Tech Analysis | How did Mercedes outperform Ferrari in Las Vegas?

Low temperature and smooth asphalt, the perfect combo for the W15 

Since the beginning of the season, the W15 has always been characterised by a having a small operating window. This means that the car operates well in a very narrow range, made for weather conditions, circuit layout, asphalt abrasiveness and smoothness. 

As a direct consequence of all these factors, it was always extremely difficult for the engineers to find the right setup for the car that fits into this tiny window, making the W15 virtually undriveable for most races. However, when everything was aligned and the car entered this “magical” state, then the W15 worked really well, producing a good amount of downforce from the Venturi channels while still being quick on the straights. 

The interesting aspect about this car is that, with 22 out of 24 races completed, the Brackely team’s engineers haven’t understood how to find the perfect setup that can make the it quick at every circuit yet. Even though this sounds very unlikely, these ground-effect cars are very difficult to understand and even more difficult to tune on complicated layouts (like Interlagos os Spa). Russell himself pointed this aspect out during the usual post race interviews on Saturday night: “I'd love to tell you to be honest. It's been a real surprise for all of us and it's something we need to to really review, because this is an outlier circuit. We haven't done anything out of the autumn reef specifically for Vegas, but for whatever reason, the conditions, the layout is playing in our favour.”

For this reason, during the season it happened quite often that the team experimented with a lot of different setups (both from the mechanical point of view and the aerodynamical side) during Friday’s free practice sessions, to try to find the right balance. Most of the times, they ended up choosing a slightly lower level of downforce than they competitors, resulting in sometimes a very good performance in qualifying followed then by a disappointing result in the race. 

In Silverstone, Spa and Las Vegas, the three races dominated by Mercedes, the weather and the layout matched with the W15 congenital characteristics: a very quick car on the straights and a single-seater that works really well when the temperatures are low.  

During the past weekend, the team made quite an unexpected decision after Friday’s practice sessions: Since the W15 looked very competitive in qualifying simulations but teared the tyres apart over the race pace simulations, the engineers decided to increase the angle of incidence of both wings and lower even more the car (knowing that the track was very smooth) to increase the amount of downforce generated by the W15. 

This decision changed the balance between qualifying and race pace performance: on Saturday the car seemed less dominant, despite still managing to take pole position (and it never looked like any other car could spoil their party), but the real surprise emerged during the first stint on Saturday’s race. Even though a lot of people expected Ferrari to be the favourite for the race win, Mercedes’ decision to increase the aerodynamic load allowed the W15 to put the medium tyres into the right window way quicker than other cars and make them last longer than everyone else, without having any tyre deg. 

This ability really played a crucial role, as it allowed Russell to open a 10-second gap to Verstappen in P2 before the stop, giving him the advantage to then manage this gao for the rest of the race, without having to worry about anyone else. 

The real superiority, in terms of pace, was also showed by Lewis Hamilton: after starting from P10 because of mistakes in Q3, he was able to come back quite easily during the race and almost catching Russell during the last 15 laps of the race. His race pace was the proof that Mercedes were really unreachable this weekend and both Russell and Hamilton took advantage of the superiority of their car to bring home an unexpected 1-2 for the team. 

Hamilton himself confirmed his great feelings in the car during the post race interview: “I had a great time. When you're progressing and moving forward, it's always a great feeling, but it felt very much like my old days at Rye House, like starting at the back and coming through, so it was great.”

Ferrari: How the first stint on mediums sunk any chance of victory 

Ferrari arrived in Las Vegas with the idea of scoring a 1-2 and gain a lot of points on McLaren, as the Woking-based team didn’t look particularly strong this weekend. However, since Thursday both drivers were “scared” by two factors: the low temperature and the very smooth asphalt. Leclerc pointed out that: “We know that we are better on tyres, that we are less aggressive on them, which means that the temperature builds up a little bit slower. And on a track like this, where tyre warm-up is going to be an issue, it was an issue for everybody last year, I expect it to be a bit more of an issue this year.” 

His words were proved by the fact that, during last weekend, the tyre warm-up was a critical phase for every team (except for Mercedes): if the tyres were put under too much stress during the first few laps, then the graining started to form and the tyre life, as well as the performance they offered, dropped massively, resulting in a needed pit stop as soon as possible. 

Graining, in fact, occurs when the tyre surface temperature heats up while the bulk of the tyre is cooler. As the car turns into a corner, the upper hotter rubber tears and slides along the surface of the tyre. The result of the sliding is consequently a loss of grip, which results in slower lap times. Graining generally occurs on the front tyres, which are more difficult to heat up on stop-and-go circuits when temperature is cool. 

Having said that, the SF-24 struggled a lot with tyre warm-up both during qualifying and during the race this weekend: as Leclerc said, in order to keep the tyres alive throughout a race stint, Ferrari’s engineers decided during the designing phase, during the winter, that the car had to be less aggressive on the tyres, which resulted in a series of struggles in qualifying this season. In Las Vegas in particular, this factor made the SF-24 very slow in the first sector (since from tyres were still cold) and a way better performance in Sectors 2 and 3 in qualifying. 

The race pace performance was expected to be way better, as what dashed away any hope of victory for the Scuderia was the first stint on the mediums. On the one hand, Leclerc tried to push a little bit more in the first few laps to keep in contact with Russell and tried to pass him on lap 4. After that his tyres started graining and consequently lost huge chunks of time before pitting on Lap 8. On the other hand, Sainz experienced a very early tyre degredation too, despite being a couple of seconds behind the duo Russell-Leclerc and despite using the medium in a very slow and correct way. 

This struggle was mainly caused by the very not rubbered up asphalt and the low grip available, as well as the set-up choice from Ferrari’s engineers. Ferrari, in fact, opted for a less loaded set-up (in terms of wings) than Mercedes, hoping that the track evolution would have helped them in terms of grip (if the track ramps up session after session and offers more grip, even if a car has less downforce it can still be very quick thanks to the more grip available). However, this didn’t happened during the first stint, when the track was still too slippery and the tyres couldn’t heat up correctly, graining very shortly after the start of the race. 

The situation drastically improved as the race went by and as hard tyres were fitted on both SF-24: the harder compound, matched with a more evolved track, allowed the less loaded Ferrari to come alive and make competitive lap times. This wasn’t enough to catch up the Mercedes, but the Scuderia maximised the points in a day where McLaren really underperformed. 

This said, the next round in Qatar should be a difficult track for both Ferrari and Mercedes for different reasons: Mercedes will probably suffer the warm conditions, which could generate a lot of degredation on both front and rear tyres, while Ferrari will suffer from the long and high-speed corners, which have never been one of  the SF-24 strengths during this season. However, we just have to wait a few days to see whether these predictions will be confirmed or denied on track this weekend.

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