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Sudden Inversion during flight!

Discussion in 'General Discussion' started by ArshadR, Jul 24, 2013.

  1. ArshadR

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    I just bought my Phantom and went out for my first test flight a couple of hours ago. Tried some basic maneuvers, played with GTH feature by turning off the transmitter while it was hovering a few hundred feet away, etc. Everything was great. Then while it was hovering about 20 ft off the ground (in GPS mode), the unit suddenly inverted and accelerated and smashed into the ground. I'm pretty sure I wasn't touching anything on the controller at the time. In any case, I don't think it's even possible to invert the unit like that using the controller (?)

    Luckily the enclosure itself seems to be fine, but I haven't tried flying it again. I had mounted prop guards, and two of them snapped.. which kind of sucks, but it's better than damage to the main housing.

    There was plenty of juice (I had just put in a new battery) and the green light was flashing the entire time.. so it didn't suddenly run out of power. Since it inverted, rather than falling somewhat gently towards the ground, it actually accelerated and smashed the ground pretty hard. Luckily it was a grassy field and it wasn't too high up at the time.

    Has anyone else experienced anything like this? Some other key info:

    1) Prior to my first flight I upgraded the unit to the latest firmware (3.14 if I recall correctly)
    2) There were large power line transmission towers about 1000+ feet away. Could it have been some kind of RF interference from there?
     
  2. Sac D

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    Did you accidently bump the switch to manual? That mode is about the only way to get enough power to flip like that.
     
  3. ArshadR

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    I'm positive I didn't flick any switches (I didn't touch anything on the controller after it fell, and both switches are at the top position) and I'm fairly certain I wasn't touching either of the control sticks either since it was hovering, and I don't recall doing anything when it suddenly rolled over.

    Could it have something to do with the new firmware? Is there any way to roll back the firmware?
     
  4. Claust

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    Could one of the props have become loose?
     
  5. ArshadR

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    All the props are on tight still, but the one thing I just noticed is that one of the rotors has a lot more resistance when I rotate it with my finger than the other 3. I don't know if it was always like this, or something that happened post-crash. I'm assuming this is not normal? Is there anything I can do to fix it?

    I'm hoping that this was a result of my proximity to the high voltage power lines -- although it was flying fine when it had been closer to the towers.. it flipped over when it was furthest away from the towers.

    I'll try some test flights tonight in a different area far away from power lines, and at low altitude to see if it happens again... although now I'm kind of nervous about flying this thing!
     
  6. Gizmo3000

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    good luck,. that's **** scary to hear.
    the gyro's in the NAZA are supposed to keep the craft upright, as as mentioned, the only way to do so is to go into manual mode (or if somehow it was getting a signal to go manual due to interference , but I've never heard of that happening to anyone.

    the only other possibility would be that the gyro in the NAZA is messed up, or the NAZA came loose inside.
     
  7. edunwody

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    Do you have your manual mode enabled?


    Sent from my iPhone using Tapatalk
     
  8. martcerv

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    Powerlines that far shouldn't have an issue unless much closer or having them between and the phantom I would think. If you haven't enabled manual mode via NAZA that would completely rule that out as a possibility. If its enabled then it could somehow though unlikely have been activated but if its not even enabled the phantom should never get inverted.

    Is the NAZA controller solidly attached inside? If it came loose this could happen otherwise its just failed in the way some dji 800's did in the past. Did you have a camera on board this would be an interesting video to get an idea of what happened.

    Was it anything like this wkm s800 crash? Not as costly for sure as this is one of the scariest dji fails I have seen.
    [youtube]http://www.youtube.com/watch?v=RqhwSX6VXf4[/youtube]
     
  9. ArshadR

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    No, I don't have manual mode enabled. The only thing I did with the software was update the firmware from 3.12 to 3.14.

    Unfortunately I didn't mount the camera yet since this was my first flight and I wanted to get used to the controls first.

    Just peeking through the battery bay everything seems solidly attached and I don't hear any rattling if I shake the unit, so I'm assuming the NAZA controller is not loose.
     
  10. martcerv

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    Was there much damage? Only other thing I can think of other then a faulty NAZA is a calibration after the firmware update?

    I think I remember seeing a note regarding doing an advanced calibration after updating and then you need to do the compass calibration. Poor compass calibration will flash a red led before launch and very bad NAZA calibration should also flash a led.

    I always do all calibrations after an update or any small bumps or crashes.
     
  11. ArshadR

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    Thanks for the advice guys. The only obvious damage are the two broken rotor guards. The main housing seems fine, and nothing is loose inside the enclosure from what I can tell (I haven't opened it up).

    I just did the advanced calibration. Prior to calibration the gyroscope was waaay off. Unclear whether it was like that prior to the crash (which may have caused the problem?) or something that happened due to the crash.

    My gyro mod value prior to calibration was 2.4 - 2.8... and after calibration, around 0.1 - 0.2.

    I just did a quick 1 min test flight and it seems to be working fine, and SEEMS to be more steady than before (although that could just be my imagination). I'll give it a more thorough workout tomorrow... at low altitudes in case it happens again. I might even brave the same power line field again to see if I can repro the issue.
     
  12. ArshadR

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    In this video, the s800 tilted and moved slightly before accelerating towards the ground.

    In my case it was very different. I was looking right at it when it happened. It was hovering normally, then it literally inverted without any lateral movement.. extremely quickly (less than 1s) and a full 180 degrees .. and then just accelerated towards the ground. I wish I had gotten video...
     
  13. BruceTS

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    A new Phantom, I'd contact the dealer you got it from, most likely there's something defective. Heck DJI might even want to take a look at it. What you describes should have never happened.
     
  14. CameraGuy

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    WOW, that was ugly.

    Did anyone figure it out?

    D
     
  15. Alex

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    That's exactly what I'd imagine a loose prop would sound like. The engine revs to the max just before it pitches over uncontrollably.
     
  16. martcerv

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    That was found to be a bug in the GPS unit I think and DJI addressed the issue plus replaced quite a few peoples full setups and cameras. They did quite a bit of research into the issue and think they have fixed it, maybe still not 100% sure but dji did quite a lot of tests before and after their fix.

    This video may show you something interesting as they were testing the bugfix with 72hrs flight with wkm

    [youtube]http://www.youtube.com/watch?v=6IuQSsJDlDg[/youtube]

    I dont think DJI is happy with any issues and they do the best they can to try and fix any that come up.

    There is a video of an s800 doing this at altitude which shows a big fail by the dji controller but also promotes the zenmuse so its a strange video for DJI. The home run hit finish is brutal but awesome end to this flight.

    [youtube]http://www.youtube.com/watch?v=FnT1nHoZgW8[/youtube]
     
  17. woodlandsolutions

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    OMG that is enough to make a grown man cry!
     
  18. martcerv

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    Its possible it could have been a calibration issue, possibly loose prop but that would be more erratic flight not just hover flip and fly into the ground as you described. That is quite worrying as it really should never get upside down unless in manual, seeing your figures were so far out this may have been partially to blame but it could also just be the result of the crash. If its flying better after calibration it may have been out a bit but if I was you I would let dJI or your dealer know about this as they may want to give it a look over to see if there is an issue with yours.
     
  19. ArshadR

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    I think I know what might have happened. So last night after calibration, I did a quick 1 minute test flight and it seemed to be operating fine.

    This morning I went out for some more low-altitude testing. The only difference from last night was that I now had the GoPro mounted.

    First thing I noticed was that when I powered on the rotors, one of them was not spinning... almost like it was stuck. It wasn't stationary.. it looked like it was trying to spin but not able to (I'll post a video after to show this). After powering off, I tried rotating it with my finger and it wasn't stuck or any stiffer than the others.

    I tried powering on/off a few times, but the same results. I swapped batteries and suddenly all rotors started spinning. While I was waiting on the ground a few seconds before applying throttle .. the one rotor suddenly went from spinning to stopped again!

    I suspect this is probably what happened mid-flight yesterday when it inverted. After some time of working normally, the one motor suddenly stopped causing the aircraft to lose stability and flip!

    Of course it's possible the motor issue is something that happened post-crash, but the fact that I was able to fly fine briefly last night and then without any change it suddenly failed this morning leads me to believe that it was faulty to begin with and took some time to show up. Thoughts?
     
  20. CameraGuy

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    Do you have the GoPro WiFi on?

    There are documented evidence that the two 2.4GHZ signals can cause interference. Even DJI has posted that ou should not, under any circumstances use the two at the same time.

    If that is the set up, it could cause your problem.

    Hope this helps

    Darren