[TD in DC]

Originally Posted by }{arlequin

speaking of looking at the data... do you gave a g-sum meter hooked up on the car?
what did it register at impact? just curious

I will all of the data in due time, but, as a teaser, check out these two graphs. One shows the speed, lateral Gs and G-sum. The other shows my lines. As you can see, I was a little bit earlier than usual, but not by much at all. The whole thing is very interesting.

Out of all honesty, this was not a situation where you have a serious major single error. I was skating along the razor's edge and fell off the wrong side. A few little differences here or there and I would have been just fine. That's is why I said the data was interesting. It was not all that different from all the other times I made it through the turn just fine. All it takes is for the track to be a little slicker, your tires to be a little less grippy, you turn in just a little earlier, you are going just a little faster, and you open the wheel just a little too late, which all adds up to a nice and slow (well, as slow as it can be at 86 mph) 180 that puts you into the wall at a track that doesn't really have too much runoff room there.

You live and learn. I just want to make sure that I learn the "right" lesson from the whole thing.

And yes, George is a trooper. I know exactly what it took for him to get his car fixed and get right back out there . . .

[TD in DC]

Here is a close up of the turn in so you can see it better.

[}{arlequin]

it's probably b/c i haven't played w/ the software, but i'm feeling really dumb here.... i see green, black, and red lines on the 1st graph, but i don't know what each of them means (stands for)

then, am i to understand that your first graph is read left-to-right but then the next two right-to-left?

...still need pics.........

[Vicegrip]

The legend for each line is next the the graph on the left side. Stop, go and side to side G.

[TD in DC]

Dave,

The first graph shows three variables on the y-axis: 1) speed (black); 2) lateral Gs (red); and 3) Total Gs or G-sum (green). Time is plotted on the X-axis.

If you look at it from the left to the right, you will see the speed increasing gently (that represents my foot flat on the floor in the '44) until a max of about 87 mph, which was the speed I hit at turn in. Then you see the speed gently falling off as the turned tires scrub speed. Interestingly, I scrubbed about 12 mph off by the time I hit the apex only by turning the wheel. This shows how important it is to keep the wheel as straight as possible. The red line shows that I hit about 1.3 lateral gs. You can see the lateral G's take a wave form where the car is rotating. The green line roughly matches the red line (which is not surprising since I wasn't braking and the '44 doesn't generate too much acceleration force) until impact where it shows 3g.

The next picture is a "God's Eye" view of Turn 10 from above. Each of the little lines shows one of my lines through T10 during the infamous run. The bolded line shows the line when I wrecked. The final picture is just a close up of turn in so that you can see the individual lines a little better. A little early? Yes. A lot early? I really do not think so.

Video is coming. For some reason the video is "jumpy" and "skipping" on the computer. I am going to try to use my DVD burner to capture it in hopes that the quality will be better.

[smdubovsky]

TD, Im guessing the 944 has an LSD? You look fine until halfway between apex and trackout - just like all the other lines - then the car goes straight. Something I had to teach myself early on the E30 (w/ a LSD) is that if you get into a spin, the lack of ass-end grip (only ~40% weight back there) and staying on the throttle will just keep the rears spinning. You have to lift a LITTLE to get the rears hooked back up (and can then even get back into the gas a little). Maybe your transition on/off the concrete was just enough to get the rears going?

I did a spectacular pirouette years ago in a mustang at about 70-80mph @ an autox. The 911 had more rear grip than power and I could flatfoot it onto the straight. First run in a friends 'stang proved it not so. I too flatfooted it until I caught the steering lock. Was not the right thing to do

SMD
________
IPAD ACCESSORIES

[TD in DC]

Originally Posted by smdubovsky

TD, Im guessing the 944 has an LSD? You look fine until halfway between apex and trackout - just like all the other lines - then the car goes straight. Something I had to teach myself early on the E30 (w/ a LSD) is that if you get into a spin, the lack of ass-end grip (only ~40% weight back there) and staying on the throttle will just keep the rears spinning. You have to lift a LITTLE to get the rears hooked back up (and can then even get back into the gas a little). Maybe your transition on/off the concrete was just enough to get the rears going?

I did a spectacular pirouette years ago in a mustang at about 70-80mph @ an autox. The 911 had more rear grip than power and I could flatfoot it onto the straight. First run in a friends 'stang proved it not so. I too flatfooted it until I caught the steering lock. Was not the right thing to do

SMD

Bingo. I do have LSD. You are also correct that I felt absolutely fine until halfway between apex and trackout. Actually, the car went into a four-wheel drift just after the apex BUT the rear really started to come around when I transitioned from the concrete patch onto the asphalt. "That" is where I got behind the car. You are also correct that I kept my foot all the way into the gas. Interesting that you think I should have modulated just a little bit. I thought that would just make it worse, but I see your point about perhaps getting the rears to hook up again.

You are one of the first people to describe nearly exactly what I felt, and I haven't even posted the video yet!

[nein14-6]

The guy that took photos at the event has his pictures up for purchase.
www.digidids.com

[Mark in Baltimore]

Ugh. I forgot that this guy uses shutter speeds that freeze the motion of the wheels.

[RENN 951]

Todd:

Wouldn't your turn-in point actually be at the initial inflection points for the red and green curves? That would be about time 1071 on the x-axis. You wouldn't be starting to load up all those g's at that point if you were still going straight and didn't turn in until your peak velocity.

I think the data shows you turned in where the g's started to load up, and because you had your foot on the floor you were still accelerating until you reached the peak at about 87.5 mph. I think the drop off in velocity shows where you started to lose traction and began your four wheel drift.

I'm not familiar with your software of course, so maybe I'm missing something, but my engineer's eye would interpret the data as described above.