rec.autos.simulators

I am happy to inform you that steering into a spin to break it works
well.

I've read all kinds of physics debates about it - I tried it last night
and it blew me away!

It basically happens as the first front wheels and then back wheels take
turns "anchoring".. Here's how it works:

(The example is given for a clockwise spin)

The car enters the spin as the rear wheels lose grip faster than the
front wheels; the front wheels "anchor" and the car yaws to the right.

The front wheels are turned quickly in the same direction as the spin,
i.e. clockwise in this example.

The grip of the front wheels decreases when a certain angle is reached.

The back wheels now have more grip; they "anchor" and the car yaws
counterclockwise.

That's it.

Andrew

Nice analysis.  If you really want to sound snooty and impress the
locals, say: "The car enters the spin as the slip angle of the rear
wheels increases faster than the front wheels"  <g>

What you are doing is suddenly ramping up the slip angle of the fronts
to match or exceed the slip angle of the rears to arrest or reverse
the yaw that is taking place.

It's a very useful spin technique for saving one's bacon in a race and
not losing too may spots because of the error.  I sure am glad someone
discovered it and were thoughtful enough to pass it along...

Regards,
Brett C. Cammack
That's Racing! Motorsports
Pompano Beach, FL

Yes, I believe so. Steering 'into' a skid (or spin) is not a new technique.
It's been well known for a long time.

John

Hi all

Is this realistic car behavior ???

Bash

That's what I'd like to know.

I read the original post a while ago describing this technique and
I too have had much success with it.

I guess that shows that I spend too much time spinning :)

-Nick

Absolutely realistic in general, although I think GPL allows us a
little extra leeway from, a pure physics standpoint, than "real life"
(yes, that's just an opinion)

If you watch much modern f1 with the in-car cameras, that's
what "opposite lock" is all about - this concept to the extreme.  In
fact, it was awesome this weekend watching Velleneuve just when it
started to rain.  They had an in-car shot of him opposite locking
*TOWARD* the turn exit wall where it says "Bienvenue" - whilst
travelling at around 100kph (est.) - at the last turn onto the front
straight... that guy has frickin' TITANIUM NUTS.  He did it two laps in
a row that they showed.  Spectacular stuff, on the razors edge.

-=ham

Sent via Deja.com http://www.deja.com/
Before you buy.

Now I'm confused.  I thought Gregor et al. were talking about something
completely different than traditional opposite lock.  That is, if I am
driving around a right turn and the car starts to oversteer (ie. rotate
faster towards the right) the natural instinct is to unwind the steering
wheel, and in extreme cases add in opposite lock (ie. steering left) to stop
the rotation.  But I thought Gregor was describing some magical point of no
return where opposite lock no longer works, and in fact he was saying turn a
bit more to the right.  Maybe I read it wrong.  Opposite lock is obvious and
intuitive to anyone who has driven in a Canadian winter.  The other is not
so intuitive, and I haven't had a chance to test it.

As for Villeneuve, he smacked that wall last year and walked away, so
probably thinks it is not a big deal.  The same could be said of his big Eau
Rouge wrecks which seem to have become an annual event.

Stephen

Hmmm, well, now me too.  I just re-read that and I think I'm the one
that's got it backwards.  I can't see how that would be physically
correct... I'll have to try it.  In fact, I've never heard of it...
ain't ignorance bliss (or not).  If indeed it's true, an
overcorrection/mistiming of the anchoring maneuvre would have serious
conqsequence I would think.  Food for thought [sheepish grin].

big Eau Rouge wrecks which seem to have become an annual event.

Yes, that's what impressed me even more... after his nearly head first
smack last year, he still had the nuts to do it... although the smack
last year was an entrance problem, not exit.  Also, I think at most
tracks it's no biggie, but not on his home track, I think he wants to
finish that race worse than any.  If I recall, 4 world champions bit
that wall in last years race... Schumi, Jaques, Damon Hill, and Mika.
ouch.

-=ham

Sent via Deja.com http://www.deja.com/
Before you buy.

It absolutely works, someone sent me a replay showing how to do it,
and after a few tries I got the hang of it.
But I can only do it when I focus on it, it feels so unnatural, in the
heat of the action I allways countersteer... and lose it :)

Andre

Yes, what this discussion is originally about is the opposite of the
opposite lock :), which, as you nicely put it, is effective only after
the magical point when the car yaw angle becomes really drastic, in fact
higher than the maximum possible lock of your front wheels. Why you
don't see this technique used in real racing is that a good driver
should never get into such a situation in the first place, and is still
in the regime where opposite lock is effective. On the other hand, this
effect is more pronounced the higher the center of gravity of the car
(the more the outisde wheels are loaded), so the technique does not work
as well with modern F1 cars, although I had limited success with it in
F1 2000.

May I recommend not to try the opposite of the opposite lock in the real
life? On icy surfaces there is not much load transfer onto the outside
tyres, so the effect would not be as large.

I'd love to see Villeneuve in a more competitive car! He is such a
spectacular driver even when not going over the limit, and driving a
more prominent car would give more coverage of him on the TV.

-Gregor

Well, I still am getting started with GPL.... I suck! But believe it or not,
I can do this really well...

Now if only it worked on grass.

I mean when the car is on the grass.

Regards!
Andrew

Hi!

First off: I know that your described technique works and it may be the best technique for people driving with combined pedals.
But for me, the following countermeasures always do the job as fine:
I'm driving with a seperated pedals setup, i. e. I can feed in gas and brake simultaneously. If I overcook it and the car starts to spin, I immediately give opposite lock in a manner that my front wheels point exactly to the direction I normally want to drive. I also feed in just enough throttle to prevent load travel to the front wheels, that means I balance the car. If I am still too fast and the car does not recover, I quickly give full throttle and full brake simultaneously. This causes two things: The front wheels lock immediately and therefore loose a lot of grip. But the rear wheels don't lock because the braking torque is overdriven by the engine-torque. So now I have the same result as you: Front loose, rear grip. Now the car starts to spin the other way round but this time in a controllable manner.
I have put a little replay (77kB-zipfile) onto my server for download. It shows a spectacular overtake maneuver at Silverstone where I catch two AIs in one turn ;). You can get it by clicking this link:
http://www.joachimblum.de/files/spin-recovery.zip
Watch from inboard-view or TV1. Enjoy!

Regards
Crash

Visualize for a moment each tire working in a corner.  Tires generate
their grip via hysterisis of the *** molecules when the contact
patch distorts (to a point) when the tire is scrubbing across the
pavement at a slight angle (the slip angle).

A neutral drift occurs when the slip angles of all four tires sustain
a relatively constant ratio of slip angles between one another.
(from motoring sedately through a corner with no fanfare to drifting
gracefully in an arc wider than the corner's radius until you come to
rest against the Armco.)

If the slip angles of the front wheels increase faster than the rear
wheels the vehicle experiences understeer, or "push".

If the slip angles of the rear wheels increase faster than the front
wheels the vehicle experiences oversteer, or is "loose".

If the car is understeering, you might attempt to neutralize this by
popping the throttle to take away some of the available traction for
cornering so that the slip angle of the rear tires increases, thereby
balancing the slip angles fore and aft.

If the car is oversteering, you might feed in some opposite lock to
reduce the cornering load on the rear tires to match the available
grip by widening the line a bit.

If the oversteer is too great (the difference in fore/aft slip angles
is increasing too rapidly) and the car cannot be balanced by reducing
the cornering load on the rear tires or otherwise increasing their
grip, then you can bring the fore/aft slip angles back into balance by
radically increasing the slip angle of the front tires to the point
that they have the same deficit of grip as the fronts, thereby
arresting the yaw that is occurring. (the developing spin)

The other way to arrest too high a yaw rate is to just bury the brake
pedal and lock both ends so that they have the same traction
available.

This has to be done early enough in the developing spin that the yaw
rate has not escalated to a level that the inertia of the mass of the
vehicle will continue the yaw so far that you either come to a stop
facing completely the wrong way or the car continues to rotate a
couple times until all of the stored energy of the yaw has been
dissappated.

That's the rub as we all tend to admit defeat too late when we lose
it, thinking "I can save it!" and flailing away at the controls past
the point of a graceful resolution.  As the old song goes, "You've got
to know when to hold 'em and know when to fold 'em." <g>

Regards,
Brett C. Cammack
That's Racing! Motorsports
Pompano Beach, FL

On Thu, 22 Jun 2000 14:08:35 +0200, "Joachim Blum"

Fascinating!  I'll have to give it a try during one of my numerous
opportunities... <g>

Regards,
Brett C. Cammack
That's Racing! Motorsports
Pompano Beach, FL

Extract from GRE help, which goes some way to explaining why the technique
of increasing steering as opposed to opposite locking is effective in GPL.
It also suggests GPL exaggerates the effect due to lack of some aspects
being modelled.

"In GPL, however, the addition of opposite lock during a big slide often
aggravates the slide instead of initiating recovery. This is because the
front tires are already past the peak of their slip angle curves. As the
driver feeds in opposite lock, the front tires' slip angle is reduced and
they gain grip, causing the front of the car to grip more and rotating front
of the car toward the inside of the corner.

This effect is present in real cars, but it seems exaggerated in GPL. It
seems to me that it was easier to recover from big slides in real life race
cars than it is in GPL. I am fairly certain that GPL's omission of the
weight jacking and camber change effects of kingpin inclination are
responsible for this."

"When the car is sliding and the driver feeds in opposite lock, the effects
of kingpin inclination cause weight transfer to the outside front and inside
rear wheel. This causes the rear to grip better and the front to give up
some grip, much like softening the rear anti-roll bar and stiffening the
front.

Under the same conditions, opposite lock also causes an adverse camber
change on the outside front wheel, giving up still more grip at the front.

These suspension geometry effects offset the increase in grip as the front
tires' slip angle is reduced. The result is that the car is less prone to
spin if the driver applies opposite lock during an extreme slide.

Since GPL doesn't model these effects, many GPL drivers have developed the
technique of increasing steering lock when the car is in an extreme slide.
In other words, if you're in a right-hand turn, and the tail of the car is
sliding to the left, turn the wheel more to the right."

"This causes the front tires to go further past their slip angle peak and
give up more grip, reducing the slide. It also increases drag and slows down
the car, which can be useful under such circumstances. Once the car is back
under control, the steering can be returned to a more normal angle."