For Nisskid and Tristan :
You both are right, but you should also stop considering the track itself, but the tire compound as well
Tires, and you obviously know it (but let me tell it for other people as well
), do not behave like this :
Grip | No Grip
----------------------------------------------->
Force exerted on the tire.
It behaves more like this :
Grip | Slip Zone | No Grip
------------------------------------------------>
Force exerted on the tire.
The "Slip Zone" (please tell the appropriate term since I do not know the official one) is a zone where your tire will have some slip angle, without losing its grip. Pro racing drivers, for timed runs or qualifications, tend to drive on that limit zone which separates when the tires stick to the road, and when the tires do not stick to the road.
In the slip zone, since you do not lose too much traction (and then propulsive power for the driven wheel) and since you have less resistance with the road (the tires slide a bit), it is overally faster than grip driving.
This is why some cars seem to be "flying" around the corners, because the drivers tend to stay on the Slip Zone.
To drive in that zone, you have to make all of your tires stay in it. If you only have 3 (let's say the outside front for a RWD car is the most likely to be grippy at the exit), you will create a resistance, which will not only slow the car down, but also create a mismatch between the slip angle of your front tires and the angle of your rear tires, making the rear travel faster than at the equilibrium, and tunring the "slide" (4 wheels in the slip zone), into a "drift" (Outside front grips, inside front is in the Slip Zone, Rears are in the no grip zone). If it is only your rear outside tire that is "below" the Slip Zone, in the Grip part, you will break the slip angle of our fronts, which will result in a joyful and awkward understeer.
Of course, the "width" of the Slip Zone depends on the compounds. Race slicks are designed to increase the width of the grip zone toward the right limit of the Slip Zone. It is all the more seeable on soft compounds slicks : either you have traction, either you have not. On R4 (the hardest, for instance), you see that you can lightly slide your tire without causing too much heat, in a very thin slip zone, and yet be fast.
On treaded tires, the hardest the compound is, the larger the Slip Zone will be --> this makes the Normal compound easier to get to a good slide in the slip zone.
The hardest bit to understand is that being fast in the Slip Zone has got nothing to do with the angle. It is about the force exerted on a tire, so basically, untill you reach the peak force where the Slip Zone turns itself to the No Grip zone, you can
virtually acheive whatever angle you like (may I remind that I speak about slip angle, and not angle of the car in comparison to the line).
The only problem is that : the higher the angle is, the higher the force exerted on the tire is, the closer it is to the No grip zone.
That is why having a 2° slip angle on a fast bend is useless, since the faster you corner, the stronger the Gs will be. As opposite, you can acheive angles of 13° max with the XRG in a hairpin without losing much speed. (Because less speed means that you can have a higher angle).
Then comes the tricky part : when should you get your tires to slide ?
Because obviously, carrying a slide from the entry point to the exit point is useless.
You have to progressively make your tires slide :
- After the entry point, you get a slight oversteer by increasing the angle of your rearies.
- Then, untill the apex, your fronties will progressively increase the angle : this will make you get a constant angle for your tires
and for your car untill the apex.
- Right after the apex, your fronties will still be in the Slip Zone, while your rearies will rapidly but progressively regain grip : you'll start to understeer.
- Just before the exit point (when you should touch the outside rumble pad), all of your tires will have grip again.
This is the only way when a "slide" (not a "drift") can acheive speeds that are "slightly" faster than just gripping your car.
Of course, once again, you don't see that move in official races because :
- they have slick tires with a very slip zone
- since it uses more of your tires, it creates more heat, which means to change tires more often.
However, in rallyes, slalom or uphill races with cars having other tires than slicks, this is quite common. Just take the example of Jean Ragnotti (a Renault rallye driver back in the 80's), who was sliding a lot of asphalt corners in a FWD car because back in that days, the tires did not have really impressive specs.
However, D1GP style will always be slower than grip, no matter what. However, you don't really see the cars sliding in most of the case, because having a 0°-3° slide isn't noticeable when you spectate (while it is when you drive). And those 3° can make the difference, while 53°, if they are pleasant to see, do not get the car far