The first part of McLaren’s 2022 Formula 1 season has been derailed by an unusual problem which initially emerged during testing in Bahrain in March and was not fully resolved until the Grand Prix upgrade package from Team Spain two months later.
The front brake overheating issues he suffered were the result of a “strange phenomenon” that prevented adequate cooling airflow from reaching the discs, according to technical director James Key.
McLaren introduced the definitive solution as part of its Barcelona package, with the carbon fiber brake cover replacing the rapidly produced titanium fairing that had seen it through early races. Gary Anderson explains the changes, which are pictured below, in full here. They worked well and resulted in a marked reduction in front brake temperatures.
Key described it as a “quirky” problem that took time to replicate in order to figure out how it should be solved.
“Basically it was a pressure imbalance in the system, which we hadn’t detected, either theoretically or in our repeated testing,” Key said when asked by The Race to explain the problem.
“You ended up with pressurization in the duct that was, at times, potentially greater than the flow in the duct.
“Actually, it either completely jammed or inverted, so you’re trying to cool the disc with very hot air.
“A really strange phenomenon, I don’t think any of us have seen it before. But you had to run a certain set of circumstances to see that, and we did that in CFDs in the end.
“Nothing is stacked up, none of it makes sense. When you looked at what was going on, it’s like ‘well, it all seems upside down’. It turns out that in these circumstances it was, so we replicated it.
“That’s really what led us to the design we have now to make sure we completely remove that issue.
“We have definitely added a few processes to our brake line development going forward. He was a real eccentric.
“And that’s really why we didn’t pick it up [in Barcelona testing] so well because this track does not encourage this particular set of circumstances. But Bahrain did.
Key also paid tribute to what he called a “heroic effort” to create an initial solution to the problem that was brought to the Bahrain Grand Prix.
While testing at Sakhir, McLaren made modifications on site and also flew new parts from its Woking base – including an early version of the titanium brake cover.
This alleviated the problem allowing him to improve his mileage each day with 50 laps on the first day, 60 on the second day and then 90 on the third day, but the car was not in a condition where it was possible to cover a distance race.
But Bahrain’s upgrade was a big enough step to allow Lando Norris and Daniel Ricciardo to finish the race, although by then the team had lost valuable time understanding their car during that she solved the problem.
“The developments we brought to Spain did what we expected of them,” Key said. “We were a bit cooler all around the front corner and everything went as we hoped.
“I have to say that the heroic effort of the whole team and everyone involved to get something that took us from about 10 laps to surviving five races welding together bits of titanium and making a new brake duct for the first race was outstanding, and it really served us well.
“It wasn’t as ‘Heath Robinson’ as it sounds, but it was kind of like that. The really quick turnaround kind of helped us understand the problem a bit.”
GARY ANDERSON SAYS…
With any cooling duct, you need the inlet to be at a higher pressure than the outlet. This is why the inlet to the radiator of an F1 car points forward and the outlet towards the rear.
This gives you airflow through the duct which then draws heat away from whatever is in it. Size and efficiency are dictated by how much heat you need to remove.
Looking back in time, I remember Patrick Head talking about one of his first attempts at ground effect and how it didn’t work as expected. Williams then discovered that the flow from the radiator was going in the opposite direction to that expected.
This is because the low pressure under the car was pulling the airflow into what should have been the outlet on top of the sidepods, through the radiator and around the leading edge of the floor under the car. So sometimes things don’t go as planned.
A radiator cooling system should be relatively simple, but a brake duct is not. It’s all so tightly integrated, especially now that teams aren’t allowed to run waste hot air through the wheel that everyone has to spin the same spec wheels and hubcaps. This could very easily be what led to McLaren’s miscalculations when defining the new brake cooling system.
Inside the wheel you must have the entrance and the exit. The inlet faces forward into the high pressure area where the airflow spills out of the front tire and the outlet is around the periphery of the rim to allow hot, worn air to sweep across the inner sidewall of the tire. To a very small extent this helps heat up the front tyre, this flow then being sucked into the low pressure behind the front tyre.
It is what happens between this entry and this exit that is complicated. The main cooling flow must be presented to the inside diameter of the disc. It should then flow through the drilled holes in the disc exiting at the discs outside diameter.
Some of the flux will be washed onto the disc faces and some of the flux will be transmitted onto the outer surface of the caliper and brake pads. If the pressure differential across any of these cooling requirements is not working as the simulation models indicate, then the flow could be going in the opposite direction or just not bother going there at all.
When we talk about efficiency, it’s about getting more with less and this is especially true of the airflow used to cool any part of the car.
It’s not just about installing a larger brake duct, it’s about getting it to work as intended. But as McLaren learned this year, it’s also very easy to stumble in an area as tricky as the brake duct.