Got your pass? Check. McLaren kit? Check. Okay, good, now switch off your phone and follow us through the glass doors and into the Paddock Performance Centre. Grab a coffee on your way in, and we’ll get started with our engineering briefing for the Mexico City Grand Prix.

We've been going to the Autódromo Hermanos Rodríguez for 60 years, and yet it remains one of the trickiest to set up for, making free practice crucial.

At more than 2285m above sea level, the Mexico City based circuit provides several hurdles for both driver and team, with the altitude affecting everything from downforce and cooling to the driver's breathing in the cockpit.

You'll have probably already seen this stat several times in the lead-up to the Mexico City Grand Prix – it was one of the Fifth Driver's most asked questions this week - without actually understanding the science behind it.

Explaining and simplifying that for you makes up a large chunk of this weekend's engineering briefing, which will be led by Cédric Michel-Grosjean. Take notes if you need them, but please keep them to yourself.

Engineer: Cédric Michel-Grosjean
Event: Mexican Grand Prix
Circuit: Autódromo Hermanos Rodríguez

Background

This week we have a re-run of the schedule for COTA, with another FP2 session extended to 90 minutes and given over to a Pirelli tyre test. This is to make-up for the session that had to be abandoned at Suzuka because of bad weather.

The change for this week is that we won’t be doing a young driver test in FP1. Lando and Daniel are going to be having a busy hour with lots of investigating. We’ll get another chance in FP3 but ideally, we would like to have settled on a set-up and configuration by then. Data gathering in FP1 is very important.

What do we want to find out? It’s all of the usual stuff – but with Mexico-specific tweaks.

Key points

1 | Tyre investigation

First on the list, as always, is a tyre investigation. We have the same tyre compounds as we had at COTA last week, with the C2, C3 and C4s. We’ll want to do low-fuel laps with DRS and then continuous laps to estimate tyre degradation. There isn’t much wear in Mexico, but thermal management is absolutely key because the tyres get very hot.

The ambient temperatures are never outrageous – but when the sun is out, because of the thin air, the track gets very warm. Add in the slow final sector with a lot of part-throttle and combined exits, and the rear tyres get very hot. They have to be managed during the race. How much management is something we have to study during practice.

Because of the test, we lose a set of Mediums and a set of Soft tyres from the standard allocation, so our plans for FP1 may be slightly different to usual. The tyres we take forward into qualifying is usually a choice between 5-1-1 and 4-2-1, so we’ll need good long-run data to make those decisions.

2 | Overtaking opportunities

Of course, we always want to qualify well, but in Mexico it is more significant than at a few other tracks. Overtaking can be difficult. While it has a long straight, it’s often very tough to generate a pace differential. Because tyre wear is low, there isn’t much gain from pitting for a new set as it won’t necessarily be much quicker.

The DRS has been extended on the main straight to try to combat this. DRS is powerful here, worth maybe 15-20km/h. Because we’re using the biggest rear wings, the flap has more authority. We’ll have to investigate what impact a longer DRS zone has on overtaking potential.

3 | High altitude

The altitude at the Autódromo Hermanos Rodríguez changes everything: cooling, downforce, ride-heights - the normal rules don't apply.

Mexico may well produce the highest speeds of the season, but counter-intuitively, we’re also running with maximum downforce. With air density decreased by almost 25 per cent compared to sea-level, you lose a lot of load. That makes for impressive numbers through the speed-trap but causes problems in the corners.

What we’ve seen in previous years is three-wheeling – or even two-wheeling – issues when the cars bounce around on exit, when the driver gets back on the power. Obviously, this is very damaging to the ride, and something we will want to investigate.

4 | Cooling

Another reason to want a good quali is that it will reduce the amount of following you have to do during the race. Cooling is difficult in Mexico because the lower air density that gives us less downforce also gives us less cooling performance. Following other cars reduces airflow. We’ll want to study that in practice and avoid it in the race.

To help with cooling, we have some new, looser bodywork to use this weekend. It’s common to run the car very ‘open’ in Mexico, to allow more airflow through the car in a way that we would usually reserve for the very hot ambient races.

Obviously, the larger bodywork comes with a drag penalty. If we can, we would like to run the tighter bodywork, which is more aerodynamically efficient – but we’ll start the weekend with the looser set, because that way we know we’ll be able to get through FP1 without overheating. And, as I say, getting a lot of data from this session is vital.

5 | Braking

It’s a tough track for braking, with lots of modulation on the pedal required. Turn One is very difficult. The approach is at high speed but the braking zone itself is quite small, and also quite bumpy. On a qualifying lap, the brakes will be cold here after the long straight, so drivers will need to learn and gain confidence during practice.

We have to run most of the apex kerbs in Mexico, so that means having a compliant car, especially in roll-stiffness. We’ll want to investigate this, and also things like skid wear, porpoising and so on.

Briefing complete. Time for Lando, Daniel and Alex to head out onto the track so we can collect some data and put our hard work to the test.

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