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GP SOCHI: race analysis

Articolo di  @spontonc e di @smilextech - Traduzione di  Alessandra Migale (@ Aycienta_44)

Bottas overcame the challenge: after four Grand Prix with Mercedes he won the Russian GP. Why was it a hard task? Because last Sunday the W08, even if it has improved since Bahrain, has been inferior to the excellent Ferrari SF70H.

RUSSIAN GP: a not so aggressive Vettel and the waking effect favored the excellent start of Bottas
 The men of Mercedes already knew after Friday's long run tests that the only possibility to beat the reds was to pass them in turn 2 (at least with one of the two cars). On the circuit of Sochi the start has always been crucial as the overtaking chances are minimal. A quite boring race, with no overtakings and with no one inside the top teams that opted for a two-stop strategy. Too constant was the UltraSoft compound on a smooth and unattractive track like the Russian one. Hulkenberg ran over 2/3 of the race with the softest compound. We do not like it; it is true that drivers can now push for longer races, but why at this point not changing everything, by eliminating the annoying rule of the two compulsory compounds, giving to teams the opportunity to choose the tyres to use at every race?

Coming back to the race analysis, the long straight that leads to turn 2 has been for sure an advantage for those who started from behind, mainly Bottas who was starting from the clean side of the track. He in fact exploited, after the restart caused by the unreliability of the Mclaren-Honda of Alonso, the excellent starting system of Mercedes, factor that last year caused many problems to the German team. We have also to consider the superiority of the Power Unit Mercedes in the first meters (ensured by the so called "magic button"), and the lower drag of the W08 which allows to have higher top speeds than the SF70H

There are also other things to point out about the start of the Grand Prix: the wake that the cars could have exploited and the imperfect getaway of Vettel. In our opinion the German driver of Ferrari has made two mistakes: an anticipated shift gear and a too conservative approach when Bottas went side-by-side to overtake him. If Vettel had been more aggressive, only by slightly squeezing the Mercedes' driver to the left, Bottas should have for sure slow down, perhaps losing also the position on Raikkonen who arrived in turn 2 not so far from his teammate by exploiting the wake effect. So, the wake effect: on a main straight like the one of Sochi this effect allows drivers behind to gain more or less two cars and a half. This factor has therefore played in favor of Bottas. If, as said above, Vettel had been less conservative he would definitely have won his third GP of the season. If in Bahrain a substantial part of the final win has been constructed upon the good start of the Ferrari's driver (aggressive overtake on Hamilton in turn 1), in Russia things went not so well. This is racing.

For those who do not read regularly our website, we remind that Ferrari introduced during the weekend a wing with less downforce than those already used, coupled with a double monkey seat. They also decided to install a new turbocharger in order to solve some problems of reliability that occurred during the winter tests and the first races of the season. The men who work everyday in Ferrari know it: with a substantial step forward in the aerodynamic efficiency, the championship would be within reach. The SF70H still pays too much drag with respect to Mercedes. This can have important consequences on the Power Unit (a more aggressive use of it can cause some reliability problems). The new car of the Italian team generates the greatest extent of downforce from the wings, paying this choice with an increase in drag, while Mercedes is able to generate downforce from the body of the car, paying less in terms of drag. It is not thus the Power Unit, mainly during the race, that is responsible of the difference in pure speed between the SF70H and the W08. By using extreme setups, Ferrari is however able to reach good top speeds on the straights thanks also to a flexible bottom. These values are however still inferior to those of the W08 that, to the same extent, is able to adopt a neutral setup on the straights thanks only to a soft adjustment on the suspensions, given a less emphasized rake.

RUSSIAN GP: the analysis of the first stint 
The first stint of the race is the one which actually decided the race after a so-so start for the two Ferraris. And in this 1st stint some factors played a crucial role. First of all, a Mercedes that worked very much on Friday in trying to set the first part of the race, the less favorable for the W08 in the first races of this season. Mercedes that with a high quantity of fuel has always struggled on the rear tyres. These problems, caused by an incorrect warm up of the soft compounds unlike the hard ones, were accentuated by a setup that was chosen to make the tyres work better on short stints (for instance, the Quali) and that distributed more weight on the front rather than on the rear. This problem was solved before the weekend in Sochi (weight moved on the rear), and in fact penalized the W08 in Quali but bore fruits in the first part of the race. First stint in which Bottas made the difference also thanks to some defects on both the SF70H. Defects that concerned the correct cooling of the Power Unit. During the first twenty laps, both drivers has been forced to drive with a weakened engine to avoid serious issues. This fact allowed Bottas to gain much time in the first sector and to reduce the gap accused over the weekend in the S2 and S3.  

Analyzing the graph below, Bottas has been constantly quicker than the SF70H until lap 20. After having solved the problems of overheating, mainly caused by the fact that both Ferraris were close to other cars, Vettel has been able to increase his speed and reduce the gap from the leader. In this phase of the race, both Ferrari and Mercedes suffered of blistering on the left-front tyre. This problem occurs when a part of the tyre overheats abnormally and generates small bubbles inside it. This consequently produces some detachments that can have different areas according to the level of heating and mechanical stress at which they are subjected. The bubbles become then real holes that can turn out to be very deep. According to Pirelli this problem was due mainly to the long turn 3.

But Ferrari, especially Vettel, has not been so much affected by this problem while Bottas, lap after lap,worsened his times. Even by analyzing the tendency line we see how the one of Bottas at a certain point suddenly rises while the one of Vettel tends even to decrease, thanks also to the fact that the German driver did not manage to exploit the UltraSofts properly during the first laps.

Looking at the pace of the 4 top drivers, we can see that Vettel and Bottas had a quite similar rhythm. Raikkonen was 2 tenths slower. 4 tenths slower Hamilton who, in this first stint, had some problems of overheating to the Power Unit, such those of Vettel and Raikkonen. The electronics of the Power Unit Mercedes cut the cylinders according to the temperature detected by the sensors, lowering so power and torque. In addition to this the English driver during Quali damaged the flat bottom of his car on a curb, worsening so his performance.

RUSSIAN GP: why did Ferrari choose to avoid the undercut on Valtteri Bottas?
The answer is in our opinion pretty simple: Ferrari never had a real chance of doing an undercut on Bottas. The gap has always been greater than 2 seconds (that is the gap needed to anticipate the pit stop). Mercedes, having for this reason the gap to protect the position, anticipated the pit stop of Ferrari also because the Finnish driver should have overtaken some lapped drivers within few laps. This fact could have damaged Bottas, making him slow down and favoring the Ferrari of Sebastian Vettel and his undercut. Perfect the strategy of Mercedes but perfect at the same time the strategy of Ferrari, that opted for leaving Vettel on track for more laps seeing that the performance of the UltraSofts was not getting worse and mainly seeing that Bottas was struggling on SuperSofts.

RUSSIAN GP: the analysis of the 2nd stint  
In the 2nd part of the race, on SuperSofts, the two SF70H were the fastest on track. Vettel gained the advantage of having newer tyres than the other drivers, thanks to a longer 1st stint (only Hulkenberg ran for more than 40 laps on UltraSofts).

Raikkonen was faster than Bottas of almost 1 tenth while Hamilton, on these tyres,  suffered more than during the 1st stint. Bottas, even if slower than Vettel, has been able to manage in the best way possible the advantage making only one error: the lockup in turn 13. Notwithstanding this, he held off a Sebastian Vettel who has never managed to put pressure on him finishing the race at 6 tenths. A Mercedes that seemed to struggle a bit more on SuperSofts that is the only compound which has been substantially modified from last season. The reason why Mercedes had some difficulties on these tyres is to be found in the cooler track temperature, a negative factor for the German team with the chosen setup and in the fact that this compound needs few degrees more than the UltraSoft to work properly. In addition to this, Bottas and Hamilton had troubles in keeping at a steady temperature the rear of their cars  because of the low quantity of fuel at that point of the race. Due to relevant changes in the setup and to the different characteristics of the tarmac of the track, the conditions in which Mercedes went faster than Ferrari totally reversed. This gives us an idea of the bulk of work that the technicians of the German team have to do to find the correct balance between the two situations and giving to the W08 the possibility to express its full potential. And the update that will be brought at the Spanish GP goes in this direction: trying to make the W08 a car whose balance is simple to find.

RUSSIAN GP: positive or negative race for Ferrari?
The overall picture could be seen from different perspectives. Positive because Vettel increased his advantage on Hamilton in the drivers’ standing. Negative because, after the front-row lockout of Saturday, all the fans expected a win. If Vettel had been more aggressive and a little bit quicker in the shift gear at the start, the win would have been much more easier given that the cooling problems of the car probably would have not occurred.  

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