Lewis Hamilton, Mercedes, Red Bull Ring, 2020

Analysis: Why the FIA stewards ruled Mercedes’ DAS is legal

2020 F1 season

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The FIA clearly had an inkling this one was coming, as well they might.

From Red Bull’s submission of a formal protest against Mercedes’ Dual-Axis Steering system, better known by its acronym DAS, to the issuing of a decision, took just over six-and-a-half hours.

That would be long by the standards of a ruling in a racing incident, but is good work for a complex technical matter which involved hearing lengthy submission from both parties. Never mind the added complication of having to do much of the work via videoconferencing due to Covid-19 precautions.

The possibility of a protest was raised during the build-up to F1’s cancelled season-opener in Australia almost four months ago. The device had been seen a month earlier in pre-season testing, at which time an FIA spokesperson advised RaceFans the device appeared to be legal.

Note: ‘appeared’. Reports elsewhere, and misinterpretations of them on social media, prompted a mistake belief among some that the FIA had formally ruled DAS legal. This could not happen unless a protest was raised, as has now happened.

Christian Horner, Red Bull, Red Bull Ring, 2020
The stewards rejected Horner’s DAS protest
The decision will be a relief to Mercedes. However we know they engaged with the FIA at an early stage in the design process. Technical director James Allison recently explained how the team raised the DAS concept with the FIA a year ago.

In that early incarnation, DAS was operated not by sliding the steering wheel forwards and back as onboard cameras revealed in February and showed again in practice yesterday. Instead, as Allison, described a separate lever was originally used to achieve the adjustments in toe angle DAS allows.

“They begrudgingly agreed the dual axis steering was actually legal,” Allison recalled of their dealings with the FIA. “But they didn’t much like the way we’d done it because the second axis we were getting from a lever on the wheel rather than that whole wheel movement. They said ‘no, you’re going to have to move the whole wheel in and out’.

“I think when they said that, they were hoping that would be too difficult and that we would go and cause them no more problems.”

That didn’t happen. Mercedes built DAS using the ingeniously simple and satisfyingly lateral solution of sliding the steering wheel back and forth. And more trouble followed when Red Bull objected to it.

Red Bull, represented at the hearing by chief technical officer Adrian Newey, chief car engineer Paul Monaghan and sporting director Jonathan Wheatley, objected to DAS on the grounds that it appears to be a part of the suspension system, and the technical regulations state the suspension cannot be adjusted while the car is moving.

Mercedes countered that DAS is a steering system, and therefore not subject to that regulation. The stewards essentially agreed with them, ruling: “the DAS system is physically and functionally a part of the steering system” and that “as such, it benefits of the implicit exceptions to certain suspension regulations applicable to steering.”

Red Bull’s case hung on the claim that DAS does not contribute to the steering of the car. “A conventional steering system can navigate a lap of any circuit,” they noted. “In isolation DAS is incapable of lap navigation and is therefore dependent upon the conventional steering system – i.e. DAS, in changing the toe angle of the wheels is a separate and redundant system.”

The protesters relied on examination of Mercedes’ use of the system in free practice to make their case. “Observation of DAS usage in [second practice] indicated deployment in a straight line with no change of trajectory, thus rendering DAS not a steering system,” they noted.

“By observation of the video footage from [second practice], use of DAS was not every lap and isolated to in/out or re‐charge laps thus it was not a system necessary for use in timed laps, rendering the primary purpose to be something other than steering.”

They also gave a revealing insight into the purpose of the system. “Judging by practice today, it appears to be used on out and slow laps as a means of adjusting tyre temperature, i.e. its primary purpose is not as a steering system but rather a tyre temperature management system.”

Mercedes representatives were Allison, sporting director Ron Meadows, chief designer John Owen – whom Allison credited for the successful implementation of DAS on the W11 – and trackside engineering director Andrew Shovlin. Their three-point defence began by asserting that DAS is not part of the suspension system.

As part of this they noted DAS “is mounted fully on the power assisted steering rack” – a point they might not have been able to make of its original design, prior to their exchange with the FIA, when it was lever-operated.

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While DAS allows the driver to “optimise the toe” angle, Mercedes argued a conventional steering “often also changes the toe – but it does so as a function of steering angle”. By accepting its definition as a steering system, it may therefore legally be altered by the driver while the car is moving.

Lewis Hamilton, Mercedes, Alexander Albon, Red Bull, Red Bull Ring, 2020
Red Bull argued DAS is a suspension, not steering, system
The stewards accepted that if DAS was not part of the steering system then it would be illegal. However they ruled DAS is “part of the steering system, albeit not a conventional one”.

In other words, Mercedes have pulled off the classic trick of following the letter but not the spirit of the rules, a detail highlighted by the fact the FIA has already written new rules which will ban DAS next year.

Mercedes found a gap in the 2020 technical regulations within which they could make DAS work legally. “Article 1.2 states that ‘at least two (wheels) are used for steering’ and Article 10.4.1 states that ‘the re‐alignment of more than two wheels is not permitted’,” noted the stewards. “These two articles hence limit the number of steered wheels to two, but crucially no reference is made on that realignment being of a single degree of freedom (i.e. the [left-hand] wheel having a single function of position in relation to the [right-hand] wheel).”

The rest of the stewards’ decision follows from that point. “In the opinion of the stewards, the DAS system is physically and functionally a part of the steering system,” they concluded. “As such, it benefits of the implicit exceptions to certain suspension regulations applicable to steering.” (The stewards’ ruling and summaries of Red Bull and Mercedes’ cases can be read in full here.)

Whether that will be the end of the matter remains to be seen: Red Bull do have the right to appeal the decision.

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Toto Wolff, Mercedes, Red Bull Ring, 2020
Toto Wolff already has his first win of 2020
Why Red Bull of all teams raised the protest is easily answered: They look like being the closest realistic threat to Mercedes in performance terms this year, and therefore stood to gain most by compromising them.

Ferrari do not appear to be the force they were last year. Racing Point may have been the second-quickest team in practice on Friday, but they are hardly likely to protest their engine supplier, upon whose 2019 championship-winner their RP20 is so clearly based.

Ferrari, indeed, have admitted they researched creating a similar system to DAS previously. They may already have been satisfied the device was legal, but hadn’t solved how to build it.

But F1 teams, of course, do not just request clarifications and lodge protests with the sole goal of getting them banned. The process of protesting can allow them to glean new information about rivals’ systems, aiding their efforts to replicate them. Perhaps we shall see a DAS-equipped RB16 before the season is over.

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Author information

Keith Collantine
Lifelong motor sport fan Keith set up RaceFans in 2005 - when it was originally called F1 Fanatic. Having previously worked as a motoring...

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5 comments on “Analysis: Why the FIA stewards ruled Mercedes’ DAS is legal”

  1. I saw it as a webinar for Newey to learn Merc system too.

    1. I am quite sure clever people, not just Newey, but mechanical/suspension experts from the Red Bull team have had a lot of thoughts on how to get a system like it working on the current Red Bull while they were stuck at home @ruliemaulana, and if it brings a few tenths (that was an estimate earlier this year), it seems silly for them not to throw lots of money at it while they still can to try and beat Mercedes this year. It’s probably something that can be done independently from other aero work which will remain useful next year.

      1. ColdFly (@)
        4th July 2020, 9:09

        Maybe add a question to the Prediction Competition: when will RBR introduce it’s own DAS.

      2. The other reason for protesting is to find out if it is worth a team trying to replicate that technology. Sort of like when … was it Racing Point protested Renault using some computerised system on their car? Yes, I think it was something like that. Racing Point wanted to develop the technology themselves, so they protested Renault’s use of that technology only to have the Stewards uphold the protest.
        Red Bull might already have designs for this sort of technology, but what’s the point in manufacturing and installing it if it isn’t legal? The easy way to confirm that is to protest Mercedes’s use of DAS. Now that its been confirmed as legal then don’t be surprised to see it appear on their car this year.

  2. What about the moveable aerodynamic device bit? Aligning the wheels to the air, reducing drag surface?

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