Renault's Pat Symonds (Chassis) and Denis Chevrier (Engine) look at Shanghai, and the unique challenge of racing on a 'virgin' circuit.
Pat Symonds
Racing on a new circuit remains one of the most appealing challenges for any F1 engineer, and when that circuit is both brand new, and in a new country, it merely adds to the enjoyment and the challenge. Of course, as we have discussed previously, our work begins with a simulation of the circuit, but beyond the mathematical perspective that such simulations provide, we also take a more generalised, subjective view.
For Shanghai, we have had our usual challenges of simulating the circuit using track maps that do not always have the required level of detail. Once we have established the general speeds of the corners, we begin to design a set-up aimed at achieving the best possible lap time but also giving us our best possibility of racing well. Looking at Shanghai, the circuit is dominated by two straights, one over a kilometre in length and the other around 600m - indicating that a competitive top speed will be an important factor to protect our position. However, there are also twelve corners, and many of them lead directly into one another - while also being surprisingly long for a modern circuit of this type.
Looking at circuit maps, it is clear that the characteristics of the lap vary as it progresses. The first part is full of slow corners, from the long, tightening turns at the end of the pit straight, to the relatively straightforward hairpin at turn 6. After this, though, we enter a much more challenging sector, with three left-right-left corners that are taken at sequentially decreasing speeds, and will certainly represent a significant part of the lap time. The drivers will need to find a flowing line through here. After this sequence, a short straight leads to a tight left, and then a very long right-hand corner that introduces the final sequence of the lap. This corner leads onto the main straight - which is over a kilometre long - and it will be important to get a good exit as the next corner, a tight Magny-Cours style hairpin, will be a good overtaking opportunity. This slow corner leads to another straight, followed by a medium-slow left-hander leading into the second long straight and the end of the lap. These different parts of the lap will prove a good all-round test of the cars' and drivers' abilities.
Their implications for car set-up are also tricky to assess. The circuit initially demands high downforce settings to give an optimum lap time, but the penalty in lap time for reducing downforce in order to gain straight-line speed is relatively low (what we call the 'aero profile' of the circuit is relatively flat), and this means that by the time we come to race day, I think the downforce settings are more likely to be termed 'medium downforce'. The circuit's sensitivity to engine power is very similar to that of Melbourne, that's to say in the bottom quarter of the circuits we visit but the fuel effect - the penalty in lap time for carrying a given quantity of fuel - will be quite high, largely due to the importance of the fast corners we mentioned earlier, and the average lap speed should be quicker than in Bahrain. Indeed, that circuit was also dominated by the issue of brake usage. Shanghai should be more normal in this respect, and the total braking energy is slightly below average. Equally, the long straights will give the brakes time to cool.
Looking at tyre usage, the total energy the tyres must absorb per lap is expected to be quite high. However, the race is only 56 laps - and we therefore anticipate tyre usage will be similar to the circuit such as the Nürburgring. The distribution of front/rear tyre usage should be relatively well balanced, but may be biased slightly rearwards owing to the fact that a number of the corners open out as the cars are under hard acceleration. This characteristic means that the balance of tyre usage shifts from front to rear as the cars go through the corner, which subjects the rear tyres to high lateral loadings as well as the traction demands. Equally, the acceleration out of the slower hairpins will place high stresses on the rear tyres.
The final factor to consider is the weather. The climate in Shanghai is a reasonably normal four season climate and by the end of September, we can probably expect to see maximum temperatures during the day of around 25°C. Being a port, Shanghai is obviously at sea level and therefore atmospheric pressure is normal, though the rainfall can be quite high. September is the month when the area moves out of its rainy season and while the average rainfall in October is 61mm, September sees 156 mm of rain, while we can expect to see 9 days during September with rainfall greater than 1mm. Any delay in this seasonal transition could mean changeable weather for the race weekend.
Of course, we must remember is that while such preparatory work is essential, it remains theoretical - reality can be quite different once grip levels are established, and the drivers know the lines they can take. The circuit looks to be a difficult one to learn, and we can expect a rapid evolution in lap times both as the grip levels increase and the drivers become more familiar with it. It appears to be a track where mistakes will be easy to make, and by Sunday evening, we could well view Shanghai as rather an interesting driver's circuit.
Denis Chevrier
For the engine team, preparation for a new Grand Prix such as the inaugural race in China begins on the dy namometer. Once a theoretical optimum racing line has been established using circuit maps and simulation tools, and once we have made our estimates of grip levels, we can then predict the duty cycle the engine will undergo at a given circuit. From this starting point, we run a simulation on the dyno in order to identify any defining characteristics that might potentially be troublesome for the engine.
