Thursday, January 6, 2011

Track Day Driving Techniques

Tight Corners and Hairpins
At the opposite end of the spectrum is the very tight, continuous-radius corner, which might vary from something greater than 90 degrees to a tight 180-degree “hairpin” where you will be completely reversing your direction within a fairly short distance.
In the case of the tight corner, all the aspects of the standard 90-degree corner apply, but must be performed to an extreme. You need to slow down significantly and will probably drop two or even three gears, you need to wait to make your turn-in until you can exit the corner on almost a straight line, and you need to make a very late apex on the corner.

We can take the aspects of the turn one at a time. The first step will be to brake hard to reduce speed, while at the same time downshifting. On many racetracks, hairpins are often found at the ends of long straights, so that a period when the car is at its maximum speed in its highest gear is followed immediately by a turn that requires that the car be moving at a very low speed in its lowest practical gear.

Needless to say, this transition takes a lot of practice, but these types of corners reward the good driver with excellent equipment and solid driving experience. At almost any track, this corner will see the greatest number of changes of position, since the corner is often almost a game of chicken, with the drivers seeing who can wait the longest before hitting the brakes, knowing that the driver who brakes last will be the first out of the corner, provided he or she has left enough room to slow the car sufficiently to be able to get around the corner.

Typically in these corners, the turn-in point will actually be past the apex point, and the apex point itself will be well past the geometric turning-point of the corner. All of this is necessary so that the driver has the maximum distance over which to accelerate. The drivers who turn in early have to wait until they are completely around the corner before they can begin that drag race to the next corner. Such drivers are generally passed by the driver who turns later, but gets back up to speed earlier.

On these turns, the trick is to look around the corner, and wait until you can see well around the track before making your turn. It is not unusual to feel as if you’re looking over your shoulder in an open car before you can see your line out of the corner and begin your turn. In a closed car, you’ll probably be looking out the side window for your cornering line before beginning the turn.

Once you’ve slowed down and made your turn, then all that’s left is to begin accelerating and wind the car up through the gears. In a normal rear-wheel car you might actually induce a little rear-end slide to bring the rear end around. In a MINI, by lifting off the throttle for an instant once you’ve begun your turn, you may be able to release the rear end. Then when you get back on the throttle you can use your speed to pull you around the corner.

Changing Radius Corners

In our modern world of carefully-engineered highways and geometric city streets, most corners have the same curve from the beginning to the end. For these corners, once you’ve turned the steering wheel, you can usually hold it at the same angle until you are through the corner. However, on back roads which were probably laid out to follow the contours of land or the boundaries of some farmer’s property, it is not unusual to encounter a corner that surprises you half-way through by changing its curvature.

On road tracks, such corners are much more common. Track designers delight in making things difficult for the driver who is new to the track, or new to track driving, and the folks who lay out autocross courses positively delight in making things as difficult as possible. Two such corners are typical, ones that become more open as you go around them, and ones that become tighter as you go around them.

The first types are called “increasing radius corners.” On public roads, these are usually a positive surprise, since you find that you can get on the accelerator earlier and harder than you had expected when you entered the corner. On the track, they can be disconcerting because it usually means that you didn’t need to have slowed down as much as you did on the entry and could have been going even faster on the exit.
But in general, they’re not of too much concern for safe driving since it isn’t likely that you’re going to find yourself in an unexpected precarious situation coming out of the corner.

By contrast, corners that become tighter, with progressively smaller curvature, as you go around them can be quite dangerous. These corners, called “decreasing radius” corners, can deceive you into carrying too much speed on the entry. As the corner begins to become sharper, you realize you are going to have to turn the steering wheel tighter in order to keep from running off the road, but realize that if you do you may lose control of the car.

When driving an unfamiliar road, the best way to avoid this situation is to go more slowly, of course, and particularly wait until you are further into the corner before making your turn. That way you can see more of the exit and be able to gauge your speed more accurately.

However, if you do find yourself in the situation of having to turn the wheel more tightly after entering the corner, the worse thing to do is to follow your instinct and try to slow down by abruptly letting off the gas and hitting the brakes. If you do this, the car’s nose will go down, making it even harder to get the car to turn, and you may very well find yourself going straight off the outside of the curve.

Instead, you need to try to keep the car as balanced as possible. Try to keep the car going at the same speed while as gradually as possible turning the steering wheel more sharply. If the situation was serious, you’ll be rewarded by hearing your tires squeal as they start to slip a bit, but 99 times out of 100, you’ll be all right.
Few people outside the realm of professional high-speed driving ever push their cars anywhere near their limits of adhesion or roll-over potential and all that will happen is that the car will scrub off speed as the tires slip a little. The car will make it around the corner without any problem, though you and your passengers may find your hearts beating a little faster when you’re through.

It’s the alternative that’s usually where trouble arises. When you see a car off the road, or worse on its side or top on the side of the road, you can pretty much assume that the driver got into a difficult situation, started to slide off the road, then either jerked the steering wheel hard or jammed on the brakes, or both, and wound up putting the car into a skid or roll.

It’s worth remembering as you mentally prepare for decreasing-radius corners, that you are driving a MINI with its front-wheel drive. On the positive side, you can usually power your way around a decreasing radius corner by using the throttle and front wheels to pull you through. On the negative side, the MINI is more likely to bite you if you take your foot off the throttle, or worse, hit the brakes. This action will cause the car’s weight to transfer to the front wheels and off the rear wheels, and it’s very likely the rear end will skid out to the outside of the corner, leaving you facing the wrong way or worse.

Learning to handle tight and decreasing radius corners is where some practice in advance can pay dividends, and one of the reasons why some track time or autocrossing is a good idea even if you never expect to do any competitive racing. The first time your tires start to squeal, you’ll be startled, but you’ll begin to get some confidence in the car’s ability to hold on to the pavement at speeds well beyond what you would have expected. You will also get a little more confidence in your ability to catch and correct a difficult situation without panicking and making it worse.

Of course, if you’re working on improving your line around a track, and you’re going to be taking the same decreasing radius corner again in two or three minutes, it is a simple factor to adjust your speed and turn-in point so that you start your turn a little later, and a little more slowly the next time around so that you can take the corner without scrubbing off speed and be able to accelerate more quickly coming out of the corner.

.. stay tuned for more..

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