Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Spectrogram and Doppler speed?

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Old 11-14-2007, 02:10 PM
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plasticmaster
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Default Spectrogram and Doppler speed?

I’m using a program called Spectrogram and a corresponding spreadsheet that I downloaded on my computer several years ago to calculate speed based on Doppler shift. How accurate is this program? Is there a better way to analyze high speed passes and compute speed? I think I’ve read about a German program that’s out there, but is the Spectrogram and spreadsheet method just as good? I have three good passes that yielded good clean graphs on Spectrogram and I got speeds around 140 mph. The air temp was 20 degrees Celsius and I’m using a “Factor” of 10. For my three passes, I got Fcoming and Fgoing readings of 701 and 502; 682 and 486; 670 and 482. My in-flight rpm was around 17K. Could someone double check my numbers? I could upload the .wav files of the passes if necessary. I would appreciate any insight into this. Thanks.
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Old 11-14-2007, 02:26 PM
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Mike Connor
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Default RE: Spectrogram and Doppler speed?

The German program can be downloaded here for comparison.
http://www.sprut.de/electronic/soft/scope.htm
Or post your wav file I will check it.
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