Re: cf, constant for this discussion please

[Orin Eman <orin@wolfenet.com>]

> In a message dated 98-03-04 13:17:16 EST, you write:

> << We cannot go anywhere with this argument with the fallacious assumption
> > that a locked diff transfers 50% to each axle.  It simply isn't true.
> > The distribution is infinitely variable between 0/100 and 100/0.
>   >>
> For the KISS, Orin, can we go with the front and rear cf's as a constant?  I
> made it that way for a reason.  And the reality is, most turns have this
> assumption.  Otherwise, I would argue, you may want to think twice about ANY
> slip angle discussions.  For my model in a turn, the above presentation holds
> true to the letter.  I suppose we could go where you want to with this (and
> I'm not sure I'm disagreeing with you), but simplistically speaking with the
> same road cf, 1:1 BR is correct.  at 1lb/ft traction front, you have 1lb/ft
> traction rear.

On average, given the above assumptions, yes, I agree.  The 'bite'
situation you describe has the rears going slower, so there would be
some occasional slip at the rears.  Whatever, the torque distribution
isn't going to be switching back and forth...  I'd think with the
occaisional slip at the rear, it is biased slightly to the front
giving the understeering characteristic that the locked center is
known for.

 Speaking in one wheel up vs one wheel down, gets us further
> mired in a traction issue that is really irrelevent for this discussion.

Not going there, just using an extreme case to prove the 100/0/100
possibility.

 For
> slip angle to a turn, and BR f/r traction differentials assumed to be the same
> (cfrf = cfrr = cflf = cflr).  I like making simple models, you are
> complicating it unecessarily.  Given where we are with this whole torsen
> discussion, I'd prefer to stay really simple.  What you are proposing is
> jumping ahead to post f/r diff, we haven't gotten there yet.

No, we haven't gotten there, nor is there any need for the (current)
torsen discussion.

 We can have max
> Tshift in a torsen car without going there, and no Tshift in a Gen I without
> going there, T1 + T2 = maxTrg.

I agree with your scenario with the torsen BTW and I wonder if that's what
I feel slightly in the A4 on occasion.

 Go there, we are in really deep, beyond simple
> chassis dynamics too.  Your call I suppose.  I argue at that point, we all
> bail.  

At that point, we'd have to instrument the car and measure what happens.
I know I wouldn't stand a chance with the physics at that point.

Orin.