Abu Dhabi in Depth: How Di Resta helped Sauber and Williams

Posted on November 17, 2011

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In the early laps of the Abu Dhabi Grand Prix, the Williams cars which started from the back row languished behind the Lotus of Heikki Kovalainen. They were soon joined at the back by the Sauber cars, who both stopped in the first six laps, Perez because he broke his front wing, and Kobayashi to get rid of his hard tyres.

Although these cars (except Perez, who was just quick) proceeded to make the optimum two stop strategy, realistically they were a long way behind, and had slow cars to pass to get to the front. So how did they do it?

Enter Paul di Resta on his medium tyres. The Scot was not slow on these harder tyres (1.5s off the pace is about average), but he was much slower than his pursuers – Buemi, Petrov and Alguersuari the midfield cars filling 10th-12th places in the first stint. They should have been more than 1s per lap faster in that stint, but Di Resta was able to keep them behind, at least until Buemi got past on lap 14. But there was even more to it than this – for most of his stint, Di Resta was not at his full pace due to defending from Buemi – losing the Toro Rossos and the Renault even more time.

You could argue that the Toro Rossos lost points through Buemi’s hydraulics and Alguersuari’s long pitstop, but this does not tell the whole story. If we use the intelligentF1 model of underlying pace, and assume a standard 1.5s pace difference on the harder tyres for Buemi, the soft tyre shod Kobayashi would have caught him before the end. And Alguersuari would have been stuck behind Barrichello in the final stint.

As an estimate, the time lost in the first stint stuck behind Di Resta was about 10s. Without this time lost, Buemi would have been ahead of Di Resta at the end (due to Di Resta losing time in traffic after his stop), and Alguersuari would have missed out on the last point – because Petrov would have beaten him. The Saubers and the Williams would have been beaten by all three of the cars which were held up.

By not getting held up in the first stint as they started on the medium tyres, the Williams cars, which were still slower than their midfield opposition in the were able to move through when the others used the harder tyres. And Kobayashi may have lost some time passing the tail, but he lost less time than those trapped behind the Force India. His underlying pace was no better than theirs – he just spent more time in clear air.

Perez gained less by not being able to two stop with a short stint on the hard tyres. But for his first lap error, points were a certainty. He was ahead of Di Resta at the start, and that, as we can now see, was worth a great deal…

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