Just what has gone wrong for Haas in the first half of this season? Sky Sports F1's Mark Hughes explains...
Friday 26 July 2019 08:14, UK
One of the most mystifying stories of this season has been that of the Haas team.
Its car has several times proved to be the 'best of the rest' in terms of qualifying pace but it invariably sinks quickly down towards the back of the field in the race, unable to generate and maintain the correct tyre temperatures.
This weekend in Hockenheim, it plans on repeating the back-to-back experiment foiled at Silverstone by the crash between the team's two drivers Romain Grosjean and Kevin Magnussen on the first lap of the race. In a desperate attempt to get to the root of the problem, one driver will be running the car as it was in the season opener in Melbourne (where it experienced no such problems and allowed Magnussen to finish a strong sixth) with the other in the car with all the subsequent developments.
Grosjean - in the Melbourne-spec car at Silverstone - reported that although the load sensors confirmed that the newer-spec car was generating more downforce, his older-spec version felt better, with more consistent rear-end stability.
The hope is that this weekend they can get enough laps completed in the race to find if this trait correlates with differences in the inability to generate tyre temperature. In which case they would at least have clues about the direction to work in solving the problem.
The thin-gauge Pirellis of this year - introduced to prevent the blistering that at some races last year was forcing drivers to lap well off the pace for much of the distance - have proven more difficult for teams to operate this year in general.
Ferrari, for example, struggled with them in parts of the early season (including, ironically, at Melbourne), as did Red Bull. But only Haas has consistently struggled with them for race after race and to such an extreme extent. The problem first reared its head in Bahrain, the race immediately after Melbourne, where Magnussen, having qualified sixth fastest right behind Max Verstappen's Red Bull, sunk without trace to finish 13th.
Getting the tyre working properly requires both its tread and its core (the bulk of the tyre inside) to reach the correct temperature. The 'bendiness' of the rubber is a key part to the mechanism of a tyre's grip.
If it's too cold, the rubber remains too rigid. Too hot and it becomes too liquid-like to support the loads. The loads generated by the tread being at the right temperature transfer to the core and that constant loading should then bring the core up to the correct temperature, which in then supporting the tread prevents the tread from overheating. If the core remains too cold, the tread will not be able to maintain the optimum temperature for any extended period.
Team boss Gunther Steiner explained earlier in the season how that manifests: "You go into the graining phase, and then when we go into the graining phase we cannot get out of it anymore because our tyre then gets too cold and then we are done. Then we slide around.
"We've got four or five laps, we go fast, then the graining starts to go and then other people recover after the graining but we don't, because our temperature is too low and we just cannot get it to work anymore once the graining clears."
The tyre is effectively an energy store and as its tread is squeezed between the tiny gaps in the track surface's asphalt, so that stored energy is then released as grip. With the thinner-gauge tyres there is less rubber there to be forced into the gaps, hence extra downforce becomes even more important.
When working as it should, the Haas has typically been strong in fast, flowing corners but less so in slower sections. It may be that it loses too much temperature in those slow sections, with insufficient downforce to really work the core, especially when the car is heavily-fuelled and overcoming the tread's ability to hang on to that track surface.
It may be that the suspension geometry is not applying the aerodynamic loads in the way the tyre needs.
But where the big teams have specific tyre departments of 20 people or more, the tiny Haas team (the smallest of all the teams) only recently expanded this department from one man!
The problem is an unfortunate combination of a very tricky tyre exposing a weakness of the team's unique structure.
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