NHMS: more fun with the datalogger

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Dave_G
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NHMS: more fun with the datalogger

Post by Dave_G »

You give a nerd a computer, a car, and a race track, and he's gonna find a way to put them all together, which is what I have done. After getting home from NHMS Tuesday, I compared my fast lap of 1:25.996 (OK, 1:26.0 :) ) with my previous fast lap of 1:27.3 from last year. By learning where I gained time, I might be able to gain still more time to reach my ultimate goal of getting into the 24s.

Here's the South Chicane (Turns 1, 2A, and 2B). (In all of these diagrams, the slower lap is on the left, and the faster lap is on the right. Red indicates braking, and blue is acceleration. The darker the color, the more intense the braking or acceleration. The width of the little boxes indicates lateral G forces.)

In my fast lap I carried a little more speed through Turn 1, but what really jumps out here is the quick braking before 2A. In the slower lap, that braking is not there, making me faster through 2A, but causing me to lift in 2B in order to reach the apex. This kills my exit speed out of 2B, which is the most important thing. 2A is a sacrifice turn that should be used to set up for 2B.
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And here's a graph of the speeds showing exactly that. (Red is the faster lap, blue is the slower lap.) Red starts out slower, but ends up faster, and I carry that speed all the way down the straight into Turn 3. This was good for 0.58 seconds off my lap time.
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I'll skip Turn 3, because my two laps were very similar (my approach last year was actually faster by 0.26 seconds).

Here's Turn 6, where I gained another 0.58 seconds. The big difference here is that I am a little later on the brakes, sooner off the brakes, and on the throttle sooner as I go through the Bowl.
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This gives me about an extra 2 MPH all the way up the hill to Turn 9.
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And speaking of Turn 9, here it is, along with Turn 10. What I've done here in my faster lap (on the right) is push the braking zone back a little, which gives me greater speed through T9, forcing me to go through the turn at a relatively constant speed. In the slower lap on the left, I'm slower entering the turn, which allows me to accelerate down the hill, then tap the brakes (or lift, I'm not sure) before turning in to Turn 10.
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Looking at the graph of speeds, you can see that carrying more speed through 9 is faster. This was good for 0.18 seconds. If I hadn't messed up and forced myself to lift as I tracked out of Turn 10 (a somewhat dangerous move, BTW, that I don't recommend), I could have gained even more time. I think I can also carry more speed through 9 by trailbraking more.
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Finally, here's Turn 11 and 12. Mostly what I've done here is braked later and gotten off the brakes sooner, shortening the braking zone.
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This gives me much greater speed at the apex, and I carry that speed all the way down the front straight, gaining me another 0.22 seconds. (At the end of the front straight, I'm going 93 MPH vs. 90 MPH in the slower lap.)
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See that flat spot in the bottom of the red line? That corresponds to the light-colored area at the apex of T12 in the previous picture. I'm holding a mostly constant speed through all that time. I don't think that's optimal. I could probably be faster by braking a little more, allowing me to get to full throttle sooner. One more thing to try!
Dave GuertinImage
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honda8790
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Re: NHMS: more fun with the datalogger

Post by honda8790 »

WOW. Very nice.
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DaveEstey
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Re: NHMS: more fun with the datalogger

Post by DaveEstey »

mmm graphs
"Why kill it? - When you can overkill it."
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