Red Bull RB7 – Sidepods and Cooling

When the Red Bull RB7 was rolled out, it was clear the car was a neat development of the RB6, but was not an innovative car. As with well developed cars like this, its details are well thought through, a particular case is the sidepod design. If you look at the RB7s sidepods, from the radiators back they appear to slope away to nothing. This leaves the distinctive flat floor and open area ahead of the rear wheels. This creates an obvious aero gain, but how is cooling achieved with such a tight design?

Firstly the sidepod forms the main blockage to the rear wing and diffuser. We’ve seen several approaches this year to manage the airflow around the sidepods to the rear of the car. In each case the team are trying to get the best and most direct airflow to the top of the diffuser and beam wing. As the better flow these devices receive, the more downforce they produce and the less drag is required from a larger rear wing.

Since the 2009 aero rules sidepods are extremely limited in the openings they are allowed, so most of the flow has to exit between the rear wheels. Normally sidepods send the heated air from the radiators back through the tapered rear (known as the coke bottle, due to its shape). In a simple sidepod this means the coke bottle ends with an opening and the hot air passes out and over the diffuser. However this makes the tail of the coke bottle unduly wide, which creates a blockage between the rear wheels and blocks flow over the diffuser. Red Bull discovered with the RB5 that the radiator airflow can pass up towards the centre of the car and exit above the gearbox in a bulged opening. This keeps the tail of the coke bottle nice and narrow.

With the RB7 Red Bull have taken this a step further, there is no appreciable exits in the tail of the coke bottle, so nearly all the radiator airflow ends up passing through the bulged outlet. This means the coke bottle is the slimmest and simplest of all the cars on the grid. Clearly the huge floor area and exposed beam wing show how easily airflow can reach the rear of the car. The concession Red Bull has to make for this benefit is the increased blockage in front of the rear wing. But as they are aiming for downforce from the more efficient diffuser and beam wing, the rear wings effectiveness is not such a concern. Other teams have similar low swept coke bottle shapes, but each of them still exploits some cooling exit at the back of the sidepod. Given enough testing a fully enclosed sidepod with the central bulged outlet could be copied.

28 thoughts on “Red Bull RB7 – Sidepods and Cooling

  1. I was curious about that little fin near the exhaust; it seems that it would generate a vortex that would be opposite in rotation to any vortex that the diffuser would generate (since the sides of the diffuser are pretty high).

    Could it be designed to basically cancel out the diffuser-generate vortex? (similar to wing-tip vortices)

    Given that, would that then allow the exhaust to better feed the diffuser?

  2. At the end, you said that testing could allow the copying of the system. However, for it to be as effective, wouldnt teams have to significantly alter the lateral profile of the sidepod (to minimize separation an the trailing edge)? With this change, won’t the chassis need further lateral crash test results?

    In comparison to the gear-box design Williams is using this year, which one do you believe will allow for better flow over the beam wing? Do you think William’s wishbones and the added hot air exits might damage the quality of the flow?

    • I dont think the sidepod shape change is particularly complex and I also dont think any impact tests are required.
      I like the elegance of the Williams solution, I think its a better aero compromise.

      • If it was that easy to make the sidepods as small as they are on the RB7 why haven’t the other teams done it? Obviously McLaren wouldn’t have room because of the U-sidepods but teams like Ferrari and Mercedes still have much bigger sidepods.

      • Could they (Williams) possibly blow the air from the sidepods low down inside the car and right past the gearbox to enhance flow over the diffuser, possibly combined with the exhaust? Sure looks like there is enough room under that very low piece of bodywork covering the gearbox/diff.

        Btw thanks a ton for your work.

      • Maybe if you can’t vent your exhausts into you diffuser then you start looking at your second-best source of higher-than-ambient-temperature air?

  3. These two shots, (from F1

    both from a very similar angle, of the Red bull and the Sauber, demonstrate quite how incredibly neat the Red Bull rear end is. I am no engineer, but the Red bull rear end looks far, far neater then the Williams, I imagine there will be a far clearer airflow to the diffuser and beam wing, so I am interested to know if this is at all true or misguided?

  4. Super Work Craig….. Really appreciate your hard work. but i am curious to know your view about this years Ferrari-150. can you share your view with us and who is according to your produce best car so far. will be happy if you reply ………. 🙂

    • I’d also appreciate expert opinion on F150. As far as I can see, their design looks rather conservative, and seems like just applying the rules ? Ferrari claims that not all of the aero package is being shown on the tests, which is OK, but I didn’t see any radical changes (I might have missed them, however).

      • I’ve covered the launch F150 already. This is only the mechanical/structural car. The aero: wings, sidepods, engine cover, exhausts, diffuser etc will change a lot before bahrain…

      • Thanx… but what about the best car so far… we already saw testing in 3 places and a guy like you can understand more than what average people like us could grasp. for this i am asking your expert opinion….:-)

  5. Why are the radiators so crude regarding their shape? Designing a sidepod around a big flat brick surely doesn’t make an optimal solution.

    Is it because the radiators’ dimensions are regulated so? Why on earth would they force them use a cuboid?

  6. I realise that this could be an inane question, but Scarbs, given what you know of the relative pace of the cars and avenues of development since last year, what are in your opinion the order of the cars, at least visually, in terms of ultimate downforce and pace?

  7. What do you think the dark spots are on the back of the RB7’s sidepods:

    It looks like they are mesh covered outlets to the sidepods to me.

    • I’m sure mesh would be illegal. When I saw the panel in valencia I guessed it was just a seperate piece of heat resistant material to protect from the exhaust beneath. A painted section of bodywork would bubble and look messy.

  8. In your analysis you mentioned that the primary concession for this design is the increased blockage in front of the rear wing. How would you expect that to affect the effectiveness of the DRS? Is that perhaps why other teams haven’t pursued it so rigorously?

    • Yes but the point I was trying to raise (badly) is that are Redbull using the diffuser and beam wing to generate a larger % of their rear downforce compared to other teams and, as a result, the ratio of reduction in downforce created by the DRS will be less than other designs and therefore reduce its overall effectiveness?

  9. Curious if it’s possible this cooling configuration could be used to increasingly stall the rear wing as speed increases. It would seem that the greater the volume of air channeled to the rear wing the greater the potential negative effect on downforce generation by the wing, and if this is true why aren’t other teams following suit?

    • I neglected to clarify – a lack of downforce as speed increases in a straight line would be highly desirable perhaps utilizing a vortex exhaust cooling system on the Red Bull allows for this? A rear wing stall effect that is compromised when the car is turning but optimized when the car travels in a straight line.

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  11. Pingback: Launch Analysis: McLaren Mercedes MP4-27 | Scarbsf1's Blog

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