PACE DEBRIEF: How Mercedes' wing change affected their speed between sprint and qualifying
Mercedes have been unsure about their correct downforce level ahead of the Miami GP weekend, which meant that they needed to carry out experiments before committing themselves to a lower downforce rear wing for the rest of the event. F1Technical's senior writer Balázs Szabó analyses Mercedes's change of approach.
Mercedes have endured a very difficult weekend so far in Miami. Although the sole one-hour practice indicated that the team might display an impressive performance around the 5.4km Miami International Autodrome, the sprint shootout quickly delivered a clear picture of the pecking order.
Both Lewis Hamilton and George Russell were knocked out in the second segment of the sprint shootout, and they failed to make progress in the 100km dash for different reasons.
The lack of speed in the shootout was down to the fact that Mercedes drivers were unable to get the medium tyres into the right temperature window which has turned out to be a costly issue as drivers are restricted to the yellow-walled tyres in SQ1 and SQ2.
In fact, Mercedes expected their W15 to offer more speed in qualifying trim after the impressive qualifying simulation in the sole one-hour practice on Friday morning. The team was so confident about their one-lap pace that they based their downforce configuration on those encouraging soft-tyre hot laps in FP1.
The Brackley-based team's engineers elected to define the setup of the car around the high downforce rear wing which was a different choice to what Red Bull, Ferrari and Mercedes pursued.
However, with Hamilton and Russell qualifying down in P11 and P12, the choice turned out to be the wrong one as the two drivers were unable to progress in the sprint. Hamilton had access to DRS in the last 15 laps of the 19-lap race, and achieved an average top speed of 339kph compared to his direct rivals, whose average was slightly over 343 kph.
Commenting on Mercedes' wing level choice, Andrew Shovlin added: "We knew we were on a high wing level and that would have been OK if we'd qualified further forward. Unfortunately, when you are racing in the middle of the pack, it isn't ideal."
With the new parc ferme rules for sprint weekends allowing tweaks to the setup between the sprint and the main qualifying, Mercedes did not hesitate to switch to a lowe-downforce rear wing.
The different downforce configuration has altered the behaviour of the W15. Hamilton was extremely quick in Sector 1 in the sprint shootout, having been only 206 thousands of a second slower than the benchmark in Sector 1. By contrast, he was a further tenth of a second adrift of the best time with the lower-downforce rear wing in the opening section of the track which is mainly defined by medium- and high-speed corners.
However, he gained a huge amount of time in Sector 2 which features an extremely long full-throttle section. He lost half a second in the sprint shootout to the benchmark in Sector2, but this loss melted to just two tenths of a second with the lower downforce setting.
There was not much difference in the final sector with the loss having been around two tenths of a second in both sessions, albeit it was fractionally smaller with the lower-downforce rear assembly.
Expanding on the team's change to the aerodynamic setup Shovlin said: "Going into Qualifying, we modified the set-up slightly and changed our wing level. The car was improved but it was still difficult to land the tyres in the right window.
"We don't seem to be the only team struggling with that but when we got it right, the pace was strong. That said, we are well aware that we have a lot of work to do in order to improve the car. If we can do so, that should help us deliver that stronger pace more consistently."
