Entry Speed-Fastest Driver Model
03-24-2004, 03:46 PM
#31
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Just to clarify, we are all using generalizations that work only to a point. Each turn is unique and requires a different mix of these few basic techiques... so most "real world" turns deviate from the general model in significant ways.
Also that mix and the "line" used absolutely depends on where that turn is on the track. In order to get the fastest lap time two geometrically identical turns at either ends of a straight will be taken very differently in terms of both braking, line, and throttle application.
Exit speed is not always the goal. For turns at the end of a straight entry speed is generally more important.
And yes, once you have chosen the best strategy for each turn, you want to use as much of the ultimate capability of the car in executing it. DAS can help by allowing you to develop a map of the "ideal" lap and then to compare a given lap against that ideal to identify slips and bobbles, but it is not meaningful in absolute terms.... which in my mind is the inherent flaw in the g max model.
Trail braking is pretty simple in definition... it is braking after you turn the wheel... but it may be done more or less according to what you want to accomplish. Trail braking does three things.... a) extend the braking zone b) manage the weight transitions c) rotate the car.
Depending on the requirements of a given turn you may do it more or less, harder or easier depending on what you need to accomplish. In a slow tight turn the rotation becomes most important... in a fast turn the balance aspect is important.... at the end of a long straight, extending the braking zone to allow later braking is important.
Also that mix and the "line" used absolutely depends on where that turn is on the track. In order to get the fastest lap time two geometrically identical turns at either ends of a straight will be taken very differently in terms of both braking, line, and throttle application.
Exit speed is not always the goal. For turns at the end of a straight entry speed is generally more important.
And yes, once you have chosen the best strategy for each turn, you want to use as much of the ultimate capability of the car in executing it. DAS can help by allowing you to develop a map of the "ideal" lap and then to compare a given lap against that ideal to identify slips and bobbles, but it is not meaningful in absolute terms.... which in my mind is the inherent flaw in the g max model.
Trail braking is pretty simple in definition... it is braking after you turn the wheel... but it may be done more or less according to what you want to accomplish. Trail braking does three things.... a) extend the braking zone b) manage the weight transitions c) rotate the car.
Depending on the requirements of a given turn you may do it more or less, harder or easier depending on what you need to accomplish. In a slow tight turn the rotation becomes most important... in a fast turn the balance aspect is important.... at the end of a long straight, extending the braking zone to allow later braking is important.
03-24-2004, 03:49 PM
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Originally posted by Adam Richman
ColorChange, if you can set up your DA to record segment times, it would be interesting in your next outing to record the data at a school that does the no-braking exercise (several BMWCCA schools do it here in the Southeast). I'd be interested in seeing the time differentials between the no-brake sessions and the normal sessions taken from some point prior to entry to after exiting the turn on a handful of turns. Obviously, lap times would be a somewhat worthless comparison but the segment times immediately preceeding to exiting the turns should have a lot of useful data if you can record them that way. I don't have the math expertise to argue what models work better but I think as in all things that take "feel," there is a difference between what hypothetically could be done and what an individual can physically do.
ColorChange, if you can set up your DA to record segment times, it would be interesting in your next outing to record the data at a school that does the no-braking exercise (several BMWCCA schools do it here in the Southeast). I'd be interested in seeing the time differentials between the no-brake sessions and the normal sessions taken from some point prior to entry to after exiting the turn on a handful of turns. Obviously, lap times would be a somewhat worthless comparison but the segment times immediately preceeding to exiting the turns should have a lot of useful data if you can record them that way. I don't have the math expertise to argue what models work better but I think as in all things that take "feel," there is a difference between what hypothetically could be done and what an individual can physically do.
03-24-2004, 04:08 PM
#33
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Sorry JCP:
From your post:
Yes... if you think about it maximizing cornering or braking Gs is actually bad... assuming speed is equal.... a driver who can get through a turn with fewer braking or cornering Gs is actually driving better... I think one problem here is that Gs do not measure speed.
This is wrong. The driver who can maximize g’s along the right line is going to be the fastest. While g’s do not measure speed directly, the are directly proportional, sometimes to a square functioning.
That said, intuitively, we know that higher Gs are probably better... but if I pull high Gs in a turn by going off the line... that is not good...there is no way to actually measure a "good" G from a "bad" G.... and ranking G's by determing whether they are "on line" or "off line" injects a subjective opinion into the model... essentially the model says "drive the line"... which doesn't really help... because now we have a thread about the "right line"
This I agree with, but I am trying to simplify it by saying maximize the area under the g sum curve but I am still working on that enhancement. Your later posts seem to imply you understand all of this.
Mitch Buddy, I think I can certainly present meaningful data that is worthy of discussion (and I have presented it). I cannot keep my car at 10/10 for a full lap, much less repeated laps. The best I can do is about 9+/10 for turns here and there, with an average between 8/10 to 9/10. I can present data for anyone interested.
For the specific task at hand I can do it. I could enter a turn at max lat g velocity and drive it near the limit. I could then trail brake it near the limit, hitting the same lat g max velocity, and then show the difference. Could I guarantee this firs time out … no. But with a few attempts I certainly could do it, and will when I get my car hooked up!
Adam:
I can already present segment times and do use them as you suggest.
Redlineman:
You still do not have the tb definition right. It is braking DURING turn in or after, turn in. Obviously, the amount of trail braking depends upon the car, the turn, … etc. My only point is, not trailbraking is (almost always) SLOW! And this is exactly what you and others have said, and that was wrong.
I agree with your comments about novice drivers doing this wrongly, but this is not a direct recommendation, simply a discussion about what is fastest.
Regarding your family time comment, I can and do most of my studying when the kids are asleep. Track time means being gone for weekends. There is the rub for me. In general, would I benefit immensely from more seat time … ABSOLUTELY! I am just not willing to pay that price often.
From your post:
Yes... if you think about it maximizing cornering or braking Gs is actually bad... assuming speed is equal.... a driver who can get through a turn with fewer braking or cornering Gs is actually driving better... I think one problem here is that Gs do not measure speed.
This is wrong. The driver who can maximize g’s along the right line is going to be the fastest. While g’s do not measure speed directly, the are directly proportional, sometimes to a square functioning.
That said, intuitively, we know that higher Gs are probably better... but if I pull high Gs in a turn by going off the line... that is not good...there is no way to actually measure a "good" G from a "bad" G.... and ranking G's by determing whether they are "on line" or "off line" injects a subjective opinion into the model... essentially the model says "drive the line"... which doesn't really help... because now we have a thread about the "right line"
This I agree with, but I am trying to simplify it by saying maximize the area under the g sum curve but I am still working on that enhancement. Your later posts seem to imply you understand all of this.
Mitch Buddy, I think I can certainly present meaningful data that is worthy of discussion (and I have presented it). I cannot keep my car at 10/10 for a full lap, much less repeated laps. The best I can do is about 9+/10 for turns here and there, with an average between 8/10 to 9/10. I can present data for anyone interested.
For the specific task at hand I can do it. I could enter a turn at max lat g velocity and drive it near the limit. I could then trail brake it near the limit, hitting the same lat g max velocity, and then show the difference. Could I guarantee this firs time out … no. But with a few attempts I certainly could do it, and will when I get my car hooked up!
Adam:
I can already present segment times and do use them as you suggest.
Redlineman:
You still do not have the tb definition right. It is braking DURING turn in or after, turn in. Obviously, the amount of trail braking depends upon the car, the turn, … etc. My only point is, not trailbraking is (almost always) SLOW! And this is exactly what you and others have said, and that was wrong.
I agree with your comments about novice drivers doing this wrongly, but this is not a direct recommendation, simply a discussion about what is fastest.
Regarding your family time comment, I can and do most of my studying when the kids are asleep. Track time means being gone for weekends. There is the rub for me. In general, would I benefit immensely from more seat time … ABSOLUTELY! I am just not willing to pay that price often.
