From: andyh@chaos.cs.brandeis.edu (Andrew J. Huang)
Subject: Re: Rolling a car, general questions
Organization: Brandeis University
Date: Tue, 14 Apr 1992 14:58:54 GMT

In article <1992Apr13.195928.12344@fwhnm02.fwrdc.rtsg.mot.com> rlatham@fwhnm02.fwrdc.rtsg.mot.com (Russ Latham) writes:
>
>I have a few questions about rolling a car.  Is it possible
>to tell at what point a car will start sliding when going 
>around a corner, before it happens?
>And what is the possibility of rolling a car in a corner?
>What do I need to watch for in order NOT TO ?
>Any advice as to how to tell the limit of a curve, like
>how much over the posted speed is generally safe?
	<deletions>
>Any advice (except 'not to' :-) ) would be appreciated!
>I would hate to find out the hard way that my car will
>roll in that type of situation.
	<deletions>
>
>Russ Latham (rlatham@mailbox.fwrdc.rtsg.mot.com)
>             (latham@motcid.rtsg.mot.com)

The best way to approach any of these issues of "when a car will do
this under these severe circumstances" is to take a course at a
driving school.  Of course I don't mean the schools for teenagers
learning to drive and I don't necessarily mean Bondurant or Jim
Russell.  In New England there are several clubs, notable Corvettes of
Massachusetts, BMW Car Club of A, and Porsche Club of A, that rent a
racetrack and have several experienced (I believe they're also
certified SCCA) instructors talk about how to drive fast properly and
safely.  After the talk there is usually some demonstration in a
student car and then the school really begins.  Two or three classes
are formed and they take to the track.  The track is nice and safe
with lots of area for spinning off, all the cars are going in the same
direction so there won't be any head-ons, you also know that the
driver ahead of you will not slow you down (even if you have a faster
car) because you have all been told to 1) let others by if you are
slower and 2) wait for others to let you by if you are faster.  You
just drive the track as fast as you want.  You get 10-20 shots at the
same turns in a short amount of time so you can tune your driving and
your reactions.  Look up car clubs in your yellow pages.  The cost is
usually quite low ($50) and they always welcome new people, even if
they don't have the same car.

I've done three of these schools.  I drove fast before I went to the
school, and I drive just as fast now, but much safer.  When I take a
curve, I KNOW how MUCH slide I will have and where that slide will
take me.

Getting off the soapbox, I'll deal with the specific questions.  With
the Honda (Prelude?) you have to do something really stupid, like jam
on the brakes hard while cornering very hard, to get the car to roll.
This is on dry, clean pavement.  Under a myriad of other
circumstances, you can roll a car with impunity: sliding off the road
into grass, sliding into curbs, cornering with low tire pressure, etc.

As regards sliding, from my reading of your post, I think that you
mean the rear end going out, which is otherwise known as oversteer.
Most cars are not naturally prone to this.  However, all cars CAN do
this and it is nearly always the result of something the driver does.
It's not something that telegraphs itself to you, except at the very
end in which case its too late.  IN PARTICULAR, if you feel the rear
end going out, you must be very smooooth; you cannot brake without
risking rolling, if you let off the gas too much the oversteer may
accentuate.  It depends on the particular car.  With a front drive, if
you nail the throttle, you may just pull it around.

The emphasis on smoothness is why driving schools are good.  It is
difficult to learn a smooth deliberate correction to oversteer when
your heart is in your mouth and adrenaline is coming out of you eyes.
The gut reaction to do something QUICK, is dead wrong.

have fun,
andy