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Re: [pop-pop-steamboats] Re: RC help required.

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  • Donald Qualls
    The metal hull can lead to receiver glitching, both in terms of blocked signal and reflection interference (we used to see similar things when I flew R/C
    Message 1 of 7 , Oct 12, 2010
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      The metal hull can lead to receiver glitching, both in terms of blocked
      signal and reflection interference (we used to see similar things when I
      flew R/C airplanes, if you flew too near a chain link fence or baseball
      backstop), where the transmitter's signal interferes with itself when
      the reflected signal goes in and out of phase with the direct signal.
      It's also possible the metal hull could be concentrating interference
      from the motor, which would be better when you have the original motor
      with the capacitors connected -- and possible you might not notice
      rudder glitches if the throttle's glitching, so we can't rule out
      interference from the motor.

      The squatting you describe, BTW, is what I'd expect if you're trying to
      push a displacement hull past "hull speed", the speed at which the bow
      wave's first peak hasn't come back down to water level when it reaches
      the stern (there's a calculation for the actual speed, but hull speed is
      the main reason aircraft carriers can always outrun destroyers despite
      the destroyer's much larger power to weight ratio -- because a destroyer
      is shorter).

      If the controller directly drives the motor, you could connect a dummy
      load (say, a 1 watt or better, 20-or-so ohm resistance -- an old style
      incandescent light bulb made for 120 V should work) and read the voltage
      across the load with an oscilloscope, looking for stuff that doesn't
      belong in what's essentially an on-or-off square wave. Lacking an
      o-scope, however, there really isn't any useful way to test other than
      to pull the whole rig out of the metal hull and see if you still get
      glitches when the signal isn't being blocked and/or interference
      concentrated.

      Daryl wrote:
      > Thanks Donald and zoomkat.
      >
      > Progress update and of course answers beget questions.
      >
      > I put the car motor in and the same problem which maybe eliminates
      > the vacuum motor as a source of the problem. Replaced the just new
      > battery in the controller though it tested OK and a good improvement
      > but not totally right. Did find out that the little car motor has
      > enough power. The bow lifted out of the water, the stern squatted
      > down and waves came to the top of my pond (when it would run at full
      > power). Weight redistribution required. Enough power in fact that the
      > prop sliced a hole in the bottom of the boat. I did not notice that
      > the car motor was shorter so shaft and prop had moved forward and
      > under full power would touch the hull.
      >
      > I wonder if the all metal boat is affecting the controller signal?
      > Right now the controller is the prime suspect Is it OK to use
      > contact cleaner on the controller? Is there any simple way to test
      > controller signal? The original car motor has two capacitors. The
      > vacuum motor none that I can see. If I put one on the vacuum motor
      > what is "biggish"?
      >
      > All the components are 9.6V originally, no 7.2V stuff. I'm using
      > direct drive with both motors and do have reverse that is as erratic
      > as forward.
      >


      --
      If, through hard work and perseverance, you finally get what you want,
      it's probably a sign you weren't dreaming big enough.

      Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com

      Opinions expressed are my own -- take them for what they're worth
      and don't expect them to be perfect.
    • Daryl
      Thanks Donald, I ll work at it in the next couple of days and let you know what I discover. I had a tough time getting connected to the forum today so if you
      Message 2 of 7 , Oct 13, 2010
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        Thanks Donald,

        I'll work at it in the next couple of days and let you know what I discover. I had a tough time getting connected to the forum today so if you don't hear from me maybe I've been permenantly blocked.

        Re hull design:-As speed in putt putts is my main interest and knowing that scale models don't always perform like the full size I spent a couple of weeks this summer testing various hulls with engines of the same or similar power. The results were interesting. May do a Youtube video on it. I'll send you the data if you are interested. It is a fairly narrow study as regards boat length and weight and engine power but there were very distinct differences in hull shape. Did not get the expected result.

        Daryl.

        --- In pop-pop-steamboats@yahoogroups.com, Donald Qualls <silent1@...> wrote:
        >
        > The metal hull can lead to receiver glitching, both in terms of blocked
        > signal and reflection interference (we used to see similar things when I
        > flew R/C airplanes, if you flew too near a chain link fence or baseball
        > backstop), where the transmitter's signal interferes with itself when
        > the reflected signal goes in and out of phase with the direct signal.
        > It's also possible the metal hull could be concentrating interference
        > from the motor, which would be better when you have the original motor
        > with the capacitors connected -- and possible you might not notice
        > rudder glitches if the throttle's glitching, so we can't rule out
        > interference from the motor.
        >
        > The squatting you describe, BTW, is what I'd expect if you're trying to
        > push a displacement hull past "hull speed", the speed at which the bow
        > wave's first peak hasn't come back down to water level when it reaches
        > the stern (there's a calculation for the actual speed, but hull speed is
        > the main reason aircraft carriers can always outrun destroyers despite
        > the destroyer's much larger power to weight ratio -- because a destroyer
        > is shorter).
        >
        > If the controller directly drives the motor, you could connect a dummy
        > load (say, a 1 watt or better, 20-or-so ohm resistance -- an old style
        > incandescent light bulb made for 120 V should work) and read the voltage
        > across the load with an oscilloscope, looking for stuff that doesn't
        > belong in what's essentially an on-or-off square wave. Lacking an
        > o-scope, however, there really isn't any useful way to test other than
        > to pull the whole rig out of the metal hull and see if you still get
        > glitches when the signal isn't being blocked and/or interference
        > concentrated.
        >
        > Daryl wrote:
        > > Thanks Donald and zoomkat.
        > >
        > > Progress update and of course answers beget questions.
        > >
        > > I put the car motor in and the same problem which maybe eliminates
        > > the vacuum motor as a source of the problem. Replaced the just new
        > > battery in the controller though it tested OK and a good improvement
        > > but not totally right. Did find out that the little car motor has
        > > enough power. The bow lifted out of the water, the stern squatted
        > > down and waves came to the top of my pond (when it would run at full
        > > power). Weight redistribution required. Enough power in fact that the
        > > prop sliced a hole in the bottom of the boat. I did not notice that
        > > the car motor was shorter so shaft and prop had moved forward and
        > > under full power would touch the hull.
        > >
        > > I wonder if the all metal boat is affecting the controller signal?
        > > Right now the controller is the prime suspect Is it OK to use
        > > contact cleaner on the controller? Is there any simple way to test
        > > controller signal? The original car motor has two capacitors. The
        > > vacuum motor none that I can see. If I put one on the vacuum motor
        > > what is "biggish"?
        > >
        > > All the components are 9.6V originally, no 7.2V stuff. I'm using
        > > direct drive with both motors and do have reverse that is as erratic
        > > as forward.
        > >
        >
        >
        > --
        > If, through hard work and perseverance, you finally get what you want,
        > it's probably a sign you weren't dreaming big enough.
        >
        > Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com
        >
        > Opinions expressed are my own -- take them for what they're worth
        > and don't expect them to be perfect.
        >
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