We often hear that a two-stop strategy will be 6s (or something) faster than a three stopper, but we rarely see evidence of this. Well, that is about to change. Applying the intelligentF1 model to some basic assumptions on fuel load (from last year’s race), pit stop time loss and tyre life, we can get a basic idea of what sort of strategy will be the quickest way (theoretically) to tackle the Japanese Grand Prix. As we change the assumptions, we will see that the answer changes. So let’s start with the basic idea that the prime (medium) tyre will be about 1s per lap slower than the option (soft). We get the following race history chart, with Vettel (blue line) on a three stop, Alonso (red dashed line) on a two and Hamilton (grey line) on a one stop if they all have the same pace.

What we see is that two stops is 5s faster than three stops, with a one stop strategy being about 5s slower still. However, the one stopper is reliant on the option tyres lasting 30 laps without signifcant performance drop-off. If we increase the gap between the primes and options to 1.5s per lap, the picture changes to the one below.

The one stopper is now clearly uncompetitive no matter how well the tyres last, and the three stopper is within 3.5s of the two stopper. The fun starts if the options tyres struggle and do not last the 20 or so laps needed for an optimum two stopper. Staying with the 1.5s difference, but assuming that we get larger degradation after 15 laps (using the intelligentF1 tyre degradation model), we get the picture below. The one stop strategy has been removed as it is now hopelessly uncompetitive.

The three stop strategy is now faster by 8.5s. So there is much for the teams to determine in Friday practice. Will the tyres last the 20 laps necessary to ensure that a two stop strategy is the way to go (very temperature dependent)? Is the pace disadvantage of the prime tyre sufficiently small to completely rule out a three stop strategy? If the prime tyre is much slower, to best minimise the time on it, the teams will be looking to use up their option tyres first. In this is what we see, I would not expect anyone to start on primes. Unless they’re driving a Sauber. Contrary to much I’ve read, it does not make any real difference which order you use the tyres (primes first or options first). The choice is all about minimising time on the slower tyre and minimising hold-ups in traffic.

In the free practice sessions on Friday, I’ll be looking out for tyre life, and trying to get an idea of the pace of the prime tyres. Somehow I don’t think we’ll be talking about 20 laps from the option tyre, and we’ll be looking at three stoppers for the guys at the front.

*Strategy Predictions*

intelligentf1

October 7, 2011

I’ve got the data from the Friday sessions. There’s a bit of work to do, I think that there is some uncertainty assessment to do to try to understand the possible fuel loads, and the length of the stints looks a little short to do anything definitive on tyre life. I’ll post something later this evening.