McLaren's Silverstone woes

"Really?" said Jenson Button yesterday, quizzical eyebrow raised, when someone said Martin Whitmarsh had predicted that the new conventional-exhaust/revised-underbody combination fitted for Melbourne would find the McLaren 1s per lap.

"I didn't know he'd said that. I'm impressed with his optimistic spirit and I would love that to be true. Let's see." He sounded unconvinced. (Mark Hughes's Friday Form Guide, March 25th 2011)

"The gap is massive. One and a half seconds is just massive. That's all I have to say, really." (Jenson Button, July 9th 2011)

For one race at least, off-throttle blowing of the diffuser has been virtually eliminated from Formula 1, and the big loser is clearly McLaren, with Jenson Button and Lewis Hamilton 1.5s and 2.0s, respectively, off the pace of the Red Bulls in qualifying. This compares to a qualifying deficit of only 0.4s at the previous race in Valencia.

It's interesting that McLaren should be particularly disadvantaged, and the explanation for this can probably be traced to the failure of their radical, 'octopus' exhaust system in winter testing.

Barely a week before the first race in Melbourne, McLaren decided to abandon this system, and simply blow the exhaust between the rear wheels and the upper-outer surface of the diffuser. It isn't an exact copy of the Red Bull design, given that Red Bull blow their exhausts underneath the extremities of the diffuser, but it is nevertheless a close cousin of the Red Bull design. And perhaps by a fluke of fortune, this stop-gap solution seemed to integrate nicely with McLaren's overall airflow concept, elevating them to Red Bull's closest competitor over the first half of the season.

Back in Melbourne, Martin Whitmarsh estimated that McLaren had gained a second from their improvised exhaust system. Bereft of their exhaust-blown diffuser at Silverstone, McLaren now find that they've lost a second. Red Bull will also have lost a chunk of lap-time, of course, but in the chilly conditions of Silverstone, it's possible the McLarens were so deprived of rear downforce that they were unable to get the rear tyres 'switched on'. For McLaren, it's possible that the exhaust-blown diffuser was an aerodynamic tourniquet, without which they are simply bleeding downforce.