Friday, July 31, 2009

(84) Driving According to the Chump #2: Reading the Car and The Limit

I don't really have a whole lot to talk about right now so I'll do another one of these.

One of the biggest problems I had was learning to read the car. Know it's limits, know when I'm below or above them. It's probably the largest hurdle to jump. Our bodies aren't meant to drive cars. We need to calibrate ourselves.

Training sensitivity is hard. But I've got a few ideas that will help with that. Lets start with the basics.

The first thing we want to be paying attention to is the wheel. If you're at the point where driving fast is instinctual, this will be a lot easier.

Obviously, the wheel is a necessary part of the car. We need it to make corners, save our hides and attack our opponents. The ironic thing is, in theory, it's not needed at all. It's physically possible to drive a course without touching the wheel at all. Humanly impossible due to error, but given enough time a super computer could calculate a way to do it with precise braking inputs, and repeat it, and I guarantee you it would be the fastest lap time ever recorded with that particular car.

This is verifiable in real life. Watch a video of a fast driver versus a slow driver in the same car, and the faster driver will use less wheel. Those of you with a telemetry program on your car can also verify it by adding up your total steering input values over the course of a lap. The fastest lap will have the lowest value.

All you need to do, to drive the limit, is to use zero steering input.

This is because of a lot of complicated physics things that I don't understand, nor do I want to. All I know is, when a tire gets to it's slip angle equilibrium, the point at which the self-aligning torque of the tire sidewall starts to fade, is when the steering wheel goes light. When the wheel goes light, you can zero steer.

You may be wondering, "how can zero steer be fastest if F1 and Le Mans drivers don't use it?!"

The thing is, while zero steer is the fastest way around a corner, it's not the fastest way to win a long race. The heat generated and the wear rate on the tire increases exponentially even with less than a few degrees more slip angle. This is the difference between a Formula 1 "qualifying" lap and a "race" lap: literally half of a degree of slip angle difference over the course of the lap. The truly brilliant drivers operate in the angles just before the steering goes totally light, just before zero steer, because that is where the tires are working the most efficiently.

So, zero steer is fastest, but it's the hardest on the car by a long shot. To drive the limit, the steering must be at it's center. However, there's a problem with that. No human can drive the whole lap with no steering input.

As a result, your goal is to be on the limit as much as possible. Sometimes that means going over, sometimes that means going under. As long as you're on the limit most of the time, then you're golden. Those small steering inputs back and forth over the limit will tell you how much harder or softer you should be driving. Driving the limit is the most important factor for driving fast. The driver who is on the limit and taking a bad line will usually be faster than the driver who is under the limit but using the perfect line.

To help generate our sensitivity to this limit, there's a few exercises we can do. The next time you're at the track, try focusing on just one aspect of what is happening for each session. For one session, try focusing your available attention on your throttle foot, or your brake foot, or your hands, or on the sound of the engine. By focusing our attention, we're tuning into what's happening a lot better.

For instance, the first time I really tried to take the s-bend flat at the Infineon kart track, I focused on a few things:

First, I focused on my hands. Learn exactly what my hands are doing. Now store that.

Second, a few laps later, focus on my throttle foot. Store what my throttle foot is doing.

Third, a few laps after that, I focus on the engine note. If I want to take it flat, it should sound like I'm going down a straightaway. Store that.

Fourth, focus on the visual. Where am I turning in? What reference point am I using? Store that.

Et cetera, et cetera.

Now I can combine all those things, formulate a plan, alter a few things and execute it via mental imagery (yes, you can do that at high speed). Now I have my "reprogrammed" corner, all I have to do is use it.

Rinse and repeat. I've found this to be the most efficient way of correcting mistakes. The better you understand what's going wrong the easier it is to fix. Rather than just recognizing "I need to take this flat, push the throttle down harder!" I've taken the time to understand it better, and fix it faster, with less stress, less trial and error and ultimately I come out with a better platform for fixing things in the future.

If you've just started driving fast recently, then that will sound pretty daunting. You're already probably completely occupied with saving your own life, so how can you pay attention to the engine note?! Just ease into it. You don't have to get really precise right away. Just start with recognizing physical elements more, like the sound, the feel, whatever it is. It will help you become an "unconscious" driver faster. I may liken it to learning a stick shift. In the beginning, you're unsmooth, you've got to look at the gear stick to shift, all that jazz. Now, though, you shift without even thinking. Now you can think of other things.

Sometimes, when my driving is really hooked up and I barely have anything to fix, I actually stop thinking about driving almost altogether, and I think about other things, like lunch, or new one-liners. Ironically, these are some of my faster laps.

So, the quicker you stop thinking about driving, the quicker you'll be quick!

I was going to do a bit on mental imagery, but I'll save that for later. For now, know that increased awareness during mental imagery sessions will also help you become sensitive. Whether you know it or not, your brain stores more information about how your car behaves than you'll ever notice consciously while driving.

Ten tips for sensitivity and driving the limit:

1. To drive the limit, sometimes you have to go over the limit.
2. The fastest laps are the ones with the least steering input.
3. Developing sensitivity is key to driving the limit.
4. Analyzing individual factors such as brake pressure and steering angle can help you become more sensitive, and help you fix bad lines.
5. Mental imagery will help you become more sensitive.
6. Beware of false limits; they can give you false feelings and make a bad line or apex worse.
7. The limit is harsh on the car's tires. For long races, try to drive just under the limit, just under zero steer.
8. The limit is something you can feel through your butt as well as through your hands.
9. Really pay attention to your tire noise as you near and go over the limit. Sometimes cars will make very distinctive noises depending on the tires used and the setup.
10. Yes. Zero steer is fastest in all cars, not just RWD cars. You may not be able to use it in all cases (throttle-on in a FWD car) but you should still use it where you can.

Friday, July 17, 2009

(83) Driving According to the Chump #1: The Apex

Over the past year or so, I've been sort of avoiding getting into the really nitty gritty of actually driving fast. Truth be told, I didn't have a really good idea of it myself - I was still learning. I still am. I talked a little bit about g-forces and the stuff I was being taught in school, but I think it's time I formalized all that into a series of tip articles. So here we go. Driving According to the Chump - the apex.

I suppose I could start with something really basic, like full throttle, or braking, but you should know how to do that stuff. That's easy, and obvious. Didn't stop me from getting it wrong, but that's not the point.

You know, that's not actually true. The apex is really basic in the end, it's just complicated. It's one of those things that, once you figure it out, is really easy and makes a lot of sense.

So what exactly is the apex?

Firstly, the apex is the point at which the car is at the inside of the corner. You start on the outside, then as you turn into the corner, you gradually cross the track and "clip" the inside of the corner. After that, you gradually allow the car to cross back over to the outside of the track and exit the corner.

Secondly, why do we apex? There's a number of reasons.

* The apex opens the corner, and makes it wider than it actually is.
* The apex gives us a really good reference point for things like throttle application, and what we're supposed to be doing with our steering wheel.
* The apex can be used as a racing weapon, both defensive and offensive.
* Finally, a proper apex allows the car to stop, go and corner at it's optimum.

If you're just starting out with performance driving and you're on your first track day or autocross, the most common thing to do wrong is to apex at the geometric center of the corner. You've got the right idea, and it's certainly better than following the corner to the letter. However, while not totally wrong, it could be more optimal.

Lets imagine a standard 180 degree hairpin. It's got no tricks, no radius changes, no weird crests or bumps.

Now lets imagine that we take a perfect geometric apex to this corner. We start on the outside, cross over to the inside, clip the inside curb right at the top of the corner, unwind the wheel and cross back over to the outside and exit the corner.

The problem with this is not immediately apparent. If it is, kudos. I didn't get it. The problem with it is, the exit radius is the same as the entry radius. This means the car cannot exit the corner any faster than it went in. It's a dud, a throwaway, a waste of time, and so is the next straight.

So, if radius = speed (the car only has so much grip available) we must open up the outside of the corner if we want to carry more speed out of the corner. How do we do that? The late apex.

We'll get to that, but I think now's a good time to list exactly what affects the apex point.

Basic factors:

* Turn-in point.
* Steering wheel input speed.
* Rolling speed.

Advanced factors:

* Car angle.
* Brake release.
* Throttle application (if before apex).
* Tire slip angle.

Some technical aspects like drive configuration and differential setup also affect the apex point.

So, how do we use the above aspects to give us a later apex? Well, assuming we're using a perfect geometric apex, it's going to be a little bit of everything at first.

Lets focus on just the basic points for now.

The first thing we're going to change is turn-in point. This has the largest effect by far. But, if we keep the same steering input speed and the same rolling speed (assuming we're at the limit of the car given the conditions), we're going to miss the apex, whether we wanted to hit a later apex or a geometric apex.

We have to use all of the points, otherwise we'll miss. So, the answer would be: (try to figure it out before you read the answer)

* Turn in later.
* Faster with the hands.
* Slower rolling speed.

Turning in later is obvious. It delays the geometric apex of the corner based on our position and the ending point of our line, like rotating a picture a few degrees.

Slightly less obvious is faster hands. Since we're now trying to turn more in the beginning portion of the corner to make the end portion of the corner much wider, we need to move the hands a little bit faster, make the car respond a bit quicker.

Even less obvious is rolling speed. Since radius = speed and our beginning radius is now tighter, we have to slow down a bit more.

But how does all this work translate into a faster lap time? As I said before, with a geometric apex, we're exiting the corner at the same speed we went in. This means that we're not taking advantage of the track. With a later, proper apex, we're extending our acceleration capability - making the straight longer, in layman's terms. By sacrificing the entry of the corner, we're making the exit quicker, thus increasing our average MPH and our lap time.

So how do we know how far to take it? How do we know when we did it right or wrong? How do we know what we did wrong? That's the hard part.

Lets go back to our geometric apex. The entry to the geometric apex feels easy. The car isn't really working all that hard, and you feel like you could go in a lot faster. The exit, however, doesn't go so well. You start adding throttle at the apex like you see racers do on TV, but you feel like you're going to understeer straight off the track so you back out, maybe add more steering and heroically save the car.

This feeling needs to be completely reversed. You need to feel like you're working the hardest on corner entry, then have a relatively easy time on the exit. The exit sensation should be "am I going to go off the track?" not "I'm going off the track! Stop stop stop!"

One of the first things I tell new drivers when they enter our series is, it's easier to fix an overly late apex than it is to fix an early one. At least with the later apex you've got the right sensations going through your head.

So now that we've got those sensations reversed, we're zeroing in on the perfect apex. Now we need to listen more to the car to really hit the bullseye.

The first thing you want to pay attention to is your steering wheel. Put some tape on the top of the wheel to help you see exactly where it's pointing. The wheel should be gradually adding as you approach the apex, then unwinding as you pick up the throttle and gradually coming back to center as you exit the corner. If you're adding steering, or backing off the gas after the apex, it's still too early.

The second thing is to feel the car under you. If you feel like you have the least control on the exit, you're probably doing it right. The car should float out to the edge of the track as you add more power and decrease steering angle. Everything that happens after the apex, other than throttle-on oversteer, is related to something that happened either at or before the apex, such as turn-in or the apex point itself.

And that's just the basics! It gets even more fun when you start to really factor in your feet.

As I said before, the advanced factors are:

* Car angle.
* Brake release.
* Throttle application (if before apex).
* Tire slip angle.

The reason why I call these "advanced factors" is that every advanced factor needs a basic factor value to work, and a culmination of all of them. I'll run through them.

* Car angle can be used to adjust your exit point. Sometimes your apex point is fine, but you need to use your steering input speed and your brake release to increase or decrease the car's "angle of attack" going into the corner. A higher angle can scrub a little bit more speed on entry, or help supplement your steering unwind, or any number of other adjustments. Car angle directly affects tire slip angle.

* Brake release will affect your angle, but also the "dartiness" of the car. Adjusting your brake release can help you get down to the apex if you find yourself going slightly wide.

* Throttle application, simply put, too much too soon will cause you to miss the apex. Too late or too little, and you won't exit in the right spot.

* Tire slip angle will directly affect the radius of the corner. Typically, tire slip is directly related to car angle, but knowing how to read your optimum slip angle will help you determine the angle of attack for each corner.

I'll leave you with my top-ten tips for apexing:

1. Don't be afraid to hold an apex for a few feet. Many long corners require long apexes.
2. The faster the corner, the earlier the apex should be. The less the car needs to work on the exit, the less room you need to give it.
3. The faster you enter a corner, the more likely your tendency will be to turn in early, giving you a "false limit". As you increase your rolling speed for new corners, force yourself to not turn in early and apex at the normal point.
4. The more rearward the drive configuration, the earlier the apex. RWD cars have the earliest apex. AWD cars are in the middle, and FWD cars have the latest apex. This is tied to understeer levels.
5. The tighter the differential, the later the apex. Locked differentials have the latest apex, open differentials have the earliest. Again, based on understeer.
6. Steering unwind happens as you add throttle, not at the apex, as is commonly misunderstood.
7. Do the most work before the apex.
8. The exit should feel like you have no choice but to track out, under normal throttle application and steering unwind.
9. There is always a varying degree of steering angle hold in the middle of the corner.
10. On a new track, or with a new car, apex much later than you plan to at first. It's easier to fix a late apex than it is an early apex.

Sunday, July 12, 2009

(82) The first of many

Yes, yes, yes! I WON! My first win! Oh man, I needed that!

Okay, story time.

During the first practice session, I half-spun coming out of the pits. I really hate cold tires. The rest of the practices went fairly well, but I had to run way out into the marbles to avoid a spun kart and nearly understeered straight off the track. It felt like I was going through gravel.

In qualifying I thought I did quite well. But, I ended up off pole by a tenth with a 54.709.

The race start was fast. We started by going into the sweeper, which is a 50 MPH corner. I was forced to the outside and lost a bit of ground to my rival, who started in first. He gained more ground through the next couple of corners, then I managed to stop losing ground and started gaining very gradually.

The start. Go go go! I'm on the outside front row.

I finally got within range around lap 5, and started work. It was intense because where I was fast, he was slow, and where I was slow, he was fast. I was gaining coming out of the tic-tac-toe (right left right) complex and outbraking him heavily into Sand. (I bumped him there once, sorry man!) Meanwhile, he would pull me going into Kramer (after the sweeper), and through the two back-to-back hairpins.

He had a bobble coming out of tic-tac-toe and I managed to gain a huge amount, but he looked back, saw me there, and ran a defensive line. I tried to stick to the outside but there wasn't enough room.

Then I bided my time, rubbing my brake to stay at the perfect range. I tried a move going into the no-name hairpin but I went slightly too deep and he re-passed me.

Then, I had a really fantastic run out of tic-tac-toe and punched it down the inside at the end of lap 8. I led for 5 laps with only a nosecone showing from my rival. Then, we hit lap traffic. I got around just fine, and so did my rival, but the very next corner he overcooked his braking zone and pulled an "Evans", sliding wide, half-spinning and stalling the kart. Since this was behind me, I had no idea he'd dropped out.

Leading the race.

However, 3rd place was now in second and I kept looking back to see where he was. He was close, close enough to beeze by if I made a mistake. So I didn't. I held that pace and won the race by 1.2 seconds.

Now look at this. These are the fastest lap times of the race:

First (me): 54.713
2nd: 54.771
3rd: 54.771
My rival (7th): 54.703 (fastest of race)

Seven hundredths separating the front four karts, and two setting the exact same laptime. That's some close competition right there.

Now I'll stop boring you and you can go watch the video.

Round 6. Watch the cooldown lap for my celebration.

What a race. I needed that so badly. I've gained a lot of ground in the championship and I have my second wind. Also, my neck hurts.

But most importantly, I GOT MY FIRST WIN!!! And a medal.

Thursday, July 9, 2009

(81) Practice makes perfect

Practice for round 6 went well today. We're running the Sprint track in the normal direction this time. I think this is the first time I've seen the ProKart guys run this track.

My best time was a 54.8 and I was the fastest guy there today. My main rival has had to cut his track time for budget reasons, and he's never driven this track so I'll have an edge on Saturday.

Overall I focused on trying to get smoother with the wheel and rely less on my hands and more on my feet. The less steering you use the faster you go. In theory, if you could drive the track without touching the wheel it would be as fast as the car could go, but that's humanly impossible so you have to get as close as possible to that. The steering wheel is just a fancy brake, remember.

At the level I'm at right now, the differences between which is the accepted control for what gets more mixed together. It's harder to tell what will help you or hurt you. For instance, if I'm doing 50% of my steering with my brake release, and 50% of the steering with the wheel, then what's causing me to lose speed when entering corner x? Is it my brake release or my steering? So things take longer to figure out and it requires even more trial and error.

I'll get it sorted by Saturday, I'm sure. I keep studying my onboard footage and doing mental laps of the track.