A while back, an article in Racecar Engineering Magazine discussed the effects of “self-aligning torque” on the driving task. Self-Aligning Torque is the effort or force required to turn the steering wheel. It is measured in pounds and is the vehicle’s way of communicating to the driver that everything is cool, no worries, or that in a few tenths of a second, you will be experiencing a lot of excitement.
The article notes that when a vehicle approaches its adhesion limit, a driver receives two conflicting signals. The first signal is the steering wheel getting light, which means that it requires less effort to increase steering input (turn the steering wheel). The reason for this is that the tire’s adhesion to the road is decreasing rapidly. The second signal is the vehicle load the driver feels at the back of the seat (their butt), which is high at the limit of adhesion.
Therefore, at a critical moment in decision-making for the driver, the computer chip in their butt is telling them one thing, but their hands feel another (little to no steering response). And to make life more interesting, all this is happening in the tenths of a second.
The Racecar Engineering article goes on to say that this can create a conflict with even the most experienced race car driver. The article points out that a good driver (Security Driver) has to be able to separate the two conflicting signals. Race car drivers who are paid significant sums use computers to sort all this out, which is the primary reason computers should be used in driver training.
Self-Aligning Torque (SAT) is a “learning experience” that needs to be created and coached. Also, in my opinion, a good instructor knows the speed at which the SAT will occur in any given exercise.
The difference between good and great instructors is that great instructors understand the implications of the science of vehicle dynamics for driving in general and, specifically, for the exercise/scenario the student is maneuvering through.
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