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Iron = Bad

Discussion in 'General Discussion' started by GeneL, Jul 11, 2013.

  1. GeneL

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    This should be old news, since the information is in the DJI manual (and one video), but the subject of iron and other ferrous metals is fresh in my mind and maybe the subject can stand a bump for those who are new to flying Phantoms - which I suspect is most of us.

    This morning I set out to do a test flight after replacing the compass on my Phantom (another subject). I was a little nervous about it, since this was the first time I've had my quad disassembled, so I went to my "test field." I do my practice and test flights there because it's a beautiful wide open flat space in the middle of nowhere with knee high grass for "emergency landings," and virtually zilch for wild wi-fi rf. There, my Phantom flew great, and held as placid a hover as I have ever seen it do. Whew!

    Then, down to business, I went 500 yards away to shoot a piece of machinery in a vineyard that can be best described as an iron stake farm. From the very start, the Phantom did about 10' toilet bowls - enough to really make me nervous, especially considering the new compass installation. I never felt like I was loosing control, but the hunting for position was pronounce enough that, had that been my first day or so flying the Phantom, I might have done something rash thinking that I was about to have a flyaway.

    Sooo...it was immediately back to the safety of my practice field for the next flight, where the Phantom flew solid as a rock again. Even though I was aware of the problem with iron, and kind of ready for it when I went to the vineyard, this incident proved to me beyond a doubt the significant effect ferrous materials can have on a Phantom's flight characteristics. Both these fields were in relatively close proximity of one another, identical except for the iron stakes, and the stability difference was significant.

    Something similar happened, by the way, about a month ago. The Phantom was doing fine until I set it on a small slab of concrete to take off from. This time I got an alternating yellow-red light, something I had never seen before, but I knew indicated a compass problem. This time, I shut it down and went home to check it out on the Assistant. I'd heard too many stories about red-yellow light combinations preceding a flyaway, and didn't want risk a flight to find out for myself. I'm sure it was just rebar in the concrete that was compromising the compass.

    Sorry this is so long. You knew all this, right? In any case, happy flying!
     
  2. GearLoose

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    Your report is definitely thought provoking. My Phantom has been experiencing bouts of "toilet bowling" in recent days and I've seen many other reports of it as well. What I'm wondering, however, is whether or not all Phantom's are as sensitive as yours, or if something has changed in your quad to make it behave like that? The reason I ask is that so many Phantom owners fly in urban and industrial areas, where you'd assume that iron would be virtually everywhere and in significant amounts. Then again... what about iron as a factor in flyaways?

    It's a head scratcher for sure!
     
  3. GeneL

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    Thoughtful reply. Actually, the disturbance was worse close to the ground, as you would expect, and would have most certainly disappeared if I had taken refuge in altitude.

    I personally think that few, if any, actual flyaways are directly caused by the influence of ferrous metals in the vicinity. However, I do suspect that a lot of flyaway reports are generated by loss of complete control that starts with some unusual behavior on the part of the Phantom (like serious toilet bowl) which then causes an inexperienced pilot to overcorrect and forget which control mode he or she is in. Of course, that compounds the problem which eventually causes it to degenerate into a serious control disconnect.

    For example, if the Pilot's already off balance and gets the Phantom into ATTI without being aware of it, then gives one of the controls a good shove, the Phantom is going to take off like a rocket and not stop until he/she gets it together enough to figure out which control will arrest the motion. If panic sets in, the situation is toast and the Phantom is crashed or gone. I know, 'cause I've been far enough down that road to see where it can lead!

    The Phantom is a complex little beast that is deceptively simple to fly - until it up and bites you. We love 'em just the same, right?
     
  4. GearLoose

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    Genel, I've had the very experience you describe -- when I over enthusiastically sent the Phantom speeding away from me, it veered to the left and started to go behind a line of very tall trees. I panicked and fumbled at the controls. Ironically, I was probably saved from a "runaway" when the Phantom dove into a tree. By then, however, it was out of sight and could easily have flown anywhere if the flight path had been open.

    Although I've made progress in learning to fly my Phantom, I am definitely a nervous noobie and try to take fewer chances than when I first started.
     
  5. Mark P

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