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Analysis

Why F1's quest for rain 'spray guards' is so complex

Formula 1 took a step towards ensuring that a race is less likely to be lost to wet weather with a test at Silverstone a few days after the British Grand Prix.

George Russell, Mercedes F1 W14

Photo by: Sam Bloxham / Motorsport Images

Unfortunately, the first track running of the prototype wheel arches or 'spray guards', as some are informally calling them, was not an instant success.

However, as a first step and in terms of data gathering and correlation, it was a useful exercise, and at least provided the FIA with a starting point as it tackles an issue that was brought into focus by the red-flagged Belgian Grand Prix of 2021.

"Obviously it would have been perfect if everything had confirmed perfectly and we already had a solution to apply in October or something like that," says FIA single-seater director Nicolas Tombazis.

"But that wasn't the case. We are completely committed to getting this to work because we feel that sooner or later, it will make the difference between a race being cancelled potentially, or a race happening.

"And I think if over its lifetime, if it saves a race and 100,000 people from suffering a situation like a Spa in 2021, if even once it makes a difference, I think it's well worth it."

It was that controversial Belgian event and the pitiful sight of seeing the cars trailing around behind the safety car and a result being declared that fuelled efforts to reduce spray and improve visibility.

The aim was to create something that could be fitted to cars on occasions when rain is so heavy that in normal circumstances it would not be possible to run.

It took a lot of work to create the devices that were trialled at Silverstone. Essentially, the prototypes are in two parts, with the top of each wheel covered, and a secondary element that looks a little like a sideways bargeboard located close to ground level. The whole arrangement is attached to the upright and thus moves with the wheel.

The FIA trialled its new 'spray guards' at Silverstone, but more work is needed for them to be adopted in races

The FIA trialled its new 'spray guards' at Silverstone, but more work is needed for them to be adopted in races

Photo by: FIA

For the test, Mercedes helped out by modifying a W14 for Mick Schumacher to drive on an artificially soaked section of Silverstone with the new devices fitted.

McLaren's Oscar Piastri provided a reference for how much spray a normal car produces, while also following the Mercedes and offering feedback on the impact on visibility.

The main point of the day was to gather data on how water behaves when thrown up behind an F1 car, and help the FIA's aerodynamic team correlate that real-world info with their research.

FIA head of aerodynamics Jason Sommerville and his colleagues faced an interesting challenge, as modelling water droplets is not easy. Models developed for road car use – how rain behaves around mirrors and so on – provided a useful starting point.

PLUS: The science F1 must defy to prevent Spa shambles repeat

However, as Tombazis explains, after conducting plenty of CFD simulations "we did understand quite soon that it was not quite as simple as just put something on, off you go, and you're done".

"First of all the CFD simulations are quite tricky, because you have to simulate also the water particles," he says. "Secondly, when there's water droplets inside a flow field, it's actually quite complicated physics.

"And additionally, even then you need correlation, because we don't have the full knowledge of much of the water is sucked from the from the ground, and how much is thrown away from the tyres.

"And you also don't know exactly what the diameter of the little droplets is, for example. So the simulation gets quite complicated quite quickly. So that's why we were in need of some correlation."

The FIA is anxious to avoid a repeat of the 2021 Belgian GP that had to be curtailed before any racing laps were run due to heavy spray

The FIA is anxious to avoid a repeat of the 2021 Belgian GP that had to be curtailed before any racing laps were run due to heavy spray

Photo by: Erik Junius

The big challenge was to develop a device that could work in an F1 environment and cause minimum disruption to aerodynamics, while also staying safely attached to the car at high speed.

"We didn't want to lose too much performance of the cars and mess up the aerodynamics too much," says Tombazis.

"Although some of it is inevitable. And the actual aerodynamic load on these big mudguards or whatever you call them, if you have a complete cover, that would have quite high dynamic load. And therefore their support on the uprights would have to be fairly robust to not fly off at 300kph."

Tombazis is happy to admit that the Silverstone prototypes didn't have much of an impact on spray reduction.

"The actual devices that were used were relatively small, they were covering only small parts of the wheels," he says. "I wasn't personally too confident that they were going to work. I was thinking, is that covering enough? Is it going to have enough of an effect?

"And as it turns out, they didn't make a tangible difference. But we did gain a lot of correlation and a lot of data that we now can more confidently correlate. So I think it was a useful first test.

"We were very grateful for the teams that worked with us on that. We also proved that let's say our set-up at the track - how to measure things is not that easy – worked quite well. So we had a reasonable way of assessing the matter.

"We're not however there with the configuration. And we just need to try again. Not many engineering projects work on the first go perfectly. So we just need to work a bit more.

"There's still quite a lot of exposed wheel, let's say. We clearly haven't confirmed the concept, but also I don't think this is enough to say this doesn't work."

Modelling water is a key hurdle for the FIA to overcome

Modelling water is a key hurdle for the FIA to overcome

Photo by: Patrick Vinet / Motorsport Images

One complicated aspect is assessing how much spray is generated by the diffuser, which is something the spray guard programme can't address.

"It's an inherent issue to do with diffusers," says Tombazis. "But by and large sportscars have less of this issue. And so I'm optimistic that indicates that we have a fighting chance.

"But as I say, until we actually properly quantify it, we need to continue the R&D programme."

The next iteration is likely to be some months away, and arranging another test like the one at Silverstone won't be the work of a moment, especially once the run of flyaway races starts in Singapore and teams and cars are travelling.

If and when a device is successfully trialled and approved, there will also be practical considerations.

"Once we've got something which we think is making a tangible reduction of the spray in a noticeable way, then we will need to define that shape, pass it as a technical regulation, and we will have then some discussion," says Tombazis.

"If it's engineered properly, it's not going to take more than five to 10 minutes to fit. If you imagine it as having been red-flagged because of a downpour, by the time everything is gathered together then people would have had to fit them."

The F1 teams meanwhile remain supportive – everyone understands what a disaster it will be for grand prix racing to have another Spa 2021, or even worse, a day when the cars cannot take to the track at all.

"There's more work to do on them," says Mercedes trackside engineering director Andrew Shovlin.

Teams remain supportive of the FIA's mission and recognise the greater benefit that can be derived from the spray guards successful application

Teams remain supportive of the FIA's mission and recognise the greater benefit that can be derived from the spray guards successful application

Photo by: Glenn Dunbar / Motorsport Images

"But it's a problem that will be useful to have a solution for, because I think the teams and certainly the fans hate it if a race can't go ahead because the conditions are too difficult.

"They're not ready to be moved into production and regulation at the moment. So there's definitely work to do. They do improve the spray that you get from the tyres, but you still get a lot coming from the diffuser in the way that the rear wing's pulling it up, that's all very powerful.

"But interesting first steps, and we're providing the car and some bits to do that development. It's FIA's project to decide where that goes next, and what happens in the future."

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