Mid-season technical review part 1

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It's now a three-way battle at the front

Guest writer John Beamer examines how Ferrari and McLaren have closed the gap to Red Bull.

Red Bull has a healthy, 103-point lead in the constructors championship. But does it still have the fastest car on the grid?

The RB7 has not won for three races, its lead in qualifying has been cut, and on race pace McLaren and Ferrari have often had faster cars.

It pays to be careful when making sweeping statements about performance, especially when track layout and tyre performance can have a dominating effect on race results.

But consider the Hungarian Grand Prix, where last year Red Bull were a second clear in qualifying, while this time Sebastian Vettel took pole position by less than two-tenths of a second partly because Lewis Hamilton made a couple of small errors on his final run.

The top teams’ recent technical developments gives some insight into how the battle for victory has changed.

Exhaust blown diffusers

Ferrari won their only race of the year so far at Silverstone – a weekend clouded by the row over exhaust-blown diffusers.

Prior to the race the FIA mandated that teams restrict off-throttle blowing to 10% of the full amount.

However, during Friday practice it emerged that Renault had permission to run up to 50% off-throttle based on a historical analysis of how it used its engines to aid valve cooling. This was in response to Mercedes being allowed to fire four of its cylinders off-throttle to relieve crank case pressure.

These changes remained in place for the race but were rescinded afterwards. That Ferrari won the race and McLaren struggled gave a lot of insight into the design of their 2011 cars.

The EBD restrictions were to limit the amount of hot-blowing, which many believed is what helped Red Bull secure such a large qualifying advantage, especially when it turned up the engines in Q3.

It turned out that Red Bull does not use hot-blowing. The team had tried hot-blowing in testing and free practice but it wrecked the rear tyres.

McLaren’s ‘octopus’ exhust

McLaren struggled at Silverstone

McLaren , on the other hand, spent most of the off-season designing the MP4-26 around the infamous ‘octopus’ exhaust system, which did hot-blow the diffuser floor. The octopus exhaust was designed to release gasses across the full width of the diffuser but created too much aerodynamic sensitivity.

So they switched back to a conventional EBD layout before the Australian Grand Prix and picked up over a second a lap in time.

Although the diffuser was changed to accommodate the new exhaust system the aerodynamic principles relied on hot-blowing the exhaust. Fast-forward to Silverstone where hot-blowing was banned and McLaren suffered the most as the delicate balance of the car so apparent in the ‘octopus’ days returned.

Ferrari’s resurgence

Ferrari were off the pace early in the year partly because of wind tunnel calibration issues. That changed when they brought a radical upgrade package at Silverstone consisting of new rear bodywork, a revised exhaust layout, a new rear wing and floor.

That Ferrari got the harder compound working so well after struggling in previous races is a testament to the increased downforce generated.

Rear wing

Ferrari's earlier rear wing seen in Valencia

One significant performance differentiator in 2011 is rear wing design. This is intrinsically linked to the Drag Reduction System, which has a significant effect on laptime, especially in qualifying where DRS can be used feely.

To achieve this the wing needs to stall more aggressively in DRS operation. The trade-off is that this typically results in worse performance in total as airflow struggles to reattach when the DRS is deactivated – Mercedes suffered from this issue in the first few races.

Ferrari extended the main plane and increased its camber. In turn the flap cord length is reduced. When DRS is activated the effect of the flap slot disappears and the air under the main plane stalls causing downforce to drop away more quickly.

The rear wing Ferrari raced in Hungary

The wing was updated for Hungary practice. The flap chord was further shortened to give even greater drag reduction but so as to avoid losing too much downforce a Gurney was attached to the flap’s trailing edge. We may see this wing return at Spa, where drag reduction is especially important.

Rear bodywork

The other feature of the RB7 which Ferrari have tried to replicate is its distinctive coke-bottle rear bodywork, which allows cleaner airflow to the diffuser. Ferrari altered their rear bodywork, reworking the exhaust and radiator layout. The sidepods have also been extended rearward.

Normally designers try to create as much space as possible so superficially this seems an odd choice. There are two possible factors: first, the airflow wasn’t staying attached to the bodywork so by lengthen the sidepod this phenomena is being encouraged. Second, this new arrangement allows the exhaust construction to be simplified – it is now sunk into the floor.

The back of the RB7 is very tightly packaged

Ferrari’s front wing has also been modified, with the most recent version appearing in Hungary. They have wavered between using a two- and three-element front wing. In one sense this allows them to choose the wing depending on the circuit but this approach is likely to be more expensive in development time and resources.

The outer section of the wing has reduced camber, which will cut downforce but feel more consistent and stable to drivers when steering. There have been changes to the cascades which now appear a lot more detailed than in the past – the cascade is now dual element with a separator midway across its length.

Also, the forward-facing camera is mounted directly behind the central section where it looks like a second section. The two cameras appear to join so it looks like a single section – presumably the FIA is happy with this construction.

Red Bull’s rake

The thin wedge of light under the RB7 shows the angle of rake

A noticeable trend over the last few months has been the degree of rake the Red Bull cars run. For the uninitiated, rake is the nose to tail angle that the car runs. A car with a lot of rake has its nose closer to the ground while its tail is higher.

Why is this an advantage? The theory is that by running a lot of rake the front wing is closer to the ground where it is more effective. In addition the diffuser is at a steeper angle. Both phenomena, in theory, create more downforce. Let’s look at both of these in more detail.

Rake and the diffuser

Downforce in the diffuser is a function of height above the ground and slope. The steeper the diffuser the greater the downforce. A higher diffuser creates less downforce and also raises the centre of gravity. Both of these are only true up to a point – push them too far and all performance is lost. Adding rake to a car is trading off these phenomena.

One of the reasons why increasing diffuser height cuts downforce is because the diffuser becomes more prone to stalling. Red Bull realised that it could harness the power of the exhaust blown diffusers to mitigate this.

The exhaust gasses add energy to airflow in the outer part of the diffuser and prevent turbulent air from rear tyres entering the diffuser (acting as a seal). This reduces the effect of increasing the height of the diffuser.

Rake and the front wing

The 2009 technical regulations allowed the front wing to be run much closer to the ground than in previous seasons. This meant that the ground effect came back into play.

Ground effect is the same phenomena associated with changing the diffuser height. The lower the wing is to the ground the more downforce is generated – this is commonly known as the Venturi effect. Adding rake in conjunction with exhaust blown diffusers results in a considerable downforce benefit.

Teams follow Red Bull’s lead

Visible rake on Massa's car in Hungary

Red Bull has run a lot of rake for the best part of a year, and in recent races that McLaren and Ferrari have begun to follow suit. Is this a factor in the more competitive running order? Almost certainly.

This was particularly so in Hungary where Vettel abandoned a new front wing and floor design after Friday practice. The team had to break the FIA-imposed curfew to return the car to its Nurburgring configuration.

The main problem was the revised front wing and under-chassis turning vanes. The front wing pillar was wider and consequently the turning vane was deleted. In addition the trailing edge of the front wing flap sported a gurney and the cascade profiles were changed.

The addition of the gurney was interesting as this is usually a quick way to increase grip at low speeds. Although these changes seem minor, a small change at the front of a car can have a significant effect further back.

The updated diffuser, which was in all probability updated to work with the new front wing, sported a few subtle changes (externally at least). The central section below the rear crash structure contained a new fence structure and the vanes in the primary diffuser channel were lengthened.

It’s unclear what Red Bull is trying to achieve with these updates but presumably by adding/extending these vanes the intent was to better control and direct airflow exiting the diffuser.

This is a very sensitive part of the car as the pressure gradient aft of the diffuser determines how much downforce it generates. Too steep a gradient and the diffuser is more prone to stalling.

Don’t miss part two of this article tomorrow which will look at McLaren’s progress this year and significant changes in the midfield teams.

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38 comments on “Mid-season technical review part 1”

  1. Great article! Perhaps you should have also mentioned the vastly different tyre warm up characteristics between the top 3 cars.

    Ferrari – Easy on Tyres:
    Pro: Great in hot conditions with high tyre wear (Silverstone)
    Con: Bad in warming them up, loosing significant time in outlap (Germany)

    McLaren – Harder on Tyres (recently, post Barcelona)
    Pro: Great for quick warm up in cold conditions (Hungary, Germany)
    Con: Bad for tyre wear on warm day (Valencia)

    Red Bull – currently sits in the middle with this.

    It’s amazing just how much track temperature can make a difference and can sway the competitive balance from one car to another.

    1. I believe he made the tyre issue clear at the beginning of this piece . You should try reading it over .

      1. Fingers crossed for another cold/wet Spa then!

        1. If they install their planned upgrade of a short-flap rear wing in Spa, it would decrease their downforce in the race slightly, and would affect the speed with which they get temperature in their tyres. So be careful what you wish for ;)

          1. @ raymondu999 and BS(?)

            I am sure this sentence is easy enough t understand and since both of you can’t find it in the article ,here it is :

            “It pays to be careful when making sweeping statements about performance, can have a dominating effect on race results”

            There it is folks ! emphasis should be placed on the word tyre performance .Everyone who has been following the season from the beginning by now knows that tyres play a role in performance from track to track .

            literalf1’s initial post makes it clear that he missed the “tyre” point in the piece and proceeded to break it down for those who needed help .

            Apologies to literalf1 and everyone who made out an insult in any of my posts .

          2. cured cat, That just says “tyre performance can affect results.” We want to see John’s analyses about how each car treats and heats their tyres up.

      2. I believe he did not. He did mention it as a phrase “tyre performance” but offered no analysis on the crucial difference between the cars.

        1. @literalf1 He didn’t simplify it enough to a level that you can comprehend ,thats quite understandable .

          1. @curedcat – maybe you could help those of us who can’t find it in the article by pointing out or quoting for us which part of the article John mentions and compares the tyre warmup characteristics of each car? I can’t seem to find it either

          2. I agree with Raymondu999, I can’t find any significant tyre analysis either, simplified or otherwise.

            I really don’t see why you feel the need to insult literalf1 with your self proclaimed superior intellect that doesn’t need simplification of any kind, but it seems you’re making stuff up either way.

  2. Wow, great job! I kind of lost track at the end there (visual learner!), but this is a great round-up :-)

    1. I kind of lost track at the end there

      I agree with this :) but it was also a very good article and taught me curious things about aerodynamics and their names, which have always been a mystery for me.

      1. I could really do with a diagram of everything. A lot of it I know but a lot of it I don’t.

  3. Regarding the competitive order, I think it’s very close now on the top. McL seems to be on a par with Red Bull in terms of aerodynamic efficiency in terms of the lift/drag, with McLaren better slightly on drag but Red Bull better slightly on downforce.

    About Ferrari – you say that they made the hard tyres work; when? They didn’t run that in Silverstone.

    Also, about DRS chord lengths; it seems to me that in closed position, McLaren’s wing will give them more downforce while Red Bull’s might give them a bit more top line speed; and when everything is balanced out, it seems that in DRS closed, McLaren will be faster than the Red Bull; i.e. McLaren’s DRS design gives better race-pace while Red Bull’s/Mercedes’ gives better qualifying pace. Are you going to be talking about that tomorrow John?

    1. They did in qualifying though and posted competitive times.

      1. I’m sorry; which point are you replying to? Who did what?

        1. Presumably the hard tyres on the Ferrari? They ran them in Q1 at least.

    2. Yes, McL is on par with RB and both are a bit faster than Ferrari overall. The question is whether being on par is enough for Mcl duo to put themselves on position to fight ‘til the end and whether Alonso can compete consistently for top 3 finishes with his current (slower) package.

  4. Great article, a really good summary of upgrades and approach. I look forward to the second part tomorrow regarding Mclaren.

  5. Actually mclaren themselves have said that the reason for the poor qualifying performance is also down to the rear-wing set up.

    If Lewis has made some small mistakes in quali…then jenson has continually made big mistakes….for the 2nd year in a row!

    1. Jenson hasn’t quite got the 1-lap pace on Lewis. He has at times, but I think generally that’s when Lewis has off-days rather than Jenson pulling a blinder.

      Their rear wing flap is very large, as opposed to the shorter flaps on the Mercedes or a Red Bull. The Red Bull/Mercedes one gives better quali pace, yes, but it hurts them in the race, because in the race (with DRS closed) the McLaren wing gives more downforce than the Red Bull/Mercedes wing.

      McLaren are planning to introduce such a wing, have done since Silverstone, and I believe they are rushing to get it on the car for Spa. It will give them an added edge in qualifying, but that will hurt them in race pace.

      1. Perhaps they are introducing it now because you generally run lower wing downforce at the next two circuits anyway?

        1. That sounds like a logical assumption to make

  6. The thing I don’t understand about the rake point is this: The rules say the front wing has to be X height above the ground and but increasing the car’s rake you bring the front wing closer to the ground, surely that then contravenes the rules because the wing is closer to the ground than it should be?

    Am I missing something? When do they test the height of the wings from the ground? Do the teams adjust the rake after it has been tested?

    1. I’ll try to just help you out here. If you look at the floor, then kind of draw an imaginary “surface” extending forwards and rearwards of that, that is called the “reference plane.”

      The front wing has to be X height above the reference plane, rather than the ground/track surface. So the front wing height is regulated relative to the car floor rather than the track “floor” if that makes sense to you

      1. i believe the only parts allowed to break the reference plane are the plank and, obviously, the tires.

    2. The regulation about running height only concerns the main floor itself, not the whole car. When raking the car, they have to make sure that the front end of the floor stays high enough, but still this allows them to get the front wing lower than they would be able with a level car.

    3. Right, got you, that makes sense.

    4. Thats because the rules do not state a height compared to the actual ground (as this itself is changeable). Instead they define a height based on where the regulatory plank is and measure from there. So if the plank is closer to the ground in front, then you get a wing closer to the ground

      some information on that http://scarbsf1.files.wordpress.com/2010/08/scarbsf1-redbull-rideheight.jpg?w=300&h=199

      and an explanation of where the reference plane is http://cliptheapex.com/community/threads/where-what-is-the-reference-plane-in-f1.1782/

  7. It will be interesting to see if McLaren hold the pace advantage through the warmer tracks such as Monza and Singapore. I think they’ve had a slight edge for the last few races. 2011 could actually get substantially closer towards the end if the RB7 is no longer the dominant car.

    1. Well McLaren have been quicker then RB or at least Vettels RB the last two races, yet his lead has just increased.
      Despite this I also think the gap is going to come down, but unless McLaren start to gain some consistency with at least one of their drivers they are not going to get that gap down far enough to get even close.

      1. Yeah, it’s been annoying! Despite Ferrari and Mclaren closing the gap so impressively to the RB7, they have been taking points away from each other rather than Vettel! This has led to his lead increasing and thrown a challenge to his championship in doubt.

        The only way I can see him being challenged is if Alonso is able to win a huge clutch of the next 8 races, and the Mclaren’s close out 2nd and 3rd. I can’t ever see Mclaren favouring Lewis over Button (or the other way) which will inevitably lead to them winning in fits and starts, which is pretty much what has happened with them all season.

  8. super article, thanks

    1. +1. Can’t wait for the next one.

  9. Very nice indeed.

  10. Love these articles John! Looking fwd to pt 2.

    Thanks for running these on your site Keith.

  11. Great article! I now know what ‘rake’ is.

    Absolutely fascinating stuff.

  12. Great to have this right in time to get us back into spotting the differences to the last race. Thanks John.

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