Thursday, December 31, 2009

Overtaking and Why It’s Rare

Once past the first corner of the race, overtaking in a Formula One car is an incredibly difficult art. Here’s why.
  • Passing on the straight: The power difference between even the fastest car and the slowest is rarely enough make overtaking simply a matter of blasting by on the straight. For that to work, the driver needs to complete the move before the next corner arrives, because unlike racing on an oval track, there is only one real “line” through a corner; anything else is much slower. Therefore the overtaking car would need to get completely in front of the car it’s passing rather than just nosing ahead, in order to then take up track position for the next turn. It’s rare for such a performance differential to exist between cars to make this possible.
  • Passing under braking: This is where the moves – such as they are – are usually made. But this is by no means easy. With over 2000kg of pressure pushing the cars into the road, they can decelerate with enormous force –up to 5g. Even the act of lifting your foot from the accelerator pedal creates around 1g of deceleration – around the same as a full emergency stop in your road car – and that’s before the brakes have been applied! Consequently the braking distances for corners are incredibly short. The shorter the braking distances, the less opportunity there is to pass under braking.
  • Slipstreaming: The driver of the car behind can benefit from the slipstream effect. This is where the car ahead punches a hole through the air, greatly reducing the air resistance for any car immediately behind it. This effect means that the following driver can use less throttle for the same speed and then simultaneously pull out and floor the throttle to gain a brief surge that might get him ahead. To be successful, the driver has to carry out this move just before the cars enter the braking zone – and on the inside line for the corner. Given that the defending driver is allowed one blocking move between corners, he should invariably have that situation covered, forcing his attacker to take the long way round – the outside.

Blocking the other guy

So if the attacking drivers are allowed to change their lines more than once (as the preceding section explains), why don’t these aggressors simply pass him on the other side, knowing that their prey can’t change his line again? Because if the blocker has timed it right, he will have forced the attacker to lift off the throttle just as the front of his car is almost upon the rear of the defending car. This will have lost the attacker the advantage of momentum he had.
It’s therefore essential for the blocking driver not to make his move too early; otherwise the attacker can simply keep his right foot nailed to the floor and steer around the other side, shouting “Eat my dust!” as he flies by!

Launch control – it wasn’t always so easy

Since the 2001 Spanish Grand Prix drivers have no longer needed to judge the optimum revs, wheelspin, and gear change points to affect the best getaway. Now, a whole host of electronic gizmos are allowed on the cars, including launch control, so all the driver has to do is arm the system as he is lined up on the grid and then press a button as the starting lights change. Software systems then work out the ultimate acceleration.
Features such as this and traction control –which cuts power when the system detects excess wheelspin, thereby making the car easier to control – had been outlawed since 1994, but difficulties in policing the software meant they were reintroduced.