rec.autos.simulators

> There was some discussion of this in a debate in the letters section of Race
> Tech magazine on Ackerman/Dynamic Toe.

> In a (large) nutshell, the stabilising effect of toe in is due to the
> rearwards drag of the tyres.  If you consider a small left steering movement
> with toe in, the left tyre now has zero slip and a small rearwards (rolling
> drag) force.  The right tyre is pointing to the left with a leftwards slip
> angle, has rearwards rolling drag and sideways (axial) "slip angle" force.
> This axial force points to the left and slightly rearwards.  So, in car
> coordinates, the left wheel has only rearwards rolling drag force while the
> right wheel has rearwards rolling drag force plus the rearwards component of
> the slip angle force.

> With toe out the effects are reversed and it is destabilising.

> This was gleaned from the Oct/Nov 200 issue with thanks (or apologies) to
> Erik Zapletal who wrote the letter and Alan Staniforth who had written the
> original article (and approved the letter as a plain English explanation of
> Ackerman).

> The letter continues to discuss the amplified effect with Ackerman as the
> difference between wheel angles reaches several degrees whereas static toe
> is usually tenths of a degree.  An interesting conclusion is that while
> positive Ackerman (dynamic toe out) is destabilising during turn in,
> sharpening dynamic response, it is stabilising "at the limit" because the
> rearwards force at the inside wheel is the first to drop.

> Hopefully I didn't butcher that too much!

> Ben

>Unfortunately, there were no numbers (calculations with tire data, etc)
>supplied with that article.  Put some numbers in, then you will find out if
>this new premise is correct or not.

> >Unfortunately, there were no numbers (calculations with tire data, etc)
> >supplied with that article.  Put some numbers in, then you will find out if
> >this new premise is correct or not.
> I'm in the unfortunate position of having no way to verify or otherwise
> these kind of assertions.  I read the articles and try to decide whether or
> not I agree with them based on a combination of the arguments presented, the
> author's and editor's credentials and the credibility of the publication.

>Well, if you are going to act on the advice of tech articles (and in the
>case of a real racecar, this often means spending hard-earned money), I'd
>strongly recommend getting enough of a self-education so that you can run
>some simple numbers yourself.  Or, find someone that can do it for you.
>Really, most of the math in our book is high school algebra & geometry (but
>there is a lot of it, because cars are complex!)