Sorry, no offence intended, but I'm willing to bet my house that I have a more intricate knowledge of the subject than 'Trackpaduser'.
It's "no offense", no offense... And,contrary to your professed professional experience, tires sliding on the pavement can be a symptom of under steer, not a cause.
The cause is not determined by "are they sliding", but "why are they sliding?"....
- Too much speed?
- Incorrect size, inflation, temperature of tire?
- Non optimized suspension geometry?
Vehicle Dynamics Terminology
In standard terminology defined by the Society of Automotive Engineers (SAE) J670[1] and the International Organization for Standardization (ISO) 8855[2], understeer and oversteer are based on differences in steady-state conditions where the vehicle is following a constant-radius path at a constant speed with a constant steering wheel angle, on a flat and level surface. If the speed is increased slightly for the same radius path and, after settling into steady state, the same steering is measured, then the vehicle is said to have neutral steer. If more steering is needed at the higher speed to maintain the same radius of curvature, then the vehicle is said to have understeer. If less steering is needed at the higher speed, then the vehicle is said to have oversteer.
Understeer and oversteer are defined by an understeer gradient U that is the difference between a reference steer angle gradient and the Ackerman steer angle gradient. The reference steer angle (δR) is the average steer of the front axle wheels minus the average steer of the rear axle wheels. The Ackerman steer angle (δA) is defined for a given radius of turn as the reference steer angle that would be used at a very low speed. For a four-wheeled vehicle with steering only at the front wheels, the Ackerman angle δA (at the wheels) is the arctangent of the wheelbase divided by the turn radius (at the center of the rear axle).
Understeer and oversteer are formally defined using the gradient U: if U is positive, the vehicle is understeer; if U is negative, the vehicle is oversteer; if U is zero, the vehicle is neutral.
Different companies and organizations have different test procedures for defining U. In all cases, the gradient is taken by comparing measures from steady state tests, and expressed with units of degrees of steer (at the road wheels) divided by lateral acceleration Ay expressed in g's. In steady-state conditions, Ay = V2/R/G, where V is the vehicle speed, R is the radius of the turn, and G is the gravitational scaling factor.
SAE J670 describes three methods for measuring U:
1. Constant radius: tests are repeated at different speeds for a given constant-radius track. In this kind of procedure, the Ackerman steering is always the same, so the gradient is: U = d(δR)/d(Ay)
2. Constant steer angle: tests are repeated at different speeds for a given reference steer angle. In this kind of procedure, the reference steer is always the same so the gradient is: U = -d(δA)/d(Ay)
3. Constant speed: tests are repeated with different reference steer angles for a given speed. In this kind of procedure, the gradient is: U = d(δR)/d(Ay) - d(δA)/d(Ay)
Gillespie goes into more detail on applying the first and third measurement methods.[3]
Results depend on the type of test, so just giving a deg/g value is not sufficient; it is also necessary to indicate the type of procedure used to measure the gradient.
Vehicles are inherently nonlinear systems, and it is normal for U to vary over the range of testing. It is possible for a vehicle to be understeer in some conditions and oversteer in others. Therefore, it is necessary to specify the speed and lateral acceleration whenever reporting understeer/oversteer characteristics.
[edit] Contributions to understeer
Many properties of the vehicle affect the understeer gradient, including tire cornering stiffness, camber thrust, lateral force compliance steer, aligning torque, lateral load transfer, and compliance in the steering system. These individual contributions can be identified analytically or by measurement in a Bundorf analysis.
Not one word about tires sliding on pavement....
I am a pro drifter in real life, and to me, the handling and physics in GT5 are absolutely spot on, every single input is transferrable from game to real world and vice versa.
)?
