[ODE] Different car/tire physics

[Pawel S]

When I started modelling a car with ODE I followed the documentation for
ODE about tires. It didn't worked for me.
The car behaved like a vehicle on rails or on ice.
I wanted to model a performance car that could accelerate fast but loose
grip when to much torque was applyed and do nice drifts.
I finally got it working now. Instead of rolling direction for fdir1 I
use the right vector of the wheel.
Allthough the car behaves beautyfully the values do not look right to me.

Question 1

	// Coulomb friction coefficient
	p_pContact.surface.mu = 4.0;

A bit to high but lower values makes the tire slip like on ice. Shouldn't
it be around 0.85 for tire/asphalt contact?

Question 2

	// at start
	const SCALAR fSk = 170000.0;
	const SCALAR fDk = 4000.0;

	// on every frame
	SCALAR fERP, fCFM;
	fERP = TIME_STEP * fSk / ( TIME_STEP * fSk + fDk );
	fCFM = 1.0 / ( TIME_STEP * fSk + fDk );

	dJointSetHinge2Param( JointFL, dParamSuspensionERP, fERP );
	dJointSetHinge2Param( JointFL, dParamSuspensionCFM, fCFM );
	dJointSetHinge2Param( JointFR, dParamSuspensionERP, fERP );
	dJointSetHinge2Param( JointFR, dParamSuspensionCFM, fCFM );
	dJointSetHinge2Param( JointRL, dParamSuspensionERP, fERP );
	dJointSetHinge2Param( JointRL, dParamSuspensionCFM, fCFM );
	dJointSetHinge2Param( JointRR, dParamSuspensionERP, fERP );
	dJointSetHinge2Param( JointRR, dParamSuspensionCFM, fCFM );

Aren't the values for fSk and fDk to high? I followed the documentation
for ODE in section 3.8.2.

I don't have any webspace for uploading some videos that demonstrate the
car. 

Any help appreciated

Pawel S


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