Driver and Car Capability Influence
09-09-2004, 01:41 PM
#46
Nordschleife Master
Ok CC, this is gonna be my last attempt
Point #1 -- You believe that your car has a max G-sum of 1.1, and that you have been able to hit that g-sum some of the times on the track. Now, you do admit that a pro would be more consistent than you are, and able to turn faster lap times...and that's a start. But the fact that you think you've ever been close to a pro, even if for only 1 corner, is just fantasy. Face it, no DE driver comes close to a pro's cornering speed...not even for one corner...period.
Point #2 -- track "conditions" and g-sum. Let's assume your 1.1 is correct. At a track like Watkins Glen, where some turn are banked, and some are off camber, the max g-sum will vary per each corner. By how much? I certainly don't know. My *** DAS (aka, the seat of my pants) tells me it's probably between 0.9 and 1.3 (assuming your baseline of 1.1). Even at a flat track like Gingerman, I’ll bet the max g-sum would vary 10-15% in some corners based on pavement type. So, the theoretical 1.1 is actually more like a range of 1.0 - 1.2 depending on the corner, making it more difficult to determine if you are "at the limit or not".
Believe me, don't believe me. I'm off to Lime Rock tomorrow...yea!
Point #1 -- You believe that your car has a max G-sum of 1.1, and that you have been able to hit that g-sum some of the times on the track. Now, you do admit that a pro would be more consistent than you are, and able to turn faster lap times...and that's a start. But the fact that you think you've ever been close to a pro, even if for only 1 corner, is just fantasy. Face it, no DE driver comes close to a pro's cornering speed...not even for one corner...period.
Point #2 -- track "conditions" and g-sum. Let's assume your 1.1 is correct. At a track like Watkins Glen, where some turn are banked, and some are off camber, the max g-sum will vary per each corner. By how much? I certainly don't know. My *** DAS (aka, the seat of my pants) tells me it's probably between 0.9 and 1.3 (assuming your baseline of 1.1). Even at a flat track like Gingerman, I’ll bet the max g-sum would vary 10-15% in some corners based on pavement type. So, the theoretical 1.1 is actually more like a range of 1.0 - 1.2 depending on the corner, making it more difficult to determine if you are "at the limit or not".
Believe me, don't believe me. I'm off to Lime Rock tomorrow...yea!
09-09-2004, 02:41 PM
#48
Nordschleife Master
Originally Posted by DrJupeman
You have no stamina. My condolences to Mrs. Pesky. 
CC, DRJupeman would be a good "bench test". He runs a 3.6 Turbo with ~1.0 bar boost on a stock suspension & Dunlop Super Sports. His car should have a lower limit than your car since the suspension is 2 generations old. Jupe, any chance of getting the DL90 hooked up for LR to see what your g-sum is?
09-09-2004, 02:54 PM
#49
Still plays with cars.
Lifetime Rennlist
Member
I've been reading this thread and chuckling a little. CC makes a perfectly valid statement when he says that the limits of the machine are what they are and unaffected by the driver. A good driver will use more of the capabilities of the machine than a lesser one.
There is also the question of just how useful skid pad data is in the real world of a race track. IMO skid pad data is valid as long as we are dealing with a steady state flat corner with the same conditions (temp, surface friction etc.).
I also agree with those who say that steady state data and limits derived therefrom are not all that useful. Larry makes this point but not in a way that CC finds acceptable. Larry says that a good driver will get more out of the car than the skid pad shows is possible. Larry is correct.
Consider that if I put all my weight on my left foot I could measure body weight on a scale quite accurately. That would be a steady state measurement. If during the test I bent my left leg, lifted my self and then came down on the same foot, the scale for a few moments show a higher weight. Skiers know all about this. The scale would show that I got lighter then heavier with the average being exactly the same as the steady state measurement. When driving there is a "when" factor which does not apply to the skid pad. A driver will use weight transfer to his advantage by creating that extra weight (and grip) WHEN he needs it. At at that critical point he'll generate more grip than the skid pad says is possible.
He hasn't violated laws of physics or surpassed the capability of the machine he's just using the suspension and tires and their characteristics to his advantage.
Larry's point is that if a car can generate 1.0 G of lateral grip, a talented driver will find ways of generating more than 1.0 by dynamically affecting the weight transfer of the car - giving him more grip for the brief moment when he needs it.
If that doesn't give you the right picture, consider how rally drivers take some corners. Do a skid pad test on loose dirt and the lateral accel will be poor. To get more out of it, a rally driver will transfer weight to the inside wheels then, sling it back to the outside (loaded) wheels to increase the grip just when he needs it. At that point and for a short time he exceeds the steady state grip of a skid pad all else being equal. The great driver will time things to get the extra grip precisely when he needs it.
Now, back to your regularly scheduled arguments ...
There is also the question of just how useful skid pad data is in the real world of a race track. IMO skid pad data is valid as long as we are dealing with a steady state flat corner with the same conditions (temp, surface friction etc.).
I also agree with those who say that steady state data and limits derived therefrom are not all that useful. Larry makes this point but not in a way that CC finds acceptable. Larry says that a good driver will get more out of the car than the skid pad shows is possible. Larry is correct.
Consider that if I put all my weight on my left foot I could measure body weight on a scale quite accurately. That would be a steady state measurement. If during the test I bent my left leg, lifted my self and then came down on the same foot, the scale for a few moments show a higher weight. Skiers know all about this. The scale would show that I got lighter then heavier with the average being exactly the same as the steady state measurement. When driving there is a "when" factor which does not apply to the skid pad. A driver will use weight transfer to his advantage by creating that extra weight (and grip) WHEN he needs it. At at that critical point he'll generate more grip than the skid pad says is possible.
He hasn't violated laws of physics or surpassed the capability of the machine he's just using the suspension and tires and their characteristics to his advantage.
Larry's point is that if a car can generate 1.0 G of lateral grip, a talented driver will find ways of generating more than 1.0 by dynamically affecting the weight transfer of the car - giving him more grip for the brief moment when he needs it.
If that doesn't give you the right picture, consider how rally drivers take some corners. Do a skid pad test on loose dirt and the lateral accel will be poor. To get more out of it, a rally driver will transfer weight to the inside wheels then, sling it back to the outside (loaded) wheels to increase the grip just when he needs it. At that point and for a short time he exceeds the steady state grip of a skid pad all else being equal. The great driver will time things to get the extra grip precisely when he needs it.
Now, back to your regularly scheduled arguments ...
09-09-2004, 03:18 PM
#50
Rennlist Member
Originally Posted by Pesky 914
You'd better have your A game ready for Lime Rock. Btw, where are you staying?
CC, DRJupeman would be a good "bench test". He runs a 3.6 Turbo with ~1.0 bar boost on a stock suspension & Dunlop Super Sports. His car should have a lower limit than your car since the suspension is 2 generations old. Jupe, any chance of getting the DL90 hooked up for LR to see what your g-sum is?
CC, DRJupeman would be a good "bench test". He runs a 3.6 Turbo with ~1.0 bar boost on a stock suspension & Dunlop Super Sports. His car should have a lower limit than your car since the suspension is 2 generations old. Jupe, any chance of getting the DL90 hooked up for LR to see what your g-sum is?
Little chance on DL90, I just haven't had the time.
09-09-2004, 03:20 PM
#52
Originally Posted by DrJupeman
Car has .9 bar boost (look at you looking for excuses!). Yes, I have crappy suspension and crappy tires.
Little chance on DL90, I just haven't had the time.
Little chance on DL90, I just haven't had the time.
09-09-2004, 03:29 PM
#53
Race Director
Originally Posted by Professor Helmüt Tester
"The farther one is from the pointed end of the stick, the more one becomes enamored with minutiae."
09-09-2004, 03:32 PM
#54
Race Director
Originally Posted by Bob Rouleau
I've been reading this thread and chuckling a little. CC makes a perfectly valid statement when he says that the limits of the machine are what they are and unaffected by the driver. A good driver will use more of the capabilities of the machine than a lesser one.
09-09-2004, 03:36 PM
#55
Race Director
Originally Posted by OriginalSterm
i'm just trying to understand where he is coming from. there could be some valid points and something useful in what he is saying. although, i get a LOT of data from driving simulations on my computer, doesn't mean i know how to drive.
Originally Posted by OriginalSterm
it would seem to me, data could be valuable to analyze to find out where you could pick up a tenth or two per lap, but personally i am still cutting seconds and sometimes tens of seconds of my lap times with a real person in the passenger seat with me. data will just tell me what i already know, i'm too SLOW!
09-09-2004, 03:45 PM
#56
Still plays with cars.
Lifetime Rennlist
Member
Geo - Consider how boring it would be around here if CC didn't "stimulate us" from time to time. Heck last week I spent 3 days at the track. CC's theories made me observe very carefully where and how much I trail braked. I was conscious of "unconscious" trail braking.
What I recorded in my notes was that I used trail braking for only 4 of 15 turns. Paying attention to how I was driving, I realized that I was driving the same way as Larry described. Where I didn't trail brake, I would lift to help rotate the car (at my entry speed that was more than enough to do the job) and then get on the gas early. I was also turning in earlier than the standard DE line although my trajectory was the same. I was compensating for the greater slip angle of my heavily loaded tires. Had I trail braked I would have either gone in more slowly or, spun due to over rotation. Lastly I remember driving the same track in a race and I did trail brake more often while racing. This was not to go faster though it was to protect my line into the corner and prevent another racer from trying to pull a heroic rush up the inside of me.
I guess that makes me a bad driver. I'll get over it
So, based on my personal driving I am with my fellow ex racer and instructor Larry Herman. Could it be a GT3 thing?
What I recorded in my notes was that I used trail braking for only 4 of 15 turns. Paying attention to how I was driving, I realized that I was driving the same way as Larry described. Where I didn't trail brake, I would lift to help rotate the car (at my entry speed that was more than enough to do the job) and then get on the gas early. I was also turning in earlier than the standard DE line although my trajectory was the same. I was compensating for the greater slip angle of my heavily loaded tires. Had I trail braked I would have either gone in more slowly or, spun due to over rotation. Lastly I remember driving the same track in a race and I did trail brake more often while racing. This was not to go faster though it was to protect my line into the corner and prevent another racer from trying to pull a heroic rush up the inside of me.
I guess that makes me a bad driver. I'll get over it
So, based on my personal driving I am with my fellow ex racer and instructor Larry Herman. Could it be a GT3 thing?
09-09-2004, 03:55 PM
#57
Rennlist Member
The Professor is back. Could it be time for a Hiaku? 
09-09-2004, 04:17 PM
#58
Three Wheelin'
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Pesky
Point 1. I never said I could take a turn particularly close to the speeds of a pro. First, I don’t know the ideal line at Gingerman (different instructors have different views and I don’t have the driving capability to be able to determine it by myself yet). Secondly, I can’t keep the g-sum high enough consistently enough to call it close. Third, since I have never had a pro drive my car, I don’t have direct data, yet. Do any of you? But I do disagree in principal, I think a blind squirrel can occasionally find a nut and I do believe that on a rare occasion, a hack like me can occasionally take a nice turn, that comes within 5 or 10% of what pro driver might do (at least from the point where his speed matches yours entering the turn) IMO.
Point 2. Yes, you are all correct here, I think. Off camber turns, hills, etc. can change the maximum achievable g-sum for that turn, and it can vary by over 0.4 g’s (maybe more, I haven’t analyzed a lot of different tracks). I will grant you that the true limit of the car even at Gingerman is a range, 1.0 to 1.2 is probably correct IMO. Yes,
Have fun at Lime Rock.
Point 1. I never said I could take a turn particularly close to the speeds of a pro. First, I don’t know the ideal line at Gingerman (different instructors have different views and I don’t have the driving capability to be able to determine it by myself yet). Secondly, I can’t keep the g-sum high enough consistently enough to call it close. Third, since I have never had a pro drive my car, I don’t have direct data, yet. Do any of you? But I do disagree in principal, I think a blind squirrel can occasionally find a nut and I do believe that on a rare occasion, a hack like me can occasionally take a nice turn, that comes within 5 or 10% of what pro driver might do (at least from the point where his speed matches yours entering the turn) IMO.
Point 2. Yes, you are all correct here, I think. Off camber turns, hills, etc. can change the maximum achievable g-sum for that turn, and it can vary by over 0.4 g’s (maybe more, I haven’t analyzed a lot of different tracks). I will grant you that the true limit of the car even at Gingerman is a range, 1.0 to 1.2 is probably correct IMO. Yes,
Have fun at Lime Rock.
Last edited by ColorChange; 09-09-2004 at 04:45 PM.
09-09-2004, 04:36 PM
#59
Nordschleife Master
Originally Posted by ColorChange
Pesky
Point 1. I never said I could take a turn particularly close to the speeds of a pro. First, I don’t know the ideal line at Gingerman (different instructors have different views and I don’t have the driving capability to be able to determine it by myself yet). Secondly, I can’t keep the g-sum high enough consistently enough to call it close. Third, since I have never had a pro drive my car, I don’t have direct data, yet. Do any of you? But I do disagree in principal, I think a blind squirrel can occasionally find a nut and I do believe that on a rare occasion, a hack like me can occasionally take a nice turn, that comes within 5 or 10% of what pro driver might do (at least from the point where his speed matches yours in the turn) IMO.
Point 2. Yes, you are all correct here, I think. Off camber turns, hills, etc. can change the maximum achievable g-sum for that turn, and it can vary by over 0.4 g’s (maybe more, I haven’t analyzed a lot of different tracks). I will grant you that the true limit of the car even at Gingerman is a range, 1.0 to 1.2 is probably correct IMO. Yes,
Have fun at Lime Rock.
Point 1. I never said I could take a turn particularly close to the speeds of a pro. First, I don’t know the ideal line at Gingerman (different instructors have different views and I don’t have the driving capability to be able to determine it by myself yet). Secondly, I can’t keep the g-sum high enough consistently enough to call it close. Third, since I have never had a pro drive my car, I don’t have direct data, yet. Do any of you? But I do disagree in principal, I think a blind squirrel can occasionally find a nut and I do believe that on a rare occasion, a hack like me can occasionally take a nice turn, that comes within 5 or 10% of what pro driver might do (at least from the point where his speed matches yours in the turn) IMO.
Point 2. Yes, you are all correct here, I think. Off camber turns, hills, etc. can change the maximum achievable g-sum for that turn, and it can vary by over 0.4 g’s (maybe more, I haven’t analyzed a lot of different tracks). I will grant you that the true limit of the car even at Gingerman is a range, 1.0 to 1.2 is probably correct IMO. Yes,
Have fun at Lime Rock.
Sounds like we are more or less in agreement then. You should really try to get some rides with different instructors, as I think it really helps driver development.
09-09-2004, 04:51 PM
#60
Use DAS with some pro help is my suggestion.
I have an one off experience using DAS in a formula car.
We were not driving fast at all but the excercise was to give us an idea how DAS would help our driving. We have a pro race engineer reading the graph with us to point out what we did at all corners of the track.
To the best of my memory the pro told us what we did and suggest what we could improve on for each corner.
Through out the entire excercise we never really look at any hard numbers.
We were mainly concentrate on smoothness of the graph or curves.
Absolute numbers can be very dangerous.
I have an one off experience using DAS in a formula car.
We were not driving fast at all but the excercise was to give us an idea how DAS would help our driving. We have a pro race engineer reading the graph with us to point out what we did at all corners of the track.
To the best of my memory the pro told us what we did and suggest what we could improve on for each corner.
Through out the entire excercise we never really look at any hard numbers.
We were mainly concentrate on smoothness of the graph or curves.
Absolute numbers can be very dangerous.