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Re: GEEZ! course maps and Accuracy

To: autox@autox.team.net, bshort@AFSinc.com
Subject: Re: GEEZ! course maps and Accuracy
From: dg50@daimlerchrysler.com
Date: Mon, 9 Aug 1999 13:06:30 -0400
Byron wrote:

> In another post Dennis talks about how he determined he could go 1.5
> seconds faster in one section by sketching out a map on paper that he
> believed represented that part of the course, and which the lateral and
> longitudinal traces backed up.  We think the software should do that
> for you.

I'm gonna _try_ and keep this short, after that last missive I posted.

Don't read too much into the map - paper or otherwise. The point of my little
sketch - and to my mind, the GEEZ! course map too - was to cross-reference the
strip chart to the geography of the course.

"This peak is that tight left hander" "This peak is that big right-hand sweeper"
"This series of alternating peaks is that slalom"

I'd rather the software draw the map for me, but I've found that my little
sketches work pretty well in the meantime.

> We believe GEEZ does that better than simple strip charts.  For
> instance, going back to Dennis' strip charts and his hand drawn map.
> Dennis concluded that he could have shaved 1.5 seconds through better
> braking entering a single turn, but he misses a simple point.  And that
> has caused him to mis-read how to execute that turn better.  GEEZ would
> have provided a better way to see that point, and he would have had a
> better chance of not missng it.

Hrm, I'm not so sure I agree...

> The point?  The car won't turn and brake at the same time at peak g's.
> Either Dennis is about to draw a classic "cross" friction circle, (as I
> described in NAP a couple of issues ago), or he is going to find his
> plan very hard to execute.  GEEZ would have given him a much better way
> to view the car's performance envelope, and a better chance it actually
> executing a plan that would result in faster times.

Ah, you're reading too much into the value I've provided, and too little into
what and how I determined was the problem - not that that's your fault, I didn't
provide a super-detailed breakdown of the analyisis, just a rough summary.

What I should have seen in this corner was a nice, straight braking G peak that
slowly tapered off as cornering G's built - that indicates an agressive brake
application, followed by trail braking "riding the envelope" of the traction
circle. Instead, what I saw was four distinct braking peaks (although braking
was always positive, indicating that the brakes never went fully off), tapering
off as cornering Gs built.

There was 1.5 seconds in the application of brakes alone, in this one spot.

Now I'm fully prepared to believe that there was only 1 second there. I'm
equally prepared to believe that the higher speed/more distance travelled by
holding off braking would save 2 seconds there. But it really doesn't matter
either way. The point was that poor braking technique was costing a big chunk
o'time that was on the order of the distance between my current time and first
place - in one place on the course. In other words, fix your braking, you dork,
and good things will happen.

Guess what? I ran an event this weekend, and put my foot on the brake pedal much
more effectively - and won. I also discovered that there's room for improvement
on taking my foot _off_ the brake pedal (GEEZ! would be able to come to the same
conclusion) and on throttle control (GEEZ! is ignorant of throttle issues)

I learn something new every time I look at the data. Isn't that the point?

DG



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