Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Detail Work, Rigging, Fittings, Figures Etc. => Topic started by: Roger in France on August 26, 2006, 06:50:32 pm
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Am planning (very early days) a large model tug. As most ships eject waste water all the time when engine running I wondered if anyone has a simple method to make the expelled jet of water intermittent? I think a continuous, uniform stream would look wrong.
Before I scratch my head too much I thought I would see who has already invented the wheel!
Roger in France.
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Bonjour easy m8 get 1 water pump from a car connct +to +on wires to motor -to -on same and hey presto as motor speed inceases so does the volume of water thta is all I have done on my Sea Queen and it works
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How about a small motor with a wheel on it - use the wheel to switch a microswitch on and off as it rotates (by cutting notches in it). Use this to switch the pump on and off - this should with a bit of luck give a pulsing jet. Run the motor off the main drive and the rate of pulsing will follow the speed of the motors.
Tim the Wombat
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What about using some sort of air pump as a pump like in a fish tank filter.
The bubbles along or up a tube drawing water along with it.
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What about trying a slow speed reciprocating pump?
Maybe one driven by a crank geared down from a motor?
Ian
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The water from the hull is from the Main Engines and Generator overboard discharges.
The water is used to cool the Engines in large Heat Exchangers.
Most modern vessels have electris driven pumps eo the discharges dont vary much.
The ships with variable outlets are from engine-driven pumps.
If you want a variable output connect a speed controller on a "y" lead from the throttle.
Or
Wire in the pump via the main motor wiring which will be controlled by the main speed controller.
Main problem will be to find a pump thet will react as you want.
Possibly windscreen washer pump?
Bob
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Roger,
I was talking to JJC a couple of weeks ago and he is developing a pump for the lifeboat boys that is linked to start up, engine speed, and running etc. You might want to give him a go? Works with the smoke machine as well. all proportional?
Regards
Simon
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as you are planninga big tug, plenty of room, and presumably running on 12 volts, if you want an intermottent pulse of water coming out of the outlet, why not wire the pump feed thrugh a car indicator relay. This will pulse the pump at the same speed your indicator lights flash at. You don't get any variation with speed, but that's a different problem.
Alternative is to have a look at the Maplins web site or catalogue and look at some of the flasher circuits they have in the projects book. There are circuits where you can alter how often it flashes, and how long the power is on / off when it does.
Aston
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Hi RIF,
a friend of mine had used a so-called membran-pump, which gives a good pulsation, just like the origin. Also there was a report in a German mag, where a lad had taken a piece of silicone-tube and a slow running motor with a disc where 5 rollers had been mounted. The rollers went over the tube and pressed a bit of water outside. The tube filled up with water just before the next roller of the disc went over the tube to push out the next bit of water. Looked good to me as well.
Hope this was out of any help for you.
Jörg
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The outlet SHOULDNT pulse, it should be a constant stream, but on older engines getting faster as the main engine speeds up.
The generators are constant speed.
Bob
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The outlet SHOULDNT pulse, it should be a constant stream, but on older engines getting faster as the main engine speeds up.
The generators are constant speed.
Quite right for larger craft but for smaller ones, i.e. launch types, with diesel engines you do get a pulse effect as the exhaust gases force out the cooling water from the exhaust system. With very small boats such as yachts with outboards you just get a constant stream from the "telltale"to indicate that the cooling system is working. Not that this is likely to be apparent at model scales. With rowing boats it's just perspiration while with submarines you should be getting worried....
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Colin, if it is persiperation running down your back, passing your rear outlet I am sure it will pulse while you are rowing... ;D
Jörg
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And at times it will also blow bubbles.... ;D ;D
Roy
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What extraordinary imaginations you guys have! Is nowhere safe? Can't turn your back for a moment.... :o :o
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What extraordinary imaginations you guys have! Is nowhere safe? Can't turn your back for a moment....
Colin life is to short not to have fun as well enjoy mate,
ROGER,
If it it a large Tug model is it a large tug you are modelling, if so the exhaust would be constant as it would be powered by a generating system...
Roy
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My thoughts led me to think of an automatic loo flush, (me disturbed? perhaps)
small 'sealed' tub with a syphon arangement, to cycle in pulses. trickle in pulsed flushes out. could even fill it from a cooling coil inlet so no pumps, no motors, no batteries to go flat?
[but what does he know?]