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Lelystad (15 April 2002) |
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Back to the theory session
Going out to the trackLoaded to the eyeballs with background info on how to drive a car, what to do about understeer and oversteer, braking and what-not, it was time put it all into practice. Before going out, everybody received an original Porsche cap (not available in stores :)) and 1 liter of Mobil-1 0W40 for the car. The group was divided into three subgroups. We joined a a group that contained among others the 911SC and the 928S4 we had spotted earlier in the parking lot, aiming for more enthusiasm and less disposable income ;-)Slalom and Kart trackThe first exercises was a slalom. The waiting time between runs was shortened by driving a lap around the adjacent kart track. Big fun to drive a car around a track which is that narrow, and very good for car control. Particularly the art of backing off the throttle and using the brakes to make the car turn in sharper and faster could be practiced very well on the many tight turns of the kart track.The slalom was timed, giving you an idea how you were doing, and if a different approach yielded results or not. The cones were placed in such a way that the slalom consisted of left, right, left, right, U-turn, left, right, hard left, hard right turns. At the finish you were supposed to brake as hard as possible. The goal was to stop with the front wheels past a line, and the rear wheels still short of that line. To show what was intended, van Lennep himself went through the course in a Boxter S. It's a pity I didn't think of timing him. After a couple of turns on the kart circuit, he switched off PSM and swung the Boxter around the corners using the throttle. Very impressive on such a narrow track. After this rather impressive demo which made things look very simple, it was the turn of the participants.
To start off with, I used second gear to get a feel for the track,
never having driven a slalom before. At first I left too much space
between the car and the cones, and was too close to the inside of the
U-turn (a classic early-apex). That U-turn hammered home the point
that the way to go through it quickly was to use medium brakes well
into the turn, and then rolling through the rest of the turn on
neutral throttle. After a few runs, I had a good feeling for the kart circuit as well. According to my co-driver, this caused Gijs van Lennep to concentrate more on what I was doing on the kart track than on the current slalom driver :-) OK, I admit I was kind of enthusiastic, using first gear instead of second gear like most other participants... The results were the same as in the slalom though. The challenge was to drive the kart track so fast that you were off it before the next car would want to enter it. We did have to wait a few times for the previous car to finish before entering the track, but the car behind us never had to wait for us :-) Understeer and power oversteerFor our group, exercise number two was correcting understeer and playing with power oversteer. We had a very friendly and very enthusiastic belgian lady instructor for this exercise which took place at a large round skid pan. The friction co-efficient was supposed to be about equal to that of European ice. Undercooled Scandinavian ice is supposed to provide a bit more traction. I'm not kidding!Again, we were shown a demonstration of what was expected of us: enter the slippery bit at about 40km/h, turn the wheel all the way to the left, feel it slide, than correct the understeer by lifting and reducing the steering input. Once the skid was corrected, you could play with power oversteer if you wanted to. Most people wanted :) Catching the understeer wasn't very difficult. Keeping a nice powerslide going afterwards was a lot more difficult. Especially when the instructor is yelling "hit it!" when you cautiously open the throttle halfway. Being the kind to obey such an instruction, I "hit it", and spun round unceremoniously. Which taught me that if the back comes round, you had better be very quick recovering. Doing the powerslides was also a good illustration of van Lennep's remark that a throttle has more positions than "closed" and "wide open". Braking with ABSOr, for those in even older cars: braking without ABS. On the face of it, this looked like a simple exercise. Accelerate to 80 km/h, hit the brakes flat out at a certain point and avoid a line of cones directly ahead of you by changing lanes.My first run was interesting, as the instruction wasn't quite clear (to me anyway) about the braking point. I interpreted the instruction as 'the point where you release the throttle and start braking'. Apparently, this was a bit too late, as I ran over the cones with quite some speed. The following runs I interpreted the instruction as 'the point where you have started to build braking pressure', which worked much better. The instructor started with some tips for the driver that shorten the braking distance:
Easy though it might sound, I still found it difficult to keep my right foot planted full on the brake while changing lanes. Instinct tells you that a tyre can't both brake flat out and turn. Changing direction requires backing off the brake a little. I found that keeping maximum braking pressure and trusting the ABS to release enough brake pressure to change direction as well minimizes stopping distance, but only marginally. Obviously, this depends on how much brake pressure you relax during the steering part of the exercise. However, it makes the avoiding-the-obstacle part much smoother. My conclusion therefore: if I have even a little room to brake after the avoidance, I'll keep releasing a little brake pressure if I ever have to perform this trick in real life. Your mileage may vary, of course, and my ABS was designed before 1989, so this might be different in a more modern car. Don't blame me if you run into something after doing what I just described. The second thing to learn during this exercise was progressive steering. Don't flick the steering wheel to the right in one quick move, but do it gradually. Start (relatively) slowly, and increase the speed with which you turn the wheel steadily (but quickly). This is not as easy as it looks. If you reason backwards, you might figure you have about .8s to turn the wheel. This usually prompts a quick turn of the wheel, which is probably progressive, but also much too quick. Avoiding an obstacle at speedFor me, this exercise was the most impressive. It's the exercise that toppled the Mercedes A-class. At the beginning of the exercise, I did have the faith that it takes a fair bit more work to topple a Porsche than to topple a Mercedes A-class. Still, there are nasty things like lift-off oversteer. Again, the exercise was demonstrated in a Boxter-S. First with the stability management system switched off, a second time with PSM active. The exercise is very similar to the 'Braking with ABS' exercise, though at slightly higher speed and without braking. Accelerate to 80 to 95 km/h, lift off the throttle completely, avoid the line of cones straight ahead and straighten the car out all without touching the brakes, then come to a stop (using the brakes, of course). The length of track available to 'change lanes' was about 10 meters. Roughly speaking that gives you about half a second to move the car a little over 2 meters sideways. When you're standing on the sidelines, that doesn't look feasible...In the first demonstration, the Boxter-S without PSM threw it's back out, which was caught neatly by the instructor. The second run, with PSM, looked very unspectacular: it seemed as if the instructor just drove through the course. Must be great to have PSM as a back-up, maybe even necessary: a 996 with PSM switched off spun out quite spectacularly without going extremely fast. Doing the exercise was great fun. I started slowly (80 km/h) but still touched the left-most cone of the 'obstacle'. The remedy was simple: turn the wheel a bit more. Useful feedback from later runs: when steering to the left to avoid the obstacle, make sure it's one progressive move. Many people are inclined to divide the move into two parts. The division occurs when you move your eyes from the obstacle to where really want to go. This results in some initial steer, than a momentary break, followed by more steering input to complete the avoidance. Obviously not the quickest way to drive round something. Still, I hadn't noticed I did it (and neither had my co-driver, and she was watching what I was doing). Hat off to the instructor, who notices these things from outside the car while come flying past at 90 km/h. After sorting these details out, I increased the speed a bit to find the limit (of my abilities; I'm sure a capable driver could go faster still). At a little over 100 km/h the rear end stepped out in a serious fashion. I managed to get it back, overcorrected a bit, it swung around to the other side, caught that as well, saw the line of cones that demarcated the end of the exercise area coming up real quickly, and decided to give correction of the slide a bit lower priority and applied the brakes a bit. As a result I didn't go through the cones, did only a partial spin, but still had the nose pointing in approximately the right direction. Amazing how much a 964 will forgive if helped a little bit. Feedback from the instructor: "if you hadn't braked, you would have caught it. However, braking was a good decision. Very useful to us, too, this. [With a smile:] We figured nobody would be able to reach that line of cones. We'll have to put it back a bit further next time." Wanting to finish neatly, I backed off a bit for the last run (still 95 km/h), and ran through it smoothly. This time feedback was limited to a big thumbs-up :-) OversteerThis exercise is familiar to the viewers of the dutch TV-program Blik op de Weg. You drive over a hydraulically actuated plate at a speed of about 40 km/h. When your rear wheels are on the plate, it whips the rear end sideways.The artificiality of the exercise bugged me a bit: though the actual moment the rear end decides to break away might not be predictable, the direction it goes can be predicted accurately. In the exercise, you don't know if the instructor pushes the rear wheels to the left or to the right. This means that you're spending some valuable tenths of a second to determine which way you are supposed to correct. I even started a correction in the wrong direction once. As a result, you even modify your response. Instead of a coordinated clutch in and opposite lock, this exercise needs the slightly different approach of clutch in as soon as you feel any movement from the rear end, figure out which way you're sliding, and only then start the correction by steering into the spin like a madman. See the trip report of my outing at Zandvoort for further discussion of this issue. A second point of critique is that this exercise doesn't teach you anything about the most important part of oversteer: the beginning of it. How do you detect the first traces of oversteer? Can you catch it by applying a touch of throttle? When does the car begin to oversteer? How does it let go? Slowly or quickly? Anyway, to me this exercise was useful in a single aspect: for some reason I still tended to go to the brakes when the slide started. Which is weird, as I only brake as a last resort in solving a problematic situation. My default choice is steer around it and get away from the problem area. It might have something to do with the abrupt nature of the hydraulically induced skid. It feels more like a terminal failure of the rear suspension than as a skid, which prompts the 'both feet in' response. Circuit drivingAnother highlight of the day was driving around a little circuit. It featured a 270 degree turn over a skid pad (encouraging playing with power slides), some 90 degree turns, a long sweeping turn with a slightly tightening radius, a hairpin, some more miscellaneous turns and a short slalom. This exercise was supervised by Gijs van Lennep, who would drive the first car on every lap, rotating over all the cars. This way everybody received first hand comment from Gijs on which line to drive (there were cones around the circuit to indicate turn-in, apex, and track-out points anyway). After one cycle, Gijs would passenger in all cars, giving you feedback on your driving. Luckily, my co-driver was experienced in getting into and out of the back seat of a 911 :))One eye-opener to me was the way you make a 911 turn into a corner: keep a fair amount of brake pressure while turning in, progressively releasing the brakes while turning in more. This confirmed what I had found on the open road: sharpish turns at lower speeds are not what the engineers in Zuffenhausen had in mind when they designed the 911. If you go too quickly, it will just plow straight ahead off the road. However, if you turn in while on the brakes, it turns in very sharply indeed. A second point to pay attention to is patience: stay off the throttle until you are sure you can accelerate out of the turn. Too much throttle (even a teeny weeny bit) a touch too soon, and you can kiss your apex point and a tight turn goodbye. Oval drivingDriving on the oval, banked test track was a bonus. The turns had a 60% (!) bank to them. This looks like a vertical wall when you're standing inside the track. The idea was to slowly take the speed up to 180 km/h. For this to happen, everybody had to keep a constant distance to his forerunner. Of course there are always a few people who either don't listen to the instructions, or think they don't apply to them. This time it was a 996 who was driving in front of me. Before every turn he would loose speed (even use the brakes sometimes), drive through the turn slowly, sprint down the short straight only to hit the brakes again. The only excuse for his driving is that he might have been scared. Then again, if you're scared or can't or won't follow the instructions, get off the track! Getting tired of this (and not being allowed to overtake him), I dropped back during the straight and accelerated through the turns, ending up at his rear bumper upon exiting the turn. This was the only way to take the turns at anything approximating the intended speeds. (The turns were 'neutral' when driving 120 km/h. As a result, 160 doesn't put all that much lateral force on the car.)
The endThe day ended with drinks at a nearby restaurant. Everybody was issued with a certificate stating they had partaken in the course and passed. The drive home was uneventful. We waved at a few fellow participants on the highway, and I adopted to a somewhat slower driving style :)All in all a very useful day that lived up to my expectations. Certain exercises could be improved on (the oversteer exercise in particular), but overall the exercises certainly taught me a lot about how my car behaves and how it should be handled. Best of all, it was great fun to be able to drive a car like this to its full potential without fear of being pulled over by the boys in blue. |