rec.autos.simulators

     <<1) In the NASCAR game manual, under Rear Bias, it says (and I'm
paraphrasing) that the more weight there is in the rear of the car, the
more it tends to get loose. Also, under Fuel, it says as the tank gets
empty, (thus lightening the rear weight) the car tends to push. Ok, so
far so good.>>

     Interesting... I've found my experience with the game to be just
the opposite of what the manual says. My car gets looser as the tires
die and the fuel load lessens. I'm pretty sure the real cars are similar
to that. Look at it like this... what do you do to keep the rear tires
of a truck from getting "loose" in the snow? You add weight!

     <<However, when the manual talks about downforce, it suggests that
to CORRECT a loose condition, you add MORE rear downforce.>>

     There are a number of different ways. That is just one suggestion.
For example, are you getting loose entering a turn or exiting?

     <<2) When I watch NASCAR races on TV, cars tend to 'pair up' (the
announcers always call it finding a 'dance partner'). I would assume
this is so the car behind gets a draft, but how does it benefit the car
in front?>>

    The are drafting each other. Neither car has to work as hard to run
at speed. The car in front is in the cleaner air, though. It gets more
air to the motor. One of the long-term effects of drafting is if you
follow for too long your motor has a tendency to run a little toasty.
The fuel mileage will increase also, probably for all cars involved.

     <<And if it doesn't, why doesn't the car behind just slingshot
past? I would think they might just keep slingshotting past each other,
but instead it seems they maintain their order.>>

     Some cars just don't have the power to stay in front. Look at
Sterling Marlin. The cars ran faster when he was leading at Talladega
recently than when he wasn't. It all depends on which cars work best
together.
     Say you have two cars drafting off each other... cars A and B. They
may run faster, for whatever reason, with car A in front. Car B may not
lose any ground when he is following, but it may be apparent that car B
doesn't have enough intestinal fortitude to pull car A along and force
him to follow.
     Nick
______________________________________________________________________

#6 (will he be #28 in '97) & #94 in the *real* quest for the Cup
My home away from home... http://www.racesimcentral.net/~ntotoro/
______________________________________________________________________

Yes, that makes sense.  It also helps explain why it's so hard to pass
the car that I'm drafting! :)

--Tim

The aerodynamics was explained, so just a little to add about the racing aspect.  When 2
cars are drafting, they run faster dividing the wind flow, so they need less horse
power, and in turn, burn less fuel.  Two cars who 'team up' and draft for a while will
run faster and last longer (because they conserve fuel) than a single car, or two cars
who keep slingshotting past each other.  Tire ware also plays a roll.  Casual drafting
doesn't melt them as quickly as aggressive racing does.

: 1) In the NASCAR game manual, under Rear Bias, it says (and I'm
: paraphrasing) that the more weight there is in the rear of the car, the
: more it tends to get loose.  Also, under Fuel, it says as the tank gets
: empty, (thus lightening the rear weight) the car tends to push.  Ok, so
: far so good.

: However, when the manual talks about downforce, it suggests that to
: CORRECT a loose condition, you add MORE rear downforce.

: My question: Why do "weight" and "downforce" have opposite effects? I'm
: confused.

I've read several explanations of this, so let me put in my 2 cents worth.
Downforce is created from wind resistance such as on the rear spoiler.
The wind acts in two directions (recall your statics and dynamics here),
opposite to the forward direction of the car (drag) and downward
(downforce).  There is no force that acts to the side of the car (ie.
perpendicular to the forward motion of the car).  However, when dealing
with weight, the term "weight" is actually a misnomer.  The correct term
would be "weight distribution", because all the cars weigh the same (about
3400 lbs).  But, the teams distribute the weight in the car to get the
desired effects of speed and traction.  This is how it works:  When a car
is travelling at a constant speed, there is no weight shifting.
However, when the car accelerates, the weight shifts to the rear, and when
it slows, the weight shifts to the front.  Everyone has witnessed this in
their own cars when stopping at red lights.  Also, when a car turns left,
the weight shifts to right, and when it turns right, the weight shifts to
the left.  Now, imagine a car racing at Martinsville.  The car accelerates
out of turn 4 across the start/finish line.  The weight is shifted
backward (I'm neglecting shocks, tire pressure, etc.  I'm only dealing
with weight bias here).  When it reaches turn 1, the car slows and turns
left.  Naturally, the weight is shifted forward and to the right (ie.
mostly to the front right tire).  If I have my car set up so that there is
more weight distributed to the front than to the back, then the action of
braking and turning will accentuate this and it is very likely that the
car will push going into turn 1.  However, to offset this effect, if I had
more weight in the rear, the car would probably not push into the turn.
Then as I ease off the brake and coast through the apex of the turn, there
is no longer a difference in weight distribution between the front and
rear.  However there is a difference between the left and right side of
the car.  As I'm turning left, the weight is shifted to the right. I want
to lessen this as much as possible because I don't want to be thrown to
the outside wall.  Therefore, usually the the maximum amount of weight is
placed on the left side to counterbalance the car.  Then as I get back on
the gas to exit the turn, the weight is once again shifted to the rear
(and I think that this is where your question lies).  The shifting weight
does not create a downward force as the wind acting on the rear spoiler does;
instead it acts to the side.  In other words, if you had too much rear
weight, when you accelerated out of the turn, the lateral force would be
greater than the friction of the tires and you would slip.  Conversely, if
more weight was on the front, you would push into the wall.  Try to
imagine a shopping cart at a grocery store.  If you load all you groceries
on the very front of it, it's hard to turn.  It's the same way when you
exit a turn.  This may not have helped much, but here's one more tip.  The
best way I've found to find to correct weight distribution is to look at
the right side tire temps.  Depending on the track, I like my car either
neutral, neutral - tight, or neutral - loose.  I first learn my driving
style for a particular track and then I move the weight around so that if
I want the car a little loose, the rear tire will be a few degrees hotter
than the front tire or if I want it a little tight, the front tire will be
a little hotter than the rear tire.   Then as the tires wear, the setup
will change depending on the track.  For example, at Bristol, I set up a
little loose, and the car gets looser as the tires wear.  But at Loudon, I
set up a little tight, and the car gets tighter.  Then at Atlanta, I set
up loose, and it tightens up later.  So you must know you driving style at
a track to be able to adjust the weight.  Again, remember that I only
spoke on weight distribution.  It becomes more complicated when all the
other factors are added to the formula.

--
Danny Fe***an

re: 2) A car running alone at speed must punch a hole in the air
(increased pressure at the front of the car) then when the hole in the
air closes behind him there is actually a vacuum created which kinda
sucks him back (negative pressure at back of car). Also, when the air
goes over the roof and hits the spoiler drag is created (downforce too).
When a car comes up behind him two things occur (actually more than two
but I gotta get to work) A)The air hole is kept open. no more vacuum
behind the lead car. B) Not as much air hits the spoiler on the lead
car  which means less drag. Oh, and C) if the lead cars gets bumped that
helps too.

The main benefit for the aft car is that he doesn't have to punch a hole
in the air. It's already open.

I'll let someone else deal with the dirty/clean/turbulent air issue. I
don't type so good.

Hope this helps,
Mike Radler

Whos to say winning at Dega is more difficult than winning at Bristol or
visa-versa??  Sure everyone can run Dega, but it is sooo dang touchy
there, that its not that easy to run thoses consistant 197s that I am
seeing...(without the draft) I am sure people like Irvan & Martin would
consider a win at any track equal victory

If you are worried about skill level points, run on a league.  I was all
concerned about my skill rating when I first jumped on Hawaii.....Now I
concentrate on being a safe, patient, consistant driver. League racing
forces you to do that.

::stumbling off the soapbox::
-----------------------------------------------
vetteracer (on hawaii)

http://www.geocities.com/MotorCity/1726
If you wanna Finish First, you have to First Finish
-----------------------------------------------

Rick

Weight distribution is a completely different issue, and I'd rather someone
answer it that knows what they are talking about.

When a car is running by itself, a large area of turbulence is created at the
back of the car, causing a good bit of drag.  If a car is drafting behind this
car, it smooths the airflow behind the car.  This allows the two cars,
together, to go faster.  Hope this helps.

Pat

-----------------------------------------------------------------------------
Pat Campbell            The Chevy Monte Carlo           6,94,88,16,4,25
Lexington, AL            NASCAR's Wide Load               War Eagle!!!

           Home Page: http://fly.hiwaay.net/~pscampbe/pscindex.html
        NASCAR Stats: http://fly.hiwaay.net/~pscampbe/nascstat.html
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[snip -- since my mechanic isn't here to help on on #1)]

: 2) When I watch NASCAR races on TV, cars tend to 'pair up' (the
: announcers always call it finding a 'dance partner').  I would assume
: this is so the car behind gets a draft, but how does it benefit the car
: in front?  And if it doesn't, why doesn't the car behind just slingshot
: past? I would think they might just keep slingshotting past each other,
: but instead it seems they maintain their order.

I hope I get this right....  The car behind gets the benefit of the
draft.  But, as the air flows over the back of the rear car it will
begin to flow over the top of the car behind.  This actually has the
effect of lessening the drag on the lead car.  Therefore the theory goes
both will go faster.  It also seems that due to aero changes over the
last few years it is harder to get the slingshot effect of old.  Also
having two cars side by side disrupts the clean air flow over the
cars, thus causing more drag on the 2 cars -- slowing them down.  At
times you will see one car passing another and then "teaming up" again
in reverse order.  This is because the one car can actually go faster
than the other and thus increase the "pulling" effect.  The longer they
stay in order, the faster they will be compared to the cars that haven't
caught up to the draft.

Yeh, I know I've stated it all too simplistic, but then I'm not a Rocket
Scientist :)

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

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

1) In the NASCAR game manual, under Rear Bias, it says (and I'm
paraphrasing) that the more weight there is in the rear of the car, the
more it tends to get loose.  Also, under Fuel, it says as the tank gets
empty, (thus lightening the rear weight) the car tends to push.  Ok, so
far so good.

However, when the manual talks about downforce, it suggests that to
CORRECT a loose condition, you add MORE rear downforce.

My question: Why do "weight" and "downforce" have opposite effects? I'm
confused.

2) When I watch NASCAR races on TV, cars tend to 'pair up' (the
announcers always call it finding a 'dance partner').  I would assume
this is so the car behind gets a draft, but how does it benefit the car
in front?  And if it doesn't, why doesn't the car behind just slingshot
past? I would think they might just keep slingshotting past each other,
but instead it seems they maintain their order.

Thanks,
Tim

On the short ovals, I tend to get loose entering a turn, and tend to push
on exiting (ouch, that wall hurts!).  Any suggestions?

--Tim

One other thing to add to this.  The original poster asked why the second car
in a draft doesn't just slingshot past the front car.

Well, it used to be that way.  Cale Yarborough won two straight Daytona 500's
in 1983-'84 by waiting till the last lap to slingshot past the lead car on the
backstretch.  Darrell Waltrip, and Buddy Baker were the victims.

Before restrictor plates, it was possible for the second car to run at about
3/4 throttle in the draft (this according to the late Neil Bonnett).  All that
driver had to do to pass was lay back a little, floor the gas, pull out, and
shoot right by the lead car.

But, the plate takes away all the top end acceleration from the car.  
Consequently, all the top cars are running wide open in the draft.  It takes
an extremely strong engine for anyone to pass by themselves.  So far this
year, only Sterling Marlin has shown an ability to do this with ease, thanks
to Runt Pittman.

Pat

-----------------------------------------------------------------------------
Pat Campbell            The Chevy Monte Carlo           6,94,88,16,4,25
Lexington, AL            NASCAR's Wide Load               War Eagle!!!

           Home Page: http://fly.hiwaay.net/~pscampbe/pscindex.html
        NASCAR Stats: http://fly.hiwaay.net/~pscampbe/nascstat.html
-----------------------------------------------------------------------------

Gregory Fung

Vancouver, B.C., Canada

This is rather natural of weight transfer.  You move weight forward under
braking (going in), causing looseness.  Weight moves backwards under
power, causing push.  Personally, I counter the latter by using small
amounts of power oversteer.  You can change your driving style to minimize
the effects.

Gregory Fung

Vancouver, B.C., Canada

I hope this was clear. I'm rushing this because I'm connected via long
distance.

======
Try adjusting the rear shocks to get a gentler weight transfer under
acceleration. The problem here is weight transferring from front to rear
weight when you roll on the power. And yes, stomping the gas abruptly
will definitely worsen the conditon.

Mike.