Virgin will enter its second season of F1 with another car designed by computer without the aid of wind tunnels. It’s the way forward, states creator Nick Wirth
In 2010 the Virgin Racing Formula 1 team had a budget of 45 million euros (£37.6m). It’s a hefty sum, but compared to the teams at the front of the grid it was tiny. With a budget this small, costs were tight across the board. One of the biggest savings was in wind tunnel work, with the Virgin racer designed using Computational Fluid Dynamics (CFD).
Put simply, CFD is a wind tunnel in a computer — a very large computer that calculates what a fluid, in this case air, will do when flowed over an object. The cost savings are huge because wind tunnels require models, and these models are arguably the second most expensive race cars in the world after an F1 car.
“If you’re using a wind tunnel it’s an expensive process,” says Nick Wirth, Virgin Racing technical director. “A designer will say ‘there’s a component on the car I want to change and see what happens’. Depending on what that component is the designer will make a 3D version of it which gets sent down the chain, passing through an aerodynamicist to a model designer. Nowadays, these wind tunnel models are similar in construction to the race car, so most of the components are either carbon fibre or complex machined aluminium.
“The model is built to 60 per cent scale. A front wing model probably costs as much as a family car, about £15,000, and the top teams will test hundreds of these wings. So if you multiply that you start to see why even the midfield teams spend £10-15m on their wind tunnel programmes.”
Saving costs by using CFD is obviously a huge bonus for any F1 team, especially one on a small budget. But can it really replace wind tunnel work? CFD isn’t new to F1 — most teams use it in conjunction with a wind tunnel as many believe both have deficiencies but work well together. During Motor Sport’s audio podcast in November, ex-Renault F1 tech boss Pat Symonds admitted CFD was a viable option, but was unconvinced it could replace wind tunnels.
“There’s a future in CFD, I just don’t think that future is now,” he said. “Wind tunnels are good in dealing with turbulent flow providing you’re above a certain speed. Your deficiencies come down to inaccuracies in modelling, although the F1 models are amazingly accurate.
“CFD becomes really useful with things like the flow through brake discs. Also it’s good at helping you understand aerodynamics, because you can look at the flow. It’s just not as good as a wind tunnel when you look at turbulent flow.”
Wirth disagrees. “That’s simply not true, in fact CFD is better. Few teams, if any, do wind tunnel testing with a car in front. When you use a 60 per cent scale model (the largest allowed for F1 testing) you can’t fit that and another model onto the tunnel belt. That’s why when the [FIA] Overtaking Working Group studied turbulent air they used quarter-scale models.
“The turbulent flow that comes out the back of a car is one of the most sensitive areas, and with CFD you can increase the scale at which you look at it. We can test a 200 per cent scale model, to us it’s just a number.” What’s more, CFD isn’t limited on speed like wind tunnel testing, which can go up to 100mph. Would Wirth ever be tempted to use wind tunnels again, even with an unlimited budget? The answer is a resounding ‘no’.
A car designed solely with CFD may be new to F1, but Wirth and his company Wirth Research have been using the program with great success for Honda in the American Le Mans Series and IndyCar. But if CFD is such a good tool, why aren’t the other F1 teams following Virgin?
Wirth pauses. “It’s hard to say, to be honest. A turning point for me was when I was working on the Acura programme in the ALMS.” Honda entered the series in 2007 with the ARX-01a, and after winning the LMP2 class in that year’s first race (the Sebring 12 Hours) with Wirth’s help, decided it immediately wanted a new car without a drastically larger budget.
“We had a fixed budget and in F1 terms it was tiny,” says Wirth. “We examined what bangs for our buck we got in every area as we were running a wind tunnel and using CFD. We split the development of the 2008 ARX-01B LMP2 car between the two. When we put it on track it was better than the wind tunnel said it would be and more in line with what CFD was saying.
“We started to look into CFD more then, and I remember one of our aerodynamicists was looking at some wind tunnel results and said, ‘I don’t understand that part, I was expecting it to be better’. We put this part [Wirth won’t say what it was] into the CFD program and it made a massive difference to the car. It was the single biggest change I’ve seen in my career.
“We built the car for the 2008 Sebring race. Marco Andretti was driving it for the first time and tested this part. He came into the pits and said, ‘that is the most unbelievable change I’ve ever had on a race car, it’s like the Hand of God is pushing you into the track’. David Brabham [in the other Acura ARX-01B] got out the car after going four seconds a lap faster than the year before and said, ‘that thing is unbelievable’. That was the moment where we said ‘we don’t believe the wind tunnel any more’.”
The past year may not have been so productive in terms of results for Virgin Racing, but Wirth is adamant that its F1 debut was a success. “In terms of CFD, absolutely it’s been a success. But there’s no denying it has been a monumental task to step up a process developed in closed-wheel racing to open-wheel racing.”
Success or not, the fact remains that Virgin was last of the 12 teams in the 2010 Constructors’ Championship. But the real test for the new teams will come this year after a season of learning, and Wirth is bullish about (newly named) Marussia Virgin Racing’s chances. “If you look at the history of Wirth Research’s involvement with IndyCar [modifying the Dallara chassis for Honda] and the ALMS you’ll see a pattern emerge. The first season is spent learning, the next is ‘here we go’. In our first year in IndyCar  we won one race out of 16, in the second year it was 12 out of 17. In our first season of sports cars we won one race, in the second we won six out of 11 races.”
This may be over-simplifying things, and I can’t resist asking whether Virgin isn’t just in F1 to make up the numbers? “No, we’re here to prove our numbers make sense,” comes the reply. There will be doubt about CFD-penned F1 cars until a team like Virgin makes an impression. If it does, F1 will have to take a long, hard look at whether wind tunnels really are necessary.
Try your hand at Virgin Racing’s interactive race engineering feature on the Motor Sport stand at Autosport International on January 13-16. For tickets to the NEC event, call 0844 581 1420 or go to www.theticketfactory.com/adonline.