Friction Circle - the reality
08-08-2004, 11:16 AM
#31
Lifetime Rennlist Member
Thread Starter
Originally Posted by 924RACR
Mmmm... I am an engineer, Mechanical by training, specializing in Vehicle Dynamics (though admittedly of a different sort than the Ross Brawns et al of this world), and spend far more time than I'd care to admit in fully-instrumented cars doing nothing but taking data, analyzing it, and re-running with revised tuning. But I try not to admit it too often - if for nothing else than the fact, or at least my perception, that engineers seem to be one of the least humble groups of professionals out there!!! I try in fact to bring up that qualification only when it directly applies to the discussion at hand - ABS/TCS/ESP systems.
Beyond that, I'm still a mid-level racer trying to learn how to improve my (on racetrack) driving ability from the data I gather, and have a difficult enough time trying to boil down two simple channels enough to draw conclusions! Just evaluating AY and speed on one track (Waterford Hills) are challenging enough, for me. When I get more sensors hooked up (I'm going for yaw rate and decel, plus maybe throttle and steering if I feel like working up a steering angle sensor), I'll really be swamped by the noise.
As a personal aside, if anyone else out there has their own data from Waterford and/or would be interested in looking at mine and giving feedback, I'd be happy to send my data (AIM system). I've only had one weekend on track with data, so still am working my way into it.
Mark - good luck at the Rub-Offs! (spoken like a true IT driver!
Beyond that, I'm still a mid-level racer trying to learn how to improve my (on racetrack) driving ability from the data I gather, and have a difficult enough time trying to boil down two simple channels enough to draw conclusions! Just evaluating AY and speed on one track (Waterford Hills) are challenging enough, for me. When I get more sensors hooked up (I'm going for yaw rate and decel, plus maybe throttle and steering if I feel like working up a steering angle sensor), I'll really be swamped by the noise.
As a personal aside, if anyone else out there has their own data from Waterford and/or would be interested in looking at mine and giving feedback, I'd be happy to send my data (AIM system). I've only had one weekend on track with data, so still am working my way into it.
Mark - good luck at the Rub-Offs! (spoken like a true IT driver!
You are on the right track. If you can get someone else's data - esp if they are a bit faster in a similar car, then you will get the most possible out of data aq (or get a faster driver to drive your car).
Thanks re:rub-offs. We do a little of that too. LOL
08-08-2004, 03:44 PM
#32
Nordschleife Master
Being a great engineer doesn't make you a great driver.
Being a great driver doesn't make you a great engineer.
The problem is that of those it is driving ability that is most measureable. I'm also unsure that engineers are less humble than Porsche racers. That'd be a tall order.
Going back, waaaay back, in the thread to the initial point, the Friction Circle is a very useful and, yes, real thing. Viewing is at the vehicle level is useful for teaching but the better application is at each wheel. Also, the "circle" is more likely an oval (more foreaft) and changes shape and size with conditions and the weight applied.
Here's a test: corner at the limit and then apply full power. Back swing out? That'd be expected as the two forces (sideways and longitudinally) have combined to be more than the tires can support. And that's the FC.
No, I don't expect that top drivers bother with such mundane things.
Being a great driver doesn't make you a great engineer.
The problem is that of those it is driving ability that is most measureable. I'm also unsure that engineers are less humble than Porsche racers. That'd be a tall order.
Going back, waaaay back, in the thread to the initial point, the Friction Circle is a very useful and, yes, real thing. Viewing is at the vehicle level is useful for teaching but the better application is at each wheel. Also, the "circle" is more likely an oval (more foreaft) and changes shape and size with conditions and the weight applied.
Here's a test: corner at the limit and then apply full power. Back swing out? That'd be expected as the two forces (sideways and longitudinally) have combined to be more than the tires can support. And that's the FC.
No, I don't expect that top drivers bother with such mundane things.
08-08-2004, 06:31 PM
#33
Lifetime Rennlist Member
Thread Starter
Originally Posted by GlenL
Being a great engineer doesn't make you a great driver.
Being a great driver doesn't make you a great engineer.
The problem is that of those it is driving ability that is most measureable. I'm also unsure that engineers are less humble than Porsche racers. That'd be a tall order.
Going back, waaaay back, in the thread to the initial point, the Friction Circle is a very useful and, yes, real thing. Viewing is at the vehicle level is useful for teaching but the better application is at each wheel. Also, the "circle" is more likely an oval (more foreaft) and changes shape and size with conditions and the weight applied.
Here's a test: corner at the limit and then apply full power. Back swing out? That'd be expected as the two forces (sideways and longitudinally) have combined to be more than the tires can support. And that's the FC.
No, I don't expect that top drivers bother with such mundane things.
Being a great driver doesn't make you a great engineer.
The problem is that of those it is driving ability that is most measureable. I'm also unsure that engineers are less humble than Porsche racers. That'd be a tall order.
Going back, waaaay back, in the thread to the initial point, the Friction Circle is a very useful and, yes, real thing. Viewing is at the vehicle level is useful for teaching but the better application is at each wheel. Also, the "circle" is more likely an oval (more foreaft) and changes shape and size with conditions and the weight applied.
Here's a test: corner at the limit and then apply full power. Back swing out? That'd be expected as the two forces (sideways and longitudinally) have combined to be more than the tires can support. And that's the FC.
No, I don't expect that top drivers bother with such mundane things.
I'm not clear on what you are trying to convey. My sense is that pretty much everyone in this thread (including and especially me) understands what the friction circle implies and feels it is a good teaching tool as a concept. What is being discussed/challenged is the value of drawing a g-g graph and whether there is anyting to be learned from that, which can not be better learned with other graphical tools. I would hope that all performance drivers bother with the 'mundane' concept that adding power when you are at the cornering limit will cause the tail to step out. I doubt that any top drivers examine a friction circle drawing (g-g graph) so try to learn anything they can take out for their next session.
Can you elaborate on your point please? THX
08-08-2004, 07:29 PM
#36
Nordschleife Master
SundayD,
Not debating the g-g graph thing. Just seemed that folks were getting away from the technical.
Geo,
Absolutely! Whatever the graph shows, the goal is to minimize time. Not maximize g forces or have the most power. DJs addition is correct, too.
Not debating the g-g graph thing. Just seemed that folks were getting away from the technical.
Geo,
Absolutely! Whatever the graph shows, the goal is to minimize time. Not maximize g forces or have the most power. DJs addition is correct, too.
08-08-2004, 08:21 PM
#37
Race Director
Well, I just got off the phone with my buddy.
Q. How long to pro drivers spend looking at a FC plot?
A. Virtually never.
As has been said many times, there are so many other more important and beneficial things to look at.
Q. How long to pro drivers spend looking at a FC plot?
A. Virtually never.
As has been said many times, there are so many other more important and beneficial things to look at.
08-09-2004, 01:08 PM
#39
Only the wall is truth
Arguement is shadow and pride
The wall will always listen
(Thought it was time for some lo-ku)
Sunday... when you take the car past the fc, isn't it a good thing that you are too dumb to know any better?
Good luck.
BTW one of my favorite quotes" "great race drivers are charactorized by a total lack of imagination"
Arguement is shadow and pride
The wall will always listen
(Thought it was time for some lo-ku)
Sunday... when you take the car past the fc, isn't it a good thing that you are too dumb to know any better?
Good luck.
BTW one of my favorite quotes" "great race drivers are charactorized by a total lack of imagination"
