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Uncontrolled Descent . Help Please.

Discussion in 'Phantom 2 Discussion' started by Birdu2, Nov 13, 2015.

  1. Birdu2

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    Hi guys, its been a long time since my last post, everything was great.
    So, here is the issue. My last flight a few weeks ago was perfect, with no problem at all of any kind.
    Yesterday i was doing a test flight, and in the middle of it, my P2 start a fast descending, faster then the usual "safe land" one the one may have when running out of batt, eaven then, if i pull up, i can still have control of my cuad. but in this case, eaven switching between gps, att mode i wont be able to control it, lucky me, the its hard landed on some high grass, so no damage to the unit.
    Went home, did an advance calibration, and went to flight agein, full batt, and when the batt was at 70% 60% aprox. .... same thing. Start a fast descending, i was on ATT mode, went to GPS and nothing, .. another hard landing on hight grass, i wasnt really hight, lets say around 20/30 meters high.
    I had some minor crashes before with this P2, but i keep on flying after without any problem.
    I can also tell you that when im hovering the P2 its not stable at all, GPS or ATT mode, drift and wont keep a stable altitud.
    I have to do some video and pic for a friend of mine but under this conditions its imposible and totally unsafe.
    Im running on 3.08, 3 x batt with 8/10 flights each, so they are pretty new, and i try all of them with the same flight problem, i did also check the Voltage and i didnt see any loose of it when the uncontroled desc. was happening.
    So i guess there is some internal part that its not working, but wich one ? GPS ? NAZA ?
    Any idea / help would be great please.
    Thank you so much for your time.
    Estevan
     
  2. antares

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    Just one thought: I had the same problem then i figured out that the voltage indicated in my FPV was changing and looked very unstable. The reason i found was a poor connection at the two signal contacts. Look inside the shell you will se two gold plated spring loaded bars, there are the data connectors. I cleaned them as well as all the matching contacts on the batteries using a glass brush. After this, no more problems. Background: Even with a full battery your quad becomes confused when it gets low or unstable voltage readings from the battery.
    Another approach: Check your props. Even a small damage might cause instable flight and the NAZA controller cannot balance your quad anymore...
     
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  3. kirk2579

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    it sounds like maybe you are not getting gps lock.
    are you getting 2 sets of fast flashing green prior to take off?
    are the leds flashing green only or a combo green and red?

    +1 on check props they can mess up flight if off balance enough to crash.

    you can open cover and remove gps module with 2 small scewws and check the antenna on back side. the antenna is very easy to break in crashes and is common.

    good luck and have fun flying
     
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  4. SteveMann

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    What does the GPS have to do with holding altitude??
     
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  5. kirk2579

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    "I can also tell you that when im hovering the P2 its not stable at all, GPS or ATT mode, drift..."

    this line is why. I certainly may be wrong but under the circustnces and with "drift" it is worth looking at .
    No harm, no foal if wrong.

    do you have any suggestion's as to what it may be? he seems open to help!
     
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  6. Birdu2

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    Thank you so much guys, ill look try all your tips, it wont hurt and i didnt try those tricks.
    Now about the voltage, i did check via FTP every time the quad was descending if there was any changes and was solid stable the reading. But ill defenetly check those conectors ! Thanks !
    As i will also check the antenna.
    I feel its more related with voltage and auto landing ( exept the descent its more agresive ) but when i see the quad so unstable on hover i also think its may be something with the GPS .....
    Ill let you know ......
    Thank you so much guys !!!! really ....
     
  7. SteveMann

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    Aside from my snarky response (sorry about that, Chief), GPS has nothing to do with altitude, just position.
    Have you cleaned the battery contacts? When the P2 initiates a battery-low failsafe it is going to land - even if the low battery was momentary due to a poor connector contact.
    What happens when you try to hover with your fingers off the controls?
     
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  8. jason

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    Sounds more like you haven't been storing your batteries correctly when not using them for long periods of time. If this is the problem then you'll need to replace them.
     
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  9. Birdu2

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    @SteveMann When i hover with no hands in the control, the quad its "kind" of stable, there is some minor unusual changes in alt. and some drifting as well, ..... i try that for let say 1 min with no self landing.

    @jason To tel you the truth, it may be the case, i have to confess the i left the batt full charged after my flights. But thats because i fly pretty often, i wont stay without flying for more then 2/3 weeks. And the batt are pretty new like i mention. Now if 2/3 week are long
    enoght to ruin the batt then im screw .... still i was playing close attention on the test flights to the voltage indicators on the FPV and did't notice any abrupt changes to make the quad a hard descent.
    Something to take in consideration ....... I took the gimbal/gopro 4, and fly a hole batt without a problem ...... but when i put it back, ..... the uncontrolled descent happen. Wich give lead us more in a power / voltage issue i guess ...... and like SteveMann mention, it do not happend when hovering, but yes in the middle of a flight ... when im in demand of power ...... hmmmmmm ..... why are getting close guys ....
    Is there any way to test the batt to find out the storage problem ?? Do i have suck a bad luck that happen to all of them ? .........
     
  10. kirk2579

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  11. Gary ph2

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    The problem i have is my phantom 2 wants to change speeds all be its self.. Just ideling ,it will sit there a while and then slowly og to full speed.. Sure could use some help on what to do.. This would surely cause a fly away.....Need some input...
     
  12. phantom1972

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    I thought the GPS augmented the pressure barometer?
     
  13. Gary ph2

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    That ì dont know!
     
  14. N017RW

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    No.
    The P2s do not use GPS for anything but Lat-Long.
     
  15. Gary ph2

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    Have you attached any wires.. inside, maybe bad connection?
     
  16. Birdu2

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    Hi guys, i still cant find out whats wrong ......

    I uploaded a video with one of the uncontrolled descent, maybe you can see or ear something the i cant .... as you can see, the quad its all the time all over the place ...... i lift on GPS, and when it was getting wired, i switch to ATT, ..... Let me know what do you think ....
    Thank you so much in advance.



    Estevan
     
  17. kenjancef

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    To me, and I'm only giving you my opinion, it sounds like maybe one of the motors has a higher-pitched hum than the rest. It doesn't sound as smooth as it should... if that makes any sense... hopefully someone else can listen and agree/disagree. If that truly is the case, then it's probably not the GPS that's the issue...
     
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  18. Gary ph2

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    Have you replaced any of your props? Lòok at them very close, for chips all leading edges are the same, any defect could make the different sound , as well as change the air flow ... or a bent shaft on a motor, it doesn't take much to cause viberations.. I use to build ultralights an experimentel aircraft..
     
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  19. Mako79

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    Check your gain settings and make sure they are on default gains.
    Also check your weight. Which version P2 do you have and how much weight is the payload?
    Check you props and use DJI OEM props.
    Rev your motors on the ground and listen to them.
     
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