rec.autos.simulators

NASCAR physics questions

David Spark

NASCAR physics questions

by David Spark » Fri, 26 Jul 1996 04:00:00


>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.

This seems to be an error in the physics model. In everything I've read
about vehicle dynamics, increasing the load on a tire increases the amount
of lateral (turning) and longitudinal (brake/acceleration) force available.
However, it is not a linear function, so generally you want to distribute
the weight evenly. In other words, two tires sharing an equal load will
generate more lateral/longitudinal force than say 60/40 distribution.

I assuming you're talking about restrictor plate racing (Talladega and
Daytona). The primary reason for not constantly slingshotting past another
car is because it slows both cars down. If you're in the lead pack, you
want to hook up to drive away from the rest of the pack. If you're behind,
you want to catch up. Also, when two cars pit together, they can draft back
up to speed much more quickly together.

You'll see a lot of shuffling go on in the last 10-20 laps of a restrictor
plate race, as drivers try to set themselves up for a run to the front. A
lot of action is going on in the pits as the teams send runners down pit
road to figure out who they can hook up with to make a dash. But on the
white flag lap, all bets are off.

Dave "davids" Sparks
Sequoia Motorsports

Terr

NASCAR physics questions

by Terr » Fri, 26 Jul 1996 04:00:00


> >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.

When two or more cars are drafting the front car does benefit, but the rear car
benefits more.  The leading car benefits from the lack of air closing down
behind his car, which will create drag. The trailing car suffers from this
"vaccuum" behind his car, but the forces pulling from the leading car prevail.

Terry


David Burto

NASCAR physics questions

by David Burto » Fri, 26 Jul 1996 04:00:00


> Question: Do you guys on HAWAII mind if someone 'bump-drafts' you?

Add a note about Bump drafting to your hotkeys (F1-12) Its tough in
pickup races when you don't know everyone quite so well.  Join a
league, you will get to know all the drivers and the trustworthy-ness
of their driving... Last night on my league I was only gettin 196s alone
at 85 degrees, got in a bump draft and was seeing 202 going into
turn 3.  What a rush!!

vetteracer
http://www.geocities.com/MotorCity/1726

Eldred Picke

NASCAR physics questions

by Eldred Picke » Fri, 26 Jul 1996 04:00:00



>Subject: Re: NASCAR physics questions
>Date: Tue, 23 Jul 1996 19:08:59 GMT
>The physics are such that two cars drafting can actually go faster
>than one car alone.  And, add to that a bump from the car in the rear,
>and the effect is compounded.
>Rick

Question: Do you guys on HAWAII mind if someone 'bump-drafts' you?

________

Eldred Pickett

I am NOT paranoid.  And why are you always watching me?!?

Chuck Stuar

NASCAR physics questions

by Chuck Stuar » Sat, 27 Jul 1996 04:00:00

I don't since it only slows the one doing the bumping. Assuming it is not in a turn and
he isn't going twice my speed.

--
Chuck Stuart - Mesquite TX USA  
VBTrace 96 is a runtime Procedure Trace, XRef,
Debug, Profiler and much more. Shareware $49.
http://www.apexsc.com/vb/ftp/coop/cstuart


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