Tuesday, October 20, 2009

(94) Driving According to the Chump #3: Basics of Racing in the Wet

If you watch motorsport very often, you've probably seen a wet race. In it, you've probably seen your favorite driver, who is usually dominant, get destroyed. The announcers will probably slag this off as the rain being, simply, "the great equalizer". Tosh. Racers win in the rain because they understand rain racing. Racers lose in the rain because they don't. Setup is still important, smoothness is still important, and driving the limit is still important.

Nowhere is this more apparent than at the 2009 FIA CIK World Karting Finals in Macau. You can see that race here on Youtube.

However, the part I'm interested in is this:

[sorry, the video got removed]

Being American, I don't like the French a whole lot. But I have to say, Mr. Kozlinski is doing something that the Finn, Mr. Vainio is not. Well, actually, he's doing many things that Vainio isn't, but one thing in particular that gives him a lot of speed. Can you spot it?

A rain line.

Of course, Vainio did start emulating Kozlinski after a couple laps, but, you snooze, you lose.

It really is staggering how many very good drivers seem to refuse to deviate from the rubberized parts of the track. It's really not that hard to figure out. Smooth surfaces get slick when wet. You want to be driving on the bits with the most corrugation. It's an instant rain tire, in theory - it gives the water somewhere to go when the tire presses down on it. Even disregarding the academic differences, it's incredibly easy to feel when you play with it on the track.

The theory behind a rain line is simple. Try your best to minimize the time spent on the rubber in a corner. Easy in theory, hard to do for real. You need to know where the rubber is and isn't, so get on out there and have a gander when it's dry. Just because it's black, doesn't mean it's rubbered in. Nincompoops make black marks everywhere. Black marks only indicate where people are having trouble with sliding. Highways and freeways have tons and tons of rubber on them - but they're not black like a race track (darker color sure).

To see the real rubber, crouch down to track level, facing the sun, and watch for the silver reflections coming off the track. This is an extremely graphic depiction of where the rubber is, and it will show you just how progressive it is, and it will explain why you felt like you were losing a bit of grip by being just half a car or kart width off-line in the dry, even though you were still in the black bits. It only takes one errant slide or brake lockup to make a black streak. It takes hundreds and hundreds of passes to make silver reflections. Seeing the silver is the only way to know 100% where all the rubber is. That and simply having raced at the track for a long time.

So, now that we know exactly where the rubber is, we can avoid it should it start raining. Again, just watch Mr. FIA CIK World Champion Kozlinski up there. Brake to the inside, cross the rubber to the outside, stay wide, apex extremely late, and what ever you do, do not track out - go straight and avoid the exit rubber.

Now that we've got the track working, we need to get the car working too.

In the dry, we know that the harder we corner, the more the side wall of the tire bends and contorts. There is a point, depending on the construction of the tire and the conditions of the track, when the tire is bending at just the right angle and generating maximum grip. We experience this in the form of slip angle. Too much body slip angle, and we need to countersteer, slowing the car because of scrubbing. Too little angle, and the car doesn't respond as well and we go slower (push understeer).

Rally drivers probably already know what I'm going to say.

Since the track itself has less grip, no matter how hard we try to corner using our normal methods, the tires will never bend like they did in the dry, and we will never achieve that same cornering speed. To counter this, we need to rotate the car more. Rotating the car more puts more load on the tires. The less grip the track is giving you, the more you need to rotate. See: ice racing and rally driving. You'll notice that both of these examples display huge drift angles, and if you watch closely, you'll see that even though the drivers are carrying 15 or 20 degrees of drift into corners (or more), they're still adding wheel, fighting understeer. Understeer while drifting? That seems impossible! It all has to do with balance and the relative slip angles of each tire. The more you start to think of each tire as it's own "car", the more you start to understand how rotation works, why it's so critical, and why all the fast drivers are good at it.

With this in mind, two major things happen in the wet regarding the way the car behaves balance wise:

1. Understeer is very, very understeery.

2. Oversteer is very, very oversteery.

As a result, we need to have the car very well under control. Oversteer with the same kind of aggressiveness shown in dry racing is likely to result in a spin, and understeer is likely to result in an off-track excursion, provided we're carrying a good amount of speed into the corner. So we need to be careful and precise about how we rotate the car.

If our normal body slip angle is about 7 or 8 degrees (something like a street car or GT club racer), then our ideal rain slip angle will probably be somewhere in the 10-15 degree range, or possibly even more (or less), depending on the tires and the conditions. It's really surprising how much more drift angle you can get away with before the car even suggests that you might want to start countersteering. I say drift angle because, while we're not drifting really, it's a whole heck of a lot more than your everyday slip angle, and in dry conditions we certainly would be drifting at that point! The same rule as dry racing applies: the less steering you use, the faster you'll go.

Again, I suggest you take a look at the video up there. For the first few laps, Vainio is fighting understeer, only rotating the kart a little bit, and using tons of steering input to keep the thing on the island, while Kozlinski looks like he's competing in Formula Drift, yet he's still working the wheel in the same way as he was in the dry (furiously). He's easily carrying 30, 40, maybe even 50% more slip angle than he was in the dry. Again, once Vainio gets passed he figures it out, but he's still not as fast as the Frenchman. That part is experience, and thus is the difference between the 28 year old Frenchman and the 15 year old Finn. Vainio has a chance at Formula 1, though, so age and wisdom isn't all that. But I digress, blatantly.

I suppose all the scribes in the world could go on and on about the benefits of one style of driving versus another (the above is just my opinion on what works, I'm sure plenty of people go about it differently. Fact is there never is that one perfect way to do something in racing), and I can sit here reiterating various points that are surely covered in dozens of books, but the best way for someone to see how to do something is to see it, so watch what is probably the best rain drive in history: Senna in his last race at Donnington, 1993.

Far be it from me to analyze the most adored Formula 1 driver in history, but, I have to say, that's pretty much perfect. You see how he gets to that nice early slip angle really quickly while the other cars are still fighting to turn, and how he holds it through the corner straight to the exit without any twitches or anything dramatic? The other cars are entering the corners a good bit slower than he is. Slow in, fast out this is not - Senna's exit speed comes from his massive momentum, which comes from his (relatively) massive slip angle. That is how you drive fast in the rain.

I only have five tips for you this time since I'm far from a wet guru (this is just a basic article):

1. You lose a lot of grip in the rain, but braking suffers the least.
2. You need to rotate the car more to make it work optimally in the rain.
3. You need to stay away from the rubber line in the rain. And paint.
4. Pay very close attention to car angle. Understeer and oversteer are greatly exaggerated in the wet.
5. I advocate trail braking in the wet, but some people don't. Try it both ways and see what's fastest for you. You definitely trail brake a lot less in the wet.

Sunday, October 11, 2009

(93) Jim Russell sprint karting 2009 finale

It was cold yesterday morning, colder than Thursday. The conditions were so bad it felt like we were going out on new tires every session. In the first session on brand new slicks, I actually got wheelspin taking off from a standstill in the pits, even with the minuscule torque of sprint kart engines. I had to weave down the pit lane just to be able to take the exit curve. Once out on the track (National config), I got wheelspin down the first straight up to about 50 MPH. You can probably tell, but wheelspin just doesn't really happen all that much in the karts - maybe in a high speed corner you'll get a little bit more angle than you wanted because you punched the gas a bit too much, but in most corners the kart is traction limited instead of wheelspin (power) limited because even if you do mat the gas, the carbureted engine won't allow it and just refuse to rev. Wheelspin on a straight is unheard of from my point of view. So being able to kick the tail sideways on a straight at 40 MPH without tapping the brake or twitching the wheel is something new for me. But it only took a lap for the excessive wheelspin to go away.

So, the track was slicker than goose snot, and it was a challenge to drive - the brakes were touchy, the throttle was touchy, and the steering was touchy. I was about mid-field during the practices.

I think it was during one of the first sessions of the day, but I passed my one-thousandth mile in the seat of the kart today. That's well over one-thousand five-hundred laps.

Come qualifying, the sun was coming out, but the track hadn't heated up yet, so conditions were pretty similar. The problem was, I was mid-field, but I wasn't setting my fast laps until about lap 8 or 10 in the session, and qualifying was only 5 laps. National isn't my best configuration. I ended up qualifying 6th.

The fog backed off for the first race, round 9, and the track was heating up. I started on the outside of row 3. I had a so-so start that was highly affected by the accordion effect, and I dropped back one slot. Coming out of turn 1 I had a good run on 6th and I took him on the outside in Tic Tac Toe, hopping the middle curb pretty good in the process. 3 corners later, I dispatched 5th going into Kramer. I then followed the pack of 3 fighting for 2nd, waiting for them to battle it out and make a mistake. After a position change, 4th made his mistake in lap 3 in Helipad, and I simply motored on by going into Laguna, executing a slightly exaggerated slide-job pass.

The next lap, I made a mistake into Helipad and 5th shoved his nose up the inside, but I held my ground and put the left side of the kart in the dirt doing so. But, the basic rules of passing being what they are, outside loses going in, outside wins coming out, even if the guy to the inside puts some nice donuts on your side pod.

For the next few laps I just put my head down and drove. I was slowly catching 3rd, but in the end it wasn't enough. After the checkered, I went up to my rival and made a big shrug. I think we both expected to do a lot better.

Round 9 helmet cam footage.

After the B Group race, I was 4th in the championship, 10 points behind 3rd (who won the B Group race).

Ah well. Still one more race to go, on a new track - National Reverse. A track I'm good at.

With track conditions improving by the minute, I put it on the outside front row for race 2 (round 10). Pole was a Formula 3 racer from the school down below.

I had a good start, but I couldn't hold him off into turn 1, but I gained a run going into Monaco and tried a slide-job pass, but I carried too much speed at the apex and didn't park it, meaning he could re-pass me coming out. However, I now had the inside for Kramer. I did a slightly better job outbraking him there, but I opened up too much for the Esses and he slipped by on the inside.

A few minutes later I tried it again into Kramer, but this time he got a run and we went 2-wide through the Esses. This resulted in him grabbing the spot back in Laguna, since he was on the inside now.

I kept trying to pass, but he kept re-passing. My mistake was that I just never really parked it at the apex - I was too focused on carrying momentum through the turn and he never had to check up. By the 9th lap he was too far ahead for me to benefit from his draft and I finished in 2nd, exactly 1 second behind. The other mistake that I made was I kept looking back to keep an eye on my rival, and you can see how that affected my concentration - each corner immediately after I looked back was a bad one.

Round 10 on-board footage, the final race. It's pretty epic and climactic, even if I did lose.

So now with my 2nd and 4th place finishes, the bottom line was that to keep the bottom step of the championship podium, the guy in 4th had to finish 3rd or worse in his Group B race. A 3rd place result would have landed us in a tie. In the event of a tie, the tie breaker is based on who has the most wins. In the event of a further tie (which it was, 2 wins each), whoever has the most 2nd place finishes wins (I had 1 more than him, so I would walk away with 3rd).

We didn't have to resort to the tie breaker. He was in the lead but spun in the first corner. So I grabbed 3rd in the championship.

Meanwhile, my rival was praying for a bad finish from another racer who was tied with him for the championship lead. In the end, my rival took the championship win and the 3 days in the Formula 3 car that goes with it.

It was an absolute blast of a year. My driving improved even more, thanks to the great instructors who teach us to race closely and respectfully (most of the time) and to the mechanics who prepare the karts - you can't learn anything on a bad machine and these machines were as close to perfect as they could be all year, as well as being even and fair for each driver across the field. Thank you Jim Russell!

BUT! This is not the end of my 2009 season endeavors! There is still one race left.

You remember last year, how I missed out on the 4-hour endurance race? Well, Jim Russell is doing it again this year. I've formed a preliminary team with a couple other students and we're planning on entering with either 3 or 4 drivers. That's coming up in December, on the 5th. So far, we have very fast drivers on the team and we're confident in a very good finish, if not a win.

So, keep an eye out for that. As with last year, I'll keep updating the blog with various motorsport related things I find interesting and/or do. Over the winter I plan on making some money and finally buying a sportscar, so if I do there will be some track days in my future. If things go well financially, I may be doing a racing school in real cars, and maybe some pre-season tests if everything is ideal.

Thursday, October 8, 2009

(92) Move over, Lambo boy

Practice today went well. It's been a few months since I took tic-tac-toe going this direction - I'd forgotten how to go fast through there. But with some "go get 'em" encouragement from the instructors I managed to make it work.

The conditions were pretty bad. The first three sessions were all about 2 seconds slower than normal. It was very cold and the track was almost damp. The brakes were especially touchy. They gave absolutely no warning as to when they were going to lock up. I actually locked up pretty bad going into tic-tac-toe and stalled the engine, and the tires still didn't make any noise.

I didn't end up fastest. There was a "guest" driver who was faster than me by a tenth. He's been racing a very long time in the Jim Russell series and he's quite fast. He's definitely going to be running with us at the front on Saturday. I was faster than my rival, though, by about a tenth and a half.

After practice was over I went down to the big track to see one of my friends running his BMW in a track day. I went for a ride around Infineon and we ended up passing a Lamborghini Gallardo. See that? Come to Jim Russell, learn to pass Lamborghinis with "inferior" equipment. There was a Gallardo Superleggera a few corners behind us that had trouble keeping up as well.

I've gotta get myself a sportscar so I can get out on the big track more often.