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Old Dec 03, 2004, 08:42 PM
Michael Heer is offline
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Stockton, Ca. USA
Joined Apr 2001
10,174 Posts
I do understand the difference between airspeed and groundspreed. And I have experienced the benefit of a 100 mile plus tail wind in the jet stream. In the speed experiment I videotaped the speedometer in both runs and played it back in real time and noted the speed at different intervals on my stopwatch in viewing back the video. Those times were then compared with the FDR data readout on playback. On the down wind trip the speed recorded on the FDR matched up almost perfectly with the digital readout on my speedometer which has been checked for accuracy by doing a marked mile stretch at 60 miles per hour with cruise control on and taking 60 seconds (plus or minus one or two tenths of a second.) to run the mile. I was reporting ground speed readings from my cars speedometer and the FDR matched those (not higher or lower) going downwind. I only did one test run downwind and one into the wind. My FDR has been mailed back for diagnostic testing to see if I fried the altitude meter but when it is returned with the Seagull telemetry unit I will do further tests on speed and hope to include more test data and compare readings with a radar gun at the slope.
I hope you enjoyed the article. Mike
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Last edited by Michael Heer; Dec 03, 2004 at 08:46 PM.
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