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  1. John Locke

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    200 flights and I've never seen this happen before.

    We all know about P4's spontaneous descends of about 6 to 8' when you're cruising along and you stop the craft by letting go of the sticks, right? The craft stops like it should, but then it slowly descends 6 to 8' and usually it will ascend back up to where it stopped at originally (not always). This is apparently a bug in the P4 that P3s never had. I'm unsure why since the on-board P4 barometer is the primary sensor for altitude, just like P3P. It's something I hope DJI is working on. Yes, I have the latest firmware.

    Today I'm out flying in partially cloudy and slightly windy conditions in Anaheim hills. I had maybe 5-10mph average wind speed, not bad. I'm out doing some testing, I have clear sight of the craft, only about 300' away, buzzing back and forth in front of me. Then, while in a hover, hands off the sticks, I'm looking at the craft and it starts to ascend rather quickly, right out of the blue. My eyes got big, I'm sure, because I've never seen a Phantom act like that before in a "fly away" fashion. I'm watching it go up and up at about 4mph. So I decide to just watch it to see how high it will go. After about 40 to 50' up, it descends back down at about 6mph, and stops at the original hover point. Then it does it again, goes up about the same distance and comes back down. It never did it again, just twice. I'm perplexed how this can happen. Has anyone else had this experience? Can wind gusts change the barometric pressure enough to fool the on board barometer? Or, can nature change the barometric pressure that quick to cause something like this?

    Other than this temporary anomaly my testing went well, she flew pretty darn good.
     
  2. phantom13flyer

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    Very interesting . There's no way I could've just watched to see how high it would go. I know I would've freaked out and done gods know what with the sticks lol. You're much calmer pilot than me.


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  3. BriRi

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    Crazy. Haven't had anything like that happen to me.

    What controller were you using? P4 or Inspire?


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  4. John Locke

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    That was using the Inspire RC.
     
  5. John Locke

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    I was hovering over a valley that was 80' to 150' lower than me, launching from a cliff. The craft was only about 30' above takeoff point, but 110' AGL, kinda at eye level about 200' away. If the craft had ascended more than 100' higher I would have interrupted the ascent. When I was about to take over it stopped, so I watched it for a second and then it started is descent down. If it would have gone below 80' AGL, I would have interrupted the descent, but it stopped again. I was blown away. It was almost like someone else had control. Then a minute later it took off again, straight up, then down. The second time it went a little higher, but not much. Then it came down. There was no horizontal movement, only vertical. I'm going to load the log into msinger's flight log reader to see what I can find.
     
    #5 John Locke, Apr 30, 2016
    Last edited: Apr 30, 2016
  6. John Locke

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    Well that's interesting. When these ascents occurred the log message says To takeoff in non-P modes, toggle Flight Mode Switch to another mode then toggle it back.
    I thought that message only happens when you're on the ground. Hmmm. Now I'm thinking I may have switched from P mode (CA enabled) to S mode when this occurred. I do remember switching it the mode, but I don't remember doing that when this sudden ascent occurred. The strange thing is the log doesn't show the craft ascending 40-50'. It's as though the ascents never happened in the log. That's very weird.

    Here's the data.

    Healthy Drones log This basically says the same thing with less detail.
     
    #6 John Locke, Apr 30, 2016
    Last edited: Apr 30, 2016
    Cjasmin likes this.
  7. JamesH

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    I have no answers to your issue, but thanks for posting the data. Now I know another place to fly in OC! ;)
     
  8. Dirby

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    mine doesn't go up or down whem I take my hands off the sticks.
     
  9. BriRi

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    JL,
    Keep us informed. I'll be getting my Inspire remote w/ ItElite upgrade in a couple of days. I'll definitely pay close attention and see if anything similar happens to me.


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  10. John Locke

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    Nice, I've got the Itelite on order too from Maxx. It's in transit, should arrive Mon or Tues.
     
  11. Phantom fool

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    Sun spots


    or an alien tracking beam got hold of it
     
  12. Wibble

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    It could be updraughts from the valley. Haven't you seen birds hovering over cliffs ascending vertically?
     
  13. BriRi

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    Any more issues?

    Just got mine back from Jake...
    [​IMG][​IMG]
    Inspire RC w ItElite and iPad Pro

    Check your pm inbox also


    Sent from my iPhone using PhantomPilots mobile app
     
  14. arcaine25

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    I noticed mine do this yesterday, although not as big of a climb as yours, well, actually, it descended first, then up, but only about 4 - 5 feet. I thought it was strange, and it hadn't done it before.
     
    #14 arcaine25, May 2, 2016
    Last edited: May 6, 2016
  15. John Locke

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    As mentioned, my P4 will drop down 6 to 8' when I stop forward motion most of the time, then rise back up. I've kind of accepted that anomaly as SOP for my P4, although my P3P would never do that.
     
  16. ianwood

    ianwood Taco Wrangler
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    This looks like a defect. At first I was going to say that prop wash can have unusual effects on the barometer most of which is compensated for automatically but given the logs, this looks more like confusion in the flight controller. Send your logs to Blade Strike or Tahoe Ed on rcgroups.com so they can get these the right attention at DJI.
     
  17. Patrick

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    could it be related to the inspire RC? ive never had this problem. i've seen wierd drift over water at times, but noting like what you describe.
     
  18. taz291819

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    Sorry for going off-topic, but why do your cables connecting the RC to the antenna criss-cross? I have the same mod, but did it myself (not the clean install, drilled holes), and my cables don't criss-cross like yours do.
     
  19. ianwood

    ianwood Taco Wrangler
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    Possibly. DJI would need to test to find out.
     
  20. John Locke

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    Ian, are you referring to my 40' ascend and descend that happened twice or the 6-8' descend and ascend that happen all the time?

    I think you're talking about the 40' events since that's what I posted my flight data for, right?