Welcome to The Briefing, where we’ll be answering the key on-track questions ahead of the Azerbaijan Grand Prix.

Each week, powered by Google Cloud, we’ll be speaking to one of our trackside experts to walk you through the biggest talking points and provide you with a simplified guide of what you’ll need to know to jump straight into the action. This week, ahead of FP1, we spoke to Henry Fidler.

The Baku City Circuit is very much a modern-day street circuit - wider and faster, but still requiring absolute precision and control. From an engineering point of view, there’s plenty to discuss, including the choice of rear-wing, with certain sections of the track best tackled with much less downforce than others. There will also be some big strategy decisions to make, with Pirelli switching up their compounds for the weekend.

With Henry's help, we’ll explain how the team will make these decisions and their potential implications.

Last year’s Azerbaijan Grand Prix was a one-stop race, but Pirelli have moved down a step this year with the C6 tyre. What impact is this going to have on the weekend?

This is the big question for practice in Baku! We’re particularly interested in learning how it performs on a Qualifying lap. Earlier this year, it was used at Imola, Monaco, and the Circuit Gilles Villeneuve. In Monaco, we definitely preferred the C6, but at Imola and in Canada, there were hints that the C5 Medium could be as quick, if not a bit quicker, than the C6 Soft.

It’s an interesting challenge in that there are a limited number of Medium tyre sets available. It’s very difficult to learn what you need to learn, if you want to have Mediums available for Qualifying and the race. A team might decide to go 3-2-2 (three Soft, two Medium, two Hard), but that means only using a single set of Mediums across the three practice sessions and five sets of Softs.

Beyond Qualifying, we’re also keen to learn as much as we can about the compounds to inform our race allocation. Last year, pretty much everyone ran a one-stop race with a C4 Medium and a C3 Hard tyre, and we don’t have the C3 this year. That moves the race into a grey area at the crossover between one and two stops. It might be possible to run a Medium>Hard one-stop, but a two-stop race may be quicker. One of the things we need to learn today is how viable this year’s C5 Medium is as a race tyre.

There is then sometimes a temptation to look at what other people are doing before making a decision on which tyres to use in a practice session – but the price of sitting in the garage is that you are taking laps off your high-fuels runs, and those are going to be crucial to understanding how to drive your tyre, and learning about graining, which was the limitation last year. It was bad in Baku because there aren’t any higher speed corners, and so there aren’t opportunities to really lean on the tyre and wear through the graining phase.

The tyres are a little bit different this year and tend to be a little more resistant to graining. The cars have also developed, sliding around a little less and making tyre management correspondingly a little easier. So, it isn’t a case of simply looking at 2024 performance. The tyres in 2025 may last a little longer.

At 2.2km, Baku has the longest full-throttle section of any F1 track. How does that impact the choice of rear wings?

If we only had a Qualifying session and no race in Baku, then we would probably run somewhere around the Spa [low] rear wing level for pure lap time. The problem is that it would likely put us a long way out of bed with our competitors in terms of straight-line speed – and it can be a very painful Sunday in Azerbaijan if you have too much drag on the car. Therefore, a Monza [ultra low] rear wing level is more likely to be competitive.

Are we expecting a similar sort of race to last time out at the Italian Grand Prix?

There are similarities to Monza: lots of straight-line content and big braking zones – but, if anything, Baku is a little more extreme in terms of heavy, straight-line braking, with big stops in T1, T3 and T15. It’s also a bumpier track, which sets it apart a little bit.

It also has the usual street circuit characteristics that Monza doesn’t have: there is a premium on grip, and the drivers have to have really good confidence in the car to maximise the track width and get close to the walls. There is a lot of lap-time to be found in having that confidence, and being able to control the line, which isn’t so critical at Monza.

Azerbaijan tends to be one of the races with the heaviest demand on the brakes. What are the issues at this track?

It is always difficult here, because the length of the straight means everyone opens the lap coming into a heavy braking zone with brakes that are stone-cold – and there’s very little you can do to fix that. The lap then switches to the other extreme with lots of braking points in quick succession, where the temperatures get pretty high, and you have to manage a brake-wear situation. This is exacerbated if you spend the race following another car.

These two things are not compatible, and changing the cooling package to help one is automatically going to make the other worse. The goal through practice is to find the best compromise. You can fit brake pad materials that are a little more hard-wearing, for instance, at the cost of slightly worse braking performance.

Finally, we’re into the final third of the season now. Are there any remaining upgrades to come, or has the MCL39 evolved into its final form?

There’s nothing new on the car this weekend. We are still learning though: there were new parts on the car in Monza and, based on our analysis after that race, there are some small opportunities in terms of our race pace and how we balance the car to investigate here. But the car is basically the car now, and we’ll be spending practice firmly focused on extracting the most out of it for Sunday’s race.

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