Rod Nelson, Chassis Race Engineer, Car 5
For the chassis, the dominant factor in Canada is braking: the car must slow from over 300 kph to 100 kph four times per lap. The circuit layout means that the only significant corners are taken at low speeds – all of the high speed turns are easily flat out. As a result, the set-up compromise is biased towards low downforce in order to get good top speeds on the straights – and as the braking energy increases as a square of an increase in speed, small variations in downforce levels can have a significant effect on top speed, and therefore brake energy.
The preoccupation with the brakes is not overheating, as we have long straights on which to cool them, but rather brake wear: the high amount of energy put through the braking system simply puts the discs and pads under extreme duress. There is very little the driver can do about this, as it is a function of the speed difference between top speed on the straights and minimum speed in the corners, so it is important for the teams to prepare as thoroughly as possible. Brake wear is measured in real time, so we can call on the driver to adjust the brake balance forwards or rearwards to equalise wear if necessary. However, this can also have consequences for the handling…
Set-up is a complex issue in Montreal. The low downforce levels inevitably make the car feel ‘light' to drive and mean the drivers must be more delicate with their inputs to the steering, throttle and braking. Braking stability is a particular concern, as heavy braking often locks the rear brakes, which has the additional effect of making the car nervous on turn-in. We adapt this characteristic in part by adjusting the brake bias towards the front, meaning more of the braking is done by the front discs and avoiding the risk of locking the rears.
In terms of the mechanical configuration of the car, traction is at a premium on this circuit. This means we run the car with a ‘forward mechanical bias' – essentially, the front suspension is stiff to enable a good change of direction in the chicanes and good turn-in, while the rear suspension is softer to once again aid braking stability, but also to help traction.
In terms of tyres, wear is not usually a problem – the compounds are relatively hard to withstand the longitudinal loads generated by the high speeds, while the track surface is not particularly abrasive, and rubbers in through the weekend. The absence of high speed corners mean the front tyres have quite an easy time, but the large number of traction events do mean the rear tyre have often in the past been the limiting factor – and will almost certainly be a key parameter this year.
Rémi Taffin, Engine Race Engineer, Car 5
For the V10, Montreal sets a simple challenge: the engine must be as powerful as possible. The succession of slow corners and hard acceleration found around the circuit means the engine is used in an ‘on/off' manner – the driver frequently runs through the sequence of braking, turning and re-accelerating at full throttle until the next corner, with little time spent at part throttle or in medium speed corners. The high percentage of the lap spent at full throttle, coupled with the long straight, mean the pistons are under particular strain.
A torquey engine is always a plus-point in Canada, as it allows the car to launch out of the slow corners when accompanied by good traction. Gear ratios must also be studied carefully in order to be able to optimise the torque curve of the V10 around the lap.
The final drive is also a critical parameter and must be adjusted with care. Not only must we leave enough margin for the powerful slipstreaming effects that can occur on the long straights where the cars run in tightly-bunched groups (as we saw Fernando doing in 2003) but the wind can also play a part down the main straight. Inevitably, we have to find a compromise between the optimum performance for qualifying, and race conditions where slipstreaming will come into play or when the wind might have changed direction.
Finally, we also leave some room for manoeuvre when it comes to engine cooling. Cut grass and greenery are often found on the track surface, which can block radiator ducts, while running in close proximity to a number of competitors can also have a negative impact on cooling, and must be anticipated.
