Define: Tyre Grip

[munks]

I'm not precisely sure what Greg's argument is, but I sure as heck don't see how those graphs "prove" that sentence. I believe the sentence to be riddled with assumptions. By playing with toe or camber, for example, you could negotiate a whole turn with at least one tire at no significant slip angle. And that's not to mention transient maneuvers.

[amouzouris]

Those graphs show that with 0 degrees of slip angle the coefficient of friction is 0. Furthermore, in order to explain something you isolate it. In this case the depended variable is the Coefficient of Friction and the independent variable is the slip angle.

[GSpeedR]

Those graphs show that with 0 degrees of slip angle the coefficient of friction is 0. Furthermore, in order to explain something you isolate it. In this case the depended variable is the Coefficient of Friction and the independent variable is the slip angle.

amouzouris, I think you are being a bit too general. A vehicle will change direction (accelerate) in response to external forces, which could be aerodynamic or gravity or some "assistance" from another vehicle. This can occur whether tires are generating force reactions or not; some people have probably experienced the helpless feeling on sliding sideways on a banked icy road with no way to stop it. Your last plot also only describes one mechanism of generating "grip"; as munks mentioned, a cambered tire can develop lateral thrust without a slip angle deflection. Add in tire asymmetries (plysteer, etc) and suddenly the real world isn't as simple as what that plot might indicate.

[amouzouris]

Exactly..as i have said before..explanation on camber etc will follow on part3...i am isolating each variable and explaining it...

[ubrben]

Mistake in the second sentence, didn't bother reading the rest.

Greg..as far as my second sentence is concerned..which i assume you mean "For the vehicle to change direction, regardless of road speed, each of the 4 tires of the vehicle must have some slip angle." it is not wrong..and i can prove it..

You're wrong - sorry.

Assume a vehicle travelling in a straight line. Turning the steering wheel generates slip angle at the front tyres, and therefore lateral force. This lateral forces yaws the car (changing it's heading, or direction if you will...) and generate rear slip angle, and subsequently lateral force at the rear tyres some time after the vehicle has started to change direction.

I suggest you learn a bit more about the subject before presuming to be able to write authoritative (sounding) articles about it, and I'd also suggest as JT has suggested crediting the source of "your" illustrations.

Ben

[ubrben]

Exactly..as i have said before..explanation on camber etc will follow on part3...i am isolating each variable and explaining it...

The fact that you're claiming copyright:

http://technicalf1explained.blogspot.co ... right.html

And soliciting donations:

http://technicalf1explained.blogspot.co ... tions.html

Is just F-ing hilarious...

Ben

[Greg Locock]

Thanks Ben. A shopping trolley with 4 castored wheel generates zero slip angles at all 4 wheels, and is famously uncontrollable. Lock one of those castors and it will turn, yet 3 of the 4 wheels are still generating zero slip angles. More realistically it is not very unusual for the rear axle of a car to travel at zero slip at some point when performing a swept steer manouevre.

[olefud]

There are a couple of things to take into consideration before becoming dogmatic. When turning a car is arcing about a single point, i.e. a turn center. The tires are usually but not necessarily each developing both side and drag thrusts. The side thrusts, and certainly the drag thrusts, are not usually aligned with the turn center. Thus the portion of the side thrust aligned through the turn center generates the effective turning thrust while that portion not aligned dumps into drag. Differential drag can rotate the car around its own axis but does not contribute to turning around the turn center, i.e. centrifugal balanced with centripetal forces.

Put another way, a tire can be at its optimum slip angle and developing great thrusts while only marginally contributing to turning the car. There’s more to it than “grip”.

[Jersey Tom]

Well..you are not mistaken..they are similar to Caroll Smith's illustrations but tehy are not his...because of copyright rules i made my illustrations which are similar

Dude, c'mon now.

So you're telling me that these...






Aren't a complete rip off / duplication of these...? Yours is your own work and unique?



Right. Taking someone's presented data and digitizing it, and/or adding some colors instead of plain black and white.. does not make it your own work. You can't scan the Mona Lisa, change one pixel from black to red, then claim it as your own.

To Ben's point, going the step beyond giving no credit and then claiming copyright and asking for donations is some mixture of absurd, outrageous, comical, and embarrassing.

[munks]

Outside of Smith's book (amusingly next to a bottle of Smithwick's which I didn't know you could buy here, although I've had it mixed with Guinness at an Irish restaurant, referred to as a 'BlackSmith'), I've never really seen slip curves that look quite like that. Which of course made it a dead giveaway.

[amouzouris]

@JT i have not claimed that the graphs are mine....if i did then i would have watermarked them with my copyright logo...furthermore, i already said that they are similar...notice them carefully and you will see yourself that there are differences...

@Greg In my explanation i am talking about pneumatic tires...not casters on a shopping trolley...

@urben this conversation is getting out of hand so if you have any problems with my blog or me...please pm me...and lets keep this thrwad technical

@munks the fact that you have never seen a slip angle curve like the one i used for my blog or the other 2 i posyed...doesnt make them wrong

[Greg Locock]

I was giving simple examples that were easy to understand. I also pointed out that real cars often develop zero slip at one or two tires during quite simple manouevres, which you have ignored.

[ubrben]

@urben this conversation is getting out of hand so if you have any problems with my blog or me...please pm me...and lets keep this thrwad technical

Ok, lets keep it technical. What is your view on my post explaining why your second sentence was incorrect?

Ben

[Jersey Tom]

@JT i have not claimed that the graphs are mine

Ok. Then on your blog you should give credit that you've taken them from Tune to Win, and aren't directly from your own data, research, or experience.

i already said that they are similar...notice them carefully and you will see yourself that there are differences...

There are differences, yes. You did change a scale from pounds to kilograms. But that's not enough to make it your own. Honestly I'm not trying to make this an attack, this is me trying to help you out. I'll tell you right now, given how many people out there have Tune to Win... putting that stuff in there with no citation or reference and having the authoritative voice that its your information is not going to bode well for your own image or credibility.

I'll put it to you this way. Right now you're coming across a lot like this guy (skip ahead to 1 min 45 sec).

[youtube]http://www.youtube.com/watch?v=1s0hEi8zhmg[/youtube]

[amouzouris]

Ok..because i am getting tired of this...if you even bothered to look in my blog you would see that i had put e note at the bottom mentioning his book...instead of going to my blog just to make fun of me or my copyright page or my donations page.

The graphs i posted yesterday in the previous page DO prove that the my second sentence IS correct...if you look at both graphs you will see that at zero slip angle the coefficient of friction developed is 0... If you don't see how this proves it then it is your problem..not mine...

The tires are elastic in twist...if you have ever handled a tire you will know what i am talking about...even with the tiniest changes in direction there is slip angle developed...this is basic theory about tires...

EDIT: unless someone comes up with a decent explanation or proof that I am wrong i will not answer because I refuse to take part in this kind of conversation