Korea in Depth: How Petrov and Rosberg saved Alonso’s race

Posted on October 18, 2011

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The abiding memory of the Korean Grand Prix is of a McLaren and a Red Bull side-by-side for the best part of a whole lap. Second probably comes the assault of Renault on Mercedes to bring out the safety car. The strange thing about this second incident is that in the background we see a Ferrari disappearing into the escape road. What was Alonso doing there? He was about 10s ahead of the Schumacher/Petrov battle just five laps earlier, and all three had stopped. The story is in the race history chart below – the data traces are in solid lines, and the fits from the intelligentF1 model (for Alonso and Schumacher) are the dashed lines.

Lap 12, and the Ferraris were looking OK – ahead of Button and Rosberg, and 10s ahead of Schumacher. But on lap 13, they fell off the pace (their data curves fall away from the intelligentF1 model fit). Massa lost about 4s on lap 14 when he came into the pits, and exited well behind Button and Rosberg. Alonso lost the same time on lap 14 and another 5s on lap 15, putting him 10s behind where he should have been when he came out of the pits (difference between solid red line and dashed red line at lap 15). Due to the accident between Petrov and Schumacher, we cannot see that Alonso came out behind them in the data, but we did see it on the TV.

So if Petrov had not missed his braking point and taken Schumacher out of the race, Alonso would have been ninth, and with some quick cars to negotiate before he could think about chasing down Massa who was now seven seconds up the road. The Lotus driver did him a big favour, and once the safety car went in, he was right behind the Rosberg/Massa battle.

The next phase of the race shows something strange in the behaviour of the Pirelli tyres, which has been noted before at intelligentF1. When the tyres are treated well (by going more slowly) they tend to have more pace at the end of stints. So when Massa and Alonso passed Rosberg, they were able to lap faster on the tyres than perhaps they would have done if they were not behind him – as if the tyres were a few laps younger. Am I sure this is true? Well, there are two possibilities from the data. If we look at Massa’s pace at the end of the second stint, and fuel correct to his third stint using the intelligentF1 model, we get the chart below:

This suggests that Massa should have had the same pace as Alonso in the final stint. So either he was slow in the final stint (as I had initially thought) or his tyres were about 0.5s faster than they ‘should’ have been given their age at the end of the previous stint. Probably, it is a combination of both. Once Massa stopped, Alonso put in some faster laps supporting the contention that he was faster – so his tyres were (probably) in a better state due to the slow pace behind Rosberg. Without these disproportionately fast laps, which were about the same as Massa on new tyres, Alonso would not have jumped his team mate. Neither would he have made it if Massa had not lost 3s in the pits with a slow stop.

So the laps behind Rosberg probably helped Alonso keep his tyres in the shape to be able to get into fifth place and begin the long chase of Jenson Button.

The final stint shows clearly that the Ferraris had the pace (at least on the prime tyre) to do better in Korea, but they nearly blew it all at the end of the first stint. Alonso may have looked very impressive in the closing stages, but he has others to thank for smoothing his path to that fifth place.

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