Valentine's day present for my wife (AKA friction circle)
#1
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I spent a lot of money making this Valentine for my wife. I hope she likes it.
![](https://lh6.googleusercontent.com/_jh2HiMm4nKQ/TUd8Vo5AV6I/AAAAAAAACvc/ImgHu5f6Lyw/s512/BeMyTrackentine.jpg)
I was playing around with plotting friction circle data for some telemetry I logged at TWS last year. I believe this is the session where my brakes were toast but it is still interesting to look at.
![](https://lh6.googleusercontent.com/_jh2HiMm4nKQ/TUd8Vo5AV6I/AAAAAAAACvc/ImgHu5f6Lyw/s512/BeMyTrackentine.jpg)
I was playing around with plotting friction circle data for some telemetry I logged at TWS last year. I believe this is the session where my brakes were toast but it is still interesting to look at.
#7
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I thought the fact it came out as a heart shape was funny. Changing the dot color to red makes it even funnier. The line pattern through the center is, I believe, from the fast straights at this particular track (TWS).
But, now for the real reasons I included this in the race prep section. This shows my track Miata is achieving ~1.2g lateral accelerations on NT-01s. It also shows that there is a lot more speed to be had with this car, at least at the track where I logged the data. With some more manly driving there are some corners where I can 'spread the dots' farther out to the edges of the theoretically achievable friction circle.
Here is a quick read on friction circle analysis. I would like to see some others friction circle data if you have it. If you know how to use Excel then creating this plot is pretty easy. Just do an X-Y scatter plot on your lat and long acceleration log data from a couple of hot laps.
http://www.trackpedia.com/wiki/Data_...riction_Circle
But, now for the real reasons I included this in the race prep section. This shows my track Miata is achieving ~1.2g lateral accelerations on NT-01s. It also shows that there is a lot more speed to be had with this car, at least at the track where I logged the data. With some more manly driving there are some corners where I can 'spread the dots' farther out to the edges of the theoretically achievable friction circle.
Here is a quick read on friction circle analysis. I would like to see some others friction circle data if you have it. If you know how to use Excel then creating this plot is pretty easy. Just do an X-Y scatter plot on your lat and long acceleration log data from a couple of hot laps.
http://www.trackpedia.com/wiki/Data_...riction_Circle
#12
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I think the bunch of dots that are skewed to the left (lateral) is due to the mostly right turn nature of the track running CW. The turn 2-1 combo is a really long turn and I was definitely not carrying as much speed through there as I could have. The clumping inside of the circle reflects the lower than optimum acceleration through those corners. There is something about exiting onto the front straight, over a sharp bump from the banking transition, with a concrete wall in your face, going ~100 mph, that is a little unnerving.
I need to go back and look at my data to see where those low lateral g-spots are located so I can push harder on those next time out.
There, the g-spot pun, I used it
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#16
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I can do the exact same thing with my Professional Datalogging Set. It's easy to set up, too -- you simply install your g-meter (length of floss tied to rear-view mirror, with an Sharpie marker tied to the other end), then uncap the Sharpie (or, more precisely, your g-force recording device) and hold a sheet of paper underneath the Sharpie as you drive.
The resulting datalog looks a little different though:
The resulting datalog looks a little different though:
![](http://pubs.logicalexpressions.com/pub0009/UserImages/AI3382.gif)
#17
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That was the LS1 car. 320 RWHP, 350 ft*lbs. It is an instant throttle response torque monster compared to a turbo car of similar power level so it accelerates well out of the corners.
#19
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Your G-G shows little trail braking is occurring for whatever reason. Most Miatas aren't so hot at it. Trail braking is when you brake for a turn and then ease off the brake at the same time as you increase cornering load. This speeds you up since the car is spending more time at the limit of traction available from the tires.
Below is a G-G showing lots of trail braking into RN turns. The way that car is setup, it is easy to use the tires to the limit without premature brake lockup curtailing the fun.
Below is a G-G showing lots of trail braking into RN turns. The way that car is setup, it is easy to use the tires to the limit without premature brake lockup curtailing the fun.
![](http://www.pbase.com/sjmarcy/image/129125192/original.jpg)
#20
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Part of the trick with trail braking with this car is the torque load from back driving the LS1. With the brake balance set just right (in cockpit adjuster) if I let the clutch out under braking, especially trail braking, the extra back torque brakes the rear tires loose and the car wants to spin. So I need to work on my clutch releasing, maybe holding it disengaged until right after I get off the brakes and right before I get back on the throttle.
Life would be a lot easier if it had a slipper clutch like the bikes I used to race. Slipper clutches are really, really nice, especially in heavy braking corners.
Life would be a lot easier if it had a slipper clutch like the bikes I used to race. Slipper clutches are really, really nice, especially in heavy braking corners.