From: lallo@stsci.edu (Matthew D. Lallo   (410)338-4577)
Subject: When you're wrong, you're wrong. (was Re: ABS ???????)
Reply-To: lallo@stsci.edu
Organization: Space Telescope Science Institute, Baltimore MD
Date: Thu, 5 Nov 1992 18:12:10 GMT


In article 1@economics.adelaide.edu.au, ecrjbruce@economics.adelaide.edu.au () writes:

>
>OK Matt, we've been having a discussion inprivate email about ABS etc and
>physics and how you see the world view.
	     ^^^^^^^^^^^^^^^^^^^^^^^^^^
What the hell????


O.K. Rob... That's it. I've had it with you. I tried to keep things civil and in 
private email, even though your ignorance of some basic facts, and your insistence
of your correctness nonetheless, has been infuriating. I'm glad you decided to spill
things over onto the net, because now comes the real hammering:

Since the posting of excerpts from private email is considered so utterly tasteless,
I will paraphrase your ridiculous drivel, but if you so much as insinuate what I've
paraphrased is NOT what you claimed, I will post verbatim your incriminating, 
misguided nonsense for everyone to see.

You insist (a number of times) even after being given the chance to reconsider,that:

*Static friction occurs when a wheel has locked up (and hence is static, ha!) and 
slides along the tarmac. And you've read this in physics texts.* 

Well I don't know what kind of physics they teach in Oz.

You also insist that dynamic friction occurs when the wheel is rolling freely. 
(dynamically I guess!) 

And that *I* am the one who doesn't understand the difference between the two. 
Oh that's rich. What incredible arrogance.

As if that isn't enough, you then fail to grasp the concept that the point at 
which a tire breaks traction with the asphalt is NOT the same as the point at 
which the rotor and pads bind together, and that this is the whole concept of
threshold braking, to keep the wheels slowly turning. You dismiss this as 
nonsense despite the fact that I cited sources, including Alain Prost's 
Competition Driving,  in which he discusses this concept, and even has a 
photograph of a car threshold braking. I, and others at the track, do what you 
say doesn't happen, routinely.


O.K. Next.

>In one of your posts you claimed that the best starts are those with a tyre
>slip of about 12%, because this gets the most power to the ground.  This seemed
>absurd to me and I did some checking. 

Well for someone who doesn't believe that a tire slides in threshold braking, 
I guess it would!


> In fact I didn't have to go very far
>because we have our F1 Grand Prix right here in little ol' Adelaide this
>weekend, and naturallt [sic] the papers are covering it pretty intensely.

Oh Now there you have it! Talk about backing your arguments. Wow you just can't get
any more authoritative than the local newspaper! Give me a break!



> Williams claim that one of their major
>improvements will be a "traction control" which will limit slip at the start to
>a "fraction og [sic] 1 percent".

Now, this, in all honesty, I don't know what to make of. Unlike you, I can certainly
admit that I may not understand the entirety of a situation. It seems odd to me.
If it is true then I will have to examine the circumstance in which it is true 
further. Perhaps the newspaper reporter got it wrong and the original Williams 
statement was that wheel spin could be *controlled* to within 1% ??? 
No but that couldn't possibly be now could it? No way. Uh uh. 
Ever see a dragster launch without wheel spin? I haven't. If the optimum percentage 
of slip is less than 10% I wouldn't be terribly surprised. But it sure isn't zero.



>Guess this contradicts your "world view" and that
>theory of yours.  Now if you cantell me Williams are going to spend millions
>developing products to make their car less efficient at the start then I may
>believe you, but given your taste for making statements backed up with
>absolutly no facts I guess this also throws your somewhat questionable ABS
>psoting into doubt as well.

You know...Rob. I have been on this net for a few years now, and I've never had
a situation like this where someone was so utterly wrong, and so clearly in need
of a better understanding of things, and yet so insistent of his correctness.

Wise up guy. Learn the difference between static and dynamic friction and that
you can have both at the same time with a tire before going around telling other 
people they don't understand it.

Now do us all a favor and go do your homework. And I don't care if you've driven 
vees and karts or whatever else, when you're wrong you're wrong.
As said and written many times before, simple ABS alternates between 0% and 100%
slip, and human drivers can keep the slip at a steady 10% or so. Apparently you
don't even acknowledge the need to do so for optimum braking!

If I were you, I wouldn't dig myself a deeper hole, or I'll go back and get every
one of your ABS postings (gems of information that they are), and every one of the
emails you sent me and take them apart each line by misinformed line.


Matt