How the engineers will ready themselves for Bahrain
How does a Formula One team prepare for a Grand Prix at a track they have never even seen before? With the Bahrain International Circuit having only opened on March 17, there has been no chance for testing there ahead of this weekends race.
Renaults Pat Symonds (Executive Director of Engineering) and Denis Chevrier (Head of Engine Operations) explain how top engineers cope with the challenge of uncharted territory.
Pat Symonds: As a team, we relish the challenge presented by a new circuit. For drivers, it requires precious practice mileage to be spent looking for the nuances that can shave hundredths off the lap time. For the engineers, though, the challenges begin many months earlier with lap simulations: while it now takes just 40 seconds to simulate a lap on the computer, programming the sophisticated models behind this is a lengthier task.
Logically, the earlier one can start the process of informing the lap simulation, then the better prepared one is; however, this is not always easy. The starting point for a lap-time simulation is to obtain an accurate circuit map from which the trajectory of the car along the racing line can be described mathematically in three dimensions. Once the circuit configuration has been finalized, detailed maps are issued by the FIA, and work can begin. The boundaries of the tarmac are digitized, and fed into the first stage of the simulation programme, which uses mathematical 'cost' functions to determine the ideal racing line -this what a skilled driver does intuitively.
Once the racing line has been established, a car model with an 'average' set-up is introduced. From this, a variety of wing settings and gear ratios can be evaluated to get the basis of the set-up. Once this has been done, refinements are made to weight distribution and suspension settings in order to minimize the virtual laptime. Subsequently, the team can begin to look at energy requirements from the tyres, to help choose the appropriate compound, and at this stage brake energy requirements, and to some extent brake cooling requirements, can be calculated.
However scientific this may sound, though - as indeed it is - a number of 'imponderables' can lead to errors in the simulation, that often cannot be corrected until the circuit has been seen and, indeed, until the car has first run on it.
The first of these are the kerbs: where the simulation is only able to assume a driver will use the limits of the tarmac, in reality, they use kerbs wherever they can. If they are relatively smooth and low, they will be used to shortcut what had previously been the 'ideal' racing line.
Much more problematic, though, is the variation in grip levels: of the circuits raced on in 2003, grip levels varied by as much as 15%, and if one includes the early sessions at Monaco in the equation, this figure rises to 24%. Naturally, working 5000km from the circuit, we can do nothing but assume an average level of grip and work from there until further information is available. For Bahrain, however, we know the grip level to be similar to that at Silverstone, which is just 1% below the average. However, to put this into perspective, a 3% variation in grip level on an average circuit can bring a change in lap time of around 1 second and just to make things worse, this parameter varies continually, even during the same day. In order to insure against this, the team conducts numerous simulations at different grip levels in order to have a bank of data at their disposal in the event of changes, so that the appropriate car set-up can be decided upon as quickly as possible.
Once that has been completed, and the car is running, we then begin running more simulations for race strategy. In fact, before making our decision on Saturday, over 1,000,000 race scenarios will run through the team's computers!
Denis Chevrier: The only way for the engine men to approach a new circuit is via the computer simulations based upon the circuit layout. The main point to be defined in advance is the profile of engine usage around the lap, both in terms of the how much of the lap is spent at full throttle (between 55 and 60% of the lap here in Bahrain, an average figure), but also the single longest period of full throttle: we expect this to be around thirteen seconds, making Bahrain, on this level, the most demanding circuit of the season until we reach Montreal.
Upon arrival, our task will be to determine the physical characteristics of the circuit, and this will take a little longer than at those tracks we know well. We will examine the details of the different corners, such as kerbs, bumps, inclines and cambers in order to identify potential problems.
Our first runs will be important on a number of levels. The main objectives of the early sessions will be to choose the appropriate gear ratios, find the correct aerodynamic compromises and to quantify our cooling needs, and refine how we achieve this. This initial running data will also allow us to readjust our simulations, in order for it to be as accurate as possible in its analysis and predictions, and we will also compare different ways of using the engine through the corners.
One of the big worries is, of course, the potential risks of the engine ingesting sand. Internally, an engine cannot actually be reinforced against sand intake, so our approach will be to minimise any possible admission of this potential pollutant. This role is assumed by the filters in the intake system, but as always, the correct compromise must be found: increased filtration capacity carries a penalty in terms of performance, and we will study this compromise carefully for qualifying and the race.
In terms of our strategy on Friday, we do not expect a significant increase in our mileage simply because this is a new circuit. First of all, it remains relatively severe for the engines, as explained above. Secondly, some of the set-up changes required after initial running could prove more time-consuming than usual, limiting our ability to run extensively. And finally, it will no doubt be preferable not to rush out on Friday morning, as the prevailing conditions for tyre assessment will not be particularly reliable.
On this new circuit, though, the single engine regulations will place a premium on finding a baseline set-up quickly: anybody unable to do so may find themselves running outside their safety margins in terms of engine mileage, which could have consequences for reliability. We will aim to conduct an intelligent practice programme, completing a number of tasks in parallel in order to extract maximum value from our limited track time.