Data logging can make a difference in autoX... proof inside..
Mar 9, 2009, 09:37 PM
#1
Data logging can make a difference in autoX... proof inside..
Normally my run times are so similar that unless I do something stupid or novel, I can't learn a lot from my low budget MaxQData logging system.
Not so this weekend.
My 5th run: 75.072+1 (cone was the last cone on the course, I slid through the timing lights)
My 6th run: 74.540
Where did I gain that .5 seconds?
Well I can tell you where I was .7 seconds faster in run 6. The start! Typically there are no "launch" type starts at autocrosses (a run in then a 90* turn to the timing light), but this one was a bit different where the timing light was 10' past the start line and it was a straight line with just a wiggle to the first real turn.
The time difference from run 5 to run 6 from the time I started moving until the first turn? 0.7s (5.9s vs 6.6s, 37.1mph vs. 38.3mph -- I lost that 1 mph 2 seconds later and was at almost the same speed).
You see, I kind of bogged the start on my 5th run... and it made a big difference! The rest of the run went back and forth, but I never made up the full 0.7s.
So if this was my 1st vs. 2nd run, I would have been able to tell this immediately on review of the data.
Not so this weekend.
My 5th run: 75.072+1 (cone was the last cone on the course, I slid through the timing lights)
My 6th run: 74.540
Where did I gain that .5 seconds?
Well I can tell you where I was .7 seconds faster in run 6. The start! Typically there are no "launch" type starts at autocrosses (a run in then a 90* turn to the timing light), but this one was a bit different where the timing light was 10' past the start line and it was a straight line with just a wiggle to the first real turn.
The time difference from run 5 to run 6 from the time I started moving until the first turn? 0.7s (5.9s vs 6.6s, 37.1mph vs. 38.3mph -- I lost that 1 mph 2 seconds later and was at almost the same speed).
You see, I kind of bogged the start on my 5th run... and it made a big difference! The rest of the run went back and forth, but I never made up the full 0.7s.
So if this was my 1st vs. 2nd run, I would have been able to tell this immediately on review of the data.
Mar 10, 2009, 10:32 PM
#2
Evolved Member
Join Date: Jan 2007
Location: Dallas / Fort Worth
Posts: 671
Likes: 0
Received 0 Likes
on
0 Posts
I'm sorry but that doesn't make sense. You can not make up time before the timer starts... and the timer doesn't start until you break the starting line.
The only way starting harder will help you is in the fact that you're going faster when you cross the line. So two or three seconds after crossing the line, you've already travelled a bit further than you would have previously.
But 1 MPH = 1.466 feet per second. So if you went 1 MPH faster for the first 3 seconds of your run, then you were 4.4 feet closer to the finish line than you were at the 3 second mark on your previous run. Now, assuming your average speed was 50 MPH for both runs, that's 73.33 feet per second.
So how much time would it take to cover 4.4 feet if you're doing an average of 73.33 feet per second across your entire run? Doing the math of 4.4 feet, divided by 73.33 feet each second, we can see that the launch bought you - 0.06 seconds off your run.
Sounds off -- and I hate assumptions -- let me double check that....
[crunching numbers]
Ok -- lets do it this way instead. If you cross the starting line at 37.1 MPH and hold that speed for, lets say 3 seconds. Then you have travelled (((5280 X 37.1 ) /60) /60) X 3 = 163.24 feet.
Now lets say you crossed the starting line going 38.3 MPH and we want to know how much time did you save to reach 163.24 feet. So 38.3 MPH = 56.17333 feet per second. So you got to 163.24 feet in 2.906 seconds.
So you really saved (3.000 minus 2.906 seconds) 0.094 seconds. This way is probably more accurate since it's not based on the assumption of average speed. So your launch gave you almost a tenth of a second -- almost.
The bottom line -- the launch gave you 0.1 seconds at most and you made up the other 0.4 elsehere in the run.
The only way starting harder will help you is in the fact that you're going faster when you cross the line. So two or three seconds after crossing the line, you've already travelled a bit further than you would have previously.
But 1 MPH = 1.466 feet per second. So if you went 1 MPH faster for the first 3 seconds of your run, then you were 4.4 feet closer to the finish line than you were at the 3 second mark on your previous run. Now, assuming your average speed was 50 MPH for both runs, that's 73.33 feet per second.
So how much time would it take to cover 4.4 feet if you're doing an average of 73.33 feet per second across your entire run? Doing the math of 4.4 feet, divided by 73.33 feet each second, we can see that the launch bought you - 0.06 seconds off your run.
Sounds off -- and I hate assumptions -- let me double check that....
[crunching numbers]
Ok -- lets do it this way instead. If you cross the starting line at 37.1 MPH and hold that speed for, lets say 3 seconds. Then you have travelled (((5280 X 37.1 ) /60) /60) X 3 = 163.24 feet.
Now lets say you crossed the starting line going 38.3 MPH and we want to know how much time did you save to reach 163.24 feet. So 38.3 MPH = 56.17333 feet per second. So you got to 163.24 feet in 2.906 seconds.
So you really saved (3.000 minus 2.906 seconds) 0.094 seconds. This way is probably more accurate since it's not based on the assumption of average speed. So your launch gave you almost a tenth of a second -- almost.
The bottom line -- the launch gave you 0.1 seconds at most and you made up the other 0.4 elsehere in the run.
Last edited by Evo_Someday; Mar 10, 2009 at 11:13 PM.
Mar 11, 2009, 06:21 AM
#4
Jeremy you weren't there, but the start line was less than one car length from the staging line. In this particular instance, the time from "go" to the first turn will directly impact the overall run time since it was a straight line blast.
When I am on a computer I'll post a short clip of the maxqdata log so you can see it. I'll also post a short video of me pulling up to the staging line so you can see how close it was to the start line.
When I am on a computer I'll post a short clip of the maxqdata log so you can see it. I'll also post a short video of me pulling up to the staging line so you can see how close it was to the start line.
Mar 11, 2009, 08:20 AM
#5
Here's the videos I promised:
run 5 v 6 start comparison: http://www.youtube.com/watch?v=_M7VucX6mlE
stage line vs. timing lights: http://www.youtube.com/watch?v=PTaPR72wIRs
run 5 v 6 start comparison: http://www.youtube.com/watch?v=_M7VucX6mlE
stage line vs. timing lights: http://www.youtube.com/watch?v=PTaPR72wIRs
Mar 11, 2009, 08:34 AM
#6
I concur. You lose more time at the start by not starting hard than you think. I've outrun my co-driver to the first turn by almost a second before, just from getting a better launch. Don't forget, especially with turbo cars, the faster you cross the start line, the earlier you get into boost. It makes a big difference.
Mar 11, 2009, 09:14 AM
#7
Evolved Member
iTrader: (20)
Join Date: Jan 2007
Location: CT
Posts: 1,184
Likes: 0
Received 0 Likes
on
0 Posts
I concur. You lose more time at the start by not starting hard than you think. I've outrun my co-driver to the first turn by almost a second before, just from getting a better launch. Don't forget, especially with turbo cars, the faster you cross the start line, the earlier you get into boost. It makes a big difference.
The group I run with almost always has a starting grid with the timing equipment set up on an immediate right hander to take away the AWD launch advantage. 
Trending Topics
Mar 11, 2009, 09:44 AM
#9
If you're looking in a lot of detail, the turn on the NE corner of the map, I really jacked it up on run 5 (072 in the logs) because my foot slipped off the brake and I had to lock it up hard to make the turn. I lost 10mph through that corner compared to run 6.
I also pegged the last cone at the timing light because I was pushing it so hard trying to make up for that.
I also pegged the last cone at the timing light because I was pushing it so hard trying to make up for that.
Last edited by goofygrin; Mar 11, 2009 at 09:47 AM.
Mar 11, 2009, 02:02 PM
#13
Evolved Member
iTrader: (17)
Join Date: Aug 2004
Location: In da streetz
Posts: 3,275
Likes: 0
Received 0 Likes
on
0 Posts
funny, i was just thinking about this on the way home from an AX on sunday. I used to drag race ALOT and with an AWD turbo car, or really any car for that matter, the race is usually won or lost in the first 60'. no matter how much power you have it very difficult to make up for that lost time in the beginning.
Since I started to AX I haven't really launched my car like I would at the strip, but I think I'm going to try now for a few runs and see what kind of difference it makes.
Since I started to AX I haven't really launched my car like I would at the strip, but I think I'm going to try now for a few runs and see what kind of difference it makes.
Mar 11, 2009, 05:51 PM
#14
Evolved Member
Join Date: Jan 2007
Location: Dallas / Fort Worth
Posts: 671
Likes: 0
Received 0 Likes
on
0 Posts
It would be nice to see the maxq data with the cars "stacked" at the starting timer line then measure from there to the first corner rather than from the actual start line. That would show the amount of time saved on that segment not including the "run up" time to the timer line which could factor in.
Mar 11, 2009, 10:10 PM
#15
Wanna see a more drastic comparison (not really apples to apples though)? Pause the video at any set of cones near the beginning and notice how many car lengths the red one is behind the yellow one.
http://www.youtube.com/watch?v=g_wX9LmQe78
red evo = stock tires and feathering takeoff
yellow evo = slicks and full launch
http://www.youtube.com/watch?v=g_wX9LmQe78
red evo = stock tires and feathering takeoff
yellow evo = slicks and full launch