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Virgin Racing’s secret: Behind the scenes at Wirth Research
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Virgin Racing’s secret: Behind the scenes at Wirth Research
Posted By: James Allen  |  05 Mar 2010   |  7:47 am GMT  |  134 comments

Of the new teams in Formula 1 it looks as though the radical Virgin Racing car is probably going to be the fastest, once it hits its stride, but preparations for the season have been undermined somewhat by reliability problems in testing.

The car has been unable to hold on to its hydraulic fluid and during its first test a front wing fell off. This has been a little embarrassing for technical director Nick Wirth, who has staked his reputation on a car which has never been anywhere near a wind tunnel, but instead was designed only using CFD or Computational Fluid Dynamics, a highly sophisticated 3D computer system.

Yesterday I went to the headquarters of Wirth Research to find out more about the reliability problems and to look more closely at whether Wirth’s plan of doing a CFD-only car will work.


Wirth is someone who sees and does things slightly differently. There are many photos on the wall, but they are of The Who and Oasis, rather than racing cars.

The whole Virgin team is operating out of Wirth’s premises on an industrial estate in Bicester at the moment. The race team will shift to the Manor team base in Sheffield after the Chinese Grand Prix, but for now the cars are being built up at Wirth, which makes sense with the tight turnarounds before the first race.

Currently spread across six buildings, Wirth Research also needs more space and in the enforced summer F1 shutdown period will be moving to a new base where all departments can be under one roof.

There are many familiar faces from other teams, a few ex Renault engineers, David Coulthard’s number one mechanic from Red Bull days, all experienced pros.

Wirth employs 120 people and the F1 programme is only part of what they do here, he has research and development contracts with Honda, Michelin, FIA and Porsche, who came to to them after being beaten by Wirth’s Honda car in ALMS. One of the recent programmes was to solve an aerodynamic problem for the IRL to prevent cars from getting airborne, which has now also been applied to sports cars.


Wirth’s pitch is that he has been focussing on the technology which makes a difference, particularly in the simulation world. He has two simulators here and I was allowed in to see the new one. It’s the first time I’ve seen a 3D F1 simulator up close and it looks a but like those ride simulators you find at the Science Museum or at shows – a pod on top of hydraulic rams, standing six feet off the ground. Both Timo Glock and Lucas di Grassi were there when I visited, correlating data from the recent Barcelona test and testing the Bahrain update kit.

The pod pitches and bucks as the car goes round the virtual Barcelona circuit. When the driver hits the brakes at the end of the main straight, the nose goes down probably a metre, it’s pretty violent. I noticed the rear end twitch in the high speed Turn 3. The virtual front wheels are visible on the screen, but there are no wishbones connecting them to the pod, which is the only thing that does not look 100% realistic – the rest is just spooky. Thanks to his work with Michelin, Wirth has devoted a lot of time to modelling tyre performance, which is the hardest thing to simulate.


I also tried on a virtual reality headset and standing in an office, was able to walk around the car and nose around the cockpit, as if I was standing next to it in the pit lane. It was uncanny. Even the wing mirrors worked!

Wirth’s plan for CFD-only design came from witnessing years of wastefulness in windtunnels, where £30,000 worth of 60% scale models are routinely built, tested and then thrown away every day. Many teams employ 140 people including model makers to do windtunnel research and Wirth decided that it could be dispensed with when he developed the 2008 Honda LMP2 car. The Eureka moment was when he realised that the CFD numbers were more accurate than the wind tunnel. Honda are convinced by it. He claims that the Virgin F1 car track data is closer in reality to the CFD numbers than any car he’s built before.

The Virgin car is around 4 seconds off the pace of the front running cars at this stage. In his view, the car lacks aerodynamic refinement compared to the Ferraris and McLarens because it is the first product from the design team, “We just lack experience compared to the fantastically clever people out there” – not because of the limitations of the CFD process. And just as the team at Force India has designed a much more aero efficient car with each passing year, so will Wirth’s designers. They have an aggressive development programme for this season so it will be interesting to see how far they are off the pace at the end of the season.

The design of the monocoque was frozen in June last year, probably three months earlier than the top teams who have greater resources and experience in manufacture. The team has a strict budget of €45 million all in and so far has hit all the deadlines it set itself. It will travel to Bahrain with two cars and a spare monocoque as well as five sets of spares for most parts. Wirth says that the troublesome differential, which has been causing the hydraulic leaks and destroyed their Barcelona test, has been fixed. There were quality control problems causing it to crack. But new spec ones are in short supply, so the drivers had better not crash into the barriers backwards before the race..

The front wing collapse was a “design error” by his drawing office team, for which he puts up his hands and accepts full blame.

“The drivers know that underneath them they have quite a good car,” he says. “Timo hopped out of the car and said ‘It’s doing what you said it would do.’ We have an exciting development programme, we should be able to bring a lot of performance to the car. We have a big update for Bahrain and more for Melbourne. There is a healthy development budget.

“I would like to show during the course of the year that we can close the gap on the weakest of the existing teams and show that this way of designing cars represents a way forward, ” he said.

Photos by Pip Calvert

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1

It seems other recent posts have already covered some of the points I was going to write (with Peter Murdoch being very informative), but yes, it appears a fair few posters have got themselves confused over Virgin’s all-CFD (computational fluid dynamics) designed car, thinking it to be a massive innovation and cutting-edge thinking.

Firstly, all the teams use CFD as well as wind tunnel testing. Indeed, no doubt the likes of McLaren and Ferrari, etc, will likely (I suspect) be using CFD more extensively than Virgin, such is their resources. So it’s not as if Virgin is being radical in the sense that they’re using some super advanced technology and methodologies. In truth, it’s quite the opposite and they’re being less sophisticated (but are saving time and costs) by not using a wind tunnel/CFD combination.

I feel that some people are thinking of comparing wind tunnel testing to CFD as akin to VHS to DVD or something – i.e. that wind tunnels are a ‘manual labour’, dinosaur way of doing things that the ‘old’ teams are stuck in their ways with, and CFD – being all digital and whizzy computers – is by definition more accurate and better quality. This is the wrong way to look at it. CFD is not analogous to someone who has a calculator (the CFD engineer) being able to do calculations many times quicker than another chap stuck trying to work with an abacus (the wind tunnel tester). Heh, how many more analogies can I conjure up – I’ll stop there!

Peter Murdoch has already well surmised the deeper technicalities of CFD, but in essence CFD is a way of mathematically modelling an aspect of the physical world (in this case fluid flow: air, water, whatever), and then using numerical simulations to understand and predict the behaviour of the fluid in various situations (such as the flow around the endplates of a front wing), and to calculate properties such as drag, (negative) lift force, vorticity, temperature, etc.

However, whenever you mathematically model something you inherently have to make simplifying assumptions of the real world to arrive at a suitable model amenable for analysis; it would be impossibly complicated otherwise. So already you are approximating the real life phenomenon and so already you’re not going to be accurate as if you can see the real thing (such as the flow shapes in a wind tunnel – as long as it’s calibrated and you’re measuring instruments are suitably accurate).

Now, modelling fluid flow is extremely complicated. Except in trivially simple situations, there are no exact solutions to the equations that govern the motion and properties (pressure, etc) of any fluid flow (these are called the Navier-Stokes equations and are basically just a sophisticated advancement of Newton’s laws of motion, i.e. Force = Mass x Acceleration, adapted for fluid flow). And by exact solution I mean it’s not a case where you can plug data into an equation, turn the handle and out pops your answer (unlike, say for an equation to model the growth of your savings account based on the interest rate, where you stick in your bank balance, turn the handle of the equation governing how interest is applied, and bingo, out pops your lovely savings for the month/year)!

With CFD, to obtain solutions you have to approximate (discretise) the equations and solve them numerically on a computer. The key word here is ‘approximate’. In approximating something you’re by definition introducing an error into your answer (e.g. down-force figures), and in F1, errors can mean tenths of a second (or seconds if you’re the new teams – ah that’s unfair)! To obtain more accurate answers requires more computing power since you need to use a finer mesh (i.e. use more data points on the F1 car/component model) and a more complex model to simulate turbulence (cf. Peter Murdoch’s post above), and thus solve more equations.

Now due to the complexity of the equations and geometry of an F1 car, it is currently impossible to use CFD to exactly model every aspect of the car. That is why wind tunnels are still worthwhile. Of course they need to be correctly calibrated, since like with CFD it’s a case of, put garbage in, get garbage out. Perhaps that’s what Wirth means in his “The Eureka moment was when he realised that the CFD numbers were more accurate than the wind tunnel” quote. But as mentioned by others, you need (properly calibrated) wind tunnel data to validate the CFD so that you know your virtual model is behaving true to life.

Finally, here’s a summary of some of the advantages and disadvantages of CFD to wind tunnel testing, so that others hopefully can appreciate the worth of each and why it’s better to have a blend of the two.

Advantages of CFD compared to wind tunnels:

– Can analyse whole domains and measure many parameters (velocity/pressure, etc) simultaneously. Wind tunnels use sensors to measure a single point on the car (just like the sensors hanging off the McLarens in testing). Hence a whole wind tunnel run could be useful for just a handful pieces of data. Also, you have to ensure that these physical sensors in the wind tunnel don’t adversely disturb the flow you’re measuring too, since they won’t be there on track! By definition CFD calculates solutions across the whole domain investigated.

– Cheaper overall since quicker turnover times than having to design, build (and bin!) models. Also parts on the car can be much more easily remodelled on the computer so you can test designs tweaks quicker.

– Better visualisation of results. Computers can produce a wealth of informative graphs/flow patterns etc, and you can focus on design details of particular interest. Wind tunnel photos/videos don’t necessarily provide the same level of detail.

Disadvantages of CFD compared to wind tunnels:

– Results can be erroneous. It is well known that in some circumstances CFD results do not coincide well with reality. This is notably the case for complex turbulent flow (which is pretty prevalent in F1 eh)! Example problems include: overproduction of turbulent energy in wakes and incorrect generation of vortices/ vortex shedding. Thus due to the difficulties of modelling and unpredictive nature of turbulence, a CFD model could predict that the vortices off the front wing endplates move nicely around the front tyres, but then in the wind tunnel and on the track, a completely different flow pattern could be happening, and not just that the CFD results are a little less accurate!

– CFD is limited by computing power and thus the size of the projects are limited, though of course computers just get ever more powerful! A large wind tunnel is less compromised. Also, due to the modelling complexities wind tunnels can handle complex geometries better.

Apologies if some of this is rather dry but I hope it is of use to people. One of the great things about this site is the quality and knowledgeable discussions that go on her compared to other sites. James has done great work!

2

Thanks for that, but please keep comments shorter in future

3

Interesting “The Eureka moment was when he realised that the CFD numbers were more accurate than the wind tunnel.” Exactly how can anyone make that claim. A wind tunnel is used to verify the CFD result and show how far it is in error, not the other way around.

Seriously this has to be a misprint.

The more you know about CFD the more you understand its limitations, the less you know the more you imagine it can do.

4

Thanks for that. Please tell us more..

5

Sure James no worries.

In order to compare one thing to another you need a frame of reference. In classical science and engineering, empirical formulas are used to make estimates that are correlated to experimental data. This works great for calculations such as the strength of a straight beam and the mass of an object, but for fluid flow problems there are no empirical methods for computing the exact flow over an arbitrary complex shaped body let alone the flow over a F1 car. Hence the only way to determine the definitive flow as well as the lift and drag values on a car is with a calibrated wind tunnel. That is the frame of reference. You then compare the measured results to your CFD simulation and determine the error of the simulation not the other way round. These are basic fundamental principles of experimentation and simulation.

When talking about the accuracy of a CFD simulation you need to consider the accuracy of the turbulence model used in the simulation. The reason being is the lift and drag values on the car are highly sensitive to turbulent flow separation in the boundary layer.

There are several ways to model this turbulence in CFD, ranging from the most accurate DNS (Direct numerical simulation) and LES (Large Eddy Simulation) to the least accurate approximation method, RANS (Reynolds-averaged Navier–Stokes). F1 teams all use the RANS turbulence model.

The reason you ask? Well it’s all to do with the mesh, the mathematical base model where the Navier Stokes equations are solved.

The teams use either a tetrahedral mesh or a trimmed polyhedral mesh, which are generated by an automatic meshing program that requires a relatively low level skill to operate. The biggest problem is you can only run a RANS turbulence model on these tetrahedral meshes. They also require enormous computing resources and worst still produce fictitious results that can be completely misleading. Hence the reasons why F1 teams still keep and use their wind tunnels. They know from experience that a CFD model will generate fake vortices’ and completely miss other crucial ones.

The only way to produce a CFD result with any level of respectability and degree of accuracy is to use a high quality all Hexahedral mesh running a transient LES turbulence simulation. The next obvious question is why don’t the teams use this method? Yes indeed that is a very good high tech question.

6

Thanks for the insight

7

An excellent, insightful article.

Just one point – Manor’s HQ is in Rotherham.

It’s not as hard to believe as you might think that a F1 race team and cars will be equipped, based and resourced in the former pit village of Dinnington, Rotherham.

Coincidently, Rotherham is also home to F1 Show Cars – the proud owner of the only 3-seater F1 Simulator to date. Available to hire with virtual reality goggles included – http://www.f1showcars.co.uk/

8

previously owned by the arrows f1 team to add!

9

Andy, I would love to have a go too. I was actually going to ask here if anyone knew how the average person would fair if put in one. I would take it really seriously if I had the chance. Wonder if there is one you can hire would love to try.

Chris.

10

It’s always seemed to me that conventional wind tunnel tuning is all about where you locate the pressure sensors, as more and more sensors and readings become available for simultaneous interpretation, we’ve seen more and more barge boards, “mirror mounts”, and addons. Perhaps Wirth’s faith in CFD is better placed because of the current restrictions on appendages, allowing the computers to approach a more complete holistic aero picture of the car than would be possible with addon tuning. It still demonstrates the disproportionate amount that aerodynamics contributes to the cars, though. If Virgin do improve dramatically during the year, it’ll probably be because they’re better placed to understand results of “virtual testing” than other teams. It will be cheaper than running cars in testing, but it’s as ludicrously arcane as ever. Horsepower is limited through engine development controls, limiting downforce to x amount in x tunnel or x program makes even more sense. It would make F1 more sensible as a development environment to tyre manufacturers, rather than an insular PR environment for a single spec maker. Imagine cars coming into corners having to consider braking, corner speed, exit line acceleration if they’ve all got comparable aero grip. Put the emphasis back on mechanicals!

Sorry, Nick, I admire your ability, but F1 is paddling further and further up an irrelevant backwater. Can’t help but wonder how a Paul McReady design would go, if he was interested in F1.

11

Hey James,

That F1 Simulator at Virgin HQ is great isn’t it? There’s a good video of it being tested here:

http://www.youtube.com/watch?v=ZF_dnGVbXkM

12

Cool video but it’s nothing like that, I can assure you!

13

so Nick is mad fer it? 😀

I’m his fan now xD

14

Everything I have seen so far from Virgin is more Mickey Mouse than Avatar. The problems they have so far, in no way resemble professional. Many teams have CFD and I really doubt Virgins is the best. Without experimental results to back up / fine tune the CFD model you can be just guessing on very major issues. I am really struggling to describe the level of naivety I believe Virgin have brought with their overall approach, highlighted by the practical issues they have experienced so far. I appreciate this is not necessarily the views of the author, but of Virgin.

15

James – with teams reportedly 4 seconds off the pace, is there a potential for teams to miss the qualifying cut level of performance? and if so, would you expect the FIA to find a way to allow them to race regardless early in the season?

16

There is no cut off

17

A great piece, as ever James, quality information and insight that is sadly lacking everywhere else.

I cannot help thinking most posters are somewhat missing the point. Virgin are not really trailblazers, CFD is not new. They are skinflints trying to save a lot of money by relying solely on CFD. This is a great risk and is arguably somewhat arrogant. Some of the worlds greatest minds are currently working in F1, engineers and programmers, they have unlimited budgets and are free to try anything they fancy. The universal feeling of these people about CFD is that it is a great tool to help, alongside others, but, specifically, that while the emerging technology is great, the application to designing something as complex as the whole car is far too much for this emerging technology right now.

If you have an interest in promoting this as the way forward, you will paint it in a certain way. Branson’s Virgin brand has a PR image that just suits this, he can paint himself as the plucky underdog trying new technologies on a small budget, but in the views of most F1 engineers, Virgin/Wirth are taking a massive risk.

The fact that the car seems fast is very interesting, but if it falls away or does not perform, will they just use it as an excuse for whining about budgets and try to force F1 to cap spending, ultimately all part of Max Moseley’s attempts to attack his enemies in the big teams. Remember the murky “help” Alan Donnelley gave them getting on the grid, ahead of far better qualified teams, whilst simultaneously working for the FIA….

18

So, if I understand the Wirth phylosophy – by dispensing with the wind tunnel, not only can a great deal of money be saved, but they should be able to develop more quickly than a team that is spending time on building models and putting them in the tunnel.

If that is true, they should gradually migrate up the grid as the season progresses, it’ll be intersting to see how they get on.

It must be greener too. All those models that aren’t being built and all that power that wind tunnels consume not being used.

19

Great article James and very interesting.

In my experience have found that CFD is limited by the quality of data input and the analysis and interpretation of the output data.

Correlation with actual physical testing, which is what the more established F1 teams will be doing with their windtunnels, flowvis and other devices used during pre-season testing, is what is needed to validate the CFD results, which in turn leads to a greater understanding of the components aerodynamic properties. Without validation it could lead to taking a wrong design direction and ending up with a poor car.

Although saying that Nick Wirth is an extremely talented Engineer and good luck to him and his team, it’ll certainly be interesting to see how the team develop their cars through the year.

20

That’s because in order to simulate the violence of real breaking, it is necessary for the simulator to “dive” deeply forward.

With his eyes locked on the screen, the driver is “fooled” By having physical sensations that somewhat match what is happening on the screen.

21

Best of luck to Wirth and the Virgin F1 operation. They are doing their business in an efficient and sustainable manner and it looks like the CFD-only model is a feasible alternative to wind tunnel and CFD testing. If CFD produces more accurate results then why waste time with wind tunnels. I’m firmly routing for them this year and I’m sure they’ll creep closer and closer to the likes of Toro Rosso and Renault as the year progresses.

22

If others teams use CDF and wind tunnel, it’s not for fun.

23

No, but it falls into the “we’ve always done it this way” category, possibly revealing a stick-in-the-mud attitude.

24

Thanks for the insight James.

I think their process is fascinating (coming from the IT world myself, and also being a car nut), and the comparison of their performance improvement vs the traditional wind tunnel biased teams will be on of the more interesting aspects of the current season to watch.

As someone who has also followed Richard Branson in the business world, and knowing his style (doing things a little differently) I could well imagine his enthusiasm when talking to Nick about a totally CFD designed car with the Virgin name on it.

Good luck to them I say. Bring on Bahrain.

25

I think this year could be a struggle for virgin but if Richard Brandon sticks with it they are well set for the future.

Any chance of an article on McLarens rear wing James?

26
Mike from Medellin, Colombia

James, who takes the photos? Did you work with Darren Heath on this?

27

Pip Calvert did these

28

Really nice view into how this CFD design idea is coming about.

Thanks!

It’s odd how Adrian Newey says that windtunnels are cheaper though. Or rather that you can go through more design parameters in a shorter time with them. So you’d need less time to do the same thing with a windtunnel.

Didn’t they say anything about that?

29

I think Newey’s point was that you can get much more data from a single run in the windtunnel than from a single run using CFD – which needs about 20 runs to produce the same amount of data. Whether a single run of CFD is less than a twentieth of the cost of a single windtunnel run I don’t know – it probably varies from team to team, depending on the different equipment.

But this is covered in the article – with a windtunnel, teams need to construct accurate 60% models to put in the tunnel which can cost tens of thousands of pounds. If they don’t show an improvement then they’re useless and have to be thrown away. But with CFD the designer can create a new part or concept on screen, map it over to the CFD and run it there and then. No time and money wasted building a model.

30

Fascinating stuff!
That’s why Branson jumped aboard no doubt..

Will be very interesting to monitor progress.

Thanks for the insight.

31

Branson is in business. He jumped aboard becasue it was the best promotional return for his money.

I’m not being cynical. It’s just that you don’t make millions by following your heart!

Neil.

32

Well, I am software/computer developer with some strong background in math and physics and always had a dream of working for an F1 team. Maybe if I was 20 years younger and living in England I would try to get a job at Virgin! Anyway I do believe that CFD is the way forward in F1, and is probably much more cost effective once you get it right. I hope indeed Virgin can prove this at least by winning the bet against Lotus. This will be another interesting back story to a season already full to the brim with other ones.

33

Excellent write up.

I think it’s amazing that anyone can build a respectable F1 car in such a short amount of time. The fact that Virgin have managed it without relying on any of the old techniques makes it even more impressive. I hope it’s not going to take too long before they can iron out the problems and be in a position to score some decent points.

P.S. What was your lap time in the simulator?

34

Thanks James for such a fascinating insight! Your great reports help satisfy our F1 appetites. I wonder if they’ll get a video-games version out for Christmas?! 😉

35

So regarding the “eureka” momement…did any spill the beans on how much closer to reality CFD is than wind tunnel testing??

36

He reckons closer

37

I am expecting this approach to pay off.

38

“Of the new teams in Formula 1 it looks as though the radical Virgin Racing car is probably going to be the fastest” … James, I didn’t think you’ll say that. Because they weren’t looking too good in the tests are they?? But having read what you wrote, you could be right.

I still think they would be neck and neck with Lotus though.

I think, as I said a couple months ago, that this would be this is the future for F1 and I still think so…

What are your thoughts, James.

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