Melbourne : Keeping brakes cool

When the refuelling ban was first announced for 2010, one of the main concerns was how to make sure brakes could last a Grand Prix distance. A full tank of fuel adds around 150 kg of weight to the car, and it requires considerably more energy to slow down that extra weight. It seemed that the brakes would be in for a tough time in 2010.

However, following the Bahrain Grand Prix there were hardly any complaints at all. Renault’s Chief Engineer, Alan Permane, even declared that the brake wear on the R30 was less than on the R29 during the 2009 race. “The guys in the factory have done a fantastic job with our braking solution,” he said. “The race was a breeze for the brakes.”

So what’s been done to make this possible? Well, there have been no changes to the actual discs because the regulations remain unchanged and only allow a maximum thickness of 28mm. A materials development programme has been conducted to improve longevity, but making the brakes last the distance all comes down to proper cooling, as Head of Performance Systems Group, Nick Chester, explains:

“We did a lot of simulation work to understand the extra demands on brakes, which confirmed that there would be 10% more energy going through the brake system this year. That gave us an idea of the cooling requirements needed from our brake ducts to keep the disc temperatures in a comfortable operating window.”

Controlling disc temperatures really is the key to good brake management because wear is determined by temperature. But it’s a non-linear relationship and wear rates jump steeply once the discs get above 600°C. So the brake ducts need to keep temperatures somewhere between 500°C and 600°C across the race distance.

“The job of the brakes ducts this year is even more important,” explains Nick. “Our designs have been done primarily using CFD (Computational Fluid Dynamics) and we’re getting a lot more air through the system compared with last year. It’s not just the size of the entrance to the duct that’s important, but the path the air takes through the upright, the disc and out of the disc vent, which determines how much air is in the system and the efficiency of the cooling. The positive results from Bahrain suggest we are well prepared for all the circuits this year.”

Like any part of the car, the brake ducts remain under constant scrutiny because they also have a significant impact on the car’s aerodynamic performance. “We have more developments planned for the ducts across the year,” says Nick. “Some of the tracks that are not so tough on brake wear will allow us to focus less on cooling so that the ducts can add a bit more downforce to the car.”