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DAS Analysis Example - Putnam

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Old 01-24-2005 | 10:44 AM
  #31  
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Norm:

If you get it, can you post a graph of g-sum and speed versus distance for a lap at Putnam. I would also need lat g and long g versus distance as well.
TIA
Old 01-24-2005 | 10:48 AM
  #32  
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CC:

So if my math channel for gsum is the following :
gsum = sqrt((Acc_1)^2+(LinG)^2)

Where are you getting LinG since you have no longG sensor. What is the equation you are using for LinG ?

Thx,
Norm
Old 01-24-2005 | 10:50 AM
  #33  
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To give credit where credit is due, the above graph is Jim Childs driving my car, I sent Tim data with laps of Greg, Jim and me. The 1.21 lap is not me yet (my best was a .22) I am sure Jim could have gotten another second out of the car had it been his!! I think the key to fast learning with this data stuff is to let a hot shoe drive your car and plot against it. A world of thanks to Greg and Jim for helping me in my learning process. Without a data coach, this info is almost useless to the non tech guy like me
Old 01-24-2005 | 10:57 AM
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Sorry Norm:

Long g (or Lin g) is

deriv(Speed_1)*1.4667/32.2
Old 01-24-2005 | 11:10 AM
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Originally Posted by ColorChange
Rjay, while LFB can be nice, it is not necessary at even the best levels in the world. Barrichello tried LFB and switched back to RFB, and has won many times. Nice ... yes, necessary no, worth it? ... difficult to say. IMO, if you haven't grown up with LFB, it will be difficult to retrain yourself as an adult and outperform RFB.
Not saying I will succeed, but as my feet are reasonably proficient with heel/toe and dbl clutching, I think its worth the effort. From a feel and modulate the brakes standpoint, I LFB on the street with ease in my Truck (automatic). What I need to work on is simply the decision making with respect to the shift of the foot between the clutch and brake. Need to work to make this natural. This BTW is the beauty of becoming a fairly serious AXer. If I get confused and **** this up there are no walls to hit, just cones. One can practise these skills in a combat situation in relative safety.
Old 01-24-2005 | 12:24 PM
  #36  
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Tim, thanks for the analysis. As Eric stated, that data is me driving his F class 944 S2, and that 1:21.78 lap is the best one of about 7 laps I ran in his car. I was driving fairly conservatively, as I wasn't used to the car, and I wanted to be absolutely sure to return it to Eric in one piece. My best lap that weekend in my F class 968 was 1:20.04. I'm sure a good part of that 1.7 second difference comes in turn one, where I'm more comfortable being aggressive on entry in my car.

Greg Fishman also drove Eric's car that weekend and his best lap time was virtually identical to mine. If you're up to it Tim, it would be very interesting to see an analysis of the differences between Greg and I, as I suspect that we had different ways of getting to our best lap times.

Regarding LFB, I started out as a right foot braker, and transitioned to LFB in my 4th season of DE. I worked to develop braking sensitivity in my left foot for about a year on the street before bringing it to the track. Ever since then, I've been successfully using LFB all corners that don’t require a downshift.
Old 01-24-2005 | 12:35 PM
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Jim,

1. I understand your desire to compare two competant drivers (my bad).
2. So what your saying is that you spanked me silly without even trying hard. Thanks.

Let me know which laps are who's and I will do it. Of course you'll owe me some additional data down the road, Gingerman preferred. Nice driving by the way.
Old 01-24-2005 | 01:07 PM
  #38  
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Originally Posted by ColorChange
1. I understand your desire to compare two competant drivers (my bad).
Its not that so much as removing the differences in the cars from the comparison. You're car is quite a bit different than Eric's. For example, part of the differnece in the lateral G's between your data and mine is clearly due to Eric's car running on Hoosiers and your's running on street tires.


Originally Posted by ColorChange
Let me know which laps are who's and I will do it. Of course you'll owe me some additional data down the road, Gingerman preferred.
I think any other lap you find in the batch that Eric sent you that is in the 1:21.xx range has to be Greg's. Unfortunately, additional data from me will have to wait until I find some spare $$$ and get DAS installed in my car, or do another guest drive in a DAS equipped car.
Old 01-24-2005 | 02:10 PM
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Jim:

I have some data from the Sunday enduro. Times are 1:26 - 1:30, then maybe a driver change and then very consistent 1:22 - 1:23.

The second set has only about 10 laps at 1:21 - 1:24.

Who might be who?
Old 01-24-2005 | 02:20 PM
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Tim,
Enduro was my set of laps, start of race until the car felt wrong(tire is cording at this point)came in for a pit stop where we change the tire, Greg gets in and drives until that tire is shot. Greg came in and the rubber was within a couple of mm of blowing up. The car had the camber adj. come loose and we were running positive camber by the end of the race. The tires were getting eaten by the fender well. The second set of lap is where a great battle between Jim and Greg took place, probaly somewhere in the last 5 laps of the data you have.
Old 01-24-2005 | 02:38 PM
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I think I have the particular files from my practice session in Eric's car. I will send them to you if I can find them, Tim.
Old 01-24-2005 | 02:39 PM
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Jim and Greg: Send me your data that has your laps. Let's try Saturday practice.

tim@colorchange.com
Old 01-25-2005 | 12:02 AM
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Originally Posted by ColorChange
BrianP: Excellent drivers do this lap after lap after lap. From Schumi and well on down. Even with as little experience as I have I can get it right on probably at least 1 turn a lap, more on a track I know well. It isn’t that hard, it’s just hard to do consistently.

Your point of overbraking destroying the benefit of perfectly late threshold trail braking is correct, but the really good ones don’t overbrake. I think the time difference depends upon how far off threshold the other braker is. If I can hold even a 1/10 of a second to 140 mph versus the guy who brakes early, I not only gain the time I am at the higher speed, but all the time on the optimum decel curve until he matches my ideal rate. This can easily … and often is, over 1/10’s of a second or more per corner, just on proper entry.
As I said, do the math. I think you'll really be surprised. The truth is that there isn't 1/10's of a second per corner. There's not even a 1/10 of a second on a very long and hard braking corner. If you had 2 drivers who entered the corner at the same speed, the difference is a few tenths per LAP, not per corner. If you blow just ONE corner (and by blow, I mean enter just a few MPH too slow), you'll give up the advantage of all of the other corners combined, and then some.



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