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Altitude Conundrum

Discussion in 'Phantom 2 Discussion' started by denofr, Jun 16, 2014.

  1. denofr

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    Ok here's a hypothetical question. I think we danced around this question in the past but I'd like to flush it out.

    I'm driving on the Blue Ridge Parkway and come up to an overlook with a beautiful view. My 'Max Height' in the Assistant software is set to 1800'. I start the copter up and perform all the proper steps. The Phantom gets plenty of satellites and registers 'home'. I then fly it over the cliff (Yes I know this is probably illegal, it's just hypothetical). Within a few yards of me the Phantom finds itself 2500' above the ground. What happens :?:

    Does it
    A:) Immediately descend to 1800', try to return home, and crash into the side of the mountain. (My best guess)
    B:) Hover in place nicely.
    C:) Something else.

    Now what happens if I set the 'Max Height to 3500'?
     
  2. Killobite

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    Re: Altitude Conumbrum

    It will allow you to fly 1800' above the "home" altitude of zero. So, as long as you let it come to grips with the home location of where you are, it will let you go up another 1800' from your ground level.

    My normal flying area is 575' above sea level, I have my max altitude set to 300' and I regularly fly to 875' above sea level.
     
  3. denofr

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    Re: Altitude Conumbrum

    Interesting. As a wise man once said... "That did not occur to me, dude".
     
  4. denofr

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    Re: Altitude Conumbrum

    Actually, come to think of it, this is not necessarily the same example unless you are flying over a cliff of some sort. So in your example you put the copter on the ground which is 575' above sea level and fly up 300' to 875' above sea level, that obviously will work. The question is what would happen if you flew over a 400' deep quarry, for instance?
     
  5. N017RW

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    Re: Altitude Conumbrum

    "Nevermind Donny, it's over your head"

    Seriously though...
    Phantom altitude is based on a barometric, or atmospheric pressure sensor.
    It is measuring the 'weight' of the air at its current location.

    Upon take-off the Phantom associates the current pressure, or atmospheric weight, to be ground level or 'Zero" altitude.

    Therefore flying over a cliff will have no effect on what the Phantom associates the ground level to be.

    All altitude limits or presets are based on take-off location pressure, unless reset in flight.
     
  6. denofr

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    Re: Altitude Conumbrum

    The dude abides.
     
  7. N017RW

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    Re: Altitude Conumbrum

    Yes he does!
     
  8. NSF

    NSF

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    Re: Altitude Conumbrum

    What happens if you fly over the cliff and then below the home point altitude as set on take-off? Does the Phantom think it's back on the ground and then shut down? Or does it know it's not on the ground until the accelerometers tell it it isn't moving anymore?
     
  9. Uncle Meat

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    Re: Altitude Conumbrum

    Conundrum averted!

    U.M.
     
  10. Sanababit

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    Re: Altitude Conumbrum

    Well i fly over a small cliff, maybe 25-30 m to the bottom, when i first start my phantom it records the point of departure along with altitude, when i get my phantom over the cliff and fly it downward the altitude meter start showing you as Negative elevation, the lower you go, the higher the negative number, hope this makes sense, and nothing happens when in go lower, altough i dont go over my space limits

    Sana
     
  11. denofr

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    I would have sworn you were going to say: "I take comfort in that." :lol:
     
  12. maher

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    Re: Altitude Conumbrum


    Are you sure that the Phantom calculate altitude with a barometric sensor? I always thought it was based on GPs data. If you're right, that mean that the altitude will be precise even if the Phantom lose contact with satellites.

    Maher
     
  13. N017RW

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    Yes on the baro sensor.

    Precision ???
     
  14. maher

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    Do you know if the telemetry shown by the iOSD mini for altitude is GPS or barometric based?

    I always thought it was GPS based since I never saw a plane altimeter that accurate but GPS raw data are not really precise to the meter…

    Maher
     
  15. maher

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    Sorry, I should have said accuracy.
     
  16. ianwood

    ianwood Taco Wrangler
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    It's barometric. GPS is much too inaccurate. Limits are always relative to your home location and not sea level.
     
  17. ElGuano

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    Almost all. IIRC some aspects of no-fly-zone limits are calculated from GPS ASL figures.