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• Aasish Thottiyil

# Motorsport Physics I

Aktualisiert: 15. Nov. 2022

Acceleration and Top Speed

More weight doesn‘t necessarily mean less performance. Quite the reverse! More weight can provide more initial grip off the line and thereby better acceleration figures for example for the sprint from 0-100 kph. Of course only, if advantageously paired with enough power.

Initial grip is provided by interlocking, anchoring if you will, of the rubber into the asphalt. And for the optimal interlock of the tires, you need a little slip in the first phase of the acceleration: For initial grip, you need a little slip!

But at the top end of the speedometer, more weight can be the reason for less top speed. Because physically spoken, the car has to accelerate more weight at very high speeds, and for that you need, the more speed you have, up to exponentially more power for accelerating further. But why you may ask, because the formula for the force, which is needed to accelerate a mass is F=ma. So it should be a linear term.

But what about the air resistance and the rolling friction resistance. The air resistance itself increases significantly while gaining speed (more than linear). And the rolling friction is not to be neglected either.

Crucial for the drive power, which is needed to overcome the air resistance, is also the drag coefficient (cw-value) of a car. The drag coefficient is a multiplier for air resistance or friction, to determine, how much force is needed to move an object. The lower the drag coefficient (acts as a multiplier), the less energy needs to be provided to accelerate the car.

Weight distribution

For high apex speeds (apex: normally the point of the curve, which has the maximum curvature), the weight distribution of the car is a key factor.

Perfectly balanced cars have a weight distribution of 50:50 from front to back.

The big advantage: Perfectly balanced cars have less problems with over- or understeering. By over- or understeering, you will loose precious seconds on your lap throughout the circuit.

But it depends on, what your basic purpose is with the car and also the performance, which has to be brought to the ground. For example a drift challenge along the track, depending on the car and its power, more weight at the front and rear wheel drive can be a crucial configuration for the win.

So in summary, weight distribution depends on the intend you have with your car.

Braking behavior before and in curves

Every Grand Prix race circuit in the F1 has a very long straight part, where the pique performance of the F1 cars can be reached. At the end of the straight the bolides reach speeds of over 300 kph. And as we know, the later you brake (if possible even into the curves – latest braking method) the longer you can hold the top speed of the car on the straight and the more seconds you are able to win. But such an aggressive braking behavior must be used intelligently throughout the race. The reason: The brakes can get over 1000°C hot by this kind of braking. And as you have seen in the Grand Prix of Monza (06.09.2020) on Vettels Ferrari, this possibly can lead to dramatic and dangerous brake failure:

So the brakes are one of the general car parts, which wear off the fastest.

This means, the drivers have to dose the brake pedal intelligently through the course and they also have to decide, when to brake late and aggressive, and when to spare the brakes and work with engine braking or coasting the cars through the curves.

Aggressive braking is normally used while attacking an opponent in or/and before a curve.

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