On the aero of the 2022 WRC cars

The unknown of the 2022 WRC car generation started to clear out last week, when MSport published the first images of the mule test car and, only a few minutes later, the first test images appeared on social media. The images, together with the declarations of test driver Matthew J. Wilson to DirtFish that day contributed to putting some more light into what to expect for 2022, especially aerowise. This is our review of it all, and our view of the impact that the new regulations will have on the performance of the 2022 WRC cars.

M.J.Wilson/S.Loudon, Ford Fiesta WRC 2022 mule test car, Development test, Bages, April 2021 – picture by Francesc Rodríguez – Motoresport.cat

MSport has been the first team to show the car they are working for. And they did it by publishing some pictures, the same day the tests outside their home facilities started. The test took place on gravel roads west of Barcelona (Bages), in the same area where they started the tests of the Fiesta WRC 2017, almost five years ago. The car used in the test included the shell of a Fiesta WRC spec-2017 over a new bodywork, which included a new crash-cell and a new transmission set-up, according to test driver Matthew J. Wilson’s declarations to DirtFish.

In this interview Wilson gave the key for the interpretation of the test photos: “We’ve got through a lot of kilometers running aero trimmed into 2022 specification”. So, what the images showed, in terms of aero, are good clues for what we can expect for 2022.

M.J.Wilson/S.Loudon, Ford Fiesta WRC 2022 mule test car, Development test, Bages, April 2021 – picture by Anna Solé Genescà

The pictures from the test show that the dive planes, the fender vents and the rear diffuser are the aero parts trimmed from the car. Then, what’s the impact of removing these parts on a WRC car?

The rear diffuser contributes to accelerating the airflow under the whole car, thus reducing the pressure under it, favouring the generation of downforce. Removing the rear diffuser will reduce the level of generated downforce under the whole car. The impact will be noticed both at the front and at the rear of the car. Similarly, the absence of fender vents will have an effect on both axles: if air cannot be removed from the wheel space, the pressure under the car increases. Thus, the removal of the rear diffuser and fender vents will have a big impact on downforce generation but a small effect on the car’s aero balance, as their impact is similar on both axles.

The removal of dive planes will represent (if finally confirmed) a significant reduction of the front downforce, with a high impact on the car’s balance. Front downforce has been the main concern for all teams in the last years. Removing the dive planes will bring cars back to high understeering levels.

The result is that the levels of downforce the new cars will be able to produce will be significantly reduced, while the car balance will worsen significantly.  Thus, the cars will be slower both at the corners, as well as in the fastest portions of the stages. Precisely, those portions where everybody agrees that the current car generation excels, in terms of performance and show for the fans. But, at the same time, they will be safer and cheaper, two of the main goals FIA set for the new generation.

M.J.Wilson/S.Loudon, Ford Fiesta WRC 2022 mule test car, Development test, Bages, April 2021 – picture by Francesc Rodríguez – Motoresport.cat

Note the presence of a Pitot tube on top of the car (inside the yellow circle), which is used to check the airspeed at a certain height. These values are used to have direct measurements of the airspeed, both for the test as well as for validating the numerical results obtained in the computer.

The images suggest that the main aero elements in the 2022 WRC cars will be the front splitter, the flat undercar and the rear wing. But they also showed some of the new elements they will incorporate. One of the main problems of using batteries is the removal of the heat they generate while in operation. As shown in the image below, the batteries are located at the rear end of the car, which contributes to a better mass distribution in the car. To get fresh air into this area, to keep batteries cool, MSport has included an air inlet on both sides of the car, similar to what rallycross cars have.

The design of the inlets will be possibly modified into a less prominent inlet (possibly NACA duct shaped) in order to reduce both their air resistance (drag) and their pressure loss, as cooling efficiency requires minimal air pressure loss.

M.J.Wilson/S.Loudon, Ford Fiesta WRC 2022 mule test car, Development test, Bages, April 2021 – picture by Francesc Rodríguez – Motoresport.cat

The vent of the hot air is done through a vent located at the rear of the car. Due to its disposition, the exhaust gas exit has been relocated to the right side of the car, losing the benefits of the exhaust blown diffuser used in the current Fiesta WRC.

M.J.Wilson/S.Loudon, Ford Fiesta WRC 2022 mule test car, Development test, Bages, April 2021 – picture by Anna Solé Genescà

Rumours talk about the imminent starting of the test of the new car by Toyota, and in June by Hyundai. Sure these tests will provide us with more information about what we can expect for the next year that we will review on due time.

10 thoughts on “On the aero of the 2022 WRC cars

  • 2021-05-04 at 16:53
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    Fascinating article. Clearly the aero driven Wrc 2017 to 2021 regulations have been trimmed back. Interesting to see Msport Ford have gone for a slightly longer body reminiscent of the Focus RS WRC 06. Could this assist packaging and weight distribution or will a more compact model have inherent advantages. It will be interesting to see which way Toyota and Hyundai. if Toyota base model on GR Yaris it would be presumed their 2022 hybrid car will be shorter than the Ford and more compact. While slower heavier cars are not an exciting idea, the reduced cost overall and reduced cost of aero parts and aero development expenses will be welcome. Thanks for this timely article and looking out for more as we head into the brave new world of 2022 Hybrid Wrc Cars….

    Reply
    • 2021-05-04 at 20:31
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      Thank you, Lawrence, glad that you like it. Yes, we will have to wait for some weeks to get a more defined picture of the future cars, but it will be another busy day… like it was 2016.

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    • 2021-05-05 at 02:37
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      I think it’s also budget-related regarding the homologation rules. Toyota have mentioned their hybrid WRC car won’t be directly based on their current GR Yaris. Remember the GR Yaris itself is based on the 2017 prototype and very far away from the car they’re running right now. Longer wheelbase cars, like the one Ford’s been testing, are likely aimed at recovering lost downforce through additional floor area (much like Mercedes F1). I don’t think Hyundai will change their wheelbase because they’re pushing all five-door cars out of their factory right now for the road. Additionally, since Luis mentioned WRX, the longer-wheelbase cars there have a cooling advantage because they don’t have to protect the inlets as much, at the cost of agility (though this can be overcome by setup).

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      • 2021-05-06 at 14:57
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        We will see with the new cars, but a longer wheelbase does not always mean additional floor area. The only way to increase this area is by making the car longer… which has also disadvantages. We will see.

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    • 2021-05-05 at 19:57
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      Hello again,
      Really interesting article !
      I was wondering, which type of front bumper design (curvatures, angle attacks etc.) will create the most downforce ?
      Secondly, a little more imaginery question 🙂 As said, new cars will probably have to cope with understeer. What would you do first to solve this problem if you were engineer of one of the three teams ?

      Looking forward for more,
      Laur

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      • 2021-05-06 at 15:14
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        Hi Laur! Thank you, happy that you like it.
        That’s a complex question. You have to get use of the pressure of air impacting over the bumper and transform it into vertical (down)force and, at the same time, distribute air towards those areas where you can still get benefit of it (such as the winglets on top of the fenders, in the case of the current cars). Also, the lower part (splitter) has to minimise the amount of air allowed to travel under the car. And finally, do it with smooth, rounded shapes, in order to keep air resistance (drag) as low as possible. The final result has to be a balance of all these points… not really easy job.
        Second question is still even more difficult, especially because it is not still clear if all the current aero elements at the front will be forbidden. So, first thing to do would be to carefully read the new regulations, trying to maximise the design of those elements still allowed (bringing regulations to the limit) while I would play with the rake (inclination of the undercar) to minimise the amount of air flowing under the car, to get additional downforce, as well as with suspension settings. But hardly no solution will compensate the loss of downforce created by the removal of the rear diffuser and the fender vents.

        Reply
  • 2021-05-05 at 02:41
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    I still think going to a spec hybrid system is a wrong move from WRC. They can save about the same amount of cost if they mandate the teams use pre-existing hybrid systems from their own car factories, and give the option of spec system to privateers, then homologate and control their development. What’s the use of racing if not for road development? Now the factories won’t see the point of developing a road-relevant system in the championship and increase the risk of them pulling out. It’s also a shame for technically-minded fans like us as well. Spec parts, especially when done by an inexperienced 3rd party, is always only a cop-out solution because the organizers are too lazy to come up with something better.

    Reply
    • 2021-05-06 at 15:00
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      I agree with you, but I imagine they decided to set a common hybrid system not to favour those companies more advanced in this subject (Toyota), which is against business, I know. But, otherways, it would have probably resulted in the other manuf leaving the Championship. So yes, they have done a step back, for the sake of participation.

      Reply
  • 2021-05-08 at 07:03
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    As usual, really good post !
    You said : “not sure about the front for 2022”. Is the regulation not defenetive today (strange because the factory are working on new car, the first rally is in 6 months) ? Or you don’t know the regulation ? (a shame that is not public !)

    Reply
    • 2021-05-08 at 16:39
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      Thank you Traxx, glad you like it. As usual, FIA doesn’t publish the regulations, so we have to guess. A pity because the more you know, the more you enjoy it, but…

      Reply

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