Friday, April 11, 2008


The dynamic behaviour of their cars is of great interest to both the drivers and the engineers in F1 alike. These are nothing but, how the car behaves when it corners, brakes, accelerates, hits bumps in the race track and so on. These things that the drivers keep harping about forever is what makes them go fastest or just fast.

When the driver starts to turn his car into a corner, the amount of tyre grip that's at his disposal plays a major role. The tyres will continue to oblige to the driver's input till they enter a zone called the skid zone. When the tyres enter this zone, they start to lose their adhesion with the track surface. This results in the tyres not being able to hold the weight of the car + cornering force resulting in the front tyres losing the grip which in turn results in them "pushing wide". This is understeer in drivers' speak. When a car understeers, it wanders away from the indented racing line that gives the fastest way through the corner. An understeering car takes a wider line than the racing line forcing the driver to stay off the throttle for a longer time and give more steering input. Also, when on the exit of the corner, the driver has to start applying the power to get his car going, understeer will force the driver to keep his throttle shut for a longer time. The front tyres also taking a beating due to their sliding. This is commonly referred to by the drivers and the engineers as graining. When a front tyre grains, small pebbles of rubber from the tread start to disintegrate from the tyre ans accumulate on the side of the track. A graining front tyre will cease to give the driver the level of feedback that he expects from the front-end of his car. The only way to cure graining is to not push too hard on the first few laps until the tyres reach their optimum operating temperature window (we'll see what the optimum operating temperature windows are for different F1 tyres in F1 TECHNOLOGY :: TYRE (Part 2)). Understeer thus slows lap times.

Oversteer happens when the rear tyres've much less grip than their counterparts at the front. Oversteer happens mostly just after the apex of a corner when the driver starts his throttle input. This is more pronounced in slow turns. When a driver has clipped the apex of a corner and starts to give the throttle, the rears will start to spin faster than the front. Since the front end at this point has more grip than the rears, the rear of the car, owing to the slip of the rear tyres, will start to spin around taking the front end as the pivot point. This phenomenon makes the car look as if it is glued to the track at the front tyres while the rears are let loose to rotate about the axis which is the front end. To counter oversteer, the most basic and instinctive counter measure adopted by the drivers is opposite lock. For example, when a car oversteers on the exit of a left turn, the driver flicks his steering wheel to the right to get the whole car to the new place where the rear tyres have gone as a result of the spin. While this works most of the time, if the oversteer is big enough, it can result in a half-spin or even a full 360!

The drivers always look for a neutral car meaning that they prefer a car that neither understeers nor oversteers. In the event neutral balance is hard to be tuned in into the car, most prefer oversteer to understeer. This is because, drivers reckon, oversteer gives them a better sense of feel.

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