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Professional RTH Crash Feedback Wanted

Discussion in 'Phantom 3 Help' started by AnotherFlyer, Jan 7, 2016.

  1. AnotherFlyer

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    After 77 flights of the P3 Professional and 10 hours of flight time, I experienced my first crash. Not sure what to make of it so I'm asking for feedback.

    The facts: Installed firmware P3X_FW_V01.05.0030. Upon opening the DJI app after firmware update, it asked for a compass calibration (which I did.) Home point was set successfully. Flew to about 1200 meters in line of sight. I made a mistake (yes, user error) and went slightly around the cliff face and lost contact.

    First thing I tried was to gain altitude as to try and get the signal back. After about 10 seconds (not really sure) I tried to initiate RTH. Handset began beeping even though connection light was red. Unbeknownst to me, the drone had already tried to RTH (in a direct line) and crashed into the top of the cliff. The RTH setting was set to 30 meters. I confirmed this after recovery of the P3. As the video shows, it didn't climb 30m and return. It turned and came straight towards the home point. Watch the video for details.

    My main question is:
    When RTH is initiated automatically, shouldn't the drone climb 30 meters (from it's current altitude) and then return to home? The video shows that it clearly did not.

     
  2. Paulndot

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    Disclaimer: I'm a total noob at drones, but I recently had a bit of help here with the RTH function. As luck would have it, I was discussing flying into a valley from above. From what I understand, if the RTH was set to 30m then the aircraft will return straight to you if at an altitude above 30m. If the aircraft is at an altitude <30m then it will climb to 30 and RTH. Are you sure the cliff wall in the vid is shorter than 30 meters? Sound right?
     
  3. kptw_pilot

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    The Phantom only knows 30 meters from the home point/where it took off from. It doesn't know AGL for where it was when it lost contact. The elevation was likely different between where it lost contact and where it took off from.


    Sent from my iPhone using PhantomPilots mobile app
     
  4. AnotherFlyer

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    As of last contact the P3 was at 29m.

    OK, so I should have set RTH preference much higher if that's correct. My concern would be RTH initiating at a high altitude (with perhaps a low battery) and trying to climb another 100m during RTH.

    I live in Colorado and often fly from the top of ridges where I descend down the side of the mountain. So if I was 200m below the home point and my RTH preference was set to 100m, is it going to hit the side of the mountain before it gets back up to me? Is it going to go 200m above the home point before returning?
     
    #4 AnotherFlyer, Jan 7, 2016
    Last edited: Jan 7, 2016
  5. kptw_pilot

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    Okay, so if you were at 29 meters when contact was lost, it only had one meter to gain. The cliff must have been slightly higher than 30 meters, which is why it couldn't climb above it, and crashed.


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  6. kptw_pilot

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    The RTH altitude climbs to 30 meters AGL (above ground level from where you took off) NOT 30 meters from the altitude that it lost contact at


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  7. Meta4

    Meta4 Moderator
    Staff Member

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    The problems there are that when you fly out of sight behind a cliff, there is no way for you to either climb or to initiate RTH because the cliff blocks all signal from your transmitter.
    The only height your Phantom knows is home = zero and everything else is calculated relative to that.
    If your Phantom is below RTH height, on initiating RTH, it will climb to whatever the RTH height is (above home point).
    If at the RTH or higher, it will come straight home.
    It would seem that the cliff was higher than the RTH height and the cliff was in the RTH path.
    RTH height should be configured to safely clear any potential obstacles between home point and where you are going to fly.

    You were flying at 29m above home so RTH would only climb 1 metre to be at RTH height.

    If you only damaged props, you're very lucky.
    That's a very cheap price for this lesson.
    It often costs a lot more.
     
    Blue Bird likes this.