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How does an F1 team approach the challenges of a new circuit? Engineering Director Pat Symonds explains how simulations work… and why they don’t!
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 Malaysia, which is just 2% 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!
FOR THE RECORD..
the lap times were predicted to be in the 1min. 30s
DEAD ON ! | 
2nd April 2004, 23:55
