Interesting article on http://f1.racing-live.com/en/headlines/news/detail/050608101433.shtml about the brakes and how they use the throttle to control engine braking etc... The whole braking process is complicated further by the laws of aerodynamics. When the driver first applies the brakes at very high speeds, the downforce generated by the car prevents the wheels from locking up, by pressing the wheels down onto the track, As the speed decreases so too does the downforce and therefore the amount of grip from the tyres. But this lack of grip coincides with the point at which the brakes are fully up to temperature and are working most effectively. This means that, when the brakes are at their best, the car is least able to transmit the braking forces to the road thus leading to locking wheels and the chance of skidding off the road. In order to prevent this phenomenon, the cars can harness the braking characteristics of the engine. All 4-stroke engines produce engine braking when a driver lifts off the throttle, but F1 engineers can harness this ability to meet the specific needs of any braking situation. We can modify engine braking, the amount of braking forces generated by the engine, during the braking phase, says Baldisserri. This allows us to modulate the rear wheels locking. A lot of engine braking tends to lock the rear more and we can reduce that by opening the throttle without the driver having to do anything, as allowed by the rules. So depending if the front or the rear is locking up, we can either reduce or increase the engine braking. If the car is locking the fronts, we need more engine braking to reduce the amount of normal braking at the front. This is something the driver can adjust from the cockpit, in the same way as traction control, to suit individual corners on the track. Although F1 brakes operate at high temperatures, heat is what causes the brakes to wear out and fail. The brakes are cooled by forcing air inside and around the discs through ducts at the front of the car. However, regulations restrict the size of these ducts and in any case, large ducts affect the cars performance in other ways. You have to find a balance between cooling the brakes and the cars overall efficiency, maintains Baldisserri. The brake cooling ducts have an effect on the aerodynamic efficiency of the car. In simple terms, the bigger the brake ducts, the worse the efficiency of the car, so we have to find the right compromise.
Yup. You'll find the drivers actually have the ability to control both the high speed and low speed engine braking separately. Also, brake bias can be adjusted manually by the driver. What isn't allowed is the shifting of the brake bias electronically/automatically during braking. Towards the beginning of the race and at the beginning of fuel stints, the bias will be set further forward to compensate for the added load on the front wheels as a result of the additional weight of the fuel tranferring forward under braking. As the fuel is burnt off, the bias can be shifted rearwards.
