Will Gray

Technical Talk: The diffuser gain

Will Gray

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Long before the season-opening Australian Grand Prix, rival teams were expressing concerns that the three who had explored a loophole in the rules, which allowed them to make more complex and better diffusers than their rivals thought possible within the rules, were going to be in a class of their own.

The designs were not officially challenged until the protest in Australia. The cars were passed legal and also deflected a protest from BMW at the Malaysian Grand Prix — although the latter seemed more procedural, with the German team simply going through the motions with little expectation of success.

The teams who are not in 'the gang' also seemed to resign themselves to losing their appeal — and, most gallingly, to the fact that rival engineers stole a march on them.

But how much of an advantage did the diffuser design bring?

The fastest lap times in both Grand Prix weekends so far have been set during qualifying, in Q2, the last time the cars run on low fuel before the top-10 shoot-out.

Although allowance must be made for mistakes or traffic considering the limited number of laps available in the session, the fact that the top 10 is covered by less than a second means every car has to push as hard as possible, so the times should be generally indicative of the fastest times the cars can set.

In Australian Q2, four 'diffuser gang' cars were in the top six and the fastest of those, Rubens Barrichello's Brawn GP car, was 0.338 seconds faster than the quickest 'non-diffuser gang' car, Sebastien Vettel's Red Bull (who had set the third fastest time).

In Malaysian Q2, there were also four 'diffuser gang' cars in the top six, with Button's Brawn GP car 0.438 seconds faster than the fastest 'non-diffuser gang' car, this time the Red Bull of Mark Webber (who had also set the third fastest time).

That, of course, does not mean that all Brawn's advantage is down to the diffuser design - but trends show the 'diffuser gang' as a group are in the advantage, with Brawn, Toyota or Williams consistently filling the top positions.

In the practice sessions so far, only four times out of a possible 36 has a 'diffuser gang' car been outside the top 10. In Australia, they filled five of the top six finishing places and in Malaysia they filled five of the top six grid spots.

If the courts had ruled against the 'diffuser gang', the championship would have a rather different look...

Alonso (Renault) 10
Heidfeld (BMW) 9
Buemi (Toro Rosso) 8
Bourdais (Toro Rosso) 8
Sutil (Force India) 5
Fisichella (Force India) 3
Webber (Red Bull) 6
Vettel (Red Bull) 1
Hamilton (McLaren) 3
Massa (Ferrari) 2.5
Piquet (Renault) 1
Raikkonen (Ferrari) 0.5

But with the court of appeal ruling in favour of Brawn, Toyota and Williams, and with the diffuser giving an apparent advantage of up to three to four tenths, it will be interesting to see how quickly the other teams can catch up...



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