Re: Stopwatch Accuracy for FAI Free Flight World Records

From: <leop_at_lyradev.com>
Date: 04 Jun 2018 02:58:47 +0000

I own two AX602's and have calibrated four AX602's in total. One of my AX602's did not meet the one part in 10^5 standard when first tested. Luckily, the AX602 has an internal adjustable trimming capacitor. I was able to adjust that AX602 to meet the one part in 10^5 standard.

 I also own two AX601x's and both meet the standard. However, the AX601x is not obviously internally adjustable so one is stuck with whatever accuracy the AX601x has when purchased. Accusplit specifies that the AX601x is accurate to 0.04 second per hour. or 1.1 part in 10^5. So the chances are fairly good that any AX601x purchased will meet the FAI/CIAM standard.
 

 I also own two Ultrak 460 stopwatches. Both easily meet the one part in 10^5 standard. However, the Ultrak 460 is also not obviously adjustable. The Ultrak is my favorite stopwatch, measures with 1/1000 second precision to 100 hours, and can be purchased for less than $20. This is the stopwatch I currently recommend unless someone wants a stroke (prop rpm) measurement mode. Then, the AX602 is recommended.
 

 Please note that the FAI/CIAM specifies calibration to one part in 10^5. How to show this calibration is not specified. There are ongoing discussions to determine the calibration standards, how the calibration can be done, and who can do the calibration. Also, note that there is a measurement error when one calibrates a stopwatch so the total calibration error includes both the error between the stopwatch and the time standard along with the measurement error.
 

 LeoP
 

Received on Mon Jun 04 2018 - 02:58:49 CEST