The revolution

The push to pass
A bid to boost overtaking and the challenge of KERS tested F1’s design brains in 2009, with some unforeseen results…
By Adam Cooper

The package of rule changes brought in for 2009 presented Formula 1’s designers with their biggest challenge in years. Overall, the aim was to improve the show, and with hindsight it worked – albeit perhaps not in the way that was intended.

The plan was simply to make overtaking easier. And while there was little obvious evidence of that happening, we did get the most competitive field we’ve seen in years. A perfect combination of factors produced tightly-packed grids, where a few tenths in qualifying could see a driver drop from hero to zero very quickly.

Key to it all was that the changes gave an opportunity for teams other than regular pacesetters McLaren and Ferrari to get their sums right and steal a march. That was exacerbated by the fact that in the latter half of 2008, the two title challengers had to devote more of their research and development effort to their current campaigns as they carried the fight all the way to Interlagos. By the time they were able to fully focus on ’09, it was too late.

Added to that, the top four teams of 2008 all put a massive effort into the new Kinetic Energy Recovery System, whereas others opted not to and instead concentrated on getting the basics right. Those who went the KERS route struggled initially because a) it was their main focus in winter testing, and b) its use created specific compromises in areas such as weight distribution and packaging.

Ultimately only McLaren and Ferrari would persist with KERS. But when they finally began to get the chassis and aero side right it proved to be a real benefit, and helped them to carry the fight to the championship leaders.

Just to add to the confusion, we had a return to slick tyres, and even the best teams struggled to get a handle on them over the season. Crucially, after the first Grand Prix of the season there was no testing outside race weekends – and that not only made life harder for everyone but also did much to level the playing field.

For years it had been clear that the biggest obstacle to overtaking was that drivers could not follow each other through corners and onto straights, and therefore couldn’t stay close enough to be able to make a pass once they got to the following braking area.

The FIA created the Overtaking Working Group (OWG) with a specific aim of studying the wake effect and producing a set of aerodynamic rules that would allow cars to run close together. The project involved three vastly experienced engineers, namely Rory Byrne (Ferrari), Pat Symonds (Renault) and Paddy Lowe (McLaren), who pooled their knowledge.

“We did some work in the McLaren simulator with Pedro de la Rosa driving,” recalls Lowe, “in order to set targets for the aerodynamic research project. We determined that around Barcelona with a 2006 car Pedro needed a two-second per lap performance advantage to stand any chance of overtaking into Turn One.

“We halved that performance differential to one second per lap. That was achieved by two effects. One was halving the downforce, which pushed it down to 1.5sec. If you have less downforce, then you lose less in the wake.

“The other benefit was to improve the nature of the wake created by the lead car, and the nature of the downforce generating elements on the following car. That was achieved by the wider front wing and the narrower, higher rear wing, and moving the diffuser kickline back to the rear axle centreline.”

So that’s how we got cars which happily were bereft of most of the unsightly flaps and add-ons which had sprouted in recent years, but which had curiously out of kilter front and rear wings.

The final touch was an adjustable front wing. The idea was that as a driver went into the final corner behind someone, he would flick it up to provide extra front grip, then lower it as he came out onto the straight. “It was an insurance policy – how do we save our skins if we cock this up?,” says Lowe. “We wanted to create a car that was more balanced in the wake.”

The return to slicks, which former FIA president Max Mosley had wanted for some time, was a handy way of adding mechanical grip to compensate for the loss of downforce.

So how did it all work out? Anyone expecting contemporary racing to suddenly resemble the 1971 Italian GP was to be disappointed. The problem was that the numbers had been worked out with a 50 per cent reduction in downforce in mind. But the teams had many months to claw it back before the first race of ’09 in Melbourne.

“We fully expected the cars to achieve more than the 50 per cent downforce that was set, but we probably didn’t anticipate the progress that had been made,” says Lowe. “We expected to get back to 70 per cent by the start of the season, but the reality was nearer to 80-85 per cent, particularly with the double diffusers. With that a good proportion of the benefit was eroded.”

The double diffuser concept, pioneered by Brawn, Toyota and Williams, and then reluctantly copied by the rest, made a big difference to downforce levels. It was no coincidence that the teams involved with the OWG did not initially exploit the loophole. “The OWG people were, let’s say, established teams who’ve understood how the rules work for many years,” says Lowe. “We still don’t think the interpretation the others made was correct, because it denies all previous practice and intention.”

Not only did the double diffusers create a significant downforce gain, there were suggestions that the wake they created also undid a lot of the OWG’s R&D work, although there was no proof.

“Did the diffusers make a difference? We just don’t know, it wasn’t something that was studied,” says Lowe. “Williams tried to defend it and said they had done some Computational Fluid Dynamics work that showed it made no difference at all. I don’t go with that because one of the first decisions the OWG made was not to use CFD. It’s good for the front of the car but the quality gets worse the further you progress [to the rear], the errors build up through the length of its trajectory. If you then want to study the wake behind the car, that’s even worse.”

There’s another obvious factor. The OWG’s remit was to make overtaking easier with a notional lap time difference of a second. And at times in 2009 virtually the whole field was covered by that margin – which as we’ve suggested was largely a result of the rule changes. Catch 22… But though there was little evidence of more overtaking, Lowe says the consensus now is that cars could follow each other more easily.

“It came up in a meeting recently, and there was a general view from all the technical directors that the situation was better than in 2008.

“If nothing else, the OWG has maintained the status quo or made it slightly better. If we hadn’t done it we’d have been in a lot worse situation, especially with such narrow performance gaps.”

That’s a good point. Even without a remit to improve overtaking, either last winter or this the teams would have faced the sort of downforce cuts that come along every few years. At least this time there was some science involved.

“It was a good project, the first of its kind, a properly researched study with a proper set of rules. During the programme we determined that with all the aero rule changes made over the last decade or so, if you’d researched how to make overtaking worse, those were the ones you’d come up with! At least we’ve learned that when we make performance adjustments they need to be looked at as to their effect on overtaking, and not just be a shot from the hip.”

The adjustable front wings proved to be a useful tool for playing with car balance over a lap or a stint. But even McLaren gave up on them halfway through the season – rushing the latest front endplate updates into action was hard enough without the need to incorporate electronic gizmos to make the flaps move. They were also an extra distraction for the drivers. Just ask poor Giancarlo Fisichella, who struggled to come to terms with the fully loaded Ferrari, and was bombarded with requests to press this or that button.

The Italian was equally all at sea with KERS, but the new toy did prove – literally – to be a boost for the sport. It was a fascinating technical challenge, and it’s not by chance that only two teams made it work. As noted, KERS helped McLaren and Ferrari catch and challenge the teams that had set the pace since the start of the season, and that improved the racing. The fact that the KERS cars could always expect to gain places on the first lap (and could use it as a defensive tool) added an extra dimension to strategy, and crucially the clever use of screen graphics meant that it became a familiar part of the TV show.

KERS is gone for 2010, and with the aero rules unchanged, teams have the benefit of continuity. Except of course with no refuelling the cars will have much larger tanks and will start with a heavy load. Drivers can no longer rely on pitstops, and that means they’ll have to create their own overtaking chances. And that may have more impact than any aero tweaks…