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Runaway phantom

Discussion in 'General Discussion' started by Spiritskeeper, Feb 28, 2015.

  1. Spiritskeeper

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    My bird exhibited some strange behavior tonight. I haven't been able to fly for a little over a week so the plan was to fly today. Tomorrow will be rainy here.

    Got up today and got saddled straight with honey-dos. Including a trip to a neighboring town, Lowes and wife and daughter had to hit a couple of stores. By the time we got home and chores finished there was no more light left to fly. So I decided I would do a quick ground station flight.

    I setup about 1500 meter total length flight at 250 feet, we have some tall trees here and at night the branches are not easily visible. Got her up, hit go and she went off. With the light mod I have on her she was easily visible through the trees as I watched her go about the flight. It was windy but she didn't have any problem. 3 waypoints later she came back to me and hovered 250 feet above my head.

    The wind was starting to pick up so I brought her down and set her down not far from me. It's going to be another week before we can fly again so I was going to let her sit there and idle to burn off some battery. I was at 72% still. While she sat on the ground idling I switched to the GS view in app to see the waypoints.

    I don't know what the props turn at idle but they are pretty quiet. I heard the props increase in rpm which got my attention. The rpm increase was not enough for flight and it was steady after. I watched her for a minute and then went back to what I was doing. I heard the rpm increase again. Where you going? The props increased rpm to lift off about 4 inches. I quickly double checked I hadn't inadvertently put control input into the stick. There was no control input from the remote. The rpm increased a little more and the bird started drifting rearward.

    Oh No! You are grounded. Reaction took over and instead of lifting her up to about 6 feet I pushed left stick down. Wrong move when the bird is about 4 inches drifting rearward quick down is not the right move. She hit the skids and fell backward eating up her props on the pavement.

    I have new props coming. I am going to recalibrate my remote before the next flight. She has never behaved this way before. She has sit on the ground with the props idling several times without incident. My best guess is the remote has gotten out of calibration so the throttle stick seeps up. If that makes since.

    Any ideas?
     
  2. PhantomFanatic

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    What Phantom model do you have? Any modifications? I'm surprised that you had to ordered new rotors as my Phantom came with extra rotors, plus I purchased more. I'm still on the first set. I hope you get an answer. In the meantime, my 15 Watt bulb is on! :)
     
  3. dirkclod

    dirkclod Moderator
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    I would suggest to you when it lands to shut it off . No idea really what went on there but I just don't let it sit with the motor's turning.
     
  4. Spiritskeeper

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    She is a P2.2 Vision. Anytime she is idling I always have the controller on just in case. I am thinking of ordering carbon fiber or 4350 props.
     
  5. Andrey320

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  6. Spiritskeeper

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    Thank you so much for this link. It makes me feel better that it is a known issue and not a specific problem with my setup. I am not happy about this being an actual problem but I am happy to know she can hover at 100 feet and not hVe to worry about her drifting up.
     
  7. Larry L

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    Glad it was not damaged bad. Yes leaving it idle after landing can cause it to take off again.
     
  8. sdtrojan

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    Calling it "she" as much as you do is a little creepy, to me at least. We never call it he. Why is that?
     
  9. ccase39

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    Ok so how do you run down your battery to discharge it? Take props off? Last time I discharged my battery I let it just sit there powered on without the motors running and it took over an hour to discharge.
     
  10. IflyinWY

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    My thoughts on wearing the battery down are go fly.
    That's not why I posted though.
    Sorry for somewhat hijacking your thread Spiritskeeper.

    Does anyone else feel this subject "DO NOT IDLE AFTER LANDING" is worthy of becoming an "Important Sticky?

    I do, that's why I replied. ;)
     
  11. turbodronepilot

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    Hey ccase39. .
    I fly my phantom down to 30 % then hand catch it , hold it and drain the battery down at about half throttle till it losses power. .
    turbo. .
     
  12. IflyinWY

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    Thanks for posting this Andrey320.
    I've sent a PM to LuvMyTJ suggesting we add this subject to the "Important Stickies".
     
  13. Spiritskeeper

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    Did you want to know why I call it she? Or did you want an anthropological discussion? Briefly as men we are wired to associate she with things we love, wife, daughter, etc. other men are helpers. Essential things I need to provide for my family get male names and things I derive pleasure from get female names. Things get anthropomorphised by everyone. Each has their own rules.

    But I digress, this thread may not be the best sticky, but this issue should definitely be a sticky. A forum like this is where we go to find the known real world issues that are not in the manual.
     
  14. PsychopathRC

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    Surprised this isn't widely known. But you should never leave it idling on the ground as the motors will speed up slowly. This is because the Phantom doesn't actually know it's on the ground. It just thinks it's hovering. A breeze will cause it to try and compensate, resulting in the motors spinning faster.
     
  15. LuvMyTJ

    LuvMyTJ ADMINISTRATOR
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    RC 101 - the first lesson is to NEVER turn on the RC unless the controller is on. Controller first on, last off, always.
    Also, if you e=want to run your Phantom down by running it, remove the props. If your Phantom has the smart batteries they will drain themselves if you have them updated. Another lesson would be to never leave your Phantom running unattended. Your focus should be on your running Phantom at all times.

    PS - you could get the carbon fiber props but the stock props work great too.
     
  16. Spiritskeeper

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    This makes perfect sense. I guess the other times I have done it with no wind.

    Always. My controller is always on before the phantom and after its off.

    Just ordered a set of DJI 9450. Decided against the carbon fiber. Maybe when someone makes a cool looking 4 blade prop.
     
  17. stanpisarski

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    I agree that this is a design flaw. What I do is make a few short flights each time landing...disarming the escs...then rearming and go for another flight...why does anything I said here seem wrong. I landed very gently on uneven ground...tipped backward on the skids and the prop guards...disarmed the escs to stop the props...went over and stood it back upright on the skids...rearmed the escs...advanced the throttle and came up to about four feet. It immediately took tilted backward went to full throttle and arched over the roof of the house...pulled the throttle as I saw it disappear from sight. crashed in the backyard severly damaging the gimble/camera assemble and breaking two propellers from the fall. Removed the gimbal...put on new props...it flys as if nothing happened. Need about $600 now to fix or replace the camera and gimbal...Nothing I did was out of the ordinary....disappointed with the quads behavior...been flying quads for a few years not and never has this happen with any other brand!
     
  18. CryoEng

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    Nav and control aids may be trying to "help" as we "hover" at ground level, but morp000 asked a couple of good questions.

    If we could answer these, maybe we'd get to the guts of the issue.

    Cheers!

    morp000 asked:

    "So... just to confirm the theory here:

    Unless the bird has intentionally landed as a result of auto-land etc it doesn't know it has in fact landed, it thinks it is fact hovering above ground level and so perceives the changes in flight data like elevation, compass and barometer data as unwanted deviations from where it should be and so any attempts, either by itself in the case of excessive positional error data or when lift-off is user initiated, to move to where it thinks it should be which can result in a tip-over, due to the fact it is on the ground and therefore has landing strut/ground friction as well as low prop speed.

    If so, this raises 2 questions to me:

    1. Why wouldn't full ascend stick cause lift-off and avoid a tip over ? ie Does telemetry data take priority over stick input ?
    Effectively, the bird when landed and idling is in the same state as pre first take off now isn't it !

    2. Imagine a scenario where the bird is hovering for a while above ground in ideal conditions. ie very minimal flight data change.
    Couldn't the same tip happen for the same reason ?"
     
  19. Spiritskeeper

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    No. At startup the bird knows it is definitely not in the air. When it has landed the quad does not know confidently that it has landed. The aircraft may still be in very calm air.

    If the quad was just hovering in one spot 6 feet off the ground it would not tip, it would drift rearward and then correct for that. The ground friction on the skids is what causes the tip. My quad was drifting rearward when the skid caught causing the tip.

    I just realized I didn't answer your first question. Up left stick could theoretically prevent a tip if at the right moment. Usually the quad will have started drifting unexpectedly and the knee jerk reaction is left stick down, which is what I did. When I did that the quad all ready had enough rearward momentum to cause a tip when hitting the skids.
     
  20. Ezookiel

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    In Australia, inanimate objects, especially ones of "beauty" were regularly referred to as 'she' ... buy a new car and show your mate, and he's likely to say, "Wow, isn't she a beauty"
    Upgrade your dinghy to a speedboat, and they'll make some comments like, ", Man, She goes like a scolded cat"
    So I'd refer to a quad as a 'she' quite comfortably, because to me it is a thing of beauty, and so deserves the feminine pronoun.