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Re: RC help required.

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  • 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 1 of 7 , Oct 13, 2010
      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.


      --- 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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