Technical review: Australia and Malaysia

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How much of Brawn's performance is down to their controversial diffuser?

F1 Fanatic guest writer John Beamer examines the technical changes and controversies over the first two races of 2009.

Formula 1 never changes. We’re not even two races in and controversy continues to rage around the paddock – as it has done so every year since 1954 and will do so until we humans are extinct. Putting McLaren’s astonishing fib aside most of the brouhaha is down to the revamped technical regulations.

‘Diffusergate’ continues to gobble column inches; Toyota was booted out of qualifying because of it flexing rear wing; and the podwings on the Red Bull and Ferrari were called into question by Williams.


One outcome of the first race was that a date was set for finally resolving diffuser gate. The FIA meets on 14th April to arbitrate on the legality of the device.

For the uninitiated let’s remind ourselves how a diffuser works and what the kerfuffle is about.

The diffuser is the device attached to the back of the car (starting at the rear axle) that manages air under the floor. This air has been squeezed under the floor so is going fast. In order to maximise downforce this flow must be transitioned back to freestream (normal) speed. Failure to do so creates unwanted turbulence at the rear, which feeds back into the diffuser harming downforce. The larger volume of the diffuser (compared to the floor) allows the air to slow down to freestream speed – this is what creates rear downforce. Generally the larger the diffuser volume the more effective it is.

It will come as no surprise that the reason that the double diffuser creates more downforce is because it has a larger volume. Brawn, Williams and Toyota are taking advantage of three loopholes:

(1) The rules don’t prevent double-decking as the diffuser is defined in the articles labelled ‘bodywork facing the ground’ – the upper tier does not face the ground.

(2) The reference plan and step are not treated as a single continuous surface so holes can be carved in the step transition to feed more air to the diffuser.

(3) A longer, higher central section that integrates with the rear crash structure is allowed – Toyota exploits this (think of this as a narrower version of the central section allowed last year).

The prevailing view in the paddock is that the FIA will not outlaw the double-diffuser, at least not this season. Expect 75% of teams to be running them when the F1 circus lands in Europe.

Other controversies

Toyota's flexing rear wing gave them a headache in Melbourne

It’s not all about diffusers. In Australia there were two further points of contention. First, Toyota was found guilty of having a flexing rear wing after qualifying and was excluded.

Flexing wings are outlawed because at high speed the main plan will flex upwards and close the ‘slot’ to the flap. This causes stall over the rear wing, which reduces drag and allows the car to go faster.

Given the tight rules around flex-testing it appears to be a manufacturing glitch on Toyota’s part rather than anything malicious.

The second controversy surrounds the podwings of Red Bull and Ferrari. Williams protested the legality of these devices after Melbourne qualifying. The protest was later withdrawn so it isn’t 100% clear what Williams’ gripe is but Red Bull and Ferrari’s podwings are unique in that they sprout up from the axehead in front of the sidepod unlike a traditional podwing.

Aero Innovations – Red Bull and Williams

Most teams finalised their Melbourne/Sepang package in late preseason so there weren’t a huge number of innovations for the opening two races. For this article we’ll look at two of the more innovative teams over winter: red Bull and Williams.

Red Bull has probably the most radical looking car on the grid. The design philosophy is to make the nose as small as possible to minimise disturbance and feed the floor. Look closely at the chassis and you’ll see raised section along the front edge. This is required so the chassis meets the cross-section area requirements and also help funnel air to the rear of the car to feed the rear wing.

The other noticeable feature of the Red Bull is its tiny sidepods. This allows air to be channelled under the sidepods to the coke-bottle zone and over the diffuser. This ‘pumping’ of the diffuser leads to considerable downforce benefit as it creates a lower pressure above the diffuser – in other words the diffuser is working against a less adverse pressure gradient, which makes it more efficient.

Williams has also innovated over the winter – it pioneered the skate wings (now dropped) and the snow plough (effectively a splitter under the nose). In Melbourne the Didcot-based outfit ran revised axe-heads. The axe-head now curls up at its leading edge and has a couple of horizontal fins. The curl helps to funnel more air under the floor which is then transitioned into a vortex by the fins. This vortex acts as a virtual skirt sealing the floor and increasing downforce.


In Melbourne we witnessed the sort of havoc that the new tyre rules will bring into play. Not only must teams get used to slicks but the option and prime are two compounds from each other – super-soft and medium in Australia. From what we saw the super-soft needs work. Although it was the fastest qualifying tyre its performance degraded to such an extent that within 8 laps it was virtually un-drivable. It made for a fun end to the race but a tyre that causes a 3 second a lap difference in time shouldn’t be used in a race.

Malaysia had the opposite problem. The soft was the tyre of choice by a mile as teams struggled to get the hard compound ino its operating window.


Much has been about the fact that the cars at the front of the grid are KERS-less while those at the back have KERS. Is KERS to blame? No – I don’t think so.

Let’s clear up one common misunderstanding. KERS doesn’t add to the weight of the car – all it does is move the weight distribution back and raises the centre of gravity.

Granted, neither of those are benefits, but the 80bhp boost will more than offset that loss. The teams that run it believe they gain two-tenths a lap from KERS depending on the track. These data will have been borne out in testing as team alternate between using and not using KERS.

We’ve seen that KERS is especially useful at the startline and for passing/defending. Once the large teams master the technology it will make a difference.

However, had the boffins at McLaren, Ferrari, BMW and Renault focused on aero rather than KERS perhaps they too would be at the front of the grid.

29 comments on “Technical review: Australia and Malaysia”

  1. Excellent article, thanks for this.

    On the other hand, I read an interview of Rubens Barrichello in a Spanish newspaper (ABC).

    He comented that Brawn GP excelent performance is not only based on the double diffuser. During Australian GP, his double diffuser was seriously damaged when Kovalainen touched his back, and the behaviour of the car was still excellent.

    I’m afraid he’s wright. I’m not an expert of technical issues (quite far to be, indeed) but when one see Brawn’s car they are totally different from the rest. Clean design, no side pods or small parts arround, and very articulated front wing.

    They are different and I guess that the combination of Mercedes engine with the best design of the grid will push Brawn to the WDC/WCC, independently of double diffuser.

    The only concern should be how long they can mantain the step ahead of the rest, keeping in mind their actual resources. The starting point has been fantastic but McLaren, Ferrari and maybe some others will develope their cars faster than Brawn.

    Finally, I love to see pure engineering going beyond lawyers. At the end, the word “engineer” comes from “ingenuity”.

  2. no mention of adjustable front wings? still?

    1. During the last race Smedley mentioned to Massa on the radio that he has to start using the wing on the two straight sections because it would make a big difference.

      I think it would make more sense if they automated the front wing – a bit like the McLaren last year how it had enough flex in it that it would close up with high speed.

    2. To date I don’t think teams use them much. There is the odd radio transmission where engineers suggest an adjustment but it is more of an in the race set-up tool than anything else.

  3. @ F1Yankee
    You took it right out of my mouth!
    Everybody talks about when the drivers press the KERS button or when they don’t press it, when they can use it, when they can’t use it, etc.
    But what about the front wings, huh?? They all’ve got it. When/how do they use it? Have there been any problems with that system in Aus and Mal? Hmm.

    1. I think both Hamilton and Alonso said it makes very little difference, so rather than take your mind off the overtake by adjusting yet another control they are better leaving it be. It can only be changed twice a lap anyway, which isn’t enough really.

  4. I understand that Bridgestone have developed 6 different slick tyres for this season. At each race, they select a softer and harder compound from these six and have the harder as the prime and the softer choice as the option. It might just come down to Bridgestone not doing a good job of choosing which tyres to take to both Melbourne and Malaysia. I am not sure when or how they make this choice, but it obviously happens in advance of the entourage arriving at the circuit, so if they find that their choices are not optimal by then it is too late. Lets hope that they learnt enough about their tyres during the first two races to make better decisions in the future races.

    I also believe (can’t remember where I read or heard it) that both the prime and option in Melbourne were softer than both the prime and option in Malaysia – so it might have been Bridgestone experimenting with the ideal composition (and it also makes sense considering Melbourne is a street circuit and Malaysia a race track, being much stickier).

    Great post, btw.

  5. Ronman (ex Ron)
    7th April 2009, 10:47

    Hi there everyone,

    What an incredible race that was, too bad it was so short.

    I agree with all that the mayhem and confusion was disconcerting, but those 31 laps were really what I needed to wake up that day.

    So far, we can notice that the new regs. have shaken up the field. Although i don’t have the expertise John has in judging technicalities, I can see that it’s more than the diffuser that it putting the diffuser trio ahead.
    all of the drivers at the front are complaining of instabilities and balance difficulties, especially Button, but as he said, they are going much quicker and the cars are easier to dial down (perhaps because there is less aero stuff to fix?).

    i believe one of the things that shows the most this season is that the former top teams relied too heavily on aero grip rather than mechanical grip, whereas the rest of the field, without private wind tunnels had to keep their hopes pinned to mechanical grip and supplemented by aero.

    this year, when aero grip is very limited, the former top teams’ Achilles heel shows. they have problems sticking the cars to the ground. diffuser or not.

    i bet if Brawn, Toyota and Williams install a Ferrari diffuser, they will still beat the rest on sheer overall fluidity of the car’s basic design and how it rolls.

    as to Kers or No Kers, if the technology is costing so much, it’s a no brainer just scrap it if you are crying about costs.

    and with respect to tires, I never liked different tires. why not just settle on one type for everyone. like when Good Year was the sole supplier (those were good years). This soft hard super slick soft medium concoction drives me nuts, and confuses me regardless of the color of the strip. and what is so green about a tire that Bridgestone put a green strip instead of a white. tires are the foremost pouting object in cars, if Bridgestone and the FIA want to cut costs and be green, they should develop tires that last longer and with more relevant rubber to road cars.

    as for the missing part of the moving front wings, i really like that part of the regulation, reminds me of a comic strip (Michel Vaillant) in one of those books they design an open wheeler with moving rear wings to provide more traction depending on the orientation of the turn. now that was cool to see done to some extent on a real competition car.

    anyway, sorry i deviated so much off the initial post. which is always great to read, looking forward to the next one Mr.Beamer

    1. Thanks Ronman – i think there is little doubt that Brawn has supurb aero characteristics even if you ignore the diffuser. The main difference is that the top teams haven’t had as much time to develop their cars and, quite frankly, it shows.

      The intersting team is BMW. We know they have spent a long time developing the car yet it is still midfield pace. I wonder if this is down to BMW’s conservative design philosophy whereas a Newey and Brawn and more prepared to go out on a limb with a radical design

    2. Yes, I’m worried about BMW, seems like thay’ve bitten off more than they can chew, sacrifising 2008 half way through to focus on 2009, and 2009 isn’t really coming to them yet. It’s been quite the opposite, Which is a shame. I hope they can get it together come the European season.

  6. Ronman (ex Ron)
    7th April 2009, 11:12

    you are welcome John – well history has shown us that Newey and Ross can hold their own on a design board. and it seems that they have. i noticed the Red Bulls are strange, but only realized how effective their design is after reading your post. and it is possibly one of the finest looking cars on the grid. but what’s up with Toyota, I’m still convinced that the simplified aeros will allow more teams to tackle the field rather than domination be monopolized by established teams.

  7. John, I have a couple of questions that you might be able to answer.

    Firstly, on his grid walk on Sunday Martin Brundle mentioned Toyota had a “triple diffuser”, as opposed to the “double diffuser” of Williams and Brawn. What does he mean by this, and is there a chance that Toyota’s diffuser is therefore ruled illegal and the others legal or visa versa?

    I also heard around the time of the Australian GP that Red Bull were leading the diffuser protests as the back of their car is radically different due to their suspension. Can you shed some more light on this – does this mean it is harder for them to adapt to the double diffuser?

    Finally – how long should it take teams to adapt and will they be as good as the 3 diffuser teams when they do? Can’t remember who, but one non-diffuser driver said that the diffuser has wide reaching affects across the car and it’s not just a case of attaching a new diffuser, that it might take months. Do we have any way of knowing which teams have aero most suited to adapting to the new diffusers?

    Thanks for an interesting article.

    1. I think Brundle is referring to the extended central section protruding from the Toyota. Williams and Brawn don’t have this. The central section is definitely legal so no chance that will be outlawed – seach the F1 Fanatic archives as I wrote about it in a rules brief earlier in the year. The controversy is that hole that is cut between the step and reference plane.

      By Spain we should see the first team adopt the new diffuser for the main teams – McLaren has a very quick manufacturing time so perhaps even quicker but I doubt it. Teams have to rework the rear of the car, gearbox casings etc, tune the rear/beam wing … given that all the flow is dymanic across the car it is a biggggg job.

      Red Bull suspension is a bit of a myth I think. They use a pull-rod suspension system, which is different but shouldn’t affect their ability to do a double-diffuser. Red Bull are just slower at manufacturing so that is probably the issue – saying that I haven’t taken a close enough look at the suspension.

    2. Cheers John. I’ve heard rumours BMW will have a new diffuser for China, maybe with all the extra development time they’ve had they understand the rules better and maybe even designed a prototype themselves before deciding to play it safe.

  8. One thing I don’t understand is why the softer of the two compounds for each race is always green-stripe.
    Why not have say blue, green, yellow, red for the four (?) compounds; that way watchers can tell which softer and which harder compound is being used at each circuit?

    1. The commentators mention what the two compounds are that many times during the broadcast that I don’t think this is needed. Though using green is a bit bleh. Cmon, who are they trying to kid that F1 is a “green” sport? lol

  9. I know Alonso had said KERS was not helping him in Australia, however, Glock stated the opposite. He said it was impossible to pass Alonso in Australia as every time he was close enough, Alonso was able to pull away with KERS. I have a feeling that guys like Alonso and Hamilton are saying KERS doesn’t work, because they can’t believe their cars are so slow, but it seems like they are!

    I will be interested to see the Williams with their flywheel KERS, Rosberg ftw? :)

  10. Great article!

    Particular thanks for reminding everyone KERS doesn’t add any weight at all to the car when they go racing (as all the cars are built well under weight anyway).

    I’ve been surprised at how many commentators / writers, particularly last weekend, who made the mistake of linking the slow pace of KERS cars to being overeall heavier than their counterparts.

    Was it Leggard or Jake who even speculated whether the KERS cars would have to brake earlier because they’re heavier. Tut!

    1. Maybe they don’t need to brake earlier just because of the “extra” weight of KERS, but still. KERS might mean a car needs to brake slightly earlier.

      From what I understood, KERS is indeed a bit of a problem under braking. The KERS is adding braking power while it’s charging the batteries, but when those are full it stops. So the actual “brake power” is not entirely depending on how hard the driver presses the pedal.

      Not sure if it matters that much, but drivers were complaining about braking instability due to KERS. So they might feel the need to brake earlier.

      KERS might also mean lower cornering speed (due to sub-optimal weight distribution) and thus again this would mean earlier braking for KERS equipped cars.

  11. I’ve often thought one of the reasons the Mclaren doesn’t efficiently generate downforce, is because it has bulky sidepods. The car always looks fat when looked at from the side. This is probably starving the diffuser region of free flowing air.

  12. Isn’t the diffuser about creating a low-pressure area underneath the car so that the high-pressure air on top of the car pushes the car down? If the air exiting the diffuser is at freestream velocity, there will no low-pressure area underneath the car.

    1. The diffuser does do that but if the air is close to freestream when it exits there will be less turbulence at the back of the diffuser – ie, so less dirty air feeds back into the diffuser harming performance

      It’s best to get low (ish) pressure at the the back of the diffuser to reduce the pressure graident the device is working against

  13. The commentators mention what the two compounds are that many times during the broadcast that I don’t think this is needed. Though using green is a bit bleh. Cmon, who are they trying to kid that F1 is a “green” sport? lol
    P.S.: Wanted to mention good post!

  14. About BMW: They have a pretty good race pace. Kubica had a “chance” at first in Melbourne and Heidfeld took “second” in Malaysia. Had they not experienced other problems it could have been a strong showing. But yes they are still behind on raw speed.

    [quote]Granted, neither of those are benefits, but the 80bhp boost will more than offset that loss.[/quote]

    How do you explain Heidfeld running KERS in both races and Kubica not? KERS makes a difference, and a positive one if the team can find a way to balance the car. Otherwise the small Heidfeld would use his ~20kg advantage to fully balance his car over Kubica’s and scrap KERS.

    Bridgestone: The Green tires are a joke. This year the stripe placement is difficult and on top of that they choose pastel green. Viewers can’t see that. The only time I can clearly see the green is on pit stops and in car cam, unless I’m really looking for it. Another thing is that Bridgestone is skipping a compound between softer and harder. That is why there is such a difference between the two. One is optimal and the other a compromise. I think we will see this at most of the races. From last season I remember hearing that this is a marketing ploy from B. They included the two compunds in the contract to promote discussions about Bridgestone tires. Which obviously works since we are discussing the brand right now. Otherwise it would be a single tire and nobody would speak about it.

    BMW: I heard a rumor that BMW is working for a May update to lighten Kubica’s car. This is good, but its sad that driver weight is affecting the cars so much. I think there should be a regulation that a driver + seat should weigh say 80kg and have a specific range of center of gravity. A ~55kg Heidfeld would need some lead in his seat while ~70kg Kubica would need less. This seems fair to me since its unreasonable for a 180cm driver to weigh much less than 70kg. And these guys are not jokeys. They should not be disadvantaged by their physical build. They are athletes and need to watch their weight to be fit, but they should not have to slim their self to borderline unhealthy levels. I’m glad Webber stood his ground and said he knows whats good for him and isn’t going to loose weight for split seconds like others.

    1. Easy – Kubica is a better driver than Heidfeld. Just look at their relative performances last year and QED.

      BMW will have done the testing to work out the advantage of KERS – although for them to run it in one car only it will, for that team, be marginal. That indicates their KERS system is not that well developed but they expect it to be at par in a couple of races time.

  15. KERS is the one interesting new innovation in F1 and it should be supported.

    I suggest increasing the minimum weight by 20 kg to 625 kg. This would give KERS cars a bit extra to play with to get their balance right, and make the extra power more welcome.

  16. HounslowBusGarage
    9th April 2009, 13:06

    And these guys are not jokeys. They should not be disadvantaged by their physical build. They are athletes and need to watch their weight to be fit, but they should not have to slim their self to borderline unhealthy levels.

    Sorry Polak, but if they are *athletes*, then their physical build has everything to do with their relative advantage or disadvantage.
    And actually, I think the term ‘jockey’ fits them very well as the combination of rider and horse, driver and car operating to mutual advantage is similar.

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