Mercedes’ 2015 challenger, the W06, was an exceptional Formula One car. The vehicle and driver combinations proved to be one, if not the most dominant in history. Watching the Silver Arrows dart off into the lead was a common occurrence, but in dirty air or following even lapped cars the W06 visibly suffered the greatest performance loss of all due to the aerodynamics’ high sensitivity to turbulent air flow coming off the cars in front. Looking at the almost impossibly complex front wing on the W06, it is not hard to see that some “dirty air” is going to be an issue for front aerodynamic grip.
In the past two years, but particularly in 2015 we’ve seen the field generally struggling to follow nose-to-tail, which has resulted in a lack of overtaking. This is why strategy has become more important recently. Last race in Abu Dhabi showcased Mercedes switching Hamilton onto a different strategy to give him a chance at passing Rosberg. They kept Hamilton out for 10 laps after Nico pit, and finally put Prime tyres on his car on lap 41. It didn’t work, but I was convinced it was the right idea, just imperfect execution, and decided to investigate and find the optimum strategy for the world champion.
Firstly, let’s take a look at the lap-times of the Mercedes’ races, starting with the champion and then Nico Rosberg. Also included are the forecasted lap-times as a result of factors such as fuel loss and tyre wear:
What is interesting with Hamilton’s race is that he suffers a great deal more tyre degradation on the option compound compared with Nico, but in the second stint on the prime compound tyre was able to overtake Vettel, close a 7-second gap to his team-mate and even set personal best lap-times after Nico had pitted. This same consistency didn’t show in the final stint, however, suffering traffic and being told to set seemingly unachievable lap-times put an end to the pursuit.
Nico Rosberg, on the other hand, had much better performance on the option tyre, which may explain his phenomenal qualifying lap. After just 7 laps into the first stint of the race he had a one second-per-lap advantage over Lewis. After calibrating the tyre wear into my Excel-made lap-time composer, the respective traffic-free races and tyre degradations for their individual races are as follows:
With this information the spreadsheet runs the lap-times for every possible pit lap and tyre strategy for one and two stop races (Using 470,000 cells per driver!) and the fastest strategies calculated are as follows:
| Tyre Strategy | Nico Rosberg | Lewis Hamilton | ||||
| First Pit Lap | Second Pit Lap | Total Race Time (seconds) | First Pit Lap | Second Pit Lap | Total Race Time (seconds) | |
| Option-Prime-Prime | 11 | 33 | 5907.5 | 11 | 34 | 5902.5 |
| Option-Prime-Option | 13 | 41 | 5909.2 | 13 | 42 | 5906.8 |
Now, Lewis could’ve pitted the lap after Nico and had a faster theoretical race time, but would’ve had only a small tyre advantage and most likely spend 20 laps trying to fight past an invisible shield (Rosberg’s dirty air). What Mercedes tried to do was maximise the tyre performance difference between Hamilton and Rosberg to give Lewis a shot at a last-lap attack. Nico Rosberg’s actual race-winning strategy was pitting on laps 10 and 31 which is 0.9 seconds slower in total according to the spreadsheet & his race was complete in 5918 seconds, which is 10 seconds slower than the forecast because yellow flags, traffic etc haven’t been considered.
The next graph shows Hamilton’s time gap to Rosberg vs the lap Hamilton makes his second pit stop for prime tyres on:
The larger the lap-time advantage Hamilton has, the greater the chance of passing Nico. Pitting on Lap 38 shows Lewis could catch up and be right on Nico’s gearbox at the start of the final lap, and with a performance advantage of 0.9 seconds. Whilst not guaranteeing the overtake, lap 38 instead of 41 would’ve been the optimum lap for Mercedes to pit Lewis.
But Mercedes could have put Hamilton onto supersoft tyres, surely? How would this have played out? Here’s how:
The problem was that Lewis began to lose nearly two seconds per lap to Nico by extending his middle stint and by the time he’d made the gap back up, his tyres would’ve lost performance. The supersofts were not working well for Lewis as shown in qualifying and the first stint. This shows that Mercedes were right to pit Hamilton for prime tyres as they did.
I hope you found this revealing. If you have another strategy you’d like to be analysed this season in hindsight, then please suggest it below.
