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Why is metal around dangerous?

Discussion in 'Pro/Adv Discussion' started by t2adze, Jan 7, 2016.

  1. t2adze

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    I hear a lot of concerns about metal. What is it dangerous for? Compass of the craft or RC signal?
    If i took of from a place with a lot of metal around it and all went fine, this means that all went well and there is no danger ahead anymore? (Only when landing)
     
  2. Ted4797

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    It affects the compass for calibration. Stay off metal buildings....lol
     
  3. msinger

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  4. t2adze

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    And what if i cLibrated somewhere else? In a perfecr conditions. And flew up from my neighbors balcony?
    Whats the danger there? I tried it before no problem with p3s. Its a balcony on the top floor, right between two roofs.
     
  5. N017RW

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    Some metals distort the local magnetic environment.

    This distortion can prevent compass calibration and/or confuse the magnetometer and cause unpredictable control reactions when flown 'into' it.
     
  6. tcope

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    As mentioned it can throw off the compass. Also, the controlling signal is microwave. What is between you and the microwaves in your microwave oven?
     
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  7. Ted4797

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    good question. I know people do it but I never have. Someone smarter than I will chime in soon.
     
  8. t2adze

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    I understand. But if it took of from that balcony, and all is fine. After that it means the danger has passed right?
     
  9. rcfanatics

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    If would should fly in atti mode around metal would the flying still be affected?
     
  10. bbfpv

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    correct.
     
  11. Meta4

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    Don't worry about metal. Worry about iron or steel.
     
  12. Volantis

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    Metals work as antennas, they absorb photons and convert them into electrons. Metal buildings are usually grounded to Earth, so the electrons are then fed into the Earth. Those photons were signals to and from your quad and also from the GPS system in space.

    If a metal structure is between you and your satellites and between your controller and your quad, needed signals will be absorbed by the metal and lost to ground. The closer you are to a building, the more radio signals will be absorbed. Even trees with leaves will do the same thing, which is why you need line of sight with your quad to fly it. Tall buildings often have a metal frame inside them. Also, certain weather conditions with high humidity can absorb the radio signals.

    There will always be those weird circumstances where a building is so designed as to act as a repeater or reflector of the signal wave, rather than an absorber. This can give a false sense of security and as soon as the quad moves out of the narrow window of the refocused radio signal, it will suddenly lose all contact. Similarly, there will be days when the ionosphere directly overhead of the operator is highly charged and reflects signals back to the quad and allows for an unusually long distance flight. Then at a different time of day the effect is lost and you can't fly except for line of sight.

    Radio waves are not homogeneous due to the many factors just mentioned, but in nearly all cases, they are clear enough when you have direct line of sight of your quad and there are no nearby structures such as buildings, metal structures, and trees.
     
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  13. t2adze

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    Couple of days ago someone on this forum was saying that controlling your drone from the car is dangerous because of all that metal. How is that remotely dangerous if of course ur not taking off from the roof of the car?
     
  14. msinger

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    You can control your Phantom from locations that are around metal. Just don't take off, fly, and/or land your Phantom in those locations.
     
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  15. t2adze

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    Thanks! Thats what i thought also.

    But today i talked with Dji cs rep on chat and was told that you can take it of from balcony as well, if it doesnt give you any warnings... was "pleasantly" surprised)))
     
  16. ianwood

    ianwood Taco Wrangler
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    DJI customer support is more or less useless when it comes to the compass. Many people have taken off from balconies successfully. Some have had issues.

    Putting it simply: if there is a big enough difference in the magnetic field between calibration, take off and in flight, you will have issues. Those three situations need to have the same general magnetic field in order to work properly.

    If there is something close by disturbing the compass (most likely during calibration and take off) you may have a bad flight.
     
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  17. With The Birds

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    I think you will find metal structures principally inhibit the transmission or RF energy through reflection, absorbtion occurs in dieletrics which are non metallic.
     
  18. Volantis

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    Absorption also works in antennas. Any metal grounded to Earth acts as an antenna. And you are correct, reflection also occurs. The point is that radio waves don't always work well when there is metal close by, unless the metal is intended to be the receiver.
     
  19. With The Birds

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    The message here is maintaining line of sight (aircraft and controller) around objects and structures metalic or otherwise. By the way, antenna elememts should not be grounded and dont need to be to function. The driven element in particular would be almost useless as an antenna if connected to ground.