
On an imperfect surface a suspension will help traction but the
practicalities of a particular situation might rule out adding a rear
suspension. It might not be worth the trouble in some cases-- the
compressibility of the tires themselves then are the rudimentary
"suspension".
Regards, Neil Tucson, AZ
-----Original Message-----
From: John Burk [mailto:joyseydevil@comcast.net]
Sent: Wednesday, October 15, 2003 9:37 AM
To: land-speed@autox.team.net
Subject: suspension/traction question
If you are dealing with cornering , when the tires bounce off the ground the
car moves sideways , that's easy - With foreword acceleration the downward
pressure on the contact patch always averages 1 g (50% air time means 2 g
ground time) - I know that traction is inversely proportional to unit
pressure (2 g's on a 8" tire is like 1 g with a 4" tire) and that sliding
friction is less than static friction (an off the ground tire comes down
spinning) - I also know that with the high unsprung weight of a solid rear
and heavy wheels at high speeds suspension cant keep up and that for a fast
car the average speed is high - Is the benefit of suspension actual or a
perception - John
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