Claude Rouelle explores the possibilities of qualifying and quantifying a racecar design or set-up through grip, balance, control and stability. In the racing industry, I often find engineers that perform simulations in the same way barmen create cocktails: by (sometimes randomly) mixing ingredients and varying quantities until they eventually find something that matches their taste.
Our analysis of yaw versus lateral acceleration continues with Claude Rouelle’s explanation of the yaw moment diagram and how to interpret it. We will start this article
by reviewing some basic concepts. As we have seen in the previous articles on the yaw moment versus lateral acceleration method, an understeering car is defined as a
car that doesn’t have enough yaw moment and an oversteering car is a car with too much yaw moment.
What makes a car quick in steady state and in transient? Claude Rouelle develops his analysis of lateral acceleration and yaw moment variation. In April’s RE (V27N4), we saw that there are 12 causes for the yaw moment: four tyre lateral forces Fy, four tyre longitudinal forces Fx; and four tyre self-alignment moments Mz.
One important part of a racecar performance engineer’s job is lap time simulation. Simulating and comparing the effect of car design and set-up parameters on the lap
time is essential. With the many inputs and outputs that exist in such simulation, it is always worth having metrics other than the lap time to know if and why we improve the car’s performance.
