Doug,
On another note, off the top of your head can you recall any typical load
sensitivity values? Your book, "Race Car Vehicle Dynamics", has an example
discussing the effects of downforce and tire load sensitivity in combination on
an Indy car during high speed cornering. In that example it uses .00064mu/lb
load sensitivity, which is set to a constant value after a certain high loading
point for simplification.
I'm also curious what the shape of these curves might look like. When assuming
a linear drop in friction coefficient with load, one example tire that I read
about with a peak mu of 1.7 at almost 0 load drops to about .7 at 1000 lb load
(very roughly). Adding just a few hundred more lb would cause mu to become
negative.
So... Do you suppose the load sensitivity curve might really be more "S"
shaped in general? If so, that would be great news for me :0)
Looking at it from another perspective, the slope of the lateral force plot at
a given slip angle levels off as load is increased (page 29 of your book has
one of several examples of this). Does the lateral force continue to climb
slowly at very high loads, or does it tend to level off, or perhaps even drop
at some point? From this trend, perhaps I can approximate load sensitivity
curves more appropriately, as these curves vastly change the amount of
downforce I need to apply to my Champ car, for instance, to get 4.5g's
acceleration at a given high speed, and cause under/oversteer characteristics
to be effected much differently from spring/anti-rollbar changes.
Thanks,
Todd Wasson
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