Ultimate test

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.