New ballast system: WTC test
08-06-2008, 08:41 PM
#1
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New ballast system: WTC test
This system uses a flex bag and a automotive 12 volts pump.
Now I included a video made during the tests in a WTC.
The difference with other systems is that it almost doesn't compress air into a tight compartment, instead the air inside escapes through a small tube, glued to the bag. When emptying the ballast, water is pumped out; as the tube is (now) submerged, the water tries to enter the bag but it can't because the tube has a very narrow inner diammeter (1mm), so a vaccum is created inside the bag and it shrinks, making the submarine surfaces again once some amount of water is pumped out.
Once the small tube gets into contact with the air again, if the pump is still running it sucks air into the bag, emptying it more quickly, and the sub is on the surface again.
A clunk is needed to be sure that water will be pumped out from the bottom of the bag, and the tube has to be raised enough to let the bubble escape through it.
Simple, reliable, cheap, no valves needed, just a flex bag (I use a serum bag, those you see at the hospital), the pump has to be a geared one but no need for a strong one, since it doesn't have to cope with the pressure created when you pump water compressing air in a pressurized bottle; the pump is designed to run on 12 volts, I make it run in 6volts with success!
This trial was made using a glass coffe container, its lid modified to accomodate two tubes (air exhaust/intake, water exhaust/intake) and made watertight:
(pics and vid)
(please forgive my English...)
http://www.youtube.com/watch?v=x2gxy-6iqRs
Now I included a video made during the tests in a WTC.
The difference with other systems is that it almost doesn't compress air into a tight compartment, instead the air inside escapes through a small tube, glued to the bag. When emptying the ballast, water is pumped out; as the tube is (now) submerged, the water tries to enter the bag but it can't because the tube has a very narrow inner diammeter (1mm), so a vaccum is created inside the bag and it shrinks, making the submarine surfaces again once some amount of water is pumped out.
Once the small tube gets into contact with the air again, if the pump is still running it sucks air into the bag, emptying it more quickly, and the sub is on the surface again.
A clunk is needed to be sure that water will be pumped out from the bottom of the bag, and the tube has to be raised enough to let the bubble escape through it.
Simple, reliable, cheap, no valves needed, just a flex bag (I use a serum bag, those you see at the hospital), the pump has to be a geared one but no need for a strong one, since it doesn't have to cope with the pressure created when you pump water compressing air in a pressurized bottle; the pump is designed to run on 12 volts, I make it run in 6volts with success!
This trial was made using a glass coffe container, its lid modified to accomodate two tubes (air exhaust/intake, water exhaust/intake) and made watertight:
(pics and vid)
(please forgive my English...)
http://www.youtube.com/watch?v=x2gxy-6iqRs
08-07-2008, 04:23 PM
#2
RE: New ballast system: WTC test
That is very neat my friend! And no worries about your English, I hear you loud and clear! 
Anyways, what would be the recommended diameter of the narrow tube? Would a small hollow wire do the trick?
I am actually willing to test this on my submarine if I can find the materials[8D].
Anyways, what would be the recommended diameter of the narrow tube? Would a small hollow wire do the trick? I am actually willing to test this on my submarine if I can find the materials[8D].
08-07-2008, 05:38 PM
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RE: New ballast system: WTC test
Hi Captain Nemo12:
Thanks! In my system I combine a cheap, practical, effective and easy way to have static dive capability in our RC subs.
Most (water) pump system compress air in a tank, which must be very strong, the pump intself must be stronger, not to mention the current drain. AND you need a valve. All of this is expensive and most modellers just try to buy the system because it is quite complicated to homebuild.
My theory was proved, because I designed it many years ago, and I just tested it now, I admit I feel proud and happy. My 1:144 trumpeter Seawolf will be in the shipyard soon!
As for the tube, well, in my first try (video below), using a 500cc bag, I glued the tube that comes with the W..40 spray, you know.
http://www.youtube.com/watch?v=c9ME3slfbKU
But the glue didn't work well with the plastic bag, so I came to this idea: a nylon 4mm wide screw, with a 0.5 mm (25.4 mm = 1 in.) hole through it, the screw, with an o-ring, is inserted in the bag, inside-out, protruding, another o-ring from the outside, a nut and a washer, the two o-rings provide the sealing. Attaching the screw to the bag was the difficult part.
A hose connected to the screw, then the screw and the hose are the air exhaust/intake. The water intake is simpler, a brass tube sealed to the bag intake, connected to the pump.
The wire should work, as long as you can effectively attach it to the bag. The bag (a picture included in this post) is made of polyethylene, or maybe Polypropylene, which are hard to glue to anything. Better a mechanical attachment, as mine.
Well, I hope this helps. This saturday (9th) we have a meeting in a pond in Buenos Aires, it is RC subs related, but just a few of us hava a sub (I don't, just this system to be tested, first "sea trials"). Our club is
www.camne.com.ar
in Spanish, sorry, but with plenty of pictures of our fleet.
Regards
Robert
Thanks! In my system I combine a cheap, practical, effective and easy way to have static dive capability in our RC subs.
Most (water) pump system compress air in a tank, which must be very strong, the pump intself must be stronger, not to mention the current drain. AND you need a valve. All of this is expensive and most modellers just try to buy the system because it is quite complicated to homebuild.
My theory was proved, because I designed it many years ago, and I just tested it now, I admit I feel proud and happy. My 1:144 trumpeter Seawolf will be in the shipyard soon!
As for the tube, well, in my first try (video below), using a 500cc bag, I glued the tube that comes with the W..40 spray, you know.
http://www.youtube.com/watch?v=c9ME3slfbKU
But the glue didn't work well with the plastic bag, so I came to this idea: a nylon 4mm wide screw, with a 0.5 mm (25.4 mm = 1 in.) hole through it, the screw, with an o-ring, is inserted in the bag, inside-out, protruding, another o-ring from the outside, a nut and a washer, the two o-rings provide the sealing. Attaching the screw to the bag was the difficult part.
A hose connected to the screw, then the screw and the hose are the air exhaust/intake. The water intake is simpler, a brass tube sealed to the bag intake, connected to the pump.
The wire should work, as long as you can effectively attach it to the bag. The bag (a picture included in this post) is made of polyethylene, or maybe Polypropylene, which are hard to glue to anything. Better a mechanical attachment, as mine.
Well, I hope this helps. This saturday (9th) we have a meeting in a pond in Buenos Aires, it is RC subs related, but just a few of us hava a sub (I don't, just this system to be tested, first "sea trials"). Our club is
www.camne.com.ar
in Spanish, sorry, but with plenty of pictures of our fleet.
Regards
Robert
