rec.autos.simulators

--
John Wallace

Turnpike evaluation. For information, see http://www.racesimcentral.net/

You're welcome. Perhaps next time you could take just a LITTLE time to
see I was joking, or maybe I should make it more obvious for the Nigel
Mansell's among us....

Cheers!
John

--
John Wallace

That old green eyed monster again....tut tut.

John
--
John Wallace

Turnpike evaluation. For information, see http://www.turnpike.com/

That's where gravity comes in.  8^)

Oh really, I'm getting a bit sick of this "bash F1GP for being years
older than ICR2 and it's lacking features".

If ICR2 is so damn accurately modelled and beloved of physics professors
the world over, why is it that when you DO leave this wonderful piece of
equipment on a hill, it DOES roll down it? The damn car is still in
gear, it shouldn't go anywhere....

So much for accuracy.

Cheers!
John

--
John Wallace

Turnpike evaluation. For information, see http://www.turnpike.com/

Austin, Tx
============================================================
Scott Pruett 1996 PPG Cup Champion!
============================================================

This isn't quite right. Friction force is not constant, but depends on the
weight of the car. Lets call if Fr:
Fr = u*N , where N is the the force the car presses on the surface (the
weight of the car)  and u is a constant depending of the tire and the surface
(don't know what it is called in English, but direct translation from the
Finnish term would be "friction factor").
N = m*g when the car is on horizontal surface (ie. direction of gravity is
perpendicular to the surface). This gives:
Fr = u*m*g , so the force is directly related to the weight (and mass) of car.
Actually, this is not the real friction force, but is the maximum possible
force engine can use to accelerate the car before wheel spin occurs (well,
in fact wheel spin occurs much earlier, because only the rear wheels are
accelerating the car, so N should be te part of the cars weight which is
distributed on the rear wheels... To make it more complicated, this will
change when the car accelerates...)

Fr is the limiting factor only when the car is accelerating at a slow speed
(as in the start or after a slow corner for example). At these situations,
the weight of the car has no effect on the acceleration:
a = Fr/m
a = u*m*g/m
a = u*g , so at these situations, the acceleration is only affected by
friction factor and g (acceleration caused by gravitation).
This is of course when the driver is not spinning wheels.

But, when the force engine can generate stays below Fr, a car with less fuel
(and thus with less mass) will accelerate faster:
a = F/m , F is the force generated by engine, and m is the mass of the car.
As F doesn't depend on the weight or mass of the car (depends on rev and gear,
can be considered constant in this calculation), lighter car accelerates
more quickly at speeds where Fr is no longer the limiting factor.

Aerodynamics affect these figures quite a lot, especially at higher speeds,
causing the increase of N and Fr (downforce), and loss of acceleration
(negative force due to drag). However, it has nothing to do with the fact
that lighter car accelerates more quickly.

To sum this up, there is no need to simulate gravity to make the car accelerate
differently depending on fuel load.

I hope I make some sense,
Samppa
--
Samuli Takala, Pajamaentie 14 C 38, 00360 Helsinki   | "Ron Dennis smiled like

URL: http://www.hut.fi/~tax/ (soon)                  |  -- Matti Kyllonen

Actually John, it should stall.  But your point is well taken (and
totally agreed with <g>).  The lack of a clutch mechanism (or at least
neutral gear) and wheelspin is one area where I think the Papyrus sims
are weak.

Steve.

Ah, but presumably you have to assume that the simulated driver
has his foot on the clutch pedal otherwise the car would have
stalled!!

Fraser

Never! <g>

contructed posts as well.<<

Thanks - I started scanning this newsgroup after somebody mentioned it
over on CompuServe.  It confirmed my thoughts about the internet - some
useful stuff strung amongst the free for all.

Cheers,

Steve.

Uh, if the car is in gear, and not moving, how the engine can be running?
ICR2 must have some sort of automatic clutch, with some traction control
elements included (it's hard to make the car spin, when you want, but it's
quite easy when trying to stay on track. I mean here spinning as a result
of wheel spin).

Samppa
--
Samuli Takala, Pajamaentie 14 C 38, 00360 Helsinki   | "Ron Dennis smiled like

URL: http://www.hut.fi/~tax/ (soon)                  |  -- Matti Kyllonen

Give up, you can't argue an indefensible position. So what you're saying
is that when I fly into the pits for a splash of fuel, the mechanics
turn off my engine to stop it stalling? NOT very accurate....

Or perhaps the Indycar has an automatic clutch with traction control.
Does a REAL Indycar have this? NOT very accurate....

I'm not knocking Indycar, it's a good program but please don't hold it
up to be so much more realistic than GP because it isn't. It also falls
down on the fundamentals.

Cheers!
John

--
John Wallace

a) Circuits which have elevations, such as at Spa (Eau Rouge). A more
massive car will accelerate more slowly up this hill than a lighter
car because it gains more potential energy.

b) The tractive force produced by the car's tyres is related to
gravity by the equation F=uR (where F is the force acting against
the car's direction of travel, u is the coefficient of friction and
R is the normal reaction, which equals the weight of the car
(determined by the value 'g' for gravity) + the downforce produced
by the car. (O.K., this is a simplification because you get static
and dynamic friction et cetera... ).

Fraser

In fact, adding stalling to ICR2 wouldn't be that hard. Just make the gear
shift to neutral when shifting down from 1, and if you stop with gear on,
the car stalls. Also, you'd have to apply some throttle when stationary and
changing from neutral to first gear.

--
Samuli Takala, Pajamaentie 14 C 38, 00360 Helsinki   | "Ron Dennis smiled like

URL: http://www.hut.fi/~tax/ (soon)                  |  -- Matti Kyllonen