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Old 4th August 2003, 03:59 PM   #341 (permalink)
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That's the fella Mycroft!


(It's my age, my memory's going )
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Old 4th August 2003, 04:00 PM   #342 (permalink)
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Why?

I don't really want this thread hi-jacked... start another and I'll respond, Simon at the moment is flying in the face of the evidence and I want to ensure that this stays on track for the final denouement.

Cheers.
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Old 4th August 2003, 04:04 PM   #343 (permalink)
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In actual fact, an open forum isn't the best place....(Not that it's anything exciting mind, just unfair)



Sorry for the thread hijack, do carry on.....
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Old 4th August 2003, 04:20 PM   #344 (permalink)
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Summary.

Simon says... Grip and slip are the same thing...

Mycroft says... they are not.
----

Simon says... that grip 'somehow' decreases as weight increases.

Mycroft says... that only happens after a certain weight once all the purchase is complete.
----

Simon says... as little as possible now as he is trying to 'save face'...
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Old 4th August 2003, 05:07 PM   #345 (permalink)
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Wouldn't it be nice to move on... no more bickering...
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Old 4th August 2003, 05:23 PM   #346 (permalink)
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simon,

not going to take sides, as I have only read up to page 4 of this trhead and frankly got bored.

But Up to and including what I have read, what mycroft was saying with regard to the two graphs was exactly true.

you had a parabola or possibly something else by the looks of it.

I believe mycrofts 45 degree reference was so that people could appreciate what part of the curve he was talking about, obviously the scales will determine the angles, but I think it is fair to say that anyone reading this will take that as a moot point.

The point is that if you will find that for an appreciable fraction of it, y = kx in other words, if you double y, you will effectively double x.

This is only because the first portion of the curve directly from the origin appears to be a straight line relationship.

What mycroft was saying was that if you only operate within this section of the curve, then it is entirely true, double load and you double grip.

it isnt chassis dynamics, it is maths a level.

consider sin x, where x is in radians for small angles sin x is approximately equal to x and tan x. simple harmonic motion is pretty much dependent on this for us to understand it. if these are the only angles we are concerned with then it doesnt matter what happens when the angles are approaching 90 degrees (foergive change of units could be ****d to find a pi symbol).

It is an approximatin which holds for the region of the graph we are interested in.

I also have to say but reading what you wrote on the early pages, it does appear that you are confusing mass (a constant except when approaching relativistic velocities) and weight which is dependent on gravity.

i only point this out now, as it seems to be at this point that this thread broke down into a slanging match.

don't mean to be rude, by I can see mycrofts frustration, if you are unwilling to accept that there might be a different explanation from your own understanding.

People have accusedhim of being arrogant, but isn't it just as arrogant to decide he is wrong without looking closely at what he has written?
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Old 4th August 2003, 05:41 PM   #347 (permalink)
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22b [Adam?] thank-you for that.

I feel it is best not to show any support in my direction at the moment, this little issue has nothing to do with truth or reason, and you will only be subject to the same degree of ire I encounter.

A number of people on here [GTR and some other marques] have also pointed out the same thing to me offf forum, but have not 'risked' voicing their opinion for just that reason... this whole episode is quite the worst indictment of some here, but it must run its course now.

Shameful.
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Old 4th August 2003, 05:59 PM   #348 (permalink)
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Am not keen on not speaking up where I see an issue.

and yes it is Adam
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Old 4th August 2003, 06:05 PM   #349 (permalink)
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Thumbs up

It befits you.

'Contra terrentum bracchia dirigere'
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Old 4th August 2003, 06:30 PM   #350 (permalink)
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Quote:
Originally posted by Mycroft
Wouldn't it be nice to move on... no more bickering...
We tried. Pages ago. But like a dog with a bone you just wouldn't let go and continued with the abuse and condescending posts towards Simon and many other people.

I think to be honest it would just be better if this thread were locked, or Mycroft agree to just not post any further. I for one would like to hear other peoples opinions without the constantly condescending Mr Wiltshire.
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Old 4th August 2003, 06:39 PM   #351 (permalink)
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Quote:
Originally posted by Thorin
We tried. Pages ago. But like a dog with a bone you just wouldn't let go and continued with the abuse and condescending posts towards Simon and many other people.

I think to be honest it would just be better if this thread were locked, or Mycroft agree to just not post any further. I for one would like to hear other peoples opinions without the constantly condescending Mr Wiltshire.
Are we now to have the 'spectacle' of everyone saying 'it wasn't me guv, it was Mycroft who kept it going' hahaha

So are YOU now having another look at things and reconsidering your position or do you still think Simon is right?

We move on when you are all up to speed with the maths and the nomenclature.

Add to that I am composing another part at the moment on this subject... I like this thread...
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Old 4th August 2003, 06:57 PM   #352 (permalink)
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Quote:
Originally posted by Mycroft
We move on when you are all up to speed with the maths and the nomenclature.
Yes, it is blatently obvious that we will move on when you feel like it.
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Old 4th August 2003, 07:25 PM   #353 (permalink)
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I would like to see Simon de Banke answer Mycroft's questions and Adam's comments rather than saying that Mycroft is not worth talking to. That's pointless and seems inaccurate, given the amount of effort (including getting hold of Prodrive's dynamics engineer) that went into Simon's replies in the beginning.

Simon's "Anybody else...?" stuff (ignoring Mycroft) sounds more like an admission of defeat than a convincing "I am ignoring him because he talks BS". I dont know who's right or wrong here, but SDB's attitude is not very constructive.

Also, I would like the people reading this thread to consider the following: attacking the person who states an argument does not invalidate that argument. It just makes you look unable to answer the question. Likewise, saying "this comes from X or Y who is an expert" does not make it absolute truth, although it may sound convincing.
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Old 4th August 2003, 07:31 PM   #354 (permalink)
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Quote:
Originally posted by Claudius
I would like to see Simon de Banke answer Mycroft's questions and Adam's comments rather than saying that Mycroft is not worth talking to. That's pointless and seems inaccurate, given the amount of effort (including getting hold of Prodrive's dynamics engineer) that went into Simon's replies in the beginning.

Simon's "Anybody else...?" stuff (ignoring Mycroft) sounds more like an admission of defeat than a convincing "I am ignoring him because he talks BS". I dont know who's right or wrong here, but SDB's attitude is not very constructive.

Also, I would like the people reading this thread to consider the following: attacking the person who states an argument does not invalidate that argument. It just makes you look unable to answer the question. Likewise, saying "this comes from X or Y who is an expert" does not make it absolute truth, although it may sound convincing.

...ok without Mr Wiltshire and his lapdog.
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Old 4th August 2003, 07:33 PM   #355 (permalink)
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That is Dr Wiltshire thank-you.

Claudius is his own man as is Adam.

I don't think you should mention lapdogs... as that seems to have been your role here, one which, may I say, you have excelled yourself at...
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Old 4th August 2003, 07:45 PM   #356 (permalink)
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I would very much like this thread to continue providing useful, if complex, information. Mycroft did impress me when he came back with the explanation of Co-efficient of Grip, the difference of slip, and how friction ties into it.
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Old 4th August 2003, 07:48 PM   #357 (permalink)
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Quote:
Originally posted by Thorin
...ok without Mr Wiltshire and his lapdog.

If you agree with my comments, why do you feel the need to insult me? Do I insult you (or anybody else) here?

Your dismissing me as someone's "lapdog" is exactly the attitude I found Simon to display and commented on as being destructive. As a consequence:
- either you do not agree and just say so to look fair
- or you just wanted to throw in an insult because you didnt know what to reply
- or both
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Old 4th August 2003, 08:13 PM   #358 (permalink)
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Hi Adam

If you had read the rest of the thread you would understand why I have neglected to engage Mycroft in conversation further. It has proven to be futile.

Now that *you* have brought these points up (I have been asking for about 10 pages if anyone else thinks Mycroft has a point worth answering, which has not been requested until your post - so I have assumed everyone "got it" ), I will be absolutely delighted to explain it.

I apologise this is not going to be a short reply....

Firstly. This thread is about "If you add mass, can you corner as fast?". My personal guess is that only one person contributing to this thread thinks that the answer is yes.

Oposing views range from, myself, through the rest of the vehicle dynamics world including (just a few that have been mentioned in this very thread...

Doug & Bill Milliken
Damian Harty
William Mitchell

and are based on the notion that doubling the load on a tyre less than doubles the grip it produces. For clarity (as explained early in the thread. By "grip" I think we would all realise that I am talking about Limit Lateral Acceleration, or effectively the amount the tyres are able to resist the lateral forces of the car.

Please refer to the link containing the graph (with the linear portion on it) for quotes on this specific topic as clear as can be. Then while I'm here I'll quote you an excerpt from Ervin R D, (UMTR Institute) - report number UM-HRSI-78-31 named "The State of Knowledge Related to Tyre Design to Those traction properties which may influence vehicle safety" (Catchy Title!! )...

"Increasing vertical load is know categorically to reduce frictioan coefficient under both wet and dry conditions"

I'm not sure how many published, renowned, and celebrated experts we need to confirm this before some people won't think "I reckon Mycroft knows better".

Secondly. The graph stretching I did, was purely to disprove mycroft's statement that "any graph showing an angle of greater than 45 degrees proves [that the y axis *more than doubles* with doubling of the x axis]". Now, it is obvious to me that the *angle* of a specific point of the curve, does not prove anything about what will happen when you double the x axis, it is the curve that proves this. And the curve in the graph I stretched (which mycroft commented on) is continually curving downwards, which means that the y axis increases by less than 100% when you double the x axis.

So we'll move on to your points.

The graph showing a liniar section. I absolutely agree that (Assuming the graph is correct) during this proprtion of the range (I look forward to Mycroft quoting this isolated sentence as a statement of victory ) doubling the load will exactly double the grip.

Now, the important thing is. This is not even slightly relevant.

Why?

The linear portion of a tyre's load / friction curve is the portion in which hysteresis is not dominant. Hysteresis is the dominent function in heat generation in the carcas of the tyre tyre. In order to bring a tyre up to temperature, you must operate it well into that non-linear portion of the graph otherwise it will never produce anything other than marginally more than a cold tyre. This effectively means the graph would be at less of an angle.

So. Whilst it is true that it would be possible to put a car on tyres that do not reach the non-linear portion of the graph, the tyres would produce very little grip compared to one which operated IN the non-linear portion of the graph.

[edited to add>]
This is why cars of different loads do (as mycroft correctly states) require different ideal tyres. As they are designed so that the tyre will be operating enough in to the non-linear range to produce heat, but close enough to the linear part to reduce the amount of reduction in grip loss as load is increased.
[end of edit]

Of COURSE, it is possible to take a single aspect of a tyre's properties (like the friction of the actual rubber - as though it were a laboratory sample block) and show that "a tyre DOES double the grip when you double the load", but a tyre is a little (Actually one hell of a lot) more complicated than that.

So. In summary, the reason I have not been answering Mycroft's questions was because every time we got through proving one point, he would simply pick up another one and run with it, regardless of how relevant it is. This is detrimental to the thread and the learning within it.

Bare in mind, that I haven't "made this notion up" (about doubling the grip, blah). This is one of the key cornerstones of understanding in vehicle dynamics.

Hope this is clear, off home now, so speak soon.

Simon
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Old 4th August 2003, 08:23 PM   #359 (permalink)
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Quote:
Originally posted by SDB
Firstly. This thread is about "If you add mass, can you corner as fast?". My personal guess is that only one person contributing to this thread thinks that the answer is yes.

Oposing views range from, myself, through the rest of the vehicle dynamics world including (just a few that have been mentioned in this very thread...

Doug & Bill Milliken
Damian Harty
William Mitchell
What a dreadful corruption of the truth...

I append the contention that you finally had to agree with...

''2 cars... 1 weighs 1 tonne the other 2 tonnes they both have equal power-to weight ratios and torque curve/gearing coincide exactly for each... they are perfectly matched... even down to the 'G' force each can generate in any given curve...

In a race the 2 tonne car will eat the 1 tonner... quite easily....''

To the different poser:-

"If you add mass, can you corner as fast?".

Then there is no doubt that if you do nothing else but add weight, then there is no debate, it will be slower.

----
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Old 4th August 2003, 08:30 PM   #360 (permalink)
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Quote:
Originally posted by SDB
By "grip" I think we would all realise that I am talking about Limit Lateral Acceleration, or effectively the amount the tyres are able to resist the lateral forces of the car.
= slip, you are defining slip, not grip.
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