It's all about mu

[jvincent]

Originally Posted by mrceltic

Double or nothing; Suberman apologizes to Maloney for his personal attack and admits he's a paralegal of average intelligence.

No bet. I only have room for one car. On the other hand I would be taking the oversteering defective monster off your hands.....

[wparsons]

Originally Posted by Jagular

None of the posters actually understood what I wrote. I'm not sure if anyone understood what they thought I wrote. I have implemented a policy of never responding to wparsons as he is clearly an idiot, or so good at imitating an idiot no one can tell he's not really an idiot.

Bullshit, you just can't find something to disprove what I'm saying. I've made direct references to posts made by guys from RCE and CSG that say exactly what I've been saying, yet you chose to ignore that so you don't have to admit that you're wrong.

Originally Posted by MrSmith

Most hilarious was the comment on Stig's lap in the 458. About the only places the Stig does allow a bit of oversteer is at the apex of hammerhead (logical, it's a tight bend and a transition bend, hence the name) and on the exit to hammerhead. All the remaining corners clearly show the 458 with the front wheels turned somewhat into the corner, as you would expect from an expert driver. I believe that's Ben Collins. I don't think many drivers in the world could beat Collins on that track although Rubens Barrichello did....

Most hilarious is the irony in you commenting on MY comment about the 458 immediately after stating you have a policy of not commenting on my posts. Brilliant.

The bolded part needs to be kept right at the forefront of any argument you make though. I find it very amusing that you honestly believe a car can't be oversteering unless the front tires are turned into the slide. That right there is your single biggest failure in understanding any of this. If a car is oversteering by a few degrees, the front tires will still be pointed very much into the turn.

You must be equating any and all oversteer with a full out opposite lock drift, which is simply not even close to reality.

If you watch the video again, there is clearly mild oversteer happening at every turn, the only place there's any understeer is at the entry to the hammerhead, and it's VERY minor.

Originally Posted by Mikey

Thanks for the info, your text is not so useful and although your thesis is somewhat interesting and one can glean relevant information it isn't very helpful to the topics at hand. Engineers still avoid taking English at university except the mandatory course. Thanks anyway.

What relevance does anyone's writing abilities have in a discussion about vehicle handling dynamics? Why don't you stick to relevant facts instead of grasping at anything you can use as an argument against someone?

Originally Posted by Jagular

I haven't read it

And here we have it, the actual reason for everything Suberman.

Originally Posted by MrSmith

Use of the gravitational constant g isn't useful in analyzing oversteer relative to understeer because it is assumed to act through the imaginary CG. Use of g and fractions of g (which is actually absurd if one considers things properly) began with the aeronautics industry who do need to measure vertical g so it makes sense to use g for all accelerations in the pilot's 3D world. However, even there g is used for the entire vehicle and the entire pilot, not one end or the other. I'm pretty sure yaw, pitch or roll is neither measured nor displayed to the pilot in g, but I'm not a pilot.

G is a measure of acceleration, lateral acceleration is a measure of grip. You can't measure under or oversteer in G, but that wasn't what I said. I said that if you try to get one end to sustain more G than the tires can provide that end is going to slide. You managed to skip right past the point and land on some completely irrelevant point, again. If it makes you happier, forget that I used G and instead look at any unit of measure that makes you happy. At the end of the day, if you ask the tires at one end of the car to provide more force against the pavement than they can that end is going to slide.

Originally Posted by CopyrightLawyerCantRead

I was particularly amused by the poster who suggested I get rid of understeer by pumping up my front tires and letting some air out of the rear tires...no, I won't be doing that.

Reading comprehension isn't your strong suit, is it? That post was sarcastic, but the point was that since you like understeer so much you could create more by lowering rear tire pressure and increasing front tire pressure.

Originally Posted by Mikey

http://www.whiteline.com.au/search_2011_4.php

Link fail, that just takes you to a blank search result.

Originally Posted by Jagular

Maybe somebody will actually quote a specific refutation from an actual suspension engineer?

That won't change anything for you, I've provided direct quotes from crew members of F1 teams that stated the more oversteer a driver is comfortable with the faster the car can be setup.

I've said this before, but I'll repeat it again. A car biased towards understeer is easier for a novice driver to drive to the limits, but a neutral car that properly rotates off power (very mild oversteer) will ultimately be faster.

Before suggesting stiffer roll bars again you should remember that a stiffer roll bar changes the handling balance by actually reducing grip at that end, so a stiffer front bar is increasing understeer by reducing front grip. So now you're claiming that less grip up front makes a car faster, chew on that for a bit.

[jvincent]

Props for the excellent selection of quotes tags.

Sent from my Nexus 5 using Tapatalk

[7thgear]

this feels like a bar fight with a drunk homeless man with cognitive incensitivity to pain, he's too weak and disorientated to throw any real punches but god damn it he won't fall down.

[PMPB]

Originally Posted by Suberman

I was particularly amused by the poster who suggested I get rid of understeer by pumping up my front tires and letting some air out of the rear tires...no, I won't be doing that.

I can't believe that you accuse other poster of having poor reading comprehension, and then you write this. Read again what I wrote, and then read again what you wrote.

Originally Posted by Suberman

Again, this is odd tuning if oversteer is faster.

I'm fairly certain that nobody is claiming that a power off oversteering car is faster, and the BRZ certainly does not suffer from this. A neutral car is fastest. Depending on the application and the drivers comfort, a car setup to slightly oversteer off the power may be better in an autoX, And a car that slightly understeers may be pushed harder by a skilled driver on a high speed track. The only reason for slight understeer is to allow a margin of error, after all, a car in the gravel is the slowest.

We're all just here to tell you that a car that is significantly understeering IS NOT the fastest car, as you suggest. By your own admission, tires without grip means that a car is already going slower that it could be. Subsequently, trying to steer an understeering car through a corner by power oversteering (4 wheel drift) is definitely not the fastest, that's just drifting; not a grip run.

[7thgear]

Clear as day I remember a funny incident in grade 6 design and technology class. I was looking for a fretsaw to cut out a delicate design in a thin board and noticed that the only one our class had (cuz we low budget like that) was missing. I went around the room seeing who was using it and found the class hottie (Lindsey, ohh how I remember you) using the damn thing TO SAW OFF A PIECE OF TWO BY FOUR. She was going at it in a way a young boy could watch for hours… but I had to get my damn project done so I interrupted her and offered a trade. In my hand was a simple but reliable ripsaw. I explained to her that what she had in her hand was for delicate work, which I needed it for, and that the ripsaw was the perfect tool for her activity, all she had to do was keep the blade straight and put some power into it on the downstroke. She didn’t believe me, told me I was trying to trick her (wtf?) and to get away from her popular self (or something to that regard). My English wasn’t too good at the time and I was already nervous from having approached her so I just said fuck it and went on to do something else. She later snapped the blade and had the teacher yell at her for being an idiot (in much nicer terms though). She never did apologize to me however.

Suberman

You’re that blonde twat without a brain. Your intelligence is fake. You know things yet you do not understand. And you keep hacking away at life using the wrong tools. One day those tools will break and you’ll be in a very bad place. It’s probably too late for you now , though, to change your mindset, but maybe, just maybe tomorrow or the day after you’ll wake up with a eureka moment and stop pissing in your own coffee for once.

[stugray]

dbl post

[stugray]

Originally Posted by Suberman

Use of g and fractions of g (which is actually absurd if one considers things properly) began with the aeronautics industry who do need to measure vertical g so it makes sense to use g for all accelerations in the pilot's 3D world. However, even there g is used for the entire vehicle and the entire pilot, not one end or the other. I'm pretty sure yaw, pitch or roll is neither measured nor displayed to the pilot in g, but I'm not a pilot.

It is not absurd in any way. 1"G" is 9.8m/s^2 (meters per second per second).
It IS a constant and is used in every physics class I have ever taken.
Of COURSE the "force of gravity" can vary based on altitude and even where on the Earth you are, but 1G is defined "1G = 9.8m/s^2" this holds even if you are standing on Mars.

And "Use of g and fractions of g (which is actually absurd if one considers things properly) began with the aeronautics industry " Umm... NO It started with these guys called Galileo and Newton just a bit before the "aeronautics industry". Their "1G" = 32.17 feet/s^2

If you dont like using 1G as a unit, then just convert to m/s.

And the reason 1G is used when talking about auto handling characteristics is that with 1G of downward acceleration, the most lateral acceleration a car can handle is 1G. This of course assumes no aerodynamic downforce and a max tire frictional coefficient of 1.0 (we all know that cars DO have downforce AND at least race tires can have a frictional coefficient of greater than 1.0 = "Sticky")
You could use m/sec^2 when discussing this, but it just shorthand to say "1G" instead of "nine point eight zero six meters per second per second"

Originally Posted by Suberman

Engineers still avoid taking English at university except the mandatory course. Thanks anyway.

Apparently you did not even read any of maloney2's paper (I read almost 40 pages of it) because his "English" is just fine. I did not find any errors. Do you care to point out any of his poor writing skills? (didnt think so). And as an Engineer myself, I take offense at your statement.
Maloney2 has presented evidence that he knows what he is talking about as his paper was reviewed by experts in the Automotive Engineering field.
How many peer reviewed papers have you written on tire handling characteristics? None? Oh, thought as much.

[wparsons]

^^ Slight correction, you can have more than 1G of lateral grip without downforce and a coefficient less than 1. As weight transfers in a corner you end up with more normal force than just the force due to gravity.

[that_guy]

Originally Posted by 7thgear

this feels like a bar fight with a drunk homeless man with cognitive incensitivity to pain, he's too weak and disorientated to throw any real punches but god damn it he won't fall down.

I think I peed a little.

[maloney2]

The use of the unit g in lateral acceleration makes absolute sense. This is done so because the maximum lateral force that acts on the vehicle is a function of the mass. However, the acceleration of the vehicle itself is also a function of the mass so the mass term effectively drops out. The use of the unit g is really to give a sense of the overall effective coefficient of friction. When used to present results such as skidpad numbers it allows for easy comparison of a vehicles overall handling capabilities independent of its tires, mass, suspension etc.

A = F/M
F = FnMu
Fn = Mg

therefore,

A = MgMu/M --------> A = gMu or A/g = Mu

Where, A = the lateral acceleration of the vehicle, F = the lateral force acting through the vehicle's mass center, M = mass of the vehicle, Fn = normal load of the vehicle, Mu = the coefficient of friction, g = acceleration due to gravity on earth.

So really when someone reports the skidpad lateral g's of a vehicle, they're really reporting how effective the handling package of the vehicle as a whole is.

So when you made your point that g isn't useful for understanding handling balance your both correct and incorrect. It's true that you can not tell if a car is oversteering or understeering based on the lateral g's the car pulls on the skidpad, but if a car understeers very strongly or oversteers very strongly you can bet the car won't achieve very high skidpad numbers.

BTW I haven't been able to thank any posters due to my lack of posts but rest assured I appreciate many of your posts.

Sean

[stugray]

Originally Posted by wparsons

^^ Slight correction, you can have more than 1G of lateral grip without downforce and a coefficient less than 1. As weight transfers in a corner you end up with more normal force than just the force due to gravity.

No you cannot.

The "normal force" IS the force due to gravity.
What you just said means "A car can weigh more than it weighs"



where

• is the force of friction exerted by each surface on the other. It is parallel to the surface, in a direction opposite to the net applied force.
• is the coefficient of friction, which is an empirical property of the contacting materials,
• is the Normal force exerted by each surface on the other, directed perpendicular (normal) to the surface.

If the "normal force" (Fn) is 9.8 m/s^2, and u (coefficient of friction) is 1.0, then the force of friction is 9.8 m/s^2 and cannot be any greater unless the coefficient of friction is greater than 1.0.

[stugray]

Originally Posted by maloney2

When used to present results such as skidpad numbers it allows for easy comparison of a vehicles overall handling capabilities independent of its tires, mass, suspension etc.

And in Suberman's defense (I know I will regret this).

The BRZ is rated at 0.92Gs on the 300 ft skidpad.

Just beneath the 1988 Vette (0.93Gs) and barely above the 1985 Honda CRX (0.91Gs).
Note: The 2008 Bugatti Veyron gets exactly 1.00G. If you could get significantly greater than 1.0G in a skidpad test, dont you think a multi-million dollar car could do it?

So based on those numbers, the BRZ is a poor handling car (by today's standards).
(caveat: the above 0.93G skidpad test was done with the well known "crappy" stock tires)

[7thgear]

another caveat is that lateral g's tell only half the story

theother is how do you get to that place of maintainign maximum traction.