Ted Kravitz gives his inside line on the Spanish Grand Prix, bringing you the stories behind the headlines from the fifth race of the Formula 1 season.
Want to know why the Red Bull RB6 is so fast? It's the exhausts.
We learned more about this area in the Barcelona paddock at the weekend and while it's not the only explanation for their speed, rival engineers estimate Red Bull's exhaust solution accounts for about half their performance advantage.
Regular readers of this column will remember that we featured the innovative Red Bull exhausts after they first appeared at the
final pre season test
in late February.
Red Bull came close to a repeat of their one-two in Malaysia
More traditional exhausts exit at the top of the rear bodywork, whereas the RB6 has them located low down, at the side of the gearbox and rear crash structure.
This is where it gets technical. Not only do the exhaust gases feed air into
the double diffuser
, giving extra downforce by sucking the car on to the track but, being positioned in this way, they help tidy up the airflow around the rear wheels and out of the back of the car.
The rear tyres are quite big, and the wake they produce is damaging to the airflow leaving the car. The exhaust gases meet the tyre wake and force that air outboard, neatly and cleanly round the outside of the car.
You could see this in action at the wet Chinese Grand Prix, when the moist air vaporised around the exhaust area and showed a visible vortice around the rear tyre.
I know it's hard to picture, but it's a crucial part of what makes the Red Bull so quick, so watch out for a feature explaining it visually with some CFD (computational fluid dynamics) data on our pre-qualifying show on BBC One soon.
Just one extra thing to add from the race, as well as recognising a crushing win from Mark Webber. It turns out that Red Bull's clearing of the garage for Sebastian Vettel was not, as I reported during the race, precautionary at all. Vettel revealed afterwards that they called him in to retire on safety grounds, reasoning that they couldn't let Seb continue knowing he had a brake problem that could see him suffer a nasty accident.
But by electing to stay out and go for whatever points could be gained, Vettel effectively relieved the team of their responsibility and took the risk into his own hands. Brave.
It was a massive effort from Fernando Alonso, whose second place felt like a victory. His lap times were very impressive, culminating in a one minute, 24.84 seconds as the fuel burnt off and the tyres warmed up, just 0.018 seconds slower than race winner Mark Webber's best.
During the television coverage over the weekend, we made a lot of Alonso's frequent use of the
but Alonso was right to say he was never driving with one hand - his thumb is always wrapped round the steering wheel even if his palm is not gripping it, and if anyone can make it work while driving one-handed, it is Fernando.
By Ferrari's own admission, these are early days with their F-duct. It's at the experimental stage. The proper Mk 1 version will debut in Turkey at the end of the month and be rather more sophisticated.
We spoke to Ferrari's genial chief engineer Chris Dyer after the race. He underlined the need for the team to concentrate on finding performance now that they have fixed their engine problems.
As Alonso himself says: "There is a very aggressive plan of developing the car with some good gains and good improvements to come in the next races, so we are very optimistic".
Despite his recent setbacks, he's right in the championship and remains many people's favourite. Dyer was positive that Ferrari has the ideas and the resources to make the step forward to challenge Red Bull, especially in qualifying.
There are a few factors that added to Jenson Button's difficulties in trying to overtake Michael Schumacher. Firstly, the dashboard readout problem Button described after the race. Not knowing when to shift gear will lose you a lot of lap time, as will hitting the rev limiter.
Button frustrated by mechanical problems
Schumacher was running more wing, so was quicker through the slower corner complexes, including the one in the last sector before the main straight. Button was much quicker on the straight - with rear wing stalled thanks to the F-duct, Jenson topped 311kph, against Schumacher's 303kph.
Schumacher knew that, of course, so was always prepared when Button closed up onto his rear wing and 'tried it on' under braking for Turn One.
But the tactic that raised eyebrows in the McLaren garage was Schumacher's trick of braking in the middle of a corner, which caused Button to brake, before accelerating away. This is a fairly common move, but didn't go down too well with those on the receiving end.
Schumacher's defending tactics needed to be pretty ruthless. Ross Brawn confirmed with a smile that Schumacher had been very effective with the ways he covered his lines and blocked Button's attacks. It's the first time Jenson has been attacking his previous car, engineered by his previous race engineer Andrew Shovlin and overseen by his previous team boss.
There's no nostalgia in F1. Brawn and Shovlin would have been using every detail of their knowledge of Button's racecraft to help their new charge stay ahead.
On Saturday, Brawn gave some more details about his car's innovative fin-shaped roll structure.
Mercedes unveiled a dramatic new shape in Barcelona
It goes without saying that it passes all the FIA crash test loads, when they effectively drop the chassis upside down from a great height. Brawn wouldn't be drawn into discussion of a 'what if' scenario should the fin come into contact with grass and 'plough' itself into soil.
But particularly interesting was that the small 'nostril' air intakes either side of the fin will change size depending on the circuit to ensure sufficient air is taken into the engine. They will grow for Monaco this weekend and contract for the high speeds of Monza.
The one drawback with the Mercedes fin is that it appears to preclude the option of fitting an F-duct in the style of McLaren's, with a high channel from the airbox leading directly onto the rear wing.
Lotus made a bigger step forward compared to their rivals than any other team, even Red Bull.
To explain: Most teams with upgrades found about 0.3secs per lap. Red Bull (in qualifying trim at least) found half a second, while Lotus improved by a whole second.
Kovalainen failed to make the starting grid after gearbox problems
But this work went largely unrewarded. A gearbox problem left a very disappointed Heikki Kovalainen with nothing to do but watch the race and think of ways to improve his golf swing (he has become obsessed with the sport, apparently), while Jarno Trulli drove round in a solid but underwhelming 17th place.
It was almost as if, with all the bad luck Trulli has been having recently with unreliable hydraulics, he was nursing the car home from the start of the race.
When Timo Glock's Virgin closed in on him, the Italian suddenly upped the pace from 1.31s and 1.32s to a best race lap of 1:29.5, two tenths quicker than Glock's best in the upgraded and no longer fuel-limited Virgin.
Trulli is a Monaco specialist, so his team will be expecting a better race result from him round a track that has seen a fair amount of Lotus success over the years.
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