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Compass Error & Crash

Discussion in 'Pro/Adv Discussion' started by AD7ZW, Aug 14, 2016.

  1. AD7ZW

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    Was flying yesterday was about 2300 feet out when i got a compass error. Aircraft went into Atti mode i was unable to recover & crashed. Retrieved aircraft replaced busted props & snapped case back together where it had separated about a 1/4 inch. All appeared good took out for a test flight and it will not hover. Motors start & will lift off once i get off the ground it immediately acts like the rudder is pushed full right. Have tried multiple compass calibrations & a IMU calibration. Where do i go from here? Attaching a screen shot of the compass values and also the txt file from the flight last night. Healthy Drones report here.

    Reed
    AD7ZW
    Northeastern Utah
     

    Attached Files:

  2. Northern Observer

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    Is the unit still under warranty? If so, you might be able to salvage this situation with DJI. Sync your flight log, and open up a service ticket with them.
     
  3. AD7ZW

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    Bought the Aircraft used i have the original reciept. Will check the date but i believe i'm a month or better past the 12 month mark.

    Sent from my HTC 10 using Tapatalk
     
  4. AD7ZW

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    Forgot i had the dat file from the crash. Maybe it will shed some more light on what happened.
    FLY107.DAT
     
  5. BudWalker

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    I'm going to guess that the P3 had some kind of propulsion issue with one of the prop/motors.
    View attachment 62205
    In the last 10 secs of flight the P3 was spinning at 180 degrees/sec. Generally, with a lost prop the spin rate is higher. Maybe a partially operating motor?

    The compass errors observed started at 248 secs. It's not immediately apparent if there is a connection between the compass errors and the propulsion issue(if there was a propulsion issue). To know more you would need to retrieve the .DAT and provide a link. Go here to see how to retrieve the .DAT.
     
  6. AD7ZW

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    Could be a motor that would explain why it is pulling hard to one side when i try to take off. Dat file is in the post just before yours. Uploaded it this morning

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  7. BudWalker

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    I'm gonna guess there is something wrong with the LeftBack motor.
    upload_2016-8-15_7-40-15.png
    Commanded (blue) maxes out several times but the speed (green) doesn't follow. The spinning is associated with maxing the commanded. I think the onset of the compass errors is related to the spinning, although I'm not sure of the cause.

    The right front (opposite) motor attempts to compensate for the problem with the left back
    upload_2016-8-15_7-46-51.png
    It gets commanded to the max but, unlike the left back, the speed increases.
     
  8. AD7ZW

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    I assume the refrences to the motors are with the aircraft facing forward. So going clockwise it would be right front, right rear, left rear, left front? Will take it apart this evening & see if i can see anything obvious.

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  9. ElGuapo

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  10. Northern Observer

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    Very good analysis !


    Sent from my iPad using PhantomPilots mobile app
     
  11. BudWalker

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    Yes, that's correct on the orientation. If it's convenient a .DAT from one of the subsequent attempts might be interesting. One of those flights where it lifts off but then yaws without stick input. I'm assuming that's CCW.
     
  12. AD7ZW

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    Will pull one & post later today. I want to say it yaws clockwise with the camera/ front at 12:00

    Sent from my HTC 10 using Tapatalk
     
  13. AD7ZW

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    Here is the latest dat file. Compass error almost immediatly after takeoff. FLY123.DAT
     
  14. AD7ZW

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    Compass on order from ebay. Next step take shell off & check motors & order replacement
     
  15. BudWalker

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    This .DAT doesn't have a motorStart. It can be a challenge getting the right .DAT. Go here and look at the bottom half of the page for advice on picking the right .DAT.

    Why did you order a new compass? The compass errors you saw aren't due to a hardware failure in the compass.
     
  16. AD7ZW

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    Ordered compass last night assuming it was bad before i had posted.

    Sent from my HTC 10 using Tapatalk
     
  17. AD7ZW

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    here is the right dat file i think.FLY122.DAT