Sunday, May 22, 2011

Look, but don't stare

On the restart of the Spanish Grand Prix, Fernando Alonso used his KERS boost to swoop inside Mark Webber's Red Bull. Webber, however, wasn't ready to concede the position, and immediately ducked out of Alonso's slipstream, aiming his Red Bull inside the tightest of gaps to re-take the position under braking into turn 1.

That, of course, was 2009. In 2011, the roles were reversed.

Alonso got excellent traction away from fourth position on the grid, quickly alongside Hamilton to his left. Ahead of them, Vettel was swooping about, looking to take the inside of Webber, then flicking back to the outside as the Australian covered him. Alonso had already latched onto Vettel's slipstream, and as Sebastien went left, Fernando was able to pick-up Webber's drag-reducing wake. Like a honey-bee flitting from one nectar-laden bloom to another, Alonso took advantage of his good traction and successive slipstreams, to thrust his Ferrari down the inside of Webber.

Shaving the white line bordering the grass on his right-hand side, and the turbulent outwash of the Red Bull on his left, Fernando took the lead under braking into the first corner. A single twitch from the Red Bull could have put the Ferrari onto the grass at 180mph, their wheel rims sufficiently close to generate a Casimir effect.

Webber, for his part, may have been slightly distracted by watching Vettel on his left, but once Alonso shot down the inside, Mark appeared slightly cautious on the brakes, allowing his team-mate to take second place.

Michael Schumacher, meanwhile, had also got away to a decent start, getting alongside Massa on his right, but momentarily finding his passage blocked by Button and Rosberg. Button, however, drifted left, and Rosberg moved right to cover a move by Massa, leaving Michael to drive straight between them.

Under braking into turn 1, Petrov challenged Hamilton on the outside, but ran slightly wide. On a tighter line, Rosberg was immediately inside the Renault, which placed him on the outside for turn 2. Behind them were Schumacher and Massa, also side-by-side, and Button in ninth.

Petrov got a little squirrelly through turn 2, which gave Schumacher the opportunity to try the outside line into turn 3, and for a moment Petrov had a Mercedes either side of him. This pinned Rosberg on an excessively tight line, and by the exit of the corner, Petrov emerged in fifth position, with the two Mercedes wheel-to-wheel behind. Rosberg, however, was rather boxed-in behind the Renault, and Schumacher took sixth place into turn 4.

Behind that battle, Buemi's Toro Rosso drove clean inside Button in the first part of turn 3, and Massa in the second part of the corner! Button got alongside Felipe in the second part of turn 4, but was boxed-in behind Buemi on the exit, and Massa was then able to out-brake the Toro Rosso down the outside into turn 5, reclaiming eighth position.

From that point on, things became rather strategic. In fact, the logic of the entire race was determined by the performance of the new harder tyre. The underlying problem, of course, was that the harder tyres were between 1.5secs and 2secs slower than the soft tyres, but the soft tyres were only lasting 10-12 laps. Moreover, even the hard tyres could still only survive somewhere in the region of 20 laps. Thus, in a 66 lap-race, that meant four stops were the only viable strategy. Unless, that is, you could nurse your soft tyres to survive 15-lap stints...

And here, I feel, it is necessary to provide a simple piece of arithmetic for the assistance of some commentators, who may still be struggling to follow the strategy this year. Let P denote the number of pit-stops, and let S denote the number of stints. Then the following rule applies:

S = P + 1

Thus, if you're doing a 3-stop race, then you'll be running 4 stints; if you're doing a 4-stop race, then you'll be running 5 stints.

Now, the number of stints equals the number of sets of tyres you need, and there's only three sets of soft tyres, and three sets of hard tyres. Hence, if like Fernando Alonso and Mark Webber in Sunday's race, you're running a 4-stop race, then you'll be needing 5 sets of tyres. And if, like Alonso and Webber, your soft tyres are only lasting for nine or ten laps, then you'll stop around lap 10, lap 20, and lap 30. At that point, you've done 3 stops and you've used all your soft tyres. There's no more. They're finished. Kaput. You'll have to spend the rest of the race on hard tyres.

And this is where Button's 3-stop strategy obviously reaped significant dividends, placing him on soft tyres between lap 30 and lap 48, during which time Alonso and Webber were struggling with the hards.

Ferrari, in particular, have generally struggled this year to get the hard tyres to their optimum operating temperature, and from the beginning of qualifying should have been planning to minimise the number of laps spent on them in the race. Doing so would have required a 3-stop strategy, but that would have required saving at least one set of soft tyres in qualifying. Unfortunately, Ferrari needlessly blew a set of Alonso's soft tyres in Q1, and from that moment on, Fernando's race was never going to work.

But perhaps Fernando already knew this, as the scarlet Ferrari squeezed through that frighteningly small gap, just seconds after the start.


johnh said...

"Their wheel rims sufficiently close to generate a Casimir effect."

Excellent write up as always. I wish to join you in the 'frustratingly simple equations that DC should look at' series:

T = P - S

Where 'T' is the overall time lost for a pit stop, 'P' is the time spent in the pit lane and 'S' is the time taken on track to travel from the pit lane entrance to exit.

Forgetting the aforementioned 'S' term means you might think Hamilton will come out behind Alonso & Webber, which is of course was not the case.

Gordon McCabe said...

Brilliant John!