Thanks Barney and all who have commented - hopefully the following addresses
the issues you raise.,
On 17/06/2011, at 8:38 AM, Barney Gaylord wrote:
> Yup, I got the answer. Nice video. You were driving, so it's your fault.
The car doesn't handle well, and you didn't handle the cantankerous car well
either. It's one of those things where you have to drive whatever is put in
your hands, and fix the handling problem later.
>
> It starts in the first turn at the 8-second mark when you get the LR tire
off the ground, followed immediately by oversteer and squeal from the
overloaded RR tire. You caught that one, tturned the steering wheel quickly
right to keep the nose going in the right direction, and got your foot right
back on the throttle to keep it straight. But you should have gotten the
message from that trick. On the next turn you got the same thing at the 38
second mark, a little body roll, LR tire up, oversteer, and RR tire squeal as
it goes sideways. You caught that one too, turned the steering wheel quickly
right to keep the nose going in the right direction, but you over did the
steering correction, didn't bring the wheel back soon enough, and didn't put
the throttle down, so you got immediate and accentuated oversteer in the other
direction (fish tail). When that gets out of hand you're going backward, and
the game is over.
>
> You have a real quick autocross car there that will turn in quick and
oversteer on demand, but that's not the fastest way around a long curve. What
you need is more front sway bar (or less rear sway bar) intending to keep the
inside rear tire on the pavement to prevent overloading the outside rear tire.
If you over do the front sway bar you can end up with understeer and push in
the corners, also not the fastest way around the track. For road racing you
want near neutral steering for the highest speed in a long constant radius
turn. Then lifting off the throttle makes it turn in better at the entry
point, and back on the throttle kills the oversteer and drives the front end
to the outside of the curve. (Just don't step too hard on the throttle when
one rear tire is off the ground).
>
Ouch! ;-) Thanks for the analysis.
That hill and dip beyond is always a bit scary at the end of that long
straight and on that lap I would have lifted and would have been feathering
the throttle - the idea would have been to accelerate once the car had apexed,
down the hill. The apex is a little further around the corner so it appears I
had entered a little early (I was still "learning" the track).
My car is a little down on power and that always makes me take a few
additional risks (OK... some call it "over drive" ;-) I often catch other
cars, when I am down on power, by braking a little later and getting through
the twisty bits faster, as Barney has spotted.... I PUSH. At that time I was
chasing a lovely and very quick bugeye Sprite, thinking if I could keep up
with him then I must be doing decent lap times. I can remember thinking that
I wasn't going to back off too much for that corner - and I certainly wasn't
going to brake.
I had lower pressure than normal in my rear tyres in an attempt to get them to
warm up faster on the cold track on a very cold morning. At this time that is
what I am putting down to right now the way the rear end broke away so easily.
I thought I had caught it for a moment but, as they say, it all happened
rather quickly from that point. I was more surprised than anything.
It would have been easier to analyse what I was doing throttle-wise is the
audio was better but as the guys at the Vio-POV camera place have now
confirmed, the "internal" microphone is NOT disconnected when an "external"
microphone is plugged in - which in my experience usually happens. The
external mic was taped to the back of my seat so there should not have been
that wind noise... I now know what to do to fix that.
I am still a little annoyed. ;-) It will be a learning experience.
Eric
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