India in Depth: Why Schumacher wouldn’t normally have beaten Rosberg

Posted on November 3, 2011

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One of the stories of a relatively quiet Indian Grand Prix was the old master’s defeat of his young countryman team-mate. Many sources have been recorded as declaring a new dawn, and that Michael Schumacher is now back. Using the intelligentF1 model, the races of the Mercedes drivers can be simulated, and we can see how Schumacher beat Rosberg, and also how it needed a very particular set of circumstances to play in favour of the older driver.

Let’s start by looking at the race traces of the two Mercedes drivers. Rosberg is the line with crosses, and the intelligentF1 model fits are the dashed lines.

The fit for Rosberg is very good across the whole race, and the fit for Schumacher is good after the first stint. It seems that Michael was taking it easy in the first stint in the knowledge that he had a new set of the soft tyres for his second stint having not made it through to Q3. A few notes need to be made about the fits.

  • The underlying pace of the two drivers is identical (1.0s behind Vettel)
  • Rosberg is 0.2s faster on the hard tyre in the last stint
  • The tyre degradation is extremely low
  • Schumacher has new tyres in the second stint – these are worth about 0.3s in pace based on drivers who used old and new tyres in the race

The reason cited in most articles for the position swap after the final stops is that Schumacher went five laps longer on the soft tyres. While this is true, there is much more to it than this. One element is the pace advantage from the new tyres. The second, and more important factor is that the tyre degradation is very low. In most races (every race from Monza to Korea), the laptime loss due to tyre degradation is approximately the same as the laptime gain due to the lightening fuel load. This leads to the traces on the race history chart having a constant gradient. Here this is clearly not the case as we can see the traces curving upward during the stint. This means that the tyre degradation is low – in fact the intelligentF1 model has to use close to a zero value for degradation in order to match the traces. As an aside, many teams experienced large phase 2 tyre degradation which precipitated pitstops during the race, but the normal phase 1 degradation did not occur in India. Essentially, the tyres were consistent in pace (unusual in 2011) and then went off.

So what could have happened in the Rosberg/Schumacher battle if the tyre degradation was more normal by 2011 expectations? Well, this can be shown using the intelligentF1 model. In the chart below, the race data traces (solid lines) are the same, but the intelligentF1 model fits use a higher tyre degradation value (but still not as high as used in most races). It looks like this:

The intelligentF1 model has been matched to the race traces at lap 22, the start of the second stint. The pace difference between the two cars due to Schumacher’s new tyres can be seen clearly and he would catch Rosberg at about lap 38. however, his pace advantage would only be only 0.3s, so he would be unlikely to overtake. However, if we assume that he could just drive past his team-mate, then Rosberg’s earlier stop would have been enough to get him back ahead. The story is different here due to the degradation – this means that the laptimes at the end of the second stint are much slower, and thus that the new hard tyres are comfortably faster than the used soft tyres.

So the race essentially would come down to whether Schumacher could pass his younger team-mate on the track, as the leading driver would (most likely) have the choice to stop first, and that would be the decisive move in the battle. With only a 0.3s pace advantage, an overtaking move is possible, but unlikely in identical cars, even with KERS/DRS.

In reality it doesn’t matter. The degradation was low, the cars were quick at the end of the second stint, and Schumacher finished fifth. But it doesn’t mean that he drove better, or was tactically better than Rosberg. Reduced to the basics, the only difference between the drivers in the race was that Michael had a set of soft tyres due to not having made it through to Q3, and that the low degradation happened to work out for him. On such small things…

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