rec.autos.simulators

Well, I have read all this thread with a grin on my face, some say canned
and others not. My personal opinion is not. People have made comments on the
laws of physics which are the thing in question here. F1 cars are an
individual breed, they rely   (especially at present with the grooved tyre
regulatons) mainly on the downforce given by the front and rear wings. They
reckon you could drive one of these things on the ceiling because of the
speed and downforce combination. If you took the wings of these cars
cornering would be seriously difficult (obviously) even at low speeds.
If you watch TV coverage of the sport, which I have been lucky enough to see
here in the UK from being a young lad to a 30 year old man on a regular
basis, you will have seen the many accidents and unfortunate fatalaties that
have occured in the sport.
Most of these occur because the driver is on the absoloute limit, obviously
only a fraction of speed , late braking etc.. takes you beyond that point.
You find that That the cars just go ping!, and there out of control,
spinning away or just sliding sideways at some serious velocity leaving the
driver helpless and at the mercy of fate. These cars are not designed to be
powerslided it`s not efficient, it costs laptime, there designed to stick by
downforce. When downforce is gone you are usually travelling at a silly
speed ( hair on fire ) thus regaining control is not easy. I`ve seen some
good recoveries, but they usually entailed spinning 540 degrees heading off
backwards on the grass, track or wahtever with the driver being able to get
the car pointed in the right direction and get away without hitting anything
and without loosing much time ( oh! being alive aswell).
I`ve heard people give it the old " it`s no GPL " routine, and I couldn`t
agree more. It is NOT GPL,as in it is not trying to replicate hoe cars back
then handled, It is trying to replicate how cars handled in 1998. I
personally like the physics model, the best way to regain control of a lost
car is too bleed off the speed, try to get it back within the limit, I think
this is correct. Most low speed spins are caused by over acceleration at a
time when downforce is not working at it`s true potential, people surely
don`t think that upon loosing control putting your foot down and turning
into it is going to help a recovery. Taking your foot off the gas and
fighting it is what is called for, remembering that sharp movements of the
wheel will result in sharp movements of the car which will alter the cars
sensitive characteristics.
Gp3 seems to give a good idea of how things work in a modern day F1 car,
bearing in mind it`s not a easy thing to model.

Shit I didn`t intend to waffle on that long, anyway thats my humble take on
the handling.

Snake.

Marko

Alan

Marko

  True (if you can fuel it and stay in your seat, of course) :-).  F-1 cars
have been known to generate upwards of 4.5 g's cornering acceleration with
maximum downforce, if I'm not mistaken.  That's enough to not only drive upside
down, but drive upside down and run a skidpad on the ceiling at 2-3 g's.
Better wear your harness!  

  Compared to driving at high speed with the downforce, DEFINATELY yes.
However, modern F-1 tires (not sure about the new grooved ones) are capable of
upwards of 1.8 g's cornering at light load.  It's probably safe to say that a
modern F-1 car could still pull 1.5 g's or so through a corner if you removed
the wings and all downforce stuff.

  >Most low speed spins are caused by over acceleration at a

   Definately true, and being in a low gear on top of this doesn't help either.
 Indycars (not sure about F-1), should be able to spin their rear tires through
80+mph or so, even when they aren't in a corner.  

  Bingo.  I'm not sure about the '67 F-1 cars, but I suspect a modern car has a
much lower polar moment of inertia.  (For those who don't know, imagine
spinning a dumbell with the weights far apart vs. close to the center, then
changing the spin direction as quickly as you can.  Same weight, but it's a lot
easier to change directions when the weights are in the middle).    

  Another thing folks may keep in mind are the current F-1 tires vs. '67.
They're stickier, but that's not the point, really.  A modern F-1 tire
generates it's peak force at a very small slip angle compared to the '67's,
probably.  Everybody know how the GPL cars will rotate sideways pretty far and
perhaps wobble, then travel at a pretty good angle?  I'd expect the same basic
behavior from an F-1 sim, but the angle should be much smaller (if noticable at
all, we're talking 3-5 degrees probably), and the short wobble should be much
more rapid and halt very quickly, if there's a perceptable one at all.  

  This should still be apparent at speeds of maybe 50-70 mph or less.  One more
thing, modern F-1 tires MAY have a tendency to drop peak force more quickly
after the optimum slip has been reached than a '67 tire (if a '67 tire did this
at all).   This, on top of lower polar moment of inertia and higher grip
levels, should give a more snappy feel to the modern car.

  I forgot where I was going with this, but that's a long winded enough
know-it-all reply for me today!

 Todd Wasson
^--- Never played GP3

--
Ian Parker
"Ambition is a poor excuse for not having sense enough to be lazy."

<email invalid due to spam>

The best way to stop a spin is to get rid of all side force
on the front wheels, preferably while keeping it in the back.

Slamming the breaks is a bullet-proof way of losing the fronts,
and since you probably have the brakes biased to the front you
may also keep some grip at the rear as long as you don't push
the break pedal all the way to the floor. This is easier than
only steering into the spin and moderating the throttle since
neither is going to help at all unless done almost perfectly.

      _
Mats Lofkvist

GPLRank +3.69

Your acceleration to the centre of the corner  (i.e. G force) is
proportional to the grip of the car.

If you have NO downforce, the only force keeping you on the road is the
weight of the car.

The maximum cornering 'force' is therefore the same ammount.

F=ma

Hence, only ever 1 g.

Doug

% Then again, the tyres and subsequently the mechanical grip between '68 GP cars
% and '98 GP cars is like comparing apples with oranges.

Very true, but both apples and oranges must follow the same laws of
physics.

--
**************************** Michael E. Carver *************************
     Upside out, or inside down...False alarm the only game in town.

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Some numbers for peak friction coefficients reported
in "Race Car Vehicle Dynamics":

Goodyear Eagle GT-S P215/60R15:        1.16
800/820-15 Stock Car Short Oval:          1.62
Formula One Front 25x9-13:                    1.83

Another example:
Goodyear Formula SAE Tire 20x6-13:     1.9

"Race Car Vehicle Dynamics," W.F. Milliken and D.L. Milliken,
SAE, 1995. ISBN-1-56091-526-9

--
Matthew V. Jessick         Motorsims

Vehicle Dynamics Engineer  (972)910-8866 Ext.125, Fax: (972)910-8216

Assuming that gravity is the only force acting on the car, which is not true
once the car is in motion.

G is constant, relatively. The mass of the car remains constant, relatively.
The "weight" of the car -- that is, the force vector acting on the car --
changes as it lightens at the top of a rise, or becomes heavier at the
bottom of a dip, or tilts as it accelerates laterally or longitudinally.

Examining F=ma: Mass, as we said, is relatively constant. Also, G from
gravity remains relatively constant. Thus, F should remain constant.
However, we know that the force acting on the car changes for various
reasons. We found nothing new by examing this simple, if important,
relationship in isolation.

A tire's available grip is strongly coupled to its normal loading. However,
there is no simple relationship between the two.

Michael.

Yes, but just because a sim doesn't act like GPL doesn't mean that it's breaking
the laws of physics. The parameters involved are just so different.

% Yes, but just because a sim doesn't act like GPL doesn't mean that it's breaking
% the laws of physics. The parameters involved are just so different.

Since GP3 is wrapped around 90+% of GP2 code, I don't see how GP3 could
even hope to have as sophisticated physics model as GPL.  That is the
point.....  Whether we are talking about a 1998 F1 car or a 1967 F1 car,
the laws of physics were the same for both.  However, GP3 doesn't seem
to actually simulate the physics as much as it mimics them....

--
**************************** Michael E. Carver *************************
     Upside out, or inside down...False alarm the only game in town.

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./.  [-  < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=