can somebody (i guess joe) explain again what the rolling drag parameter really does? i thought one calculates the rolling drag from the rolling coefficient, the radius of the tire and the mass of the car, so as such it should be superfluous (given the rolling coefficient). confused.
--alex--
The rolling resistance coefficient of the surface is used along with the radius of the tire, the tire's rolling resistance coefficients, and the angular velocity of the tire to generate a drag torque that is applied to the wheel.
The rolling drag of the surface is used along with the ground velocity of the wheel (linear velocity, not rotational) to generate a drag force that is applied to the car body (not the wheel).
So short answer is that the rolling resistance causes the tire's rotation to slow the faster the wheel rotates, while the rolling drag causes the car to slow the faster the car body moves. The rolling drag is independent of the speed of rotation of the wheel... of course, if the wheels aren't rotating the tire friction with the ground will be generating huge forces anyway.
thanks joe. one more question: what units does vdrift use? metric or imperial?
--alex--