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Phantom 2 landing & takeoff problems

Discussion in 'Phantom 2 Discussion' started by uscpsycho, Mar 24, 2015.

  1. uscpsycho

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    I don't know what the heck is going on with my Phantom 2 but I'm having the weirdest problem.

    I do my compass calibration, lock into GPS and takeoff. Everything is seemingly fine. Until I land...

    When I land the props don't throttle down like they should. Instead they keep spinning at a pretty high speed. Then if I try to take off it just sort of tips forward instead of going back up. If I gave it enough throttle the props would hit the ground instead of going up.

    Now if I stop the motors and start them up again I can take off and then when I land again I have the same problem.

    Anyone have any idea what is going on here and what I can do to get things back to normal?

    TIA
     
  2. Turbazz

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    You may need to calibrate your sticks again in the assistant software..
     
  3. IflyinWY

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    The Phantom's little brain does not understand the concept of idling. To put it very simply. :D
     
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  4. dirkclod

    dirkclod Moderator
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    When you land shut it down . When you are taking off jump it up or ya gonna tip over . I don't land but hand catch mine now but when I did I always shut it down first thing . If it was idling to fast it wouldn't sit there anyway .
     
  5. uscpsycho

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    I'm not a total noob here. That is a band aid that doesn't solve the underlying problem. Something is wrong and I'd like to get it fixed.

    I've had this Phantom for a year and it never did this before. Normally when I land the props spin down to the same speed they are at when I first start. Now when I land they keep spinning so fast that it's on the verge of taking off.

    In the past I could land and take off as many times as I wanted without having to totally stop the props between each takeoff. Now I can't. I have to stop the props and start them up again if I don't want to tip forward and shred my props.

    I'll try calibrating my sticks as Turbazz suggested but I feel like if my sticks weren't calibrated the problem would always be there, not just between take offs. Isn't it weird that everything is normal when I first start the props but then everything goes bonkers after I land. And then back to normal if I stop and restart?
     
  6. IflyinWY

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  7. dirkclod

    dirkclod Moderator
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    :shock: Didn't mean to offend ya there and hope you good luck with your problem . It does seem strange . Mine never comes back happy and seems to act odd at times but like yours when I change battery's to go again all is good so I just live with it .
    Maybe someone with your issue will see this and chime in !!
     
  8. thestone11

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    Advance IMU may help! Just make sure the surface is level when you do the calibtation. Good luck
     
  9. IflyinWY

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    Not to contradict thestone11, but click the link in my signature.

    It's the NAZA Module which must be level.
    Some, it sounds like "most", NAZA Modules are not mounted level within the Phantom.
     
  10. Turbazz

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    Yeh try imu calli too... Let us know how you get along. Maybe you had a knock or a bump without realising or something has moved the Imu internally by few mm..
     
  11. lake_flyer

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    I'm hoping I don't sound too much smart ***...

    Your P2 is behaving exactly as it should. Exactly as all the other P2's out there. If you say your bird always allowed you to idle between flights in the past, then maybe your IMU (Inertial Measurement Unit?) or barometer wasn't working as it should, but maybe now it does.

    I can imagine if you feel upset, now your P2 is finally doing what it always was supposed to do, but it really is the only way a Phantom should react after a intentional landing.

    If you don't hold the stick down at least 2 seconds the Phantom assumes it's still supposed to hover and start spinning up again. If your P2 is not perfectly balanced, like most, it will tip a bit while it's trying to lift off. This is perfectly normal.

    You always have to keep the throttle down until the motors stop. Only THEN the P2 knows it's on the ground.

    The only time a Phantom 'knows itself' that it's landed, is when it has landed itself with RTH or Failsafe. It keeps the virtual throttle stick down until it senses it isn't descending for more then 2 seconds, and it shuts down. Even with a battery low auto descent, the motors would still spin after 'landing', because it descended because of low power (the motors spin slower simply because the voltage is dropping), not because of 'down stick'. In that case, the Phantom will keep the motors spinning until they are shut off by you or because the voltage drops even further. It just wouldn't know it had landed at all.

    Be happy it is finally working as it should.:)
    I wouldn't trust a Phantom acting the way yours originally did. It could just fall out of the sky during hovering because it could think it is idling on the ground...........

    The throttle lock on the new controllers is there to prevent from unintentional take off, directly after landing. I guess DJI wouldn't have added that if it wasn't an intended (or unavoidable) behaviour.

    edited a bit for typo's, sorry it was late last night......
     
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  12. lake_flyer

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    I would add that the Phantom or Naza isn't designed to idle on the ground in the first place. Only right after start up you are allowed to keep it idling. But once it has been airborne it will always try to keep airborne unless the motors have shut down.

    Center stick is always hovering. After take off, the center position maintains the hover.
    If DJI would have programmed an idle function it would be liable to situations where users accidentally flip the RTH switch, during idling, and the birds rises up to do a failsafe procedure, in the process flying into someones nose. This still happens, but only when people let their Phantoms idle one way ore the other. NOT because DJI allowed them to.

    Rule of thumb here:
    If the Phantom is in a downward motion, directed by a (less than centred) throttle stick input, it will power down AFTER it senses no more downward motion AND the throttle stick is held down full. Raise the throttle stick before that, will try to resume hover.
     
    #12 lake_flyer, Apr 4, 2015
    Last edited: Apr 4, 2015
  13. lake_flyer

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    I had to edit my rule of thumb, I put it wrong.
     
  14. AgentOrange2015

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    When I got my Phantom 2, I would push both sticks inwards to start the motors and do the same when I landed and sure as ****, it would tip over. I originally thought that to shut down the motors you had to put both sticks in and towards the center, wrong. I finally, figured out that the best way to stop the motors was to leave the right stick alone once I had it close to where I wanted to land and then leave it alone and then use the the left stick alone, to stop the props. I would not let the left stick go all the way down, but just before it hits that "click" point. As long as anyone stays above the click point on the left stick, all Phantoms will land and once it lands, then go past the click point and the motors should or will turn off. It might take a second or two for this to happen, but if you go beyond the click point, the Phantom, even if flying, will stop the motors and fall out of the skyl Do not go beyond the click point when landing. You can feel it. Dahhhh.
     
  15. Meta4

    Meta4 Moderator
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    Have you tested this?
    It is completely wrong.
    If you study the manual, you won't find this mentioned .. and don't you think it would be something DJI should mention .. if it was true???
    Left stick down won't kill the motors in flight.
    Left stick down is the normal way to descend - as described in the manual.
     
  16. TeamYankee

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    This is the second post on here that tells users not to go below the "click" on the left stick..

    Use the "Click" - it's there for you to use to aid landing... Left stick all the way down "click" then it will auto land.. simple really.,

    The ONLY way to turn the motors off in flight is to use the dual CSC stick command.. don't do that or it'll cost you.
     
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  17. SteveMann

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    It's not necessary for the NAZA module to be perfectly level, but the aircraft does have to be level. What IMU calibration does is to tell the NAZA what "level" is.
     
  18. Hughie

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    This makes sense to me too. The point of the calibration is to record what offsets are needed to make the inertial platform true with respect the fuselage.
     
  19. lake_flyer

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    This is SO not true.

    Only when the Phantom doesn't sense downward motion for more than 2 seconds it will shut down the motors. That's why it takes 2 seconds in the first place.

    The click point is nothing more than an latch that holds the stick down in the full negative throttle position which is the same position as on the old transmitter that doesn't have a click. I descent with the P2 almost always with full stick down because it doesn't descent faster than 2m/s. The FC40 will go to 6m/s so that bird needs a little less neg throttle.
     
  20. lake_flyer

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    I found out the same thing. Keeping the quad perfectly level with a ruler on the propellor shafts is ideal. Opening up and do the same on the naza controller itself didn't make a difference for me. Tried it once because of the discussion going on here, but it was a waste of 35 minutes. After calibrating on the shafts with ruler and a bubble it was perfect. Both my quads yaw within less than one square foot, even in a light to moderate breeze.