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Crash, what happened? Need to view flight logs

Discussion in 'Pro/Adv Discussion' started by kns1313, Sep 5, 2016.

  1. kns1313

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    I'm trying to access my flight logs after my first crash today. Aircraft was at ~15 ft AGL in Course Lock mode and I was proceeding downtrack. Went a short distance, then the aircraft did a few loops, aileron rolls, Lumshovics, and god knows what before it impacted the ground. Prop guards flew everywhere, but otherwise, aircraft seems to be intact and functional.

    However, what caused the crash? The right rear prop was not on the aircraft and not to be found, indicating to me that it perhaps flew off in flight. My two years of Google drone test pilot experience indicates this possibility and would be indicated by RR motor spin-up. The other viable option is that a gust of wind came and did a flight upset from which it could not recover. Can't tell without flight logs.

    I've followed the steps on the internet for this but I do not see the .dat files they allude. Need adult supervision on this one.

    Any help greatly appreciated.
     
  2. msinger

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    It sounds like you already solved your own case. The prop was most likely either not attached properly or damaged.

    Try these steps.
     
  3. kns1313

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    It was preflighted and checked as I removed all props this morning. And although I agree that you are probably right, If this is the case then the RR motor would have spun up when the load was removed, thereby proving it. However, if the prop WAS in fact preflighted correctly and only came off on impact, then there is something else unknown going on.

    If it was a wind upset, I would think the telemetry would catch the motors responding appropriately, just not fast enough or perhaps overloaded due to high winds.

    I really don't want to fly until I get a definitive answer. I now have the flight log (thanks, msinger) but can't interpret it. It is 33 MB, anyone have an idea how to make it public so one of you kind souls can put it into English for me?
     
  4. BudWalker

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    Can you upload it to Dropbox and provide a Dropbox link? If not, then you could 1) install CsvView (go here to obtain CsvView), 2) use CsvView to produce a .csv from the .DAT, 3) zip that .csv, and 4) attach the .zip in a post here.
     
  5. kns1313

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    DropBox won't let me in and CsvView says the CSV file is not recognized. Open for other suggestions.
     
  6. BudWalker

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    You should be loading the .DAT into CsvView. It'll recognize that.
     
  7. kns1313

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    OK, worked with the .dat file, it's now down to 4.7 MB. I tried to upload it using the Upload a File option but it doesn't recognize the .csv extension. What is a good extension that this board recognizes?
     
  8. BudWalker

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    Well, you can zip it. Or you can change the extension to .txt.

    Since you've got CsvView going you can view the motor speeds with the pre-installed Motor Speeds SigPlayer. After you see which motor it is you can then modify the SigPlayer by removing the other motors and then including the motorCommanded and motorLoad for the problem motor.
     
  9. flyNfrank

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    Place your DAT in dropbox and post a link here.
     
  10. kns1313

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    flyNfrank - Dropbox won't let me in.
    Right rear motor rpm obviously instantaneously died. Trying to figure out how to get MotorCommanded and MotorLoad.
     

    Attached Files:

  11. kns1313

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    OK, here is the rest of the RR motor data. Command 10000, load 0, looks like the prop flew off. Inputs?
     

    Attached Files:

  12. BudWalker

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    The top of the SigPlayer has a "Add/Remove Signals" button. There is also a User's Manual - in the main window Help->User Manual.
     
  13. BudWalker

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    It'd help if you could zoom in on the area. Is load actually flat lined at 0. If so, that's indicative of an ESC issue. But, since you're prop came off I suspect that there is some load, just less than it was before the incident. BTW, ace job on obtaining, installing, and then using CsvView.
     
  14. kns1313

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    If the prop flew off, this prompts the question so I can find it - How far will a P3P prop fly if free-wheeling through space before it loses speed? Throw in a 15 knot wind.

    Aren't you glad this wasn't on a final? :)

    Thanks to all. If anyone has a dissenting opinion (prop flew off), let's continue the thread, otherwise, appreciate your inputs!
     
  15. kns1313

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    Hmmm, ESC failure is interesting. Command is around 9000 then drops to zero, motor speed is about 200 until impact, and load becomes 56 to -34. ESC failure is possible, what else can I do to confirm or deny?
     
  16. kns1313

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    BTW, the other three motors show a motor command of ~2400 up until impact where the RR is high and instantaneously drop to zero, then all heck breaks loose.
     
  17. BudWalker

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    Please post the .csv, either zipped or disguised as a .txt.
     
  18. Mocho

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    Guys are trying to help you kns1313, you need to upload the .csv file in order for this conversation to continue.

    Just rename the xx.csv file to xx.txt and use the upload button to upload your file to the forum.
     
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  19. kns1313

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    OK, got it figured it and attached as a .txt.

    Found the missing prop 50' downwind of the accident site. Threads were damaged but it would go back on securely.

    Look at the data for the RR motor, just prior to impact motor command was zero. I don't know the sampling rate, but the ESC may have failed.
     

    Attached Files:

  20. BudWalker

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    Looks to be an ordinary lost prop to me.
    upload_2016-9-6_5-58-10.png
    At the onset motor load is reduced indicating the motor isn't turning anything. My comment about load flatlining to 0 was meant to describe going to 0 and staying there. Like what would happen if a wire came loose and no current was delivered to the motor.

    The sample rate is 30 Hz. If you want to see a higher sample rate you'll need to get that by running DatCon which can go to 200 Hz. Then submit the .csv produced by DatCon to CsvView. To reduce the size of that .csv use the options in DatCon that will restrict the time interval to include just the relevant part of the flight.