Analysis: Red Bull DDRS

It’s rare a technical development passes without anyone noticing and of all teams its surprising Red Bull pulled off that trick in the past few races. As they were seen to have a Mercedes-like Double DRS (DDRS) system in use in Japan. It transpires the system was track tested in practice at Monza and raced in Singapore. Part of the secret of the Red Bull DDRS is that the system is wholly contained within the rear wing. Only the plate over the end of the rear wing flap gave away the systems existence. With this system Red Bull are able to shed even more drag when DRS is open, thus giving them a top speed advantage in qualifying and when DRS can be used in the race.

Layout

Oversize plates (yellow) on the flap move when DRS is opened, but keep the duct covered when DRS is closed.

Red Bulls adoption of DDRS is also surprising; as it’s the first time a team have exploited this technology since Mercedes introduced it for the start of 2012. This might be in part due to the system being banned for 2013 and teams are looking at the passive Drag Reduction Device (DRD) as tested by Lotus\Mercedes. As already mentioned the Red Bull DDRS stalls the rear wing and not the front wing, as with Mercedes solution. Thus the system is self-contained within relatively conventional rear wing elements. We can clearly see the oversized plate that seals the duct when the rear wing flap is in the closed position. When DRS is activated the flap swings open and the duct is revealed. The high pressure that builds up above the rear wing main plane, invites flow to pass through the duct and this flow can be used to stall other parts of the rear wing. From the shots of the system with the DRS open in Korea it’s clear to see the duct routes vertically down, passing inside the double skinned endplate.

When DRS is opened the duct is uncovered to blow a slot lower down on the wing

What surfaces are being stalled?
Middle of the wing
Quite where this duct exits to stall the wing is not clear. Most reports suggest is stalls the centre of the beam wing or the centre of the diffuser. This is entirely possible, the Mercedes system routes through the endplate and then into the beam wing. If this is the case for Red Bull then the duct would either exit through a slot in the middle 15cm beam wing or ducting further down to the diffuser. Blowing a slot in the area will stall the airflow and this would lead to the reduction in downforce. The middle 15cm of beam wing is allowed to have a slot, as this area is exempt from the closed section and minimum radius rules, introduced to ban F-duct style stalling slots in 2010. However these central areas of the beam wing and diffuser are quite efficient, as they do not induce a lot of drag from tip vortices. Stalling the flow in the middle of the wing would have a knock on effect in stalling the general flow behind the car, but I don’t believe this would be an effective use of the stalling on the back of the car. It would be better to stall areas which do induce a lot of vortices and therefore drag. These areas tend to be at the wing tips, so the obvious areas to stall are top rear wing tips, the beam wing tips and the outer corners of the diffuser.

Wing tips
Both of these wing elements are allowed to have slots in the outer 5cm or in the endplate itself, while the diffuser is not allowed to have slots in this area. So the focus moves to stalling the wing tips. As the top rear wing is already rendered ineffective by DRS being open, the flap being open leaves the relatively flat main plane unloaded, so little drag will be induced at its tips. Looking at the Red bull wing at the past few races show only one sign of holes under the top rear wing, but these were only seen in one practice run in Japan and have not been seen again. Its possible Red Bull evaluated blowing this area and discounted it. It’s also possible that a system could blow both the upper rear wing and then beam wing simultaneously for the maximum effect. The Mercedes system manages to blow a wide slot some 3m forward of the rear wing to stall the front wing, so they should have enough energy in the stalling flow to stall two different areas of the rear wing. It will be important to keep an eye open for holes returning to this area.

A small hole was evident under the top rear wing which could stall the main plane

This leaves the beam wing, its wing tip is heavily shielded by the endplate, although there will still be some drag induced by the flow off of the wing tip. Looking for evidence in this area under the beam is even harder to view, than the area under the top rear wing. some images appear to confirm that this is the area Red Bull have been focussing on.  As two small slots have been visible in some shots of the car on the grid.  Although on the grid a mechanic was positioned in the middle of the rear wing, this appears to be a decoy, as the outlets are at the side of the wing!  Of these two slots one is positioned directly under the beam wing and the other about halfway between the first and wings trailing edge.  The first slot would be most efficient at stalling the wing, is its positioned at the suction peak, the point where the airflow is moving fastest.  The subsequent slot may be used to break up any residual airflow not stalled by the first slot.

Image Copyright: Tobias Gruener

Summary

The internal duct blows two slots under the beam wing to stall the flow for less drag

From what I’ve seen and heard of the Red Bull DDRS I would suggest that when the DRS flap opens, the duct feeds vertically down to blow through a pair of slots underneath the endplate\beam wing junction. This would stall the outer tip of the beam wing and the resulting vortices would be broken up reducing drag for a small, but useful top speed increase. Red Bull have just a few races left to exploit this technology, as rules ban the use of DRS having an effect on ducts within the rear wing. But as we have seen so front this year, having pole position and managing the race and tyre wear from the front is a strong strategy. Having DDRS will only aid the team in qualifying with almost not performance penalties from having the system fitted.

24 thoughts on “Analysis: Red Bull DDRS

      • It seems plausible, but another benefit of the tunnel appears to be the cleaning up the area around brake ducts and beam wing/endplate area. Keeping the flappy air of the exhaust (like you described so elegantly on The Flying Lap last week) in one area and cleaner smoother air into the tunnel. It appears the rb8 is coming together nicely. Do you think now the combination of tunnel and DDRS will be copied by another team before years end? Sauber?

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  3. How do you think Red Bull will cope next season when the DDRS will not be allowed, surely Red Bull will struggle for speed against Ferrari and McClaren in Qualifying/Race ?

    Regards

    • Next year is a different story, there’ll be new cars optimised around the tyres and exhausts. I see no reason that they will be disadvantaged.

  4. Does McLaren have a similiar system?
    This seems very simple so I’d assume they would? Also do you think that this wing has given RBR a big advantage since Suzuka? Surely McLaren would have been onto it since Merc has said a DDRS system since the start..
    Thanks for a great blog and twitter feed.

  5. Just wanted to point out that at the end of the race as the drivers got out of there cars one of the BBC camera crew took a shot through the redbull rear wing / gerbox area. Maybe the shots might reveal something?

  6. Fascinating article. I thought I was noticing RBR mechanics putting their hands in carefully placed positions on rear wing during pre race coverage recently. Now it all adds up.

  7. A question about how actually stalling the airflow works. In aviation, feeding air to a low pressure side of a wing is done in order to avoid stalling. Naturally I thought, that that is in a case of blowing the fed air tangentially to wing surface along the ‘original’ flow. Thus, if you feed some air against the ‘original’ flow (or at the right angle to it’s direction, as in your drawings of this article), you’d spoil the natural flow forcing it to seperate… BUT then I read about counter-flow fluid injection used in aviation, which is actually used to AVOID flow seperation at high angles of attack. I beleave the principle of how it works has something to do with so callled virtual shaping which thickens the airfoil.. And most strange to me is that air-feeding slots are fixed close to the leading edge…So my question is: how does the mechanism of making the ariflow seperate works?

    • Rytis, you might be over thinking it a bit. I am of course a lay person and not craig. It seems like what is happening based on my reading is that a duct is being opened between an area with high pressure and an area with low pressure. By “stall” I read “is not producing downforce”. By negating the pressure differential you are stalling.

  8. Oh.. OK. I missunderstood the principle of how it works… The counter-flow fluid injection I read about is actually executed placing the air-feeding slot on the high presssure side of the wing close to the leading edge. So an injected flow virtually thickens the leading edge and after it travels round the edge against the flow, it then goes together with the flow on the low pressure side energizing it as usual (just somewhat more efficiently)..
    So, sorry for bein off topic.
    Comment on topic: you say that stalling the beam wing on its tips would be more practical because of the wing tip vortices. Is there really such powerfull vorteces generated at the wing tips? I am asking because I would think that generally a wing with such endplates as an F1 car has would not generate too powerfull a vortex to induce a lot of drag..

  9. At the Valencia race, Vettel’s Red Bull was in another zip code with pace; very scary. How has the car evolved from that race to the Korea/Japan GP’s? Would DDRS been tried at the race? Plus the development race has seen separation in the pack; Red Bull obviously leading, but Ferrari, McLaren, and Lotus seemed stalled; sorry about the pun!

  10. Awesome write up as usual!

    For beginners like me, is there any place that explains the mechanics of what happens during a “stall”? My understanding is that blowing an aerodynamic element disrupts the attachment of the airflow behind it, which in turn defeats the element’s ability to produce (negative) lift. However, based on that description, it seems that drag would stay constant or even increase – only the downforce is lost. Does stalling really decrease drag, and if so, how?

    • No, stalling does not decrease drag. It actually increases it and (dramatically) decreases lift. Mercs stall their front wing because they want to decrease the downforce in front of the car. Although it gains some drag, dissbalancend car is a bigger problem. So they stall the front wing when their DRS is open which not only deacreases drag, but in this case loose some downforce as well. This loss of downforce in the back dissbalances the car, therefore loosing downforce in front helps to regain it.

      • I don’t believe this is true. Stalling does decrease drag.

        This is from Racecar Engineering:

        “However if the flow over the ‘flap’ section of the wing can be stalled, the lift/drag ratio worsens, but the overall result is a massive drop in the coefficient of lift, resulting in a net reduction in drag, hence the benefits in relation to top speed. It should however be noted that it is only stalling the trailing edge flow that is beneficial as opposed to stalling the entire wing.”

        • well it clearly says, that it doesnt talk about a whole wing now, or does it? I believe that in this case when lift deacreases, lift-induced drag decreases as well, and (since not all wing is stalled) total drag decreases as well… obviously, if you can get rid of downforce on the front wing without increasing drag, that’s what you do
          What I said, answering Steven’s question, is that generally speaking about any kind of airfoil, stall deacreases lift and increases drag…

          • I think you have to be careful when to apply aerospace aero to race cars. Its true a stalled aircraft wing will reduce lift and increase drag. However with a highly loaded F1 wing, the majority of the drag is induced at the wing tips. Stalling the wing breaks up the flow under the wing reducing downforce and also breaking up these these vortices, which greatly reduced drag.
            I think there can be no question about a stalled F1 wing reducing drag, just look at the F-Ducts of 2010, stalling the wing had a near DRS effect on drag.

  11. Mercedes must be very embarrassed. They had the idea first but were focused on blowing the front wing. Red Bull saw the real potential of the ddrs and are outclassing the field.

    • Merc was focused on aero balance, not so much drag reduction. I would think that opening the DRS on the Merc would reduce rear down-force while without a DDRS system, the front would retain all of its down-force and lead to high-speed over-steer; definitely bad! By stalling the front wing, they reduce the front down-force and leads to a more balanced car at high speed.

  12. It looked like RB’s rear bodywork was overhauled for India to take full advantage of exhaust blowing. Kind of a nail in the coffin for the other teams if you ask me. Craig, could you do a piece detailing their India updates? Please!

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