red376 - 04 April 2008 05:24 PM

speedsense - 04 April 2008 03:02 PM

Yes I do spend too much time behind computer screens, but at the racetrack reading data on them and setting them up and massaging the driver's brain to go faster.....
JMHO..
Speedsense

Your opinion is that you massage driver's brains to make a car go faster? Sounds more like a statement...

You're putting way too much emphasis on slip angle, which I'm not fully convinced you know the whole story, to roll thru the center.

Among the other multitudes of changes one can make to the car to fix a loose or push condition, your fixes are bassackwards. A car with too much rear weight will be loose. Think of the weight in the rear of the car as a pendulum, and the weight will want to make the back of the car pass the front.

With data, one can observe every single movement a driver makes, more times per second than the drivers reaction time.. While really good drivers that have excellent recall can describe a lot of what they are feeling in the car, with a data system that recall is strengthen by 20-30 times, this is what I mean by massaging their brains....

"You're putting way too much emphasis on slip angle, which I'm not fully convinced you know the whole story, to roll thru the center."

The Slip angle is everything when one takes a issue with handling. Too much slip angle (as you stated, too much weight being one reason of many) and the car will slide losing time because it exceeded the slip angle of the tires. Not bringing the car all the way up to the full slip angle of tires, will also result in slower laptime.
When the slip angle of the tires is at it's maximum throughout the entry, middle and exit and maximum at both ends of the car, then the car would not only be at it's fastest, it could also be considered perfectly balanced. If you were to observe a car at full tire slip from outside the corner, say on the exit, you would observe that car's path as being slightly wider than where the body was pointing
Now hopefully understanding how important slip angle is, CAR ROTATION (the kind induced by the driver which I believe the reason this thread was started) is when the body or chassis direction is changed for a straighter exit out of the corner, and when done correctly is within the slip angle of the tires. This means to NOT induce a loose condition and slide the car (thus losing time). This is car rotation.

AND having too much weight on one end of the car can also create problems as well with that end of the car. The condition you describe with the rear having too much weight could create a loose condition, until the throttle went down, then it would more likely create a push condition on the exit, at least on a Cup it would.
My explainations where not "Fixes" for handling problems, but examples of what happens to a car as it moves through a corner and the weight transfer that follows with it. Movement (or transfer) of weight and tire slip are ingredients of car rotation. You can't have car rotation without them.
Rolling through the center of the corner, is probably the most stable condition of handling that you can have. A FAR, FAR cry from car rotation, at least from the perspective of handling or for that matter the perspective of a very knowledgable, experienced PRO driver.
JMHO
Speedsense

speedsense - 02 April 2008 11:37 AM

hobbymanbill - 02 April 2008 11:04 AM

To me it always meant that I could steer left for turn in and hold a steering setting while off the throttle and on the brake. At that point as I started to ease out of the brake and back on the throttle the car would take a set and further steering inputs were not required. As I completely released the brake and pushed the gas to the floor the car would mostly straighten out by me just easing pressure on the wheel. In other words, the turn in and off are one long smooth operation without having any push or loose condition in the car. The car just "Rotates through the corner".

Bill

Relates mostly to driving on pavement.
Imagine that the tires are rubber bands able to flex and move around the rim. In technical terms could be classified as slip angle.
Under braking and turning on entry, the majority of weight is on the front tires, when the car reaches the center of the corner usually there's no more braking and the car's balance and weight is just about equal on both right tires. A slight movement of the steering wheel to point the nose of the car to the inside of the corner WITHOUT sliding the car and just enough to "FLEX" the rubber bands (tires) so that pointing the car's nose further inside the corner is possible ALLOWS the throttle to be applied sooner and more aggressively because the car is now pointed a little straighter for the exit and allows more throttle and higher speed to be used.....
If all this happens without sliding the car then it will be quicker, sliding the car will slow you down below smoothly exiting. Car rotation can also be used to help drive around a pushing car.

dead center on the nail.

KartCMP1 - 04 April 2008 06:37 PM

speedsense - 02 April 2008 11:37 AM

hobbymanbill - 02 April 2008 11:04 AM

To me it always meant that I could steer left for turn in and hold a steering setting while off the throttle and on the brake. At that point as I started to ease out of the brake and back on the throttle the car would take a set and further steering inputs were not required. As I completely released the brake and pushed the gas to the floor the car would mostly straighten out by me just easing pressure on the wheel. In other words, the turn in and off are one long smooth operation without having any push or loose condition in the car. The car just "Rotates through the corner".

Bill

Relates mostly to driving on pavement.
Imagine that the tires are rubber bands able to flex and move around the rim. In technical terms could be classified as slip angle.
Under braking and turning on entry, the majority of weight is on the front tires, when the car reaches the center of the corner usually there's no more braking and the car's balance and weight is just about equal on both right tires. A slight movement of the steering wheel to point the nose of the car to the inside of the corner WITHOUT sliding the car and just enough to "FLEX" the rubber bands (tires) so that pointing the car's nose further inside the corner is possible ALLOWS the throttle to be applied sooner and more aggressively because the car is now pointed a little straighter for the exit and allows more throttle and higher speed to be used.....
If all this happens without sliding the car then it will be quicker, sliding the car will slow you down below smoothly exiting. Car rotation can also be used to help drive around a pushing car.

dead center on the nail.

Thank You.

This is very very good.... Thank heavens nobody tossed in 'Polar Moment of Inertia"...


Relates mostly to driving on pavement.
Imagine that the tires are rubber bands able to flex and move around the rim. In technical terms could be classified as slip angle.
Under braking and turning on entry, the majority of weight is on the front tires, when the car reaches the center of the corner usually there's no more braking and the car's balance and weight is just about equal on both right tires. A slight movement of the steering wheel to point the nose of the car to the inside of the corner WITHOUT sliding the car and just enough to "FLEX" the rubber bands (tires) so that pointing the car's nose further inside the corner is possible ALLOWS the throttle to be applied sooner and more aggressively because the car is now pointed a little straighter for the exit and allows more throttle and higher speed to be used.....

JAGXK120 - 07 April 2008 07:00 PM

This is very very good.... Thank heavens nobody tossed in 'Polar Moment of Inertia"...

We can, if you like. It was tossed around a few months ago.

JAGXK120 - 07 April 2008 07:00 PM

This is very very good.... Thank heavens nobody tossed in 'Polar Moment of Inertia"...


Relates mostly to driving on pavement.
Imagine that the tires are rubber bands able to flex and move around the rim. In technical terms could be classified as slip angle.
Under braking and turning on entry, the majority of weight is on the front tires, when the car reaches the center of the corner usually there's no more braking and the car's balance and weight is just about equal on both right tires. A slight movement of the steering wheel to point the nose of the car to the inside of the corner WITHOUT sliding the car and just enough to "FLEX" the rubber bands (tires) so that pointing the car's nose further inside the corner is possible ALLOWS the throttle to be applied sooner and more aggressively because the car is now pointed a little straighter for the exit and allows more throttle and higher speed to be used.....

The Polar Moment of Inertia has been cancelled due to global warming.....

speedsense - 04 April 2008 06:10 PM

red376 - 04 April 2008 05:24 PM

speedsense - 04 April 2008 03:02 PM

Yes I do spend too much time behind computer screens, but at the racetrack reading data on them and setting them up and massaging the driver's brain to go faster.....
JMHO..
Speedsense

Your opinion is that you massage driver's brains to make a car go faster? Sounds more like a statement...

You're putting way too much emphasis on slip angle, which I'm not fully convinced you know the whole story, to roll thru the center.

Among the other multitudes of changes one can make to the car to fix a loose or push condition, your fixes are bassackwards. A car with too much rear weight will be loose. Think of the weight in the rear of the car as a pendulum, and the weight will want to make the back of the car pass the front.

With data, one can observe every single movement a driver makes, more times per second than the drivers reaction time.. While really good drivers that have excellent recall can describe a lot of what they are feeling in the car, with a data system that recall is strengthen by 20-30 times, this is what I mean by massaging their brains....

"You're putting way too much emphasis on slip angle, which I'm not fully convinced you know the whole story, to roll thru the center."

The Slip angle is everything when one takes a issue with handling. Too much slip angle (as you stated, too much weight being one reason of many) and the car will slide losing time because it exceeded the slip angle of the tires. Not bringing the car all the way up to the full slip angle of tires, will also result in slower laptime.
When the slip angle of the tires is at it's maximum throughout the entry, middle and exit and maximum at both ends of the car, then the car would not only be at it's fastest, it could also be considered perfectly balanced. If you were to observe a car at full tire slip from outside the corner, say on the exit, you would observe that car's path as being slightly wider than where the body was pointing
Now hopefully understanding how important slip angle is, CAR ROTATION (the kind induced by the driver which I believe the reason this thread was started) is when the body or chassis direction is changed for a straighter exit out of the corner, and when done correctly is within the slip angle of the tires. This means to NOT induce a loose condition and slide the car (thus losing time). This is car rotation.

AND having too much weight on one end of the car can also create problems as well with that end of the car. The condition you describe with the rear having too much weight could create a loose condition, until the throttle went down, then it would more likely create a push condition on the exit, at least on a Cup it would.
My explainations where not "Fixes" for handling problems, but examples of what happens to a car as it moves through a corner and the weight transfer that follows with it. Movement (or transfer) of weight and tire slip are ingredients of car rotation. You can't have car rotation without them.
Rolling through the center of the corner, is probably the most stable condition of handling that you can have. A FAR, FAR cry from car rotation, at least from the perspective of handling or for that matter the perspective of a very knowledgable, experienced PRO driver.
JMHO
Speedsense

The slip angle is the angle of flex from the sidewall of the tire, it's not something you can necessarily adjust like a spring or shock change. You say that slip angle is everything, I say grip is everything. Will the slip angle change from how much grip each tire can provide? Yes. Grip is what teams and drivers look for, not slip angles. There is a limit to how much 'stick' the tires can produce, just like the track surface can only provide so much adhesion, an who capitalizes the most out of the two surfaces meeting is who's fastest thru the turns.

red376 - 12 April 2008 03:51 PM

speedsense - 04 April 2008 06:10 PM

red376 - 04 April 2008 05:24 PM

speedsense - 04 April 2008 03:02 PM

The slip angle is the angle of flex from the sidewall of the tire, it's not something you can necessarily adjust like a spring or shock change. You say that slip angle is everything, I say grip is everything. Will the slip angle change from how much grip each tire can provide? Yes. Grip is what teams and drivers look for, not slip angles. There is a limit to how much 'stick' the tires can produce, just like the track surface can only provide so much adhesion, an who capitalizes the most out of the two surfaces meeting is who's fastest thru the turns.

"The slip angle is the angle of flex from the sidewall of the tire, it's not something you can necessarily adjust like a spring or shock change."
Flex of the sidewall is part of slip angle, and has more to do with the "flexing of the contact patch" and is following a path that is different to the path of the wheel by 5-8 degrees different depending on the tire construction and compound. Typically a Cup at full cornering is pushing 7 degrees of slip angle.
No you can't change the slip angle of the tire, you can however massage it slightly with tire pressure.
Grip (in corners) has everything to do with slip angle, you don't have "grip" until you generate a slip angle, exceed the max. slip angle of the tire, and you exceed it's grip. Maximum slip angle of the tire=maximum grip. We are talking about the same thing.

"There is a limit to how much 'stick' the tires can produce, just like the track surface can only provide so much adhesion, an who capitalizes the most out of the two surfaces meeting is who's fastest thru the turns."

There is a limit to how much slip angle the tires can produce, IS saying the exact same thing.
An easy way to understand this concept would be to take a ballon that you can see through, draw a line on the top and bottom of the ballon. Place the ballon with your hand on top, apply a slight downward pressure so the ballon flattens slighly against the floor. With the line on top and on the bottom. The flat area on the floor is the contact patch, the pressure from your hand is the wheel and corner weight of the car. Notice that the two lines are still parallel to each other. Now while maintaining the downward pressure twist the ballon, this is g force or cornering force. Notice the two lines no longer align with each other, this is the slip (in degrees) of the ballon. If you continue to add twisting movement, you will eventually break the grip/slip angle on the floor. It is at this point a car would start sliding and has lost grip.
Also you may notice that if you increase the weight on the ballon you increase the size of the contact patch and the slip angle. The only thing missing is that the ballon needs to rotate to act like a tire. This will lessen the slip angle/grip slightly.
All of these work very much like a tire does on a car.

Traction circle ... coefficient of friction ... slip angles. All related to each other but not necessarily the same. This is a good read:

http://www.teamassociated.com/racerhub/techhelp/marc/Handling.2.html

Slip angles are different at every corner of the car whenever cornering forces are at work. Grip is dependent upon both slip angle and cf.

gray area - 12 April 2008 04:44 PM

Traction circle ... coefficient of friction ... slip angles. All related to each other but not necessarily the same. This is a good read:

http://www.teamassociated.com/racerhub/techhelp/marc/Handling.2.html

Slip angles are different at every corner of the car whenever cornering forces are at work. Grip is dependent upon both slip angle and cf.

I think you mean CT...? Coefficent of Traction... yes?
Any change in CT means a change in what the tire sees, add more weigh, you change that tires slip angle and it's grip. They work hand in hand is my point and are the same when it comes to cornering. Grip in straight line acceleration is a completely different topic all together.
I am merely trying to keep this conversation simple and accurate.
I have met very experienced drivers that could not explain the difference between slip angle, drifting and sliding. Simply put, this is probably the most misunderstood topic in racing....
The tire always has the final say in how a car handles, everything that is done to make a car handle, is done to affect how the tire works. Neglecting to understand how a tire works in a corner has led many a team in the wrong direction.......