How F1 teams are adapting last year’s chassis as “mule cars” for 2021 tyre testing

2021 F1 season

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While Pirelli was forced to shelve a change in its tyre constructions for the 2020 F1 season, that will not be an option next year, when a new 18-inch tyre format replaces the current 13-inch rubber.

F1 has been stuck on the smaller tyre size for decades. So how is the sport preparing for such a fundamental change?

The matter was brought into sharp focus at the end of last week when Lewis Hamilton issued a sharp criticism of F1’s official tyre supplier. The six-time world champion urged the sport to consider an alternative to Pirelli if they do not deliver improvements he says drivers have been demanding for years.

“We just need to make sure that we always want to be working with the best technology, the best technology partners,” he said, adding, “I hope for 2021 that we have a better [performance] target and one that they’re able to meet or a manufacturer is able to meet.” Hamilton implication, that F1 should consider a switch to another brand, was clear, punctuated by him stressing “that’s a very, very important line that we need better tyres.”

Hamilton’s closing shot was a touch harsh. Being F1’s sole tyre supplier is a thankless task. Losing drivers invariably pin the blame on the tyre company. When the FIA last put the contract out to tender only one other company bid for it, and it did not appear to be a serious effort.

Lewis Hamilton, Mercedes, Circuit de Catalunya, 2020
Hamilton criticised F1’s official tyre supplier
But F1’s new era next year will usher in a significant change on the tyre front, particularly with regard to carcass construction, suspension geometry and resistance to ‘kerbing’. Thus Pirelli, working in conjunction with the FIA and F1, has devised a rigorous action plan to ensure that the transition occurs as seamlessly as possible, particularly as the switch coincides with a sea-change on the chassis and sporting fronts.

Numerous variables which affect tyre performance are in play: A substantial increase in car weight, changes to weight distribution, plus revised aerodynamics including an element of ‘ground effect’. In addition, simulations and wind tunnel CFD runs will be greatly reduced, placing greater emphasis on getting it right first time.

The cornerstone of the action plan to submit Pirelli’s prototype 18-inch tyres is the use of “mule cars”. These are effectively 2019 (or earlier) cars adapted to provide projected 2021 levels of downforce and overall weight. Last October the FIA distributed technical directive TD040/19 which outlined the specifications for mule cars, which were in turn updated under TD005/20 issued earlier this year. Although voluntary, all teams signed up to the programme.

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Car specifications are tightly controlled, with teams required to raise their mule by 30mm to cater for the larger diameter 18-inch wheels, with a ‘false’ floor reducing the ride height to prescribed levels, different front/rear wings providing anticipated 2021 downforce levels, and ballast taking the cars to an increased minimum weight limit of 775 kilograms, details of which were revealed here on Friday.

[smr2020test]Critically, steps have been taken to ensure teams do not glean vital information for 2021 from their suspension and braking systems. No testing of 2021 parts is permitted under the programme.

“All 10 teams accepted to make a mule car for us and test with a mule car,” Pirelli head of car racing Mario Isola told RaceFans in Barcelona. “But obviously there will be 10 different mule cars because they have to modify [an older car] according to some technical directives made by the FIA in order to make a car that is representative of next year’s car

“They have to modify the suspension in order to fit the new tyres and so on. That is also good because at least we can develop our tyre not on a single car and therefore having a product that is customised for that car, but we are going to test across the cars of all the teams.

Tests are being conducted between February and October, with all teams undertaking two days of dry running, and Ferrari and Red Bull undertaking a single wet test, and Mercedes committed to two days wet running.

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Ferrari was first to get its mule car on track (pictured top). “The mule car project design is done, and the car has been produced and assembled,” team principal Mattia Binotto said on Friday. “We already tested early [8] February in Jerez. It’s only a matter of operations, going to race-tracks whatever we need to go for further testing.”

Pirelli's prototype 18-inch 2021 tyres
Pirelli’s prototype 18-inch 2021 tyres
“So it’s not affecting the design or the development of 2020 or 2021,” he added.

F1’s traditional post-season three-day test session in Abu Dhabi will be staged for mule cars only. Teams will be obliged to run a young driver on one or two of those days.

“We have all the 10 teams with the mule car, [and] we are going to test the three days with 18-inch tyres. Young driver or expert driver, it doesn’t matter. All the tests will be run on 18-inch tyres,” said Isola.

Having undertaken three tests during 2019 and with 55 ‘car days’ scheduled during 2020 – made up of 10 two-day dry tests and five single-day wet tests in addition to three days running with ten cars in Abu Dhabi – Pirelli and F1 should be better prepared than at any stage since the company re-entered F1 in 2011. Crucially, all 10 teams will have participated in the development of the tyres, so all concerns should be addressed equally.

Does that mean no more complaints on the tyre front? Don’t count on it. This is F1, which means only one winner per race and at least 19 drivers looking for something to blame.

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Dieter Rencken
Dieter Rencken has held full FIA Formula 1 media accreditation since 2000, during which period he has reported from over 300 grands prix, plus...

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  • 20 comments on “How F1 teams are adapting last year’s chassis as “mule cars” for 2021 tyre testing”

    1. “Crucially, all 10 teams will have participated in the development of the tyres, so all concerns should be addressed equally.”

      That’s a non sequitur. Just because tyres have been tested on 10 different cars doesn’t mean the data glanced from those tests was given equal value in development, nor that the resulting tyres would not fit one of the mule cars better than the others. (to say nothing of the actual 2021 machinery)

    2. ”F1’s traditional post-season three-day test session in Abu Dhabi will be staged for mule cars only. Teams will be obliged to run a young driver on one or two of those days.”
      – Don’t you mean ‘traditional’ two-day (one in 2015) test? BTW, could they even have them on consecutive days next time around since the Wednesday after the race will be the UAE national day, a day on which the Yas Marina Circuit has traditionally been booked for national day-activities? Tuesday (Dec 1), Thursday (3), and Friday (4), maybe?

    3. If the FIA is so concerned about lower cost and leveling the playing field, why not build their own F1 car comment to 2021 rules (they already have some kind of model for CFD testing). Pirelli uses that car for testing, then they decide if they want to share results to teams or not. Everyone is on the same foot and the car used, while the FIA would produce a caterham or marussia, would be closer to 2021 than retrofitted cars from 2018 or so with teams trying to collect info anyway…

      1. I seriously doubt the FIA would
        a. be even able to build a car that would be halfway competative/representative, especially to do so from scratch.
        b. do this at a cost that is not a LOT higher than any team adapting a current car
        c. be able to source a halfway representative engine anyway

        @jeanrien.

    4. All 10 teams will build a car, all 10 teams will provide the car and the driver for all test days, none of the teams will be allowed to learn anything ! Typical FIA logic.

      1. Your concern is certainly valid, but I believe you may be oversimplifying what has been said.

        Critically, steps have been taken to ensure teams do not glean vital information for 2021 from their suspension and braking systems. No testing of 2021 parts is permitted under the programme.

        In a past article, I believe it was mentioned that for all Pirelli tests the data gathered is shared out to all the teams. In this way, the teams participating don’t gain an unfair advantage by having been there and seen the data. So all the teams learn something, but no one learns as much as they would like. I imagine the more they can learn the better the tyres will be utilized, so the intention of your argument bears some fruit: let’s quit making the teams work with their hands tied behind their backs.

    5. Hamilton’s closing shot was a touch harsh. Being F1’s sole tyre supplier is a thankless task. Losing drivers invariably pin the blame on the tyre company.

      Poorly worded seeing as the criticism has come from soon to be THE most prolific winner in F1 history who constantly manages the cheese tyres better than anybody else.

    6. how can you run the same brakes with no mods?

      1. What mods do they need?

        1. @megatron With larger diameter wheels should come larger diameter brakes. But I guess the existing brakes won’t have a problem being within the larger wheels. I would think though that brake performance has some input from the wheel itself, air flow directed from by wheel design to cool the brakes for example.

          1. The spec brakes for the 2021 season weren’t much bigger than they are now. The current brakes can easily lock the tires now or in 2021, so there is no need for bigger brakes. THE “CAKE TIN” and all the carbon stuff inside the wheels can be easily changed to adjust for the bigger wheels, which will also incorporate wheel “covers” I believe.

          2. @psynrg
            Also, I’m not sure why it would be a big deal for the mule test cars. The current brakes are more than adequate for the test mules.

      2. @peartree, see @megatron, but you expose a problem for those cars that rely on heat from the brakes to get their tyres up to temperature quickly.

        1. @hohum @megatron @psynrg You make many valid points. I know the teams were given instructions on what they could mod, even so I just can’t understand how can you mod without modding.. On the brakes I know the rim is bigger in diameter, doesn’t mean the brake bolts on fine, then like you were saying there is the cake tin and I completely forgot, wheel covers, cooling, heat transfer and load. The brakes are strong enough to lock up but we don’t generally see cars lock up from high speeds, there is more than enough downforce not to lock up. Are Pirelli effectively testing the tyre, if the brakes are just an aproximation of what they’ll see in 2021? F1 is too high tech for guesstimations.

    7. it’s a joke. Williams will have to use last year’s slowest car with no modifications. They can expect to learn hardly anything from the tests. It’ll cost them a lot of money too.

    8. Well, the bigger diameter wheels will let the teams move the upper A-arm mounting point on the upright to a better position; the improved camber change certainly won’t hurt slow speed grip

    9. This is one aspect of cars that doesn’t need changing. 13inch looks perfectly fine, once they widened them a few years back, they look great. Now more pointless development costs so the cars can look like prams. Inycar has 16inch I believe, and even that looks too big. The f2 test in bahrain, running 18inch looks ridiculous. Change for the sake of change.

      1. @kpcart, Change…. I hope, for the sake of attracting better tyre suppliers.

    10. Can someone please help me out here .. I don’t understand “with teams required to raise their mule by 30mm to cater for the larger diameter 18-inch wheels” …surely the centre of a 13 inch wheel is at the same height off the ground as the centre of an 18 inch wheel if the overall (outside tyre) diameter is the same.
      I’d assumed that the overall wheel diameter would be the same with the 18″ rims compared to the 13″ rims .. is that not so ?

      1. That part did seem a bit strange to me as well @potsie159. I figure that the real point is in the line after that about the “with a ‘false’ floor reducing the ride height to prescribed levels

        That one kind of points to the car being raised by 30 cm for the purpose of the test, BECAUSE the FIA will fit a standardised “false” floor underneath to keep things consistent

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