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Launch over concrete?

Discussion in 'Pro/Adv Discussion' started by JFHughes08088, Dec 13, 2015.

  1. JFHughes08088

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    I attempted to launch from the roof of a parking garage but couldnt get a compass setting. I'm thinking the rebar in the cement caused problems. I tried to lift but control was erratic. I immediately landed and wondered.........had I kept increasing attiltude, would GPS eventually reestablish? If not, how can you lift off in this situation?
     
  2. Meta4

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    Rather than type it all out again ... read this from yesterday.
    It covers most of your issue.
    Calibrate crash | DJI Phantom Forum
     
  3. msinger

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    Smart move. Taking off in this situation often results in total destruction.
     
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  4. 4wd

    4wd

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    What does this mean, did it say compass error or were you trying to calibrate the compass at that location but it failed somehow?
    If you really needed to take off from there the way to go about it would be have a good compass calibration from elsewhere and raise it up as far from the metal as possible - hand launch perhaps even though it's tricky.
    If you have good calibration already set it would probably be OK once up in the air.
    It really isn't worth the risk though - usually.
     
  5. JFHughes08088

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    Compass calibration failure. I could calibrate it when it was a few feet of the ground though.

    What would happen if I calibrate it successfully, then place it in a problematic location (like concrete with rebar reinforcement or even the flat bed of a pickup) where the compass has trouble. Would all correct once in the air?
     
  6. Meta4

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    Don't calibrate or launch from those areas with a distorted magnetic field if you want to keep your Phantom. It's just asking for trouble.

    Read this thread to understand what compass calibration is all about:
    Compass Calibration, A Complete Primer | DJI Phantom Forum
     
  7. msinger

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    The problem would be getting into the air safely. If there is strong magnetic interference in the area, it's possible that your Phantom will crash before you're able to get far enough away.
     
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  8. 88VMX12

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    I have the same issues at work, I have to fly inside a building and take progess videos. I usually take a 5 gallon plastic bucket and take off from that, if the problem still is there than I have someone hold the bucket over their head, then I hand catch it when I am done doing the video. There might only be one problem with your situation that is different from mine. Since yours is a parking garage, there is more than likely, way more rebar within the concrete. So it possibly might affect it more than what I am experiencing. Basically you might have to hold your launch pad higher, so to speak.

    G
     
  9. dsd317

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    Whenever I'm on a large concrete area, I would always get calibration error, but it would go away the moment I lifted my P3P a few feet off the ground. In the past, I would not fly and just pack up and go somewhere else. This time, I decided to try something different; hand launch. Worked flawlessly and I was able to fly over a mile away (could of gone farther, but there was a slight breeze and I really just wanted to get the sunset).
     
  10. msinger

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    Concrete contains rebar. You shouldn't launch/land from/on objects that contain metal. All should be fine if you launch 10+ feet away from the sidewalk.
     
  11. N017RW

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    There's no absolute in these cases as construction codes and quality vary.

    I have no issues with my concrete driveway or sidewalk.
     
  12. msinger

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    Sure. But, as a general rule, don't tempt fate :D
     
  13. dsd317

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    Yes...I know about rebar in concrete. It does depend on construction as I'm able to launch on certain parts of large concrete areas. I could walk a few feet in different directions on the same concrete pad and get NO compass error. I just wanted to try something different by hand launching....to prove to myself that I can do it with confidence and fly with confidence as long as I get the "green", "Safe to Fly" on my ipad. How and where I launch should not hinder my fun of flying.
     
  14. msinger

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    Knowing is always the first half of the battle. The next time you take off and nose dive straight into the ground, at least you'll know you weren't in the correct section of the concrete ;)

    Honestly though, why do something that could cause erratic flight behavior and/or a crash?
     
  15. dsd317

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    If I get the "Safe to Fly", what could cause erratic flight behavior and/or a crash? If it's the concrete pad, then a lot of us are in trouble. I've seen so many videos where people are flying over concrete. They may be launching from grass or non-concrete areas, but they do fly over concrete, as I've done many, many times without a problem.

    There's always a risk of something going wrong. If I let that stop me from doing anything, then I would be bed-ridden.

    When we fly, a motor could malfunction, battery could fail, many things could go wrong while in flight.

    For me, if I get the "Safe to Fly",and I'm in a safe area (no crowds, airports, crazy people)....then I'm flying. I have faith in my equipment and in myself. :)
     
  16. msinger

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    "Safe to Fly" does not always mean the compass is in working order and/or not confused by surrounding metal objects. I'm just sharing knowledge here so other people passing through this thread can learn. If they choose to trust in their faith too, then we'll have to let them do that as well :)

    I often fly over concrete with no trouble. I rarely fly near the ground though, so there is no chance it'll have an effect on the accuracy of the compass and/or GPS.
     
  17. skysense

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    Would taking off and flying in ATTI mode be safe in this situation?
     
  18. dsd317

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    So 10ft away from concrete area will guarantee compass accuracy? How is this different from elevating P3P 10ft above concrete?

    At what height/elevation guarantees 100% compass accuracy before it gets interference from concrete?
     
  19. dsd317

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    Sorry, but I'm not sure about this one because I haven't tried it. Hopefully someone that has done this before will chime in.
     
  20. msinger

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    I'm only stating that measurement from my own personal experience. I've launched countless times about 10 feet away from a sidewalk that I know is chock full of rebar.

    I'm not sure there is a difference. I'm recommending 10 feet in any direction.

    DJI does not offer specific numbers. Try 10 feet and you will be smitten with the results.