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DJi Phantom Advanced (rocking on descent)

Discussion in 'Pro/Adv Discussion' started by Jeriami, Oct 9, 2015.

  1. Jeriami

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    Hello, i have been browsing here since i got my P3A a few days ago, very useful information. Today i come to you with a slight problem i am experiencing:

    On fast, or even mid way throttled descents my P3A rocks diagonally, never side to side but horizontally from each prop, & not on all 4 props just 2 horizontally across from each other, kind of like a wobble, it never gets to the point where it gets so out of control it moves to the left or right more then a foot, but its still kinda scary. I am wondering, does it have something to do with an improper calibration, like IMU or compass, or do i maybe have a defective unit? Other than this slight problem, fly's perfectly! I am still within my 30 days of purchase time frame & i got it from Amazon so its hassle free returns.

    Any advice is welcome, thanks!

    Also, i was wondering, i got my P3A September 30th & i looked @ the comparison picture on how to find out which motors are the updated & which old, & the ones with the flat bottoms are actually the new ones, labeled 2312A, right?
     
    #1 Jeriami, Oct 9, 2015
    Last edited: Oct 9, 2015
  2. Albert R.

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  3. Jeriami

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    Thank you for the reply, i noticed i found a lot of threads of this happening to a lot of P2 V+ owners, but not P3 owners, i m just wondering if other people are seeing this happen to them as well, & just not reporting it? As far as the motors, any insight? I have the ones with the flat base, are those the upgraded ones?
     
  4. Albert R.

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    Sounds like the new ones. Do they look like these? If so they are the new ones although I don't think they are the contributing factor.
    ImageUploadedByPhantomPilots - DJI Phantom Forum1444452844.532559.jpg
     
  5. RedHotPoker

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    When descending, rather than bringing your Phantom more or less straight down to the ground, try to bring the bird down with some forward direction as well. Opposed to a 90* drop, try it at 50*~60*.
    Yes, the Phantom 3 motors are slightly pitched out, which helps alleviate vortex ring state.
    You might also want to try and balance your props, and be sure they are not causing any of the uneven flight pattern and or wobble effect.

    Good luck, I do hope that you can find a solution to this situation, or simply, return to sender... ;-)

    RedHotPoker
     
  6. Jeriami

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    Thank you for the advice, i flew recently & slightly moved forward while descending, i tested descending mid throttle & full & no more wobble! thank you for the advice!
     
  7. RedHotPoker

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    @Jeriami,
    That's great news, thanks for the positive update. I used to fly until a low battery level warning came, and then frantically attempt to bring my Phantom 3 straight down. So now I fly with better attention to battery levels. And have fun, while I bring the bird back to terra firma, with a little more piloting finesse. ;-)
    Do some banked turns... And other maneuvers that look magical, to our onlookers. ;-)

    RedHotPoker
     
  8. PilotHarry

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    I routinely decent straight down with throttle full back and get the wobble but thought that wasn't an issue, just the aerodynamics of the craft.

    Has anyone actually lost control like this?
     
  9. RedHotPoker

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    Did you click the link in post 2 above? Note "Wobble of Death"?

    These videos are very self explanatory, but YMMV. ;-)

    RedHotPoker
     
    #9 RedHotPoker, Oct 10, 2015
    Last edited: Oct 11, 2015
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  10. Jeriami

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    Also, another quick questions for you since you obviously seem like an experienced pilot - when stopping the drone from a mid or full throttle forward, it rapidly rocks backwards then sits idle, it maybe rocks back 30-40 degrees, is this normal bahvior for the P3A?
     
  11. RedHotPoker

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    You can watch this video on the subject, as well.


    RedHotPoker
     
  12. JKDSensei

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    Great info. Too many noobs are unaware of the problems with fast vertical descents.
     
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  13. RedHotPoker

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    When the active braking happens, the rearward blades go into idle speed and the forward set speed up. It happens with side to side deceleration as well. The faster moving pair, will lift that side up slightly. Yes, Competely normal. You can go into the app parameters and tone this down, if it helps.

    RedHotPoker
     
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  14. bobmyers

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    I used to think that the VRS was the demon
    However, when several posters mentioned that the P3 could be descended full back stick vertically without VRS, I had to try it my self.. much to my surprise, it descended without any wobble -- so I routinely land from a vertical hover and if I am 150 ft or so, I bring it straight down full stick to about 20 ft without any adverse affects. maybe it is the tilt in the motors??
     
  15. Garrie

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    When I do a 100% descend my p3 wobbles too. Sounds exactly like your situation. But I have a very large carbon fibre gimbal guard installed too. So it may affect the aerodynamics a bit in a straight downward descend.
     
  16. Jeriami

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    I also have a fairly large CF gimbal guard, do you have prop guards as well, if so do you have the snap on/off ones or the screw on ones?
     
  17. Garrie

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    Nope I don't use prop guards. ImageUploadedByPhantomPilots - DJI Phantom Forum1444574289.762023.jpg

    Pic of my P3 without the gimbal guard attached :)
     
  18. PilotHarry

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    Guilty as charged :confused:
     
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  19. herein2014

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    I come down full throttle from any altitude all the time, never any rocking, its actually fun to watch the IMU and GPS fight to keep it stable. I have been flying for some 20+ years though and I keep my trigger finger ready on the sticks in case I need to take over. It's truly amazing the tech that is in these little quads. I have probably flown around 1,000 flights by now and every single one was full speed down until about 20' above the ground, not one single issue even in winds.

    Although I agree the slight forward or for that matter right left or back approach while landing will make it smoother, if you are flying in tight quarters like I usually am (high rises, trees, power lines, etc) you usually don't have the luxury of anything except straight down.

    If your bird is rocking severely on a full speed descent you may want to check the balance of your props, do a compass and IMU calibration, and calibrate your transmitter sticks, it sounds like something is slightly off.
     
  20. RedHotPoker

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    Nice company you keep. . .
    Thanks for clarifying that "without". I was thinking, Oh man, that's the largest gimbal guard I ever have seen. ;-)

    RedHotPoker