Quote:
Originally Posted by Glen Peciek
There are some significant differences between a drag strip and how the vBox calculates things. The drag strip has a 1' roll out, and the trap speeds are all an average of two points. I believe the 1/8 mile trap speed is the average of the speed at 600ft and 660ft, and the 1/4 mile trap speed is the average of 1256ft and 1320ft. So the vBox ET will always match the time slip, but the trap speed on the vBox will always show higher.
It is possible to write a program to read the vBox files and apply the NHRA rules to the results. Such a program does exist. When you use it, the vBox trap speed will usually match the timeslip within a few hundredths of a mile per hour.
Since there is some question about Sac's timing lights these days, it would be interesting to use such a program to scan the vBox files and see how closely they match Sac results.
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You are correct about the averages should read higher since the VBOX trap is the instantaneous speed at 1320'.
The time slip is the average velocity in the last 60'.
When Sac's slips were reading really high, it read about 2-3 mph higher than the vbox.
When I was there, it looked like the timing box at the 1260 mark was moved about 2 ft closer to the 1320 mark. This means that (T2-T1)/60 should have been (T2-T1)/58.
When I looked at my run using the reacelogic software, I played around with taking the time at 58' before and 60' before the end.
When i used the 58 before, I got the same traps as what Sac displayed.
Now, they tried to fix it but went the other way.
They really are clueless over there.
I wonder if they've heard of the word "calibration" lol.