Re: RC help required.
- 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 email@example.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
> 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.