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Uncontrolled descent... two crashes

Discussion in 'Phantom 2 Vision Discussion' started by drjay32, May 25, 2014.

  1. drjay32

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    Three times now, I've had uncontrolled descents where it's like the motors are idling but I cannot regain control.

    Each time this has happened, I've been in close range (less than 100' away) and at modest altitude (50' or lower). The Phantom just starts coming down fast and I cannot control it. This has happened in both GPS and Atti modes (the third time I switched to Atti during the descent to see if I could regain control). Moreover, I'm not rapidly descending when this has occurred... in fact one time was during slow forward flight/hovering.

    This does not appear to be a flyaway issue. The motors simply run at idle speed until impact. Luckily so far, my only damage is a single broken prop.

    However, I'm very concerned as to what the heck is going on. I have flown plenty of times with no issues outside of what is operator error.

    Basic configuration:
    Phantom 2 Vision running firmware 3.04
    Battery has been over 50% both times when this has happened; no warnings etc.
    WiFi is not interrupted; video can record normally even during crash!
    I have a RotorPixel gimbal installed but have no reason to think this is the problem (however I have removed it and will test without it on).
    I've opened the shell and all solder joints look fine and intact. Again, I'm not losing power, it just goes into idle.

    Your thoughts?
     
  2. FlyingFox

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    Check the battery cells are balanced even though you have 50% if the cells are not balanced I've read this can cause power loss to go into auto land or general loss of power.
    You can check this by plugging into assistant and looking to see if each cell has similar figures.
    This could be the reason?
     
  3. Kelso Kubat

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    was this happening before or after your upgrade to 3.04? or both? :shock:
     
  4. drjay32

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    Batteries all have cells within 5-8mV of each other. And it's happened on two different batteries!
     
  5. drjay32

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    It certainly didn't happen prior to 3.0, but part of my problem here is that it's been so windy of late that I haven't flown much. So I only flew a couple of times on 3.02 and then 3.04 came out.
     
  6. drjay32

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    Here's the video of the unplanned landing (this one didn't cause any damage). I have managed to downgrade the flight firmware to 1.08; everything else remains the same as it doesn't seem I can downgrade those components (central board, etc.).

    [youtube]http://www.youtube.com/watch?v=8y2zoI8OAp8[/youtube]
     
  7. FlyingFox

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    Wow, that was a total loss of power , if not a battery ,it's got to be a software issue ? Post this on some other forums you will get the answer ????
     
  8. Storm dodger

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    interesting...i had the exact same thing happen to me with a rotorpixel gimbal. never had this problem before the gimbal :!:
     
  9. drjay32

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    Thing is, it never lost electrical power. Just no left stick as far as I can tell. Rotors were spinning the whole time.
    I got my gimbal right when firmware 3.02 came out, and hadn't been able to fly much at all before he last few months due to weather. So I never got to test FW 3.02 or 3.04 without the Rotorpixel.

    I rolled back to 1.08 today, we'll see what happens.
     
  10. Storm dodger

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    im grounded till my new props show up. but like i say everything was fine until rotorpix......hopefully there will be a solution. once i get my parts i will test. there must be others with this problem :shock:

    firmware 1.08
    gps 6.0.1.3
    receiver-5.8g 1.0.1.3
    p330cb 1.0.1.19
    battery 1.6.0.0
     
  11. drjay32

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    Did you have the gimbal before Firmware 3.02?
     
  12. Storm dodger

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    yep.
    i just edited my last post with all my info. i have the phantom plugged into the computer as we speak
     
  13. sar104

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    It looks like you had it flying towards you at a reasonable speed and then stopped it - or was the stop (before the descent) also uncommanded? I've seen one instance of a similar descent after putting the brakes on hard, and I've been wondering if it is triggered by prop stall as the aircraft pitches back to slow down and then its forward momentum caries it into its prop wash. A bit like the vortex ring state but not vertical, but once that stall occurs it may transition to a VRS descent. It seems too fast to be an auto-descent.

    I haven't been bold enough to try to reproduce it, but I should try it with a weighted P2 minus the gimbal and camera.
     
  14. drjay32

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    I stopped it to hover but really wasn't going that fast. I've stopped harder in the past. The second crash (not recorded) was also going forward slowly when it just dropped.
     
  15. Storm dodger

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    drjay. i have my props off and fired up my pv2. if i decsend the pv2 shuts off. this happen to you too?
     
  16. drjay32

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    Not unless I hold the stick all the way down for 5-10seconds, as per normal shutoff procedure.
     
  17. fovallef

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    Hello
    Same thing happening to me. I just used mine for the first time with the help of a friend who is an expert in RC controlled helicopters, after several minutes (no more than 5) and being close to the P2 (20 ft at the most), it totally lost power and collapsed, fortunately with no damage because of the low altitude. We repeated the flight with a different battery fully charged and when flying at a higher altitude, it collapsed again. We decided to upgrade firmware (we were running on a factory firmware version), and we noticed a more stable flight. We decided to test rth, with battery depleation and controller shut down, and it worked flawlessly. When we thought the problem was resolved, we inserted a third fully charged battery and ventured for a longer flight at a higher altitude (150 ft or more). Suddenly the P2 began to fly erratically and fell to the ground again. Luckily we were on a grass field so just one propeller got broken.
    Doing research, I've found what I believe can be the reason for this sudden loss of power. The assistant app brings up a pop-up message saying: battery error not a DJI intelligent battery. This happens for the three batteries. Forums claim that the error is due to a defect in the battery contact pins that may suffer disconnection while flying.
    Can you confirm if you're getting this error message when using the sw assistant?
    I wouldn't dare to fly my P2 again until I have more certainty that the defect can be fixed. I believe I'd been extremely lucky since just one propeller has been damaged. I sent an email to DJI support, but from other users experiences I don't anticipate an adequate answer. I'm considering to open an exchange request to Amazon since the unit is still in perfect conditions.
     
  18. drjay32

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    I have no battery error messages whatsoever. All my batteries report as normal in the DJI assistant. I did not lose electrical power during these incidents.
     
  19. Happyflyer

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    I don't have that "falling out of the sky" problem, but I have also seen that battery pop-up. It only lasted for a second, but it has happened a time or two.
     
  20. drjay32

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    The "low battery" issue has been discussed at length. It typically involves poor data contacts (not power contacts) and triggers fail-safe RTH. This is definitely different, as my craft is not performing a RTH fail safe landing; it just decides to lose prop power.