October 1, 2007 The Windshear rolling-road wind tunnel in North Carolina will be one of the fastest and most advanced facilities in the world, and the only in America capable of 180mph (around 300kph) testing. The US$40 million complex will be an excellent resource for Formula One, NASCAR and most other racing teams – but interestingly, street-legal supercars like the Bugatti Veyron at the forefront of high-speed aerodynamic design still have nowhere to test their 250+mph models.

We’ve written before about the extreme effects aerodynamic design can produce on race cars operating at high speeds – past a certain velocity, the wind is such a powerful force that aeros actually become a more important factor in determining a car’s top speed than the engine power.

With his NASCAR team consistently running up to 180mph and beyond, team owner and CNC machine tool magnate Gene Haas decided to stump up US$40 million to build the only rolling-road wind tunnel in America capable of testing aerodynamics at simulated road speeds of up to 180mph.

The Windshear wind tunnel, still under construction in Concord, North Carolina, will join BMW’s Sauber facility and Audi's system as the only rolling-road wind tunnels capable of testing at these speeds.

Testing car aerodynamics on a static-floor wind tunnel doesn’t accurately recreate real-world pressure effects – but building a rolling road presents its own technical challenges. The ‘road’ in Windshear’s case is a 1mm-thick continuous steel belt. The horizontal surface is 10.5 feet wide by 29.5 feet long, allowing a wide range of vehicles, including Formula One cars, to be tested on it if necessary. This steel belt is designed to last up to 5,000 operational hours, or somewhere between 186,000 and 248,000 miles before it’s replaced. It will accelerate to top speed in a matter of around 10 seconds, and it can brake from 180 to 0 in a similar amount of time.

At top speed, the 22-foot diameter, 5100-horsepower main fan will force 2.85 million cubic feet past the car per minute, consuming around 7 megawatts of power in the process. The air is circulated through a vast closed-loop system that controls temperature against the tendency to heat up as it reaches high speeds.

Beneath each wheel, and beneath the rolling belt, are sensors measuring the downforce through each individual tyre, providing aerodynamic engineers with crucial information on where their designs are pushing down.

Once completed, the tunnel will open its doors to manufacturers and race teams for testing in what will eventually ramp-up into a 24-hour round-the-clock operation. Ironically, while race teams up to Formula One level will be well serviced by the device, 180mph is well short of the 250+mph some road supercars such as the Bugatti Veyron are now capable of.

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