Quote:
Originally Posted by winders
Would you have us believe that all of us sudden all the roll control switches to the rear the instant the front inside tire comes off the ground?
The outside front tire still has its suspension, does it not? Unless the car is rotating around a point above the center line of the front outside tire, which it isn't, that suspension is still resisting roll.
The "weight" (mass x gravity) of a car does not move around. Also, if you use weight or mass instead of load, it makes it hard to understand that the loads the tires are handling may exceed the weight of the car. For example, when a 2000 lbs car is braking at 1.2G of deceleration, the tires are dealing with 2400 lbs of load.
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Wow, did you flunk statics?
If a car is braking at 1.2G in a gravity field of 1G and there is no upward or downward acceleration due to longitudinal curvature of the road, then the car still weighs 2400 pounds. What happens is that the LOAD on the rear tires decreases and the LOAD on the front tires increases in proportion to the cg height times longitudinal acceleration divided by track width divided by 2 since there are two tires per axle.
You say "roll control" but what do you mean by that? The outside front tire now becomes one point of the fulcrum since a 9 inch wide pneumatic tire is closer to a single point than a 60" track width. That tire cannot resist roll to any significant degree. Yes, the normal force from the road is not passing through the cg so it does create a moment, partly a roll moment and partly a pitch moment.
But once the inside front tire lifts your roll
stiffness hits an inflection poiint such that the slope of the curve changes to be softer since only the rear is contributing. But again the car is now going to be squatting as well unless you have some really crazy instant center behavior.