Welcome to The Briefing, where you can get a jumpstart on the São Paulo Grand Prix with our guide to the key topics.

Every race weekend, we’ll speak to one of our engineers to discuss the key talking points ahead of the upcoming Grand Prix and simplify them so that you can dive straight into the action with a better idea of what to expect and what you should be looking out for.  

This week, powered by Google Cloud, Tom Stallard has joined us. He’ll be walking us through a busy Free Practice session, which will be followed by the return of the Sprint format. In this, he’ll walk us through the new parts we’ve brought with us, and explain the impact of Interlagos’ recently re-laid track surface and how this will affect tyre behaviour.

Here’s what we’ll be working on and what you need to know…

1. Learning a recently re-laid surface in only one practice session

The first thing to note this weekend is that there is a new surface – and it’s genuinely a new surface, put down this month, and so we’re the first series to use it. It looks super-black, lots of bitumen. It’s been treated with high-pressure water to get the oils out of it – but it’s tough to know how much has been done and how effective it has been.

It’s just an asphalt change, the kerbs and cambers are the same. I think the track character will be similar – hopefully with fewer bumps. The real question is what it will do with the tyres? That’s what we don’t know, and what we must discover in the one practice session.

2. Testing out new parts

In terms of aero, Oscar will get the upgrade this weekend that Lando ran in Mexico. So there’s a little bit of learning there. It’s not an enormous step, but it’s definitely still a step. We also have a new medium-downforce rear wing that will run on both cars in practice.

If that new medium-downforce wing continues into the weekend will depend on the weather. If the forecast of rain for Sunday becomes more certain, we may switch to a higher-downforce package, which would be similar to what we ran in Mexico. There’s currently a 60 per cent chance of rain for Sunday. The bitumen content of this new surface is going to make it very, very slippery in a wet race, so more downforce might be useful. The Sprint rules this year, however, will allow us to make a change after the Sprint, so we’re not locked into a decision taken today, ahead of Sprint Qualifying.

The plan for the moment is for both cars to try the new wing in practice, get that proved out, and then the higher-downforce wing might become an option if the weather forecast for Sunday becomes more certain.

It’s a difficult decision, there isn’t much between the options. The higher-downforce wing will be as quick, perhaps quicker, in Qualifying – but it may make life more challenging for overtaking and racing. We’ll have a better picture once the new wing has been on track.

3. We will be using different tyres than in previous years

In terms of a programme of experiments in the session, signing off the rear wing doesn’t involve adding anything to the run plan - we just have to use it. The key thing is to understand the tyre behaviour.

We’ve gone down a compound in the Pirelli range, compared to previous years, with the three softest compounds in the allocation for this year. It might be good – or there might be a lot of graining. We don’t know yet! Figuring out how much graining will be the top priority in practice.

This would have been a useful week to have three practice sessions – but it’s the same for everyone. The shape of the weekend is going to depend on how the C4 Medium copes. The Hard tyre will probably be okay – but if  the Medium grains, then even the Sprint will be challenging. If it doesn’t grain, it’ll likely perform very well. In the worst case scenario for graining, then you might see pit stops in the Sprint – which would be an interesting departure. That’s very unlikely – but not impossible.

Sprint Qualifying, you have to use a Medium in SQ1 and SQ2, so we need to know what the run plan on a Medium might look like. Is it a first-lap tyre? Can you do multiple laps? Does it need a double cool? What kind of out lap works best?

It’s tricky here because you drive slowly to the pit exit and then only really have the middle sector to energise the tyre. Not the easiest – particularly on a Medium, though it is a C4, which is the same as last year’s Soft – and challenging to get enough temperature in for this kind of asphalt.

4. We won’t have long to work out the right height for the car

As usual, we’d like to work on the ride height of the car, but with the time constraints on a Sprint weekend, we’ll probably only have one go at that. It is important: getting the ride heights into the right place is still the biggest performance opportunity from the car setup. Trying to minimise front and rear ride height, maximise the skid wear within legality, and possibly some level of stiffness optimisation are all things we would like to do.

If the circuit is smoother, as we expect, then we’ll adapt to that. One of the tricky jobs for a race engineer is how much do I bet it is smoother, and how much do I start with the setup that worked well last year, and then stiffen up if the opportunity presents? With a Sprint weekend, and just the one hour of practice, you’re a bit more biased towards taking a gamble.

On a normal weekend, we’d be a little more cautious and start with something very close to last year’s setup. There is a little bit of value in looking at what happened last time the track was resurfaced, in 2017. They did a good job then, so it’s easy to imagine they’d do a good job again. We’ve got some idea from walking the track – but there’s no substitute for getting the car fired-up and under way. 

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