How teams exploit brake rules to boost downforce

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In modern Formula One there are only a few areas where designers have any aerodynamic freedom. The outer part of the front wing is one; the zone around the rear brake ducts and surrounding floor is another.

The regulations governing the location of aerodynamic parts around the rear wheels are complex and going listing each one will be a boring exercise, but it is worth running through the essence of what they say.

Article 3 of the FIA Technical Regulations governs bodywork dimension. Bodywork around the floor is permitted as long as it does not extend a certain height above the reference plane and meets certain (restrictive) cross-section area and curvature requirements. Furthermore the floor must form a solid structure – i.e., cannot contain holes, which was a particular area of dispute in 2012.

Article 11 describes the brake ducts. It defines a cube-shaped area within which aerodynamicists are free to have as much or as little bodywork as they like. The position of this area is 160mm above and below the wheel centre line, 120mm from the inner face of the wheel towards the car, and 330mm fore and aft of the rear wheel centreline. In this area we see a proliferation of carbon fibre which is clearly designed to enhance downforce rather than improve braking performance.

The first illustration below shows some the detail around the RB10:

First, note the detail around the brake ducts. In this configuration the duct opening is quite small and there are at least four winglets protruding from the ducts. The brake ducts contribute substantially to the downforce produced at the rear of the car. This downforce is generated very close to the rear wheel, which helps get heat into the tyres and reduce degradation.

In addition there a number of flicks and vanes attached to the floor of the car. These serve the purpose of manipulating the airflow around the rear wheels to optimise the wing-wheel interaction. The tyre creates a lot of drag — this can be reduced by diverting airflow either side of the rubber or by altering the flow the structure hitting the rubber.

Also note the slot in the floor. Although this looks like a hole there is a hairline gap from the edge of the floor to the slot so it complies with Article 3 in the Technical Regulations. Again, this slot is designed to bleed air below the floor to optimise the wing-wheel interaction. This slot can’t be too large or else it would create too much turbulence, which would increase drag.

The illustration below shows the brake ducts from a different perspective – again note the complexity of the device with brake cooling being a secondary objective!

The original intention of the regulations was to ensure teams could properly cool the brakes. This is a very important safety requirement as we have seen with some recent high profile brake failures. Canny F1 engineers have exploited the regulations for aerodynamic benefit.

But as with double diffusers, exhaust blown diffusers and other inadvertent aerodynamic loopholes, don’t be surprised if FIA decide to impose tighter control over brake duct design to reduce their aerodynamic benefit in the future.

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Images © John Beamer

26 comments on “How teams exploit brake rules to boost downforce”

    1. Very nice, but the illustrations appear to have swapped from their intended position.

  1. I’d be interested to know how this compares to the Merc’s solution?

  2. @john-beamer great post btw :)

    1. +1

      Really great analysis.

  3. Cant wait to see Adrian’s yatch

    1. I’m sure it won’t have any holes in it’s ‘floor’.

      1. Now that they gybe without dropping off their foils and with flying tacks on the horizon it may not even need a ‘floor’.

        1. “Flying tacks” and “gybing on their foils”? Nice to see another dual-sport fanatic here. ;)

      2. @robbie

        Haha, COTD! :)

  4. Thanks @john-beamer . The illustrations are first rate.

    I remember the 2012 ‘look ma no hole’ debate and couldn’t believe Red Bull got away with it for a few races before appeal.

    Quick question, do you know what that raised bump is/does just before the hole? Thanks.

    1. @john-h I think the bump has an infrared temperature sensor aiming at the wheel.
      I know the front wing carries the sensor for the front tyres so it makes sense to put the rear one on the floor.

      1. Thanks @mantresx, makes sense. Surprised it’s so bulky tbh.

  5. That’s not the RB10 that’s the FW36.



    1. the first link doesn’t work, here’s another one

      1. Maybe this one will work

        1. Nope… Doesn’t work for me

          1. I noticed that too, but if you google the Williams, it looks just like i that picture unlike the Red Bul in the working link

    2. Can’t wait to see Frank’s yatch !

      1. Actually, Patrick Heads’ yatch is a Hylas 70

  6. Also note the slot in the floor. Although this looks like a hole there is a hairline gap from the edge of the floor to the slot so it complies with Article 3 in the Technical Regulations.

    Haha, that’s brilliant! Thanks @john-beamer for this article :)

  7. This little loophole has annoyed me for a long, long time. Whilst these designs are within the rules, they’re not in the spirit of the other rule that dictates all aerodynamic devices must be ‘sprung’ and not acting directly on the wheel. This rule was put in place because wings, in their infancy, were often mounted on pylons directly to the uprights. Needless to say this lead to serious accidents.

    Now I’m not in anyway saying that carbon fibre technology, plus the leaving each duct aerodynamically isolated hasn’t made this practice safe. It has. But this practice has been now going on for a loooong time, and amidst all the problems with cost-saving, curbing corner speeds, trying to improve overtaking and reduce wake, then insisting on banning the tiniest things (wheel fairings?), it just seems that this was another job that seemed a bit tricky so the FIA decided to just put it off. I don’t expect any change soon.

  8. FIA banning this loophole in 3 2 1

  9. This is why I pay for F1F.

  10. Article lacks credibility. Reads like it was written by an Armchair aerodynamicist.

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