Question about counter steering
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as a practical matter, yes. if you are pushing a car very quickly you will at times cross the limit and need to countersteer. it's flat out dangerous to attempt to drive a car quickly without knowing how to catch a slide. i'd rather start out on the skid pad at 12/10ths and learning about physics rather than have someone on a race track at 6/10ths and pretend they are making progress by being smooth and hitting apexes.
theoretically though, if a computer could drive a car at the exact slip angle where grip is maximized exactly on the limit at all times then countersteering would not be required to go faster. see wiki for Nissan GTR.
theoretically though, if a computer could drive a car at the exact slip angle where grip is maximized exactly on the limit at all times then countersteering would not be required to go faster. see wiki for Nissan GTR.
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From: Seattle, WA
Originally Posted by nissanfanatic,Jul 20 2010, 10:28 PM
If you search on youtube for a video that has logs of Schumaker's driving, it specifically annotates how he is constantly employing both steering angle correction and throttle modulation.
Originally Posted by PedalFaster,Jul 20 2010, 09:14 PM
Click on that.
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I'm pretty sure that even a computer driven car will cross the limit. Based on typical PLC understanding, the input would be increased until an error signal is generated from monitored parameters. The computer would remove input until ther error signal is infinitesimal but still continue to try and apply more input and watch for error signal to be present again, and then remove input again until the error signal is, again infinitesimal. Though, the corrections would be so minute, they would probably not be detectable by visual observations and it would appear that the car is being driven at the very limit with no correction when in fact, the computer is actually in a state of constant very minute correction.
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Originally Posted by nissanfanatic,Jul 20 2010, 09:06 PM
You are, more or less, letting the front of the car move proportionate to the rear of the car that has lost traction to keep the car from rotating and beginning to yaw. It is very similar to reducing steering angle input as slip angle begins to reduce overall tractive capacity. If you continue to increase steering input, slip angle increases and traction decreases. In this instance, all wheels are increasing slip angle as they are all being oriented in a direction that does not coincide with the trajectory of the CoG.
Very, very slight amounts of countersteer indicate that the rear of the car is at its traction limits. On a car with understeer, you would ideally never have to countersteer unless you provide inputs that put the car into an oversteer state (power-oversteer or scandinavian flick). Some cars that exhibit understeer can be countered by applying throttle proportionate to the remaining tractive capacity of the rear wheels. This would be the problem of driving the limit, as you will also demand more of the front tires at the same time. In designing a vehicle, the front and rear tires should be equally taxed with traction requirements, though things such as instantaneous weight transfer, fluid shifting, and driving forces can make this quite difficult. You should drive in a manner that taxes all tires with the maximum amount of tractive capability whether it be from lateral acceleration or applying driving force.
I would say an understanding of the car's physical limits and dynamic behavior can tell you whether the car is at it's limits or not. You can always let a known better driver take your car out for a few laps as well and datalog them. That is typically what I do. Sometimes, you can even be suprised by novice drivers who take a fresh approach to either the track or your car and can prove to be faster in a couple of areas.
This is also why it is important to do skidpad and braking tests while datalogging so you know what the capability of your car is and compare that to what youir car is doing on track. Driving a car as fast as possible is all about maintaining the highest level of acceleration in the appropriate direction.
Very, very slight amounts of countersteer indicate that the rear of the car is at its traction limits. On a car with understeer, you would ideally never have to countersteer unless you provide inputs that put the car into an oversteer state (power-oversteer or scandinavian flick). Some cars that exhibit understeer can be countered by applying throttle proportionate to the remaining tractive capacity of the rear wheels. This would be the problem of driving the limit, as you will also demand more of the front tires at the same time. In designing a vehicle, the front and rear tires should be equally taxed with traction requirements, though things such as instantaneous weight transfer, fluid shifting, and driving forces can make this quite difficult. You should drive in a manner that taxes all tires with the maximum amount of tractive capability whether it be from lateral acceleration or applying driving force.
I would say an understanding of the car's physical limits and dynamic behavior can tell you whether the car is at it's limits or not. You can always let a known better driver take your car out for a few laps as well and datalog them. That is typically what I do. Sometimes, you can even be suprised by novice drivers who take a fresh approach to either the track or your car and can prove to be faster in a couple of areas.
This is also why it is important to do skidpad and braking tests while datalogging so you know what the capability of your car is and compare that to what youir car is doing on track. Driving a car as fast as possible is all about maintaining the highest level of acceleration in the appropriate direction.
Very, very slight amounts of countersteer indicate that the rear of the car is at its traction limits.
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Originally Posted by nissanfanatic,Jul 20 2010, 10:00 PM
I'm pretty sure that even a computer driven car will cross the limit. Based on typical PLC understanding, the input would be increased until an error signal is generated from monitored parameters. The computer would remove input until ther error signal is infinitesimal but still continue to try and apply more input and watch for error signal to be present again, and then remove input again until the error signal is, again infinitesimal. Though, the corrections would be so minute, they would probably not be detectable by visual observations and it would appear that the car is being driven at the very limit with no correction when in fact, the computer is actually in a state of constant very minute correction.
Being an elite driver, in my opinion, is having the ability to get the car to the limit in such a way that is as fast as possible (corner entry) while allowing you to correct a slide if it happens very quickly through the rest of the corner. I find that a lot of people are more comfortable after turn in and at exit...the hard part is your entry as typically that includes trail braking and other maneuvers that can really upset the balance.
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From: NOVA DC area
I am an instructor for NASA, SCCA, Porsche and other schools; I even instructed race car drivers in Dubai. Anyhow, to answer your question. The fastest lap/drive when your car is on the slip angle (notice you are not sliding yet) Drift and slide are slow. However, if you have full traction it means you are not 9 ~ 10 or 10 10... (btw no one drives 10 10, maybe in few turns but it can’t be done in a full lap)
With that being said, if everything seemed under control you are not going fast enough
it should be hairy… I have a video of me on youtube counter steering left and right… It was a little more than what I wanted but watch it
With that being said, if everything seemed under control you are not going fast enough
it should be hairy… I have a video of me on youtube counter steering left and right… It was a little more than what I wanted but watch it
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From: NOVA DC area
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From: Azusa
My short answer:
Yes, driving at the limit of traction requires frequent corrections which involve increasing or decreasing the steering angle rapidly. No, it does not involve very large angle countersteer being held continuously.
Yes, driving at the limit of traction requires frequent corrections which involve increasing or decreasing the steering angle rapidly. No, it does not involve very large angle countersteer being held continuously.
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From: Marietta, Ga
I have tried to approach this in a stages type of way. I learn the fast lines of a course at 7/10ths without any counter steering.
I pick up speed and find the limits of each turn. If you are going to fast you will be overcorrecting to hit the right line. It can be easy to push the car too hard and increase the distance traveled killing your lap.
Finding the limit on a safe track is a great idea. Too much steering input to push the slip angle over the edge and catching it is great practice. As you get used to it you can focus on bribing it to the limit using your entry speed and trying not to upset the car as much.
I pick up speed and find the limits of each turn. If you are going to fast you will be overcorrecting to hit the right line. It can be easy to push the car too hard and increase the distance traveled killing your lap.
Finding the limit on a safe track is a great idea. Too much steering input to push the slip angle over the edge and catching it is great practice. As you get used to it you can focus on bribing it to the limit using your entry speed and trying not to upset the car as much.