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1st Scare

Discussion in 'Phantom 2 Discussion' started by Jdacal, Feb 16, 2014.

  1. Jdacal

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    I had my first scare today after about 70-80 flights with my Phantom.

    A couple of weeks ago I went to this same spot in the Everglades and got the longest range I've had to date. 1029 meters.

    I went back there today and tried to duplicate it. At about 700 meters my video started fading in and out, tried to turn it around and the sticks on my Futaba 14sg may have just as well been a bowl of Jello. No response at all from the Phantom, sticks in any direction had no effect. This in a place where MAYBE and air boat might be able to recover it, assuming it landed or crashed in a dry area.

    The video would pop-in and out weakly and I could see that it was moving, slowly but moving in a direction that was not taking it further or closer to me, at least not at great speed.

    Turned the transmitter off at this point and crossed my fingers. Came back and landed within 2 feet of take off point. Whew!

    Its weird that both video feed and RF feed gave issues at about the same time. Flew the rest of the afternoon with it with no major issues, but stayed close to home point. Will definitely be taking it apart and giving it a close look before next flight session.

    [​IMG]
     
  2. ianwood

    ianwood Taco Wrangler
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    Could it be that the lack of FPV created a confusing situation that felt like the P2 wasn't responding to your flight controls? I haven't done much FPV beyond LOS but I would guess that without a reasonably consistent FPV signal it would be hard to tell what your P2 was doing.

    Losing FPV would be much easier to understand than losing signals at both 5.8GHz and 2.4GHz at the very same time. It's possible but I can't think of anything that would explain it especially with a Futaba radio.
     
  3. goldfishrock

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    That's a great point Ian, I've had a couple of occasions where I’ve been watching the FPV Monitor as the Phantom is too far away to see properly and had a sudden panic when it appeared not to respond to the controls. Actually because of the height of the P2 and the terrain I was flying over it was nothing more than an illusion.

    More recently after replacing the stock receiver and transmitter with a Futaba 8J + R2088SB I had several ‘loss of control’ incidents which turned out to be antennae placement…. However when these occurred, RTH cut-in immediately where you are saying you actually had to initiate RTH by turning off the Tx?

    Jdacal what height were you at when this occurred? Are you using the stock transmitter and receiver?
     
  4. Jdacal

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    Video was fading in and out, but I was able to see enough to know that it wasn't responding to the controls. I mean pulling the left stick full right would initiate some pretty obvious spinning. Also pulling the right stick full towards me when its creeping forward would also be obvious. But neither had any effect. I guess I should clarify that I didn't lose all video, but rather, video degraded at a lot less distance than it normally would. The previous flight session the video didn't start to degrade until about 950 to 1000 meters. On this session, same area, it degraded at 700 meters and apparantly lost RF signal.

    Now it IS possible that when I turned the Futaba off it had already initiated RTH by itself as suggested in the previous post. But rather than keep fiddling with the controls I figured I'd better shut it down just in case.

    Height was about 100 meters. Only trees were the one's directly across the canal from the take-off point, probably no more than 15 feet tall. That's why I was at 100 meters to be sure that they weren't blocking LOS.

    Diversity receiver has a Spironet and a patch antenna.

    I suppose its possible that I might have gone to maybe 60 meters at some point and possibly the trees attenuated both signals. Its the only thing that occurs to me. While I didn't go into all out panic, I was focusing more on the camera video than the telemetry data. I just remember that the altitude numbers were not dropping which was a good thing. :)
     
  5. goldfishrock

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    Have you replaced the stock Transmitter and Receiver with different Futaba kit?

    The first time I lost signal I did the same thing and hit the power-off on the Tx. The second time I realised that actually the RTH had already kicked in before I turned off and presumed that this had been the case the first time too.

    I guess that the fact your video degraded at the same time indicates that there could well be external factors coming into play here, however I wouldn't imagine a couple of trees would cause it too many problems.

    The only thing I could suggest is to take it to a different location and try the same thing and see what happens. At least you know you can trust the RTH is all else fails..... It's still scary though isn't it? :eek:
     
  6. Jdacal

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    No, I haven't tried swapping Futaba Rx/Tx yet. Will probably give it some visual inspection and another flight before doing that. I have an RF power meter that should be here this week. This gives me a good excuse to play around with it.

    I doubt the problem will reoccur, probably just a fluke.

    Thanks for the suggestions.

    Sent from my iPad using Tapatalk HD
     
  7. ianwood

    ianwood Taco Wrangler
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    It's possible the trees disrupted the fresnel zone of both signals. That combined with potential reflections off of water could have created a multi-path situation. Just a guess. Anyway, if you haven't put in the Futaba RX yet, I think it would be a good time to do so paying particular attention to antenna placement. Maybe consider putting one with a horizontal polarization.
     
  8. Jdacal

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    Futaba 14sg Tx with matching Futaba Rx
     
  9. Jdacal

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    I like the water theory since I was right next to the canal.

    Rx antennas are in correct horizontal and vertical positions. Tx antenna was vertical.
     
  10. Jdacal

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    Figured I'd update on my original post since I ended up finding the problem. Apparently at some point I had removed the patch antenna and for whatever reason had removed the SMA adapter. So the antenna was put on without the adapter and was not making connection. Funny thing is I don't have any recollection of taking the antenna or the adapter off, but I definitely did.

    So to make a long story short the combination of going out of video range and being over the everglades created enough panic that I ended up shutting down the transmitter to trigger RTH. I've had lots more flights since then, so if it ever happens again I hope to stay a little more composed. :)