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Compass Error - "Remember your training Padawon"

Discussion in 'Pro/Adv Discussion' started by m0j0, Feb 6, 2016.

  1. m0j0

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    Ok... Calibrated the compass earlier today at the local AMA airfield. Flew without incident. Mod values were around 1500 no wobble or toilet bowl not a thing. Flew 4 batteries went home charged up the batteries after they cooled for a few hours and headed out. Went to a new location flew a few minutes and realized that the ND filter was too dark so I brought the copter down switched off the copter took the ND filter off switched the copter back on and lifted off. You will see that it says take-off battery 65% or something close but truly I took off on a full battery the first portion of the flight landed made the adjustment and took off. Still I monitored the voltage and noted no issues. Truly none.

    Well I'm flying getting ready to make a run toward a water tank which at that point was more than 1000 meters away... then I get a big RED: COMPASS ERROR indicator where my warm and fuzzy green box is supposed to be....NO BUENO.. Boom "remembering my training"... HAHA.. Young Padawon... I quickly switched to ATTI mode and flew directly home. I got it to about 5 feet off the deck and a few feet away. I switched back to GPS grabbed it and shut it down. I swapped in a new battery and launched again. I checked the sensors and noticed no issues..No drift.. No toilet bowl no wobble nothing.. I let the battery warmup and flew again without a single problem.. WTH happened. Anyway I thought I would ask some of the Phantaholics on here to have a look at the Healthy Drone link.. I looked at the flight on healthydrones and saw nothing related to the compass.

    Is it common to get these errors? I was flying in an absolutely vacant lot. No real problems with interference. I have flown before without incident. Anyway take a look at the flight and let me know if I did something wrong.

    HealthyDrones.com - Innovative flight data analysis that matters

    Do I need to get the other file? I'm not sure how I do that.. Any help on the diagnosis and instruction on how to pull the files needed would be great..

    Thanks Phantaholics.
     
  2. nix240z

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    I had the same thing happen to me one time , lasted about 5-6 seconds
    Any type of metals on you while doing the calibration I.e.: car keys,cell phone, belt, watch, coins in pocket. Etc?
     
    fordruid likes this.
  3. Meta4

    Meta4 Moderator
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    No ... it's not normal to get a compass error in flight.
    A compass error usually indicates that the compass is detecting a magnetic field significantly different from that where it was calibrated.
    This can be caused by calibrating the compass in a bad location like on a reinforced concrete structure.
    Sometimes the bad calibration isn't bad enough to cause obvious flight problems immediately but when further away from the magnetic influence it can show up.
    HealthyDrones isn't any help here. It doesn't mention or show any compass error so guesswork is about all there is to go on.
    I'd be wondering about the compass calibration you did.
    Was it by any chance, on a concrete area or somewhere that may have had steel above or below ground?
     
    Skypicswa likes this.
  4. 2nd2non

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    Nice save. Most people think P-ATTI is same as moving switch into ATTI mode. It isn't and behavior is quite different when encountering compass errors.
    I fly frequently in a secluded park that has an underground electrical vault. I never calibrate compass near it, but get compass errors if I take off or fly close by (intentionally to practice navigating with the error). It's good experience as you never know what is hidden below along a flight path.
     
  5. m0j0

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    I live in a small New Mexico City. I calibrated today a the old AMA / Airfield.. It is in the middle of nowhere and was there before the ballfields and dog park. They moved the airfield because they cut off the runway to put in the gravel road. Was pretty much desert prior to the airfield. Here is a pic.. Red diamond is where I calibrated. I asked my wife I call her "the Mayor" because shes been here forever and knows everyone. She confirms that the area has never been developed and as you can see there is no concrete above or below.

    I actually think the issue was the flight area. I think there might be something over there that caused my problem. I will check it out tomorrow with a compass.
     

    Attached Files:

    #5 m0j0, Feb 6, 2016
    Last edited: Feb 6, 2016
  6. WetDog

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    I'm not saying it was aliens....
     
  7. m0j0

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    Thanks for the compliment..

    I really think that the flight location may be the issue. I don't think the calibration site is the problem. I wasn't flying where I calibrated. I had no problems flying where I calibrated I flew all over the place on 4 seventeen minute flights. When I went to the new location I flew without an issue until I got to that area where I had the problem. When I flew away from it I had no problems. I'm a trained investigator by trade. I will be out there with a compass trying to see if I can find the problem.
     
  8. m0j0

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    C'mon... That's Roswell man!! That's two hours away. I am close to the Trinity site though.. About 60 miles by way of Phantom... Do you think... NAW
     
  9. NotARubicon

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    Same thing happened to me this morning as well.. Flying in an area I've flown many times before. The hardest part about flying in ATTI mode after the big red, scary "compass error" is dealing with my soiled shorts!
     
  10. shorttimer

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    Yea, that little town... you ever heard of Roswell, NM LOL
     
  11. Skypicswa

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    What was the water tank made of? How close to it when error started. That's what meta4 is trying to say
     
  12. Meta4

    Meta4 Moderator
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    The best way would be with the compass in the bottom of your Phantom.
    Go back and crisscross the site at reducing altitudes and see if you can replicate the symptoms.
    If there is a magnetic influence there and you get the compass error message, simply backing off or going higher will take you away from it.

    At 1000 metres, the water tank wouldn't have any effect.
    A lump of steel this big has no impact at this distance:
    [​IMG]
     
  13. m0j0

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    Water tank was about 1000 meters away. I have flown to it more than once. I was actually closer to the water tank at take off than when I had the error.


    Sent from my iPad using PhantomPilots mobile app
     
  14. m0j0

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    Interesting method.

    I truly didn't ever think the water tank was the issue. I think it may be something in the ground or something I couldn't see from where I was standing. I will go and see if it is something obvious when there is more light.


    Sent from my iPad using PhantomPilots mobile app