Simulating the Fuji track


Following the (well received) interview with Albert2, BMW explains how it has prepared for next week's race at Fuji.

On the weekend of 30th September the Formula One circus will stop off at Fuji in Japan – a race track where none of the current crop of F1 cars has so much as completed a lap. And yet by the Friday morning before the Japanese Grand Prix the set-up of the BMW Sauber F1 Team cars will already be very close to optimum. Advanced simulation programmes and the expansion of the team's computer capacity on the back of support from Intel have been key to making this possible. However, experience has also played a critical role.

In late 2006 the simulation experts at the BMW Sauber F1 Team received the data on the new Fuji circuit as a CAD (Computer Aided Design) file from the race organisers in Japan. On the basis of this data, one of the team's experts started by using a computer programme to establish the probable ideal line around the track. This process saw the circuit divided up into 500 to 800 segments through two stages. The radii for each individual segment were determined, allowing the experts to numerically define the ideal line.

The image of the circuit was then expanded to take on a further dimension, the engineers feeding the gradient profile of the race track into their computers. Inclines and downhill sections have a significant effect on the cars' speed – especially on long straights.

"In order to avoid losing precious time during the race weekend, we need to have as accurate as possible a picture of downforce levels, gearbox ratios and brake specification in advance," says Willy Rampf, Technical Director of the BMW Sauber F1 Team.

The engineers' next move is to define the car's mechanical set-up. First, they use values taken from comparable circuits to establish weight distribution. Then the spring and damper settings are finalised, once again on the basis of empirical values. As Rampf explains: "It is, of course, an advantage that the Fuji race is scheduled so late in the year. We have collected a wealth of data with the F1.07 over the course of the season that we can use here in Japan."

The next piece of technology thrown into the ring is the lap simulation software. This highly specialised computer programme has been developed by the BMW Sauber F1 Team engineers and allows the crew to simulate lap times. Here the team starts by testing the car – in virtual form, of course – with various levels of downforce. The car is set up with a certain configuration, and the programme calculates the lap time that this will deliver. In this way, the engineers can determine the optimum downforce for the new circuit.

A medium level of downforce has turned out to be the best compromise for Fuji. Another wave of numerous detailed wing settings will then be compared with one another shortly before the race in pursuit of further optimisation.

Now the focus shifts to working out the ideal gear spacing for the GP weekend. The top speed projected for Fuji – between 320 and 330 km/h on the long straights – prompts the engineers to set seventh gear first. This is followed by first gear. Here, an important consideration is whether first will only be used when pulling away from the start line or later in the lap as well. The remaining five gears are calculated on the basis of the engine's output curve.

The lap simulation software is able to deduce the wear on the brakes from the levels of downforce on the car and the characteristics of the track. In simple terms, the key is to discover if the brakes are subjected to high, medium or low loads. The experts use these results to select the materials for the brake discs and pads and to finalise the specification of the brake callipers. Simulation technology also helps the engineers to establish the amount of cooling air required by the brakes. Brake ventilation plays an important role in aerodynamic efficiency: the smaller the vents, the greater the downforce generated by the car.

Even the most sophisticated computer processes cannot provide an answer to two major unknowns: one is the grip offered by the asphalt of the track surface, the other the level of tyre wear. Over to Rampf: "It is only during practice after completing some long runs – i.e. ten laps or so at a time with both tyre compounds – that we see how the tyres actually behave out on the track."

This information provides the basis for the first strategy meeting of the race weekend, which takes place after the first two free practice sessions. Here, all the data collected so far is analysed and optimisation measures implemented. This data is also inputted into the strategy simulation programme, which uses the full breadth of information available to calculate all possible race strategies. It then shows the engineers – to the second – how fast a one, two or three-stop strategy would be. Adding to the team's deliberations are factors such as the weather forecast and track characteristics, which will dictate how difficult it is to overtake. These conclusions are then examined and any new information brought to the table in the subsequent strategy meetings which take place on the Saturday and before the race on the Sunday.

"Our aim is to ensure that the lap times and top speed calculated using the simulation software do not vary by more than one percent from the actual values," says Rampf, indicating just how precise these calculations can be.

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Published: 21/09/2007
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