ALTA death spiral and crash

Discussion in 'ALTA' started by Adam Varadi, Nov 26, 2015.

  1. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The curious things is that there are valid "heading" rows on the last file: SYNLog-08-58-50.csv, so the Synapse looks it created a validly formed .csv file.

    Andy.
     
  2. Adam Varadi

    Adam Varadi Member

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    That could be right, I tried to check the ALTA pp to see if it says anything abouth the crash.
     
  3. Steve Maller

    Steve Maller UAV Grief Counselor

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    So sorry for this. That must have been very upsetting. Hopefully the damage was minimal.

    My first thought when I read your account is that maybe something came loose on the MōVI, or maybe one of the ALTA arms came unclicked, or even the batteries shifted badly in flight, any of which could produce an unrecoverable situation.

    Were you filming with the camera when this happened? Is there any chance you can upload a video (with sound) of the crash? It might offer some clues.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    For what it's worth file SYNLog-08-44-51 shows an example of how a normal Synapse log file terminates with a statement of the configuration values in rows 4073 onwards.

    That terminating information is absent from both log files SYNLog-08-55-15.csv and SYNLog-08-58-50.csv so my working theory continues to be that SYNLog-08-58-50.csv is a "continuation" log file which terminates when the batteries were unplugged rather than the motors being disarmed.

    File SYNLog-08-58-50.csv shows that there were errors on the I2C bus (specifically in column "FI", "I2Ctimeouts"). This suggests an electronic problem, but I don't have enough information to be sure where to go with that information.

    If the failure occurred with Height Hold and Position Hold enabled, then you would not have been able to disarm the motors -- which is probably why you needed to unplug the batteries to stop the motors.

    Adam: Do you happen to recall whether you had Height and/or Position Hold enabled?

    Andy.
     
  5. Adam Varadi

    Adam Varadi Member

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    Seen 20.000 usd crashing, yes it was a bit upseting. :)
    The movi was tigth on the alta, had to remowe it to get it out the bush. Arm were locked in place. Batteries amazingly were where they should be.
    Yes we were filming, but I can't upload the footage since it was in a set of a Tv show witch actors. The video stopped right before the crash, I think there was such a big acceleration the camera (Canon 1D C) felt like a drop and stopped instantly the recording.
     
  6. Adam Varadi

    Adam Varadi Member

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    The continuation can be because I unplugged the batteries without stopping the motors, due that I didn't have control over them.

    I was flying in GPS hold, but the secon I saw it flying uncontrolably I switched to manual height and tried to disarm the motors, didn't happen.
     
  7. Adam Varadi

    Adam Varadi Member

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    The damage is only 1 props and 2 movi legs. Nothing else. The bush saved the day!
    But I have around 10-999999999 blody injuries on my hand, while I tried to recover the copter in the bushes. :-(
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    @Adam Orens -- I think you're more or less right regarding the second file, SYNLog-08-58-50.

    SYNLog-08-55-15 shows the last recorded barometric altitude of 53.59 meters.
    SYNLog-08-58-50 first data row (Excel row 10) shows the baro altitude of 15.19 m, dropping to 0.xx rapidly and staying essentially at 0.

    The GPS height also supports what the bar altitude is showing.

    I suspect therefore, that the SYNLog-08-58-50 file shows the "arrival" of the ALTA on the ground.

    The I2C Timeouts don't really start to accumulate until data row 92 of SYNLog-08-58-50 (the ALTA records 25 data rows per second).

    Andy.
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Unplugging the batteries would have caused a truncation of the SYNLog-08-58-50 log file without the proper terminating data rows, I think.

    I'm not sure why the ALTA would have started recording a second log file for 31 seconds though (which is the duration of SYNLog-08-58-50). The IMU Time is a millisecond clock.

    I think we're going to need FF's tech support help to find out what failed, beyond seeing I2C bus timeouts -- which is geek speak for "Something Really Bad Is Happening."

    Andy.
     
  10. Adam Varadi

    Adam Varadi Member

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    I think the 15.19 m height is the correct, no way it was 54 m height.
     
  11. Adam Varadi

    Adam Varadi Member

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    I might have plugged the batteries on for 30 sec to check something, don't want to say anything not real, but I was a bit shaky at the time..
     
  12. Adam Varadi

    Adam Varadi Member

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    Here is a picture of the unlucky prop:
    IMG_0357.JPG

    If you check carefuly you can see that one rubber ring is missing, the two small sticks that hold it in place they broke out because of the crash.
     
  13. Gary Haynes

    Gary Haynes Administrator
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    From the 08-55-1 log Cursory look the power load on booms 1 and 6 are lower than the power on the other booms. One thought would be that the gimbal was not well balanced in relation to the flight deck causing the back motors to be working harder. Have you ever considered hanging the entire rig by a single center point to see how well it balances? You can check both the gimbal and the flight deck separately.

    From the 08-58-50 log: Starts throwing lots of I2C errors. at 8:59:01 there were a total of 10 at that point. By 8:59:09 it had climbed to 80.

    Open a support ticket at support@freeflysystems.com. Point them to your dropbox and the additional file that you found. As Andy mentions they won't be back 'officially' in the office until the morning of Dec 1st but maybe someone will see the ticket.

    Until they give you some feedback you may want to consider not flying if it turns out to be a flight control issue.
     
  14. Adam Varadi

    Adam Varadi Member

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    I just did the hanging. It looks fine for me, the Movi by itself is perfectly balanced, the copter also. Together the hang quite well, nothing wrong as far as I could tell.

    I could fly it if I wanted to because the ALTA app says Motor FAIL. And by the way I would fly it util I get some info from Freefly.
    Thanks for your help!
     
  15. Mateusz Hajdziony

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    Sorry to hear that man... Looks like first ALTA is down. Can you upload just the audio from the flight? I want to hear the motors before the crash. And keep us posted once you get a reply from Freefly!
     
  16. Robert Eder

    Robert Eder New Member

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    Please keep us posted. Sorry for the crash. Hope they will find the reason for it!
     
  17. Adam Varadi

    Adam Varadi Member

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    No audio sadly, I turn it off almost every time, since it's quite loud when I playback the footage. Now I wish I had it...

    Will keep you guys posted, but don't have any news. Waiting for freefly to respond.

    I really loved this copter, flew like nothing else, but I'm a bit scared now...
     
  18. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    You might want to salvage whatever you can from the prop in the way of emergency-use spare parts.
    Andy
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I would strongly recommend that you do not fly the ALTA until you/FF/we find out what the cause is.

    There was a recent service bulletin that addressed possible issues from wires flexing after 200+ boom fold/unfold cycles.
    Was the service bulletin applied to this ALTA?

    Andy.
     
  20. Adam Orens

    Adam Orens Member

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    4000 RPM Guillotine.......o_O
     

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