RedlineMan

Quite true, Smokey;

I have just about the time it takes to pull a H&T downshift to also get slowed for Turn 9. If one tries this on the wide DE entrance line, it is a HIGHLY speculative move because on that line you are not yet straight. If you miss, you likely biff. At the speeds an advanced driver is going there, it is nearly mandatory to bail to the apex immediately, brake in a straight line, ding the curb for rotation, and keep the hammer down.

Which points to the folly of theorizing cornering styles in my opinion. One can come up with general rules, but they are so general in reality as to be useless for more than just chalk-talking.

Only real world scenarios can present useful cornering strategies. Every corner, every car, every lap, is different. What works for one does not for another, and can change as the session or race drags on. As an excercise in understanding, the theories have merit. Other than that, you'll only find out when you try it.

joey bagadonuts

This seems to contradict a previous post.

So is it beneficial for one car to go faster in the less useful direction than the other? I remember this article included a diagram showing the slow (sweeping) line and the faster (v-shaped) path. The message seemed pretty clear--the v-shaped line was faster. I don't believe it mentioned hp as being a factor in line choice but I could be wrong, here.

But S could be just as fast if it took the same line, right?

Which the article stated was the least useful place to be fast.

Agreed, but F would exit faster regardless of line choice.

So if we agree that maximizing speed in a useful direction is the fastest way through a corner, then I'm not convinced hp plays a role in line choice with all other factors being equal.

ColorChange

John:
I agree that the real world dominates and specific conditions apply. But, trail braking is still fastest in most turns (vast majority to some degree) and that is what some people are working on.

Joey:
This seems to contradict a previous post.
I don’t think it contradicts any of my posts. If it does, show me.

So is it beneficial for one car to go faster in the less useful direction than the other? I remember this article included a diagram showing the slow (sweeping) line and the faster (v-shaped) path. The message seemed pretty clear--the v-shaped line was faster. I don't believe it mentioned hp as being a factor in line choice but I could be wrong, here.
That particular article (Racecar Engineering trail braking feature last month) was comparing the classic line (brake – wait – turn in) - approach compared to trail braking approach. The article did not specifically discuss hp comparisons (I don’t think). I can e-mail you the article if you want.
But S could be just as fast if it took the same line, right?
NO! If S blew off the speed around the apex, he can never get it back because his accel is so slow.
Which the article stated was the least useful place to be fast.
Yes.
Agreed, but F would exit faster regardless of line choice.

Well yes, within reason, but the point is that this was the fastest line F could take. And, the fastest line S could take would not be nearly so V’d.

So if we agree that maximizing speed in a useful direction is the fastest way through a corner, then I'm not convinced hp plays a role in line choice with all other factors being equal.

No, not quite, maximizing accel in the most useful direction. In my example, S is still doing that. He is using all the o.2g accel he can in the best direction. He just happens to be using the remaining traction through the turn to hold a very high corner speed so that he doesn’t slow down any more than necessary (to get his 0.2 accel in as early as possible).

Why don't you go to Putnam Oct 2,3 with me and Fishman?

Glen

Well as I did in the first CC thread, I will reiterate that Cervelli is correct(in my opinion). Chris is one of the best drivers I know and was very near some of the best as a Pro , he was 1-2 secs off a Wagner for ex at most tracks ...I have been around venues with him around many times and he is very quick but always leaves a margin around him, very similar to Martini, smooth like butter...Having said that Chris is always different from what is commonly espoused, ie spring rates....I wont reveal anything else just enough to say that if Chris says it, it will result in significantly faster laps if You can follow the advice. By the way I benefit not one iota from this stance so in reference to mitch's comment on the 100 to 1 actually in the first thread it was 100-2 and still is....
Luv Ya Bro's and Sista's....

Geo

CC, you just jumped several levels IMHO here.

You've taken a lot of shots (including from me) and will probably take some more, but if you keep this attitude up, it will stop and you'll find folks will have much friendlier conversations with you.

joey bagadonuts

CC,

Thanks for the invite. I'm still trying to figure out what I'm doing during that time period but I'm sure Greg will be a great source of guidance.

No need to send me a copy of that issue of Racecar Engineering because I have it and it seems we have different interpretations of the information. My take on useful direction is when you are entering and exiting the hairpin. You're suggesting sacrificing speed in a useful portion of the corner (entry) in favor of more speed in the less useful portion, through the apex. To me, that's not what the article suggested.
I can agree to disagree.

ColorChange

Geo, I have no problem taking a beating when I deserve it. Just don't like it when I don't ... but thanks.

Joey, not sure which car you are talking about. F sacrifices apex speed by diving in with heavy tb and exiting with early throttle. S doesn’t dive in so hard, maintains a higher apex speed (and therefore is on a larger turn radius – or arc), and still accelerates early, just that his throttle leaves more room for maintaining the high speed with more lat g’s still available than F.

Hope you can make it.

joey bagadonuts

I was talking about the S (low-hp) car. Your line recommendation allows the F car to shoot past the S car into a corner. Now, does the higher apex speed allow S to catch F at the apex? If you stay on a wide arc the whole time, you're covering a much greater distance, too. So even with the extra speed you need to regain position lost at entry AND make up additional ground given the longer path around the corner.

So in summary, your recommendation is for the lower hp car to go slower into the corner, faster around the apex and on a significantly longer path than the car with higher hp. Hmmm. I'm not sure that's the right call.

Bob Rouleau

Sunday et al,
I liked your concept of the HP/Grip ratio. At our local track, my lines into fast turns are different in my GT2 from those I prefer in the lowered powered and especially lower torque GT3. Both cars are set up the same way - track aligned, R compounds. In the '2' I find it faster to take a later apex which allows me to go to full throttle earlier. This results in a 10 MPH increase in exit speed. The GT2 is a bit extreme in this regard because when the torque comes on it is extreme and easily overcomes the available grip. The same corner in the GT3 can be taken with a more conventional apex and my foot to the floor.

Rgds,

ColorChange

Yes, Joey, for a short period around the apex, S is faster. Yes, correct again, S covers a longer distance. S goes almost as fast into the corner, just doesn't dive so close to the apex and trail brake quite so deeply, and doesn't brake to such a slow apex speed.

Geo

OK, while I understand fully the concept of the parabolic line discussed in the Racecar Engineering article, something has been bothering me. I was looking at the article again and it hit me.

(I haven't been reading super closely lately, so if this is a repost, please forgive me)

Power, and power to weight are not the only issues regarding different lines. Ability to turn the car whilst maintaining momentum is critical.

I experienced this at my first SCCA school. My instructor was a F2000 driver. He showed me his lines. I didn't think they were right, but it was my first time at this track and he was the master, I was the student. So I drove his lines. I learned at racing school to throw away my preconceived ideas. It never felt quite right. OK, he knew there would be some adjustment for a sedan, but halfway through the school he realized I was driving a FWD car. We changed up the lines. Felt better. Went faster.

OK, back to the discussion. Because of the above, I knew something wasn't quite 100% right about the article. I am finally able to put that into words (and too many at the moment).

In the article they show a flat 180 degree hairpin turn and explain how the parabolic line is faster. Perhaps, but I would wager this is not always the case. Consider the hairpin at Sears Point. Yes, a powerful formula car could really take advantage of the parabolic line. Now try imagining the Nextel Cup cars following the same line. As the poor bastard who tried it tries to get turned he'll get freight trained by a half dozen cars or more. Why? Because the big lummox of a race car that a Cup car is cannot turn that easily nor accelerate as easily as say a F1 car or Champ Car. It simply cannot carry through the momentum it needs to.

So, to wrap up my verbose message, IMHO this concept, like the friction circle, is still just a concept. You need more tools in your bag. Baseball pitchers don't throw only fastballs and reach success (not even the greatest closers). You will still find F1 drivers driving the classic line. Consider the last turn of the Indy F1 course. Nice constant radius turn. Classic line.

Like anything, learn from the concept. Apply it. Try other things. Use what works.

joey bagadonuts

No problem with the repost, George. Like you, Chris C originally made the point that there are different lines when certain variables are at play, i.e. a Viper on street tires would take a different line through a hairpin than a formula car. I don't believe there was any disagreement.

What I'm not convinced of is the accuracy of this statement:
If grip is equal, then I'm not sure a different line choice is warranted. Perhaps you or someone else can clarify (CC and I appear to be going in circles). Maybe someone can explain why, say, a 944S2 w/ 210 hp would take a different line than a 944 Turbo S modified to put out 500hp. If they have the same suspension, brakes, tires, weight, etc., would there be any reason for these cars to take different lines through this hypothetical hairpin?

Geo

I'm going out on a bit of a limb now, but I would think two cars with the same suspension would probably want pretty much the same line.

With big hp cars, in practice a different line may be selected, but I would guess that would be more to compensate for something such as a bad set-up or a driver not quite getting it together. In such situations power becomes a tool that can be used to cover for another short coming. But I would think ideally they should have the same theoretical line.

All this is really theory. Things change in practical application. Driver's might like different set-ups. They feel comfortable with a different approach from another driver, etc. I'm amazed how two drivers on the same F1 team might like a totally different set-up on the car (say oversteer vs. understeer) and even perhaps have different lines, yet they still often turn in virtually the same times. Things like that pretty much prove to me this is all theory and tools for the bag and not absolutes.

Back to my SCCA school example again, the F2000 lines use much sharper turning than what I used in our FWD sedan. With the F2000 you drive in deep and hard, stand it on its end, pivot and apply power. With our SE-R I had to round out all of my instructor's lines. Truth be told, I'm still undoing some of the damage he did. I haven't quite found the line in a couple of corners that I feel 100% comfortable with.

RedlineMan

Hey Guys;

Given the same driver and setup in the two cars, the high HP Turbo might want to investigate a straighter exit line strategy that would allow him to get all that explosive power down earlier, and STRAIGHTER. Then again, maybe not. He might be even quicker with a TB strategy like Color has espoused.

I guess in the end, like we have all been saying, it is too dependant on the realities of car, track, and driver to have the theory be much ultimate good.

It's still ALL in the application.

ColorChange

Geo:

The fc is not a concept at all. To my understanding, this is exactly how every top driver is analyzed: how close he gets and how long he stays there. Your on words support my case.

You are correct and this is exactly the point. The hp/weight ration defines how V’d the line should be. Higher ratio, bigger V, lower ratio, bigger arc.

Joey:
This is absolutely true as I stated before. Maximizing g’s in the most beneficial direction is the fastest. OK. The high hp car has much bigger accel capability. The tire limits are the same for F and S. So, F uses his full accel after the apex as much as possible as early as possible and this leaves much less available for lat g’s. There fore, he is moving slower and taking a tighter radius turn at the apex just as the article says.

Geo:
No, the suspension is not of critical importance for this analysis. The hp/weight ratio is. It’s not theory. Look at F1 and how the drive hairpins. It is exactly like the article states.

John:
You were correct in the beginning. All other things being equal, the turbo driver will take the straighter line you describe.