Ultimate test

7 min read

Europe’s monopoly of giant, rolling-road wind tunnels for automotive testing is about to be smashed by the mighty US motorsport industry. Max Glaskin reports.

Track testing has long been, and probably always will be, an essential tool in the motorsport industry’s quest for improved performance. Yet, in an ultra-competitive world where success is measured in fractions of a second and technical information is guarded more fiercely than anywhere outside the defence industry, motorsport teams are increasingly turning to the use of high-speed, rolling-road wind tunnels to test their vehicles and components.

The attractions of these systems are clear. They create the aerodynamic conditions of a car travelling at high speed without it having to move a centimetre and enable teams to measure their vehicles’ performance with even greater fidelity from the relative security of their own indoor facilities.

In addition to their obvious benefits these systems, which represent elaborate integrations of materials, mechanical, electronic and control technologies, are also engineering marvels in their own right.

The European motorsport industry has been quick to exploit their benefits, and Europe is now home to the world’s two most advanced full-scale, high-speed rolling-road wind tunnels.

One is owned and operated by the BMW Sauber team, at its Hinwil centre outside Zurich, Switzerland. The other is in the UK — at Honda’s F1 operations centre in Brackley, Northants.

Though the Honda F1 team has had a quiet couple of seasons, its rolling-road wind tunnel, which has been operating since the summer of 2006, is an impressive engineering achievement.

Effectively providing the racing team with an in-house test track, the facility has been designed to test a full-size RA106 racing car. Its giant 5.3m diameter fan, coupled with a rolling road that runs at 80m/sec, enables Honda’s engineers to subject vehicles to the equivalent of a 180mph whizz round the track.

But the European stranglehold on motorsport’s most impressive wind tunnels could be coming to an end. Somewhat belatedly, the US motorsport industry is waking up to the benefits of the technology and, predictably, plans to break new ground by building a series of wind tunnels that promise to be bigger and better than anything that has gone before. In Pole position is Windshear, a $40m (£20m) project being built in Concord, North Carolina that is expected to begin operation early this year.

Windshear’s rolling road will accommodate a single, full-size vehicle on its 3m x 9m belt, which can be accelerated from zero to 290km/h in less than one minute. It can decelerate from top speed to zero in less than 10 seconds. The surface is a continuous stainless steel belt 1mm thick, designed to last up to 5,000 operational hours. During testing, through-the-belt sensors measure the aerodynamic down force under each tyre. The whole machine is mounted on a turntable, so the direction of the wind can effectively be altered, and it has a yaw range of eight degrees.

The air flow will be provided by a fan 6.7m in diameter and rated at 3,800kW (5,100hp) to accelerate the air to 290km/h. It is capable of producing a maximum flow volume of 80 million litre/min. The air in the tunnel flows from the fan to the vehicle, then is collected and returned to the fan in a closed circuit that covers 15,000m2. It has a total power consumption of 7MW. ‘They’re pulling forward the construction of a substation next to the tunnel,’ said Jeff Bordner, site manager for Windshear.

Bordner has 17 years experience as an aerodynamicist at the Chrysler Corporation but has never had the opportunity to work on something as extraordinary as Windshear. ‘It is, without a doubt, the premium wind tunnel in North America,’ he said. ‘We can measure three forces and three moments — drag, lift, sideforce, rolling, pitching and yawing.

‘The belt rides on an air bearing and there are load cells underneath which we can float around and locate under the tyres. The vehicle is held in place by struts at the side and the back and which are being designed to have as low a profile as possible. We have a ride height actuation system we can program before the test that will allow us to move a vehicle through the dynamics of a specific racetrack to simulate cornering and acceleration.’

Windshear is due to open in the next few months and, uniquely, it will be available for hire by anyone, at a starting price of $4,500 an hour. Most wind tunnels are only open to the few organisations that have subscribed to them, or even to a single team.


Windshear’s rolling road can be accelerated from zero to 290km/h in less than one minute

However, Windshear is located less than 50 km along Interstate-85 from Charlotte, the centre of the world’s most successful motorsport, NASCAR, and its owner is Gene Haas, who has his own NASCAR team, Haas CNC Racing. Haas’s team will no doubt be making use of the new $40m facility but he is keeping the wind tunnel business at arms length. It is being built and operated by Jacobs Technology, which, in turn, has hired Bordner.

With the NASCAR economy worth an estimated $22bn a year, Bordner is aware that any team using Windshear requires the strictest security and confidentiality. ‘There are three secure preparation rooms to which only the customer on the day will have access,’ said Bordner. ‘As far as data collection and security goes, we were originally going to send all the data straight to the customer’s computer but their comments have prompted us to make a small change. We will now keep a copy of the data on our server. We’ll give them a set of data DVDs and, when they sign them off, we’ll remove all the data from our servers in a way which will be transparent so that the customer can verify the action.’

Bordner expects that initially Windshear will have enough customers to keep one 10 or 12-hour shift running each day, although the facility has the potential to operate continuously. Maintenance downtime will be scheduled. ‘We have a pretty detailed preventative maintenance schedule to avoid any unplanned downtime,’ he said.

While Windshear is expected to be the first full-scale, high-speed, rolling-road wind tunnel in North America, it is unlikely to have the field to itself for long. Barely 30km up the road, in Salisbury, North Carolina, another consortium has plans for something even bigger and better.

Wind Tunnel Extreme(WTX) is planned to be the most advanced such facility in the world, with the ability to have up to three cars on the rolling road at any one time.

Kristen Helsel leads the $70m development. ‘We’ve been planning it for about 18 months,’ said Helsel, a mechanical engineer who spent almost a decade with GM before setting up her own sports marketing business and running the Swift wind tunnel.

‘I travelled the world looking at the best wind tunnels and I discovered that the United States was woefully behind any type of offering that Europe and Japan had.

‘And so I realised there was this huge need for a wind tunnel of this kind, [not only] for racing but also for the automotive industry. Both industries are vital to the economy, so it is important for an instrument of this calibre to be available to various automotive companies and motorsports entities to have the ability to do this type of testing. It’s applicable not only to racing, but also corporate average fuel economy and things that are going to be pressing the car industry for years to come.’

The business model for WTX differs from Windshear’s. Helsel is recruiting members — raceteams and other automotive organisations — that will each be entitled to share in the tunnel’s operating time. She claims to have sold almost half of the time already.

Unusually, one member has revealed its identity — Toyota Racing Development (TRD). ‘Toyota and TRD plan to be part of the NASCAR community for a long, long time,’ said Lee White, senior vice-president and general manager of TRD USA. ‘We are building an engineering facility and technical centre in the Charlotte area to focus on chassis design, development and research.

‘However, another key component to the success of our NASCAR programme is the availability of wind-tunnel time. Our commitment to this programme should alleviate that issue and provide us with an exceptional facility to utilise.’

One remarkable factor that helped sway TRD was that WTX will be big enough to accommodate three cars at once, in line or offset by up to 50 per cent, to more closely simulate the situation on a racetrack. To achieve this, the test section of the tunnel will be 26m long by 5m wide and 2.6m high. The company has not released any specifications for the rolling road or the airflow system except that the latter will have walls whose profile can be changed to match the aerodynamic characteristics of the vehicle being tested.

As air blows over the vehicles, pressure sensors in the walls detect a pattern that would produce the ideal tunnel shape. Panels then move into the ideal shape to conform to the model’s airflow and eliminate aerodynamic interference in about one minute, to create a more accurate flow field around the car, eliminating pressure gradient through the length of the tunnel and allowing better calibration of sensors to track data.

Both Windshear and WTX are buying their rolling roads from MTS Systems Corporation of Minnesota, US. The global engineering testing company is the market leader for rolling roads of all sizes, claimed its marketing manager Jake Rawn. ‘As far as sales number go, we’re in the mid-teens right now for single belt systems and we’ve done three of the world’s five-belt systems,’ said Rawn. ‘The single belt provides a complete, unbroken moving ground plane while the five-belt has a belt under each wheel and another the length of the vehicle between the tyres.’

While each design has its benefits and shortcomings, WTX is investing in a proprietary MTS system called Talingz to remove the effect of the restraint struts from the total drag number. Talingz is said to allow the separation of rolling resistance from drag measurement in a full-scale configuration and provide a higher fidelity measurement of drag, yaw moment and side force than measuring through the struts.

WTX is scheduled to be fully operational in a year but by then it could have been overtaken by yet another rival. There are plans to add a full-scale, high-speed rolling road to the fourth largest wind tunnel in the world, inside the former NASA Langley wind tunnel in Hampton, Virginia. It may be almost 600km from the centre of the NASCAR industry but that does not deter Old Dominion University, which has been operating the tunnel since 2005.

According to the tunnel’s operator, a single-belt, rolling-road system from MTS, 7m long by 2.4m wide and capable of a top speed of 290km/h, is on its way by the end of this year, to be mounted on a turntable which has a yaw range of 10 degrees. The Engineer has tried to ascertain the status of the project but university representatives will not comment due to ‘political sensitivities’.

This reserve is characteristic of those involved in full-scale, high-speed rolling roads. ‘We’re still not releasing a lot of information about the guts of our technology, about how we track and steer the steel belt,’ said Jake Rawn of MTS. ‘It’s a bit of magic, an ability that’s been a core technology of MTS for 20 years.’

It’s a clever trick that Rawn believes will attract yet more customers as full-scale, high-speed rolling roads become an accepted part of the automotive landscape. ‘There’s not been a single motorsport entity that has built a rolling road without involving MTS since the late 1990s,’ said Rawn. ‘The market has grown recently in the US. In other areas of the world, Europe and Asia, we’ve seen them used by motorsports through to auto makers and component makers. It seems reasonable that we’ll see a similar trend in the US.’

Now that NASCAR teams are realising there’s more to track racing than top-quality showmanship, technology testing facilities will be in greater demand.