ColorChange

RedlineMan: Yes, if you are driving at the limit there is little margin for error. That is why knowing the track well when you are working it up is so important. If you are truly at the limit in a turn and hit a bump or anything else (oil, water, camber change ...), you can get in big trouble in a hurry.

In DE's I try to get to the limit as much as possible on safe turns (no walls or problems with offroading). In a race, I would only do it to the extent I had to to win the race because it is the fastest. It is also the riskiest and most difficult so you have to take that into account

mitch236

The other point of fast in fast out being the fastest way around a turn should be clarified. I guess what you meant is to be at the limit of adhesion at all times which is absolutely true. The reason to teach slow in fast out is that there is greater tendency to exceed the limit of adhesion during entry than exit for novice drivers and much time is lost collecting the car. From another standpoint however, it is usually safer to lose it during entry than during exit.

I haven't used a g-force meter but it sounds interesting. I personally found that in DE consistancy is fast. I rarely drive at the limit as one accepts much greater risks when at the limit because there is no room for error. I try to keep it between 8-9/10ths most of the time. This leaves a little extra to ask of the friction circle if the unexpected occurs.

M758

DE and racing are seperate things. In DE 8-9/10th is fine. In racing nothing short of 9.5/10 will do. Funny thing is that once you start fighting for 10/10th in practice you will fine that even after many years in DE you were really only doing 6/10th even if it felt like 8/10th. This is fine for DE because it is just for fun, but racing is a whole lot different. I have gotten more speed than I ever thought possible from my 944-spec car by racing and especially from racing similar cars. In spec racing the only way to gain an edge is to drive the wheels off the car and that ain't going to happen unless you drive at 10/10th occasionally test the limits by going 11/10th is selected places. In my spec car if at any point in cornering or braking feels "nice and stable" I am going too slow at not at the limit. I have learn that it always needs to feel at little uncomfortable to be fast. Not wild and crazy, but requireing my full an complete attention.

BTW... I have yet to mention going off line. Being comfortable going off line and making the required changes to braking and turn in points is critcal to any good racer.

ColorChange

Mitch and M758: I agree pretty much with everything you guys say but offer one caution, the only way to KNOW where you are driving at ... the only way, is to have a data acquisition system. History is replete with best racers in the world saying "I was at the limit in that turn" ... until the data acquisitions system (DAS) showed they weren't. Would you guys find it informative for me to start a thread on the benefits of DAS with hard data examples?

mitch236

All true, that's why DE exists. We "older" folks like the security that comes from this controlled evironment. At my current level I don't feel ready to race. What I do is to compare my lap times to those posted by the racers. I do fairly well but I realize it's easier to be fast when not fighting for position.

Z-man

My understanding is that the 'slow in - fast out' late apex technique is also a faster way around the track. (Note: it's not typically the fastest way around a given corner!) So it's not just for teaching newbies a safer technique.

This past weekend, my PCA region (NNJR) held an advanced driver's workshop, and this topic came up. Here's my paraphrase of what Bill Gilbert (club pres) stated:

A late apex corner maximizes the exit speed of a corner. This speed is carried through the whole straight! For example, if a driver drives a geometric apex, and the maximum speed achievable for that corner is 55mph, that driver can go through the whole corner at 55 mph. His exit speed is 55mph. His speed at the end of the straight is, say 153 mph.
On the other hand, if a driver drives that same corner in a late apex fashion, he will enter the corner slower (say 53mph), but exit at a greater speed: say 57mph. This extra speed will be carried thorugh the whole straight, so at the end of the straight, his speed will be more, maybe 158mph. If a driver can consistently pull an extra 5mph on the straight, he will eventually win the race!

On caveat to this is: in racing, late apexing a corner will typically allow an overtaking car to duck in and pass you. HOWEVER: if you see a car that's way out ahead in a race, that driver typically will be driving the 'classic DE' late apex line: it is the fastest, safest way around the track. He can achieve a greater top speed down the straights with this technique. With no one on his dumper, he doesn't need to worry about someone ducking in during his slower first part of the corner.

So the 'DE line' can work in club racing!!

I am interested in learning how to drive offline: I may have to pursuade our track chair to setup some run groups where this is stressed.

Great stuff! Can't wait to get out there!!
-Zoltan.

Brian P

Is it really that simple?

Shouldn't the edges of the G-force graph (i.e., the friction circle) change a bunch as we drive around the track? For example, when you are near the top end of a gear, your amount of torque decreases and the amount of acceleration available to you decreases. Similarly, at higher speeds, you will have more braking potential as air resistance alone can slow you down quite a bit.

Also, elevation changes and banking can do wonders at giving your car more G-force capabilities. For example, going through the carousel at Watkins Glen (or the toe of the boot), you get tons of banking in your favor and the friction circle becomes really wide at that point.

If you were then to look at the G-force plot through the downhill left (an off-camber turn) into the laces, you might think that you are always leaving a lot on the table. For example, you might be at the limit there and pulling only .8Gs while in the carousel you could be below the limit and pulling 1.1Gs.

Maybe we can just look at the maximum G-force through that you pulled in that turn (the DL90 software makes that easy) but even then, how do you know if that represents the limit?

Brian P

Why couldn't you just do this on your own? Pick a corner where you don't have traffic and try taking it off-line. Why would you need an entire run group trying it?

Z-man

Brian:
There would be more time spent driving the 'offline' if that were the 'rule' for the whole session. The possibility of driving a corner offline EVERY time in a given run session would be minimal.

-Z.

mitch236

The problem in our region is that this is frowned upon by the corner workers who think you are driving poorly. You will get black flagged. I have talked to our local organizers who are trying to figure out how to incorporate driving off line into DE.

Late apexing is not the fastest way around a track. It may work OK for a high HP car but talk to the momentum drivers, they will tell a different story. I agree that maximizing exit speed is the ultimate goal. Late apexing limits entry speed and therefore also limits exit speed unless you have enough power to reclaim the momentum lost. Late apexing is taught because it is the SAFEST way around the track. As I mentioned before, it is usually safer to lose it during corner entry than exit and late apexing puts more cornering forces on the car during entry and relieves the forces during exit.

Brian P

I think each of us have different things they want to learn at DE. I may want to spend time on braking technique or mid-corner speed and not driving off-line. Alternatively, I may think I already know how to drive off-line and I'd rather not spend the whole run group watching everybody else learn.

I think we get a bunch of corners where there's no traffic. Use those to practice what you want and I'll use them to practice what I want and we can both be happy.

Brian P

Wow, at some tracks, I'd be happy to get corner workers who pay that close of attention!

At our region we get a morning drivers' meeting that the corner workers also attend. Perhaps you could ask then if driving off-line would generate a black flag? This might let them know that you know what you are doing, and you might be intentionally driving off-line.

RedlineMan

Hey all;

I feel that driving off line (An EXCELLENT drill) is best achieved in a special run group. Everyone (drivers, instructors, flaggers) will know what everyone is doing and no one will be caught out by the "sudden change in message."

As for Late apex being the fastest, Z... I gotta disagree to a certain extent. As instructors, we teach late apex because students DO NOT KNOW what to do if the car gets weird. Late apex offers them lower cornering G-loads and more straight exit lines, and therefore makes it easier for them to deal with "Oh $hits!" They have not reached the "trust is a Must" point yet because they don't understand the limit, how to get there, and how to manage it.

Let me give a PERFECT example: Turn 6 at the Glen (the Chute). We teach an EXTREMELY wide, late turn in point so that this nasty a$$ turn does not scare them to death while they learn cornering geometry and car control.

If I were to try that turn on the student line at my pace, I would fly right into the woods. I simply could not hold that outside line at the speed I go. Same with "the Off-Camber" turn 9.

Now, South Bend at VIR or Turn 10 at the Glen work much better with a mid-to-late apex. If you go early in either one, YOU ARE OFF!

People always try to late apex Turn 9 at Mosport because that puts you up the left side for Turn 10 turn in. It is doable until you get to smokin in there at which point it becomes VERY difficult. Counterintuitively, it is much faster to simply bail off the right edge and smack right into the apex curb in what seems an insanely early posture.

It is VERY much dependant on the corner as to whether you can even USE a late apex technique. Bottom line is that there is usually no one fastest way, and making generalizations about how to do a corner without actually doing it are problematic.

Did we lose the thread here?

RedlineMan

Hey M758;

You are spot on in your analysis of DE -vs- racing. I am CONSTANTLY baraged by guys who have hardly done any DE and are looking to buy Cup cars and go racing. They drive 964s or 993s or 996s even and slow ME down in turns, but they gotta race... you know? Gotta have that showpiece!

They just have no clue what they are going to find. Why spend $125k to finish behind D-stockers. Just get the D-stocker and get your butt kicked by F stockers... all the while saving about $60K! The smartest stay in DE and pay their dues. Then they go for G, H, or I and really learn how to race first. Most of them find they can't use a Cup car anyway.

mitch236

Actually the term "late apex" is the problem as it implies later than optimal. The apex is defined as the point at which you have ended entering and have begun exiting the corner, so late apex is to enter later than optimal to gain a wider exit geometry. The interesting thing that occurs as one carries more speed into the corner is that the turn point becomes earlier as speed increases. The theory is that as speed increases so does understeer and therefore you need to turn in slightly earlier to reach the apex properly.

So the fastest way around the track is correct apexing. Late is safer, and is taught to students because of that and the observation that most students do everything early, except go to the throttle.