Finding the perfect car set-up for Barcelonas Circuit de Catalunya 06 May 2005
Fernando Alonsos Renault R25 is going to have to perform at its very best if the Spaniard is to score a much-prized home win on Sunday. His race engineers, Rod Nelson (chassis) and Remi Taffin (engine) explain the technical requirements for achieving a fast lap around the highly challenging Spanish Grand Prix circuit.
Rod Nelson: Barcelona's many high speed corners make it one of the most sensitive circuits to aerodynamic performance of the year - indeed, with the aerodynamics making up such a large part of vehicle performance in modern F1, this explains why the circuit is considered a good measure of how quick a car is straight out of the box' when it first runs.
The circuit is a mixture of all types of corners, and includes two long straights. In terms of downforce, we run high levels at this circuit as both long straights are preceded by high speed corners. This means that the key to good straight-line speed is not lowering drag by taking wing off; instead, you need reasonably high levels of downforce in order to get through these corners quickly, as they condition your speed down the straights that follow. It almost goes without saying that, with high speed corners leading onto fast straights, overtaking is extremely difficult.
Mechanically, the car demands a number of compromises in terms of how we adjust the springing and ride heights. The car's basic ride around the circuit has been much improved by the resurfacing of the circuit over the winter, and the re-profiling of turn 10 early last year; the first change has eliminated a large bump on the start-finish straight that used to prevent us from running lower ride heights, while the new profile of turn 10 has removed the unsettling washboard effect in the track surface that used to disturb the cars. However, in terms of the suspension, we must stiffen the front end in order to achieve a quick change of direction through turns 1-2 and 7-8, while the rear of the car is sprung slightly softer in order to help traction out of the slower corners.
The final key parameter in vehicle performance over the race weekend is tyre management. The long corners mean tyre energies - essentially, the work the tyre is doing - are very high, which increases tyre wear, a critical factor under the 2005 regulations. The high speed corners particularly cause high front tyre wear, and the fact that they are all right-handers means that the left front is the most heavily loaded tyre. Our main set-up tool for controlling wear rates is the level of camber we run, and this will be something we study closely during practice in order to find the correct compromise between performance and durability.
Remi Taffin: Although Barcelona is a circuit that all the teams know well from testing, and with whose problems we are familiar, the higher temperatures and change in grip levels relative to testing mean that we must always re-calibrate our control systems for the GP weekend. Furthermore, as we will be running the new B spec RS25 for the first time with both cars, we will also have to conduct validations on the engine mapping.
Overall, though, Barcelona is not an engine track - it is a place where aerodynamic performance rules, and the engine is not repeatedly called upon to accelerate at full throttle from low revs. Indeed, the drivers spend just 58% of the lap at full throttle, some 4% less than at Imola. However, the engine does need to be flexible because the quick corners mean the engine is often accelerating from the middle of the rev range - and we need power delivery to be as progressive as possible, both to maintain the car's stability through the corners and because a less brutal application of power and torque will help conserve the tyres. Of course, the traction control system also plays a fundamental role in this domain.
Selection of gear ratios is also a delicate business at Barcelona, particularly in the choice of top gear. With such a long main straight, the engine is at maximum revs for a long time, and we therefore need to leave a margin in order to aid reliability, and also to avoid over-revving in the event that a tailwind is blowing down the straight; of course, these extra revs are also needed for overtaking purposes, although the configuration of the circuit makes these rare.
Finally, the 2005 engine regulations may play a significant part in how the weekend unfolds. Fernando will begin the weekend with a new engine, and as Barcelona is the first half of a pair with Monaco, the least demanding circuit for the engine, we will be able to exploit a significant part of the performance potential over the weekend in Spain - both in terms of mileage and performance.