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Friendly tip --- do not compass calibrate under high voltage

Discussion in 'General Discussion' started by MadMitch88, Sep 7, 2014.

  1. MadMitch88

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    I was flying in a field today and I tried calibrating the compass on my Phantom Vision+ and was having trouble getting the confirmatory green flashing LEDs. I tried about 3 times and had no luck and was bamboozled until I looked up. I see 345,000 volt long-distance power lines about 85 feet directly above my head. Trying to recall college physics I took 25 years ago, I knew that higher voltage means stronger magnetic field, correct? Or is it based on current?

    So anyway I walked about 200 yds. away from the power lines and the compass calibrated on the first attempt.

    Please pass this along to other folks who might be little rusty on that "Fundamentals of Electromagnetism" course they took many moons ago.

    :mrgreen: :mrgreen: :mrgreen:
     
  2. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol

    Flying in a new area ....
     
  3. ProfessorStein

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    Re: Friendly tip --- do not compass calibrate under high vol

    You'll have to excuse Krunk, he doesn't believe in college physics or electromagnetism.

    What difference does it make why MadMitch was doing a compass calibration. His "new area" could've been 200 miles away from his last flying zone (in which case, a compass calibration was a smart thing to do). But even if it wasn't, he felt he needed to do a compass calibration. That's his prerogative. And his advice to avoid calibrating while near high power lines is good and sound... no matter the reason why the calibration is performed in the first place.
     
  4. Musicman

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    Re: Friendly tip --- do not compass calibrate under high vol

    I read this and just asking myself, why would you want to fly near those things in the first place.
    But that's just me :)
     
  5. Happyflyer

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    Re: Friendly tip --- do not compass calibrate under high vol

    If you do not think there is anything there, start to climb a 345 tower. You will not go very far until you get "prickly" and want to come down. Electromagnetism or induction, there is something there. The reason birds don't land on those lines. The ACSR wire that makes up a 345,000 volt line is too large a diameter for small birds to clamp their feet on, but larger ones could. There is something that keeps them away. I had lots of "fun" building them for about ten years.
    .
    I live close to one of the largest pump storage, hydroelectric plants in the World and would never get anywhere near those lines. (worked on them)
    .
    Agreed, why would you want to fly anywhere near lines like that?
     
  6. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol

    I was on a friend's 250-acre farm that just happened to have high-voltage lines running right down the middle of it.

    But I agree --- give me a choice of large field without power lines and one with them --- and I will always pick the one without power lines :mrgreen:
     
  7. Robgunbuilder

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    Re: Friendly tip --- do not compass calibrate under high vol

    Krunk- if you don't believe/ understand that there are strong magnetic fields orthogonal to wires carrying AC current, then please educate us on what you believe is going on. This should be interesting! Please elucidate why you think flying drones susceptible to magnetic fields is a good thing. Despite the obvious. I guess I'm just Troll baiting.
     
  8. ProfessorStein

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    Re: Friendly tip --- do not compass calibrate under high vol

    I think I need to step in, here, partly because Krunk is a bit correct in pointing out that my comment was "not helpful".

    I was being a bit facetious (and probably more than a little snide). I'm sure he believes in physics and electromagnetism. He just doesn't believe that said electromagetism, radiating, in particular, off of high-voltage power lines, can have any affect on a Phantom's components. He's already made his views pretty clear on another thread:
    viewtopic.php?f=7&t=24141
     
  9. Buckaye

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    Re: Friendly tip --- do not compass calibrate under high vol

    Granted - I don't know if the compasses in the Phantom operate the exact same way as the ones you carry around - but here are two articles I found fairly quickly that suggest High Tension Wires "COULD" have an effect on getting bearings with a compass.

    The bottom line (no pun intended) for me is that one should probably be careful flying within 50 yards/meters (depending on which you read) on High Tension/ High Voltage wires.... and I would also assume that if you need to calibrate - I'd go about a football field away just to be safe.


    http://www.armystudyguide.com/content/P ... pass.shtml

    http://www.artofmanliness.com/2009/07/0 ... e-compass/

    What I probably wouldn't do is tell people that just because I have been able to fly close to a high tension wire and experienced no ill effects - that everyone will experience the same thing... or vice versa. Either way - I'd say it's a factor to be considered. :D
     
  10. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol


    I never said anywhere in my post that flying was a problem around high-voltage lines --- only that getting the compass calibrated before takeoff was impossible.

    Please read my post again before you get more confused..... :D
     
  11. Buckaye

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    Re: Friendly tip --- do not compass calibrate under high vol


    It's clear you and ProfessorStein have an ongoing feud... But I have to say nothing about what ProfessorStein is saying is a "lie"... As I posted there are several articles/information sources that suggest that compasses reading could be compromised within 50 or so yards of high-tension wires.

    The original poster said he was 85 ft directly under the wires, which is a little over 28 yards... so it is quite possible that the wires were causing a calibration issue.

    Does that necessarily mean that a flight would catastrophically be altered by flying near the wires? No. Is it possible the bearing of a quad would be changed by a degree or two? Yes. Would a pilot even notice this slight deviation during the brief time the quad was in a magnetic field? Maybe not.

    I think to suggest that the OP was not being affected by his proximity to the wires isn't a forgone conclusion that can be drawn. In fact, I would argue, that he has at least anecdotal observation to at least "hint" otherwise.

    I'm not sure I'd use multiple threads from people who have flown in or around these wires as absolute proof that there is NO effect from the EM of the wires... but more as anecdotal evidence that those wires don't always (or even frequently) cause an issue. However, calibration may be a completely different story.
     
  12. ProfessorStein

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    Re: Friendly tip --- do not compass calibrate under high vol

    Very true, Mitch.

    Though... if you had trouble calibrating the compass around those particular power lines... it stands to reason that the (presumably calibrated-away-from-the-power-lines) compass might be affected during flight as well. Not to put words in anybody's mouth, but...
     
  13. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol

    I probably didnt have to calibrate the compass since I had flown the previous day about 5 miles away. But I'm a stickler for accuracy at all levels so I'd thought I'd compass calibrate at the new location. I guess it's the obsessive-compulsive demon that lives inside me and controls my psycho-mechanical processes when I don't keep him in check.

    I'd rather get into a pre-flight routine where I do the same checks/calibrations vs. trying to always remember when and where is the last time I did a compass calibration.
     
  14. Meta4

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    Re: Friendly tip --- do not compass calibrate under high vol

    If you are calibrating for a 5 mile difference in flights, you might call it OCD.
    But it's superstitious ritual. There is no need to calibrate if you are flying 5 miles away.
    Unnecessary calibration introduces the possibility of errors as shown in the OP.
    An understanding of why can when calibration is necessary would avoid over-calibration superstition.
    viewtopic.php?f=27&t=22435&p=205776#p205776
     
  15. ianwood

    ianwood Taco Wrangler
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    Re: Friendly tip --- do not compass calibrate under high vol

    Let's establish some facts.

    • High current lines radiate EMI and have a localized magnetic field. The impact is very local, e.g. after 20m, the impact is probably 50% or less.
    • Flying within close proximity to these power lines may yield temporary loss of control (due to EMI) and/or TBE (local magnetic field).
    • Calibrating your compass near any potential source of localized magnetic interference will increase your risk for TBE, crash, and/or flyaway.
    • After 60m, even the most powerful lines will have marginal, if any, impact.
     
  16. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol

    Not sure what you mean by --- "unnecessary calibration introduces possibility of errors" ??

    You need to explain that in further detail because it sounds like hogwash to me :mrgreen:
     
  17. ProfessorStein

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    Re: Friendly tip --- do not compass calibrate under high vol

    It's the "if-it-ain't-broke-don't-fix-it" theory. If you have already calibrated your compass, and it's working properly, if you go ahead and recalibrate when it isn't necessary, you could theoretically introduce errors... whereas if you left it alone, you would have a confirmed working setup.

    I feel it's a bit of hogwash, as well. One of the first things you should do on a first flight of the day, whether you recalibrated or not, is take it up 10 feet or so and leave it in a hover for a few seconds to check for symptoms of a bad compass calibration anyway (bad drift, circling, orientation shifts). So to me, it doesn't matter how often you calibrate... as long as you're checking that your bird is flying right.

    Plus... DJI themselves tell you to calibrate often. I'm more inclined to believe the manufacturer of the product than some superstition.
     
  18. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol

    "Theoretically introduce errors" --- that sounds like total poppycock to me. Sort of like saying "Defragment your hard drive often or else it's lifespan will be reduced." :mrgreen:

    As far as I can tell, calibrating a compass on a Phantom is purely an electro-magnetic process that doesnt induce "errors" into any computer chip or cause permanent damage to circuitry, etc. If anyone has any real engineering detail about how frequent compass calibration can induce errors then I'd love to hear it. Otherwise, my BS meter is pegging rather highly on this "theory" :D
     
  19. ProfessorStein

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    Re: Friendly tip --- do not compass calibrate under high vol

    I don't think it concerns the actual act of calibration. ie - the calibration process can't break the circuits, etc

    The fear is that, since so many things can affect the compass during calibration - rebar, electrical lines, cell phones, etc - that there's a chance that you'll be in such a situation more often than not. THAT is what they mean by "introducing errors".
     
  20. MadMitch88

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    Re: Friendly tip --- do not compass calibrate under high vol

    Things like buried rebar, high-voltage lines, cell towers, etc. are exactly the reason frequent compass calibration is a good idea.

    Just because I had good calibration 5 miles away a couple days ago doesnt mean that calibration will hold if I transport my Phantom on top of a 18" subwoofer box on the way to the new flying location.