Final fine-tuning of the aero configuration of the Toyota GR Yaris Rally1

The images of the Toyota test this week in France show what will probably be the final aero configuration of the Toyota GR Yaris Rally1. It was also confirmed by Toyota Technical Manager Tom Fowler in a recent interview with DirtFish.

The car integrates most of the new solutions seen in previous tests that we have already reviewed, such as the high rake/inclined undercar, the design of the rear of the car, with the two fans combined with the new rear wheels vent duct and the new rear wing. However, during these tests yet some minor novelties have been observed, such as the refinement of the wing and the blocking strategy at the car front, while other solutions are still missing, such as the side mirrors.

S.Ogier/B.Veillas, Toyota GR Yaris Rally1, Development Test in France, December 2021 – image by Frédéric Mangeant

The rear wing used in these tests presented some differences from the wing used in November: the side winglets have been removed, and have been replaced by a small horizontal lip.

The reason behind this modification would be the presence of the side air intake, which prevents air from flowing onto the side winglet, thus making it useless. A second visible modification is a redesign of the upper profile of the endplate (1 in the image below), which is now thinner at the front. Drag reduction seems the most reasonable explanation for this modification.

Toyota GR Yaris Rally1 rear wing during November (left) and December (right) tests – images extracted from the videos by Rivierarally and Video2rallye83

The rear view of the new wing shows another important modification (2): the endplates are now separated from the shovel (lower plate), leaving a small space in between.  The original (closed) design forced air to flow over the shovel (lower plate), while with the new one, the air above can mix with the air below the shovel, thus reducing the pressure difference and the wing efficiency. Again, the main advantage would be drag reduction.

The rest of the wing design remains the same, with the four big swan-neck supports acting as vertical fins over the wing, to increase downforce generation in the corners.

At the front of the car, the main modification affects what seemed to be the front brake cooling air intakes (3), now blocked. Maybe due to the low temperatures, or maybe because the upper intakes (4) are enough to cool down the brakes.

S.Ogier/B.Veillas, Toyota GR Yaris Rally1, Development Test in France, December 2021 – image by Frédéric Mangeant

During the test, we have already seen how the front radiators will be blocked in the new car (5), as shown in the image below, and leaving only open space at the center of the intake. The blocking plates are used to keep the engine at an adequate temperature for optimal performance, preventing it from excessive cooling at low ambient temperatures.

Same as with the Puma and the i30 N, the design of the GR Yaris includes big wheel arches at the front, with no side cover (see image below). The goal is to leave an open space to air for escaping from the wheel space, to compensate for the banned fender vents. Air needs to be removed from this area to reduce the pressure under the car (increasing downforce).

S.Ogier/B.Veillas, Toyota GR Yaris Rally1, Development Test in France, December 2021 – image by Frédéric Mangeant

In opposition to the other teams, Toyota has not incorporated this solution in the rear wheels, thanks to the new duct connecting the space of the rear wheels with the rear of the car, as we already analyzed in our previous article on the rear modifications. The exits from this pipe are visible on both sides of the rear (fan) vents.

S.Ogier/B.Veillas, Toyota GR Yaris Rally1, Development Test in France, December 2021 – image by Frédéric Mangeant

In summary, Toyota (as well as the other teams) is in the last stage of refinement of the aero configuration in order to reach the optimal configuration for the next season, while still some minor details, such as the side mirrors, have to be included to complete the final aero package.

4 thoughts on “Final fine-tuning of the aero configuration of the Toyota GR Yaris Rally1

  • 2021-12-17 at 08:49
    Permalink

    Finally! As always, thank you for your hard work.

    1. It’s not ‘unuseful’. It’s ‘useless’.
    2. The rear wing’s front profile change, to me, feels more like a trick to energize the airflow near the end, creating vortices which cancel out the tip ones forming in the inside corner. Drag reduction is a secondary bonus this design achieves, I think.
    3. Is it possible the need to enlarge the front wheel fenders stems from the decision to run a higher rake (and thus lower front ride height)? Under braking in variable conditions, it’s very easy to choke the airflow across the whole car, after all, so they need some sort of passive pressure control?

    Reply
    • 2021-12-17 at 17:56
      Permalink

      Thank you, Kevin! Corrected!
      You’re surely right regarding the endplate separation, even though the free space is very small. We would need CFD or flow visualization to confirm.
      As for the front fender space, I’m sure It helps to reduce pressure (by relieving air) when the rake becomes so drastic during braking.
      Yaris under braking

      Reply
      • 2021-12-19 at 02:54
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        I think you’re underestimating what a small change in profile can do when a car’s travelling very, very fast. I agree the ‘negative arch’ on the rear wing tips is much too small to create an effect when you’re travelling at Rally Argentina, Greece, or Sardinia speeds (and for what I mean by ‘properly-sized’, check the Mercedes F1 cars’ front wing footplate area from 2016-2019), but in a medium-speed rally, the amount of energization it provides across the whole wing is significant. Questions remain about the angle of attack, though, since WRC cars obviously pass through air at a different method than circuit racing.

        For the possibility of frontal air choke, I was expecting some more overt excavation solutions like several more channels installed to the front bumper, but I guess they’re not going to run the front ride height THAT low in most places. Maybe only Rally Spain and Japan next year, or Corsica in the past.

        Reply
        • 2021-12-20 at 18:37
          Permalink

          I’m sure it will have an impact, no doubt about it, but sometimes I find it difficult to explain some details that I don’t fully understand or visualize, and translate them into plain language that can be understood by everyone. For this reason, I really appreciate your contributions, thank you, Kevin.
          And yes, the design is unique while every event is different, so they have to make them robust as well as effective when possible. This is one of the biggest challenges engineers have to face.

          Reply

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