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magnets get weak?

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  • magnets get weak?

    Took the Akula to the neighbor's pond today for some water time. Pre checks good, in the water, worked out the bubbles and got underway. I very quickly lost control of the rudder. Recovering the boat, I find that the rudder is loose, as the magnetic connector has come uncoupled. That happened when I first started running it.. but it was because the pushrod was contacting the driveshaft. I reduced travel and the issue dissapeared. Until today. With the top off, I verified that the linkage was still clear of teh driveshaft, and that there were no other interference issues. I also verified that the WTC was sitting squarely in its foundations and was on the index pin. In the water with the top off, and I find that if I cycle the rudder quickly, it comes disconnected on the pull stroke. Dosen't happen in the air. I've never had an issue with cycling the rudder quickly in the water before, so... what the hell?
    "It does not take so many words to speak the truth" Chief Joseph

  • #2
    Magnets attract more strongly exponentially as they get closer...is it possible that there is a coat of rust on the magnet's face? or paint? or filings?

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    • #3
      Is it possible that you accendently have the rudder trim set to a setting that you normally dont have set? Did you change anything-like the servo (might be faster and more powerful?) Change the ubec? (more servo voltage) change to a lipo battery? Does the rudder swing without binding when disconnected? Did you accidentally go from low rate to high on the rudder control? I got a million of them-I'm here all week!

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      • #4
        The only screw-up I pulled was running it on the 688's settings briefly. The only real difference in the two, at least at that time, was that I had set all the travels back to 100% for the new boat. The magnets look all nice and shiny and I dont' see any fod on them. Haven't changed anything electrical in the boat.. Literally, the only thing I did between the last, good run and this one was charge the battery and smear some more grease on the pushrods, from the outside...other than that nothing! That's why I'm so puzzled by this.

        The rudder swings freely when not connected, but will go overcenter if swung too far. But the servo won't allow that, I verified that it was not swinging outside of limits. Didn't drive the boat any differently.. it's automatically speed limiting, as the prop will come out of teh water if you get going too fast on the surface and then cavitate. The rudder would disconnect just sitting dockside if I swung it fast enough. No dual rates...
        "It does not take so many words to speak the truth" Chief Joseph

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        • #5
          Do you know anyone with a gauss meter? -Not being familiar with your Akula's setup...any chance of swapping the connector with a known good one?

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          • #6
            The two things that make a standing magnet get weaker is heat and impact (to my limited knowledge), but I do not think it is the issue. To me, it sounds like over travel or binding. Weeds a can accumulate at the pivot points.

            if it continues you can try a stronger connector.
            If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

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            • #7
              Originally posted by a1965l View Post
              Took the Akula to the neighbor's pond today for some water time. Pre checks good, in the water, worked out the bubbles and got underway. I very quickly lost control of the rudder. Recovering the boat, I find that the rudder is loose, as the magnetic connector has come uncoupled. That happened when I first started running it.. but it was because the pushrod was contacting the driveshaft. I reduced travel and the issue dissapeared. Until today. With the top off, I verified that the linkage was still clear of teh driveshaft, and that there were no other interference issues. I also verified that the WTC was sitting squarely in its foundations and was on the index pin. In the water with the top off, and I find that if I cycle the rudder quickly, it comes disconnected on the pull stroke. Dosen't happen in the air. I've never had an issue with cycling the rudder quickly in the water before, so... what the hell?
              How did you reduce the travel? was it done by an end point change in the transmitter, or was it done by moving a hole on the servo arm?

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              • #8
                Reduced the travel in the xmitter. I love computer radios.
                "It does not take so many words to speak the truth" Chief Joseph

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                • #9
                  It is imperative that the two magnet faces meet parallel and flat

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                  • #10
                    What also happens is whatever you are using to be attracted by the magnets becomes a little biot magnetized themselves, and therefore becomes less attracted to the magnet.
                    A man of true Frankenstinean proportions!!

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                    • #11
                      It's 2 magnets....
                      "It does not take so many words to speak the truth" Chief Joseph

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