Ballast System Query

[Albion]

A peristaltic pump is self sealing, so doesn't require this at all. All you need is a two way switcher or speed controller. But as Dave pointed out- low flow.

If your building your own, can also make them high flow, i made one , hand cranked as part of my engineeering qualifications. Not much to them, anyone with a lathe could produce one in a day or two.

[Subculture]

Agreed. They're always bigger than other pump technologies though.

All depends on how much space you have.

From my own perspective, I think it's always worthwhile to have some form of ballast trim to cater for different water densities. The gas system doesn't offer that unless it's equipped with a secondary trim tank, or you run with an exposed water surface.

Here in the UK the water pump into a sealed tank is very popular, owing to the Eden/Sheerline range of kit which use this sytem. It's reliable and inexpensive (if you build it yourself), and requires little maintenance, but you do get a little sloshing, and as a result the boats are not as stable as those using tanks which fill completely, IMO.

[Slats]

Agreed. They're always bigger than other pump technologies though.

All depends on how much space you have.

From my own perspective, I think it's always worthwhile to have some form of ballast trim to cater for different water densities. The gas system doesn't offer that unless it's equipped with a secondary trim tank, or you run with an exposed water surface.

Here in the UK the water pump into a sealed tank is very popular, owing to the Eden/Sheerline range of kit which use this sytem. It's reliable and inexpensive (if you build it yourself), and requires little maintenance, but you do get a little sloshing, and as a result the boats are not as stable as those using tanks which fill completely, IMO.

Agree Andy. The sloshing part can be overcome by baffles - Jim Russell and I are mucking about with a sphere....no baffles but each tank has to be precisely located and in a lot cases the size won't be big enough for proper scale surface trim. The sphere of course is an ideal shape for pressure.

[He Who Shall Not Be Named]

Mike and I have been kicking the sealed trim tank idea around. The magic ingredients are a small flow, minimal slosh tank; reversible, medium-high pressure, no slip pump; and pump ESC/dedicated two-way switch (Kevin McLeod, call your office).

As Andy pointed out, a trim tank, to fine tune the displacement of the submarine, is needed. And its that mission that Mike and I are now working to produce a product to perform

At this time Mike is hitting his sources up for the pump-motor and already he's found some good candidates.

Andy and others have suggested using small spun copper spheres (think: toilet float) for the ballast tank, and we'll look for quantity sources for those. I like that type tank: the sphere is ideal in shape to resist the considerable pressure the tank will be subjected to as it's crammed with trim water. And the sphere is the best package to jam into a cylinder/typical submarine hull.

A proposed installation scheme would go like this: the pump-motor and its controller, as a unit, within the forward dry space of the SubDriver cylinder. The small trim tank sphere in the ballast tank, at the center of rotation. the line between pump and tank running through the forward access bulkhead, running external of the cylinder, entering the main ballast tank through an open flood-drain hole or dedicated trim system manifold block, and into a nipple at the bottom of the trim tank sphere. The water inlet-outlet side of the pump runs between the pump-motor unit and a port within the forward bulkhead.

The system, as envisioned at this time, is only suitable for use in SubDriver's sized 3.5 and larger in diameter -- that's an assumption -- it all depends on the size of the pump-motors Mike finds out there in China-land.

For the record (Aquadeep, you listening?): This, like so many gadgets that come out of my shop, originated as an idea formulated by others. I have not invented a thing here. The idea for this type trim system has come from guys who have given of their talents and minds, freely, in pursuit of a hobby, over the years.

This game is a business to Mike and me. However, it's a business that would not be possible without the free and heartfelt enthusiasm and participation of those who have advanced the state-of-the-art. Mike and I want to make it clear that we acknowledge and appreciate the talents and practical observations offered by you guys in the field. Thank you. We stand on the shoulders of those who came before and who currently advance the Craft. Guys like: Norbert, Johann, Andy, Skip, John, Joel, Brian, Kevin (the good one), Dan, Greg, Lee, the Dave's, Bob, George, Art, Mike, Rick, and the other movers-and-shakers in the game.

(There are unaccomplished idiots in this game too, but if you look hard enough the above guys drown out the drivel dished out by the morons who today reside on many of the forums. All you have to do is cherry-pick the good info from the crap. I've learned how. Many of you have too. But so many newbies are being led astray by the bad information out there on the Net; bad information originating from guys who present themselves as experts, but who have not built/assembled and operated a single r/c submarine!).

David,

[redboat219]

If your building your own, can also make them high flow, i made one , hand cranked as part of my engineeering qualifications. Not much to them, anyone with a lathe could produce one in a day or two.

http://blog.makezine.com/archive/2008/12/make_a_a_peristaltic_pump.html?CMP=OTC-0D6B48984890http://blog.makezine.com/

Looks easy enough to replicate even without a lathe. You can see the principle in action.
Looks like the rollers aren't pinching the tubes enough that's why he getting poor outflow.

[He Who Shall Not Be Named]

http://blog.makezine.com/archive/200....makezine.com/

Looks easy enough to replicate even without a lathe. You can see the principle in action.
Looks like the rollers aren't pinching the tubes enough that's why he getting poor outflow.

The three most useless words in the English language: "Looks Easy Enough".

I'm looking forward to a full report on how your pump performs ... then tell me how easy a task it was.

There's a great deal of pride, satisfaction, reward, and fame to be had once you do. But the DOING part is never, NEVER easy.

If things were so god-damned easy, every jerk-off on the planet would be doing it!!!!

Get to work!

David,

[Slats]

Mike and I have been kicking the sealed trim tank idea around. The magic ingredients are a small flow, minimal slosh tank; reversible, medium-high pressure, no slip pump; and pump ESC/dedicated two-way switch (Kevin McLeod, call your office).

As Andy pointed out, a trim tank, to fine tune the displacement of the submarine, is needed. And its that mission that Mike and I are now working to produce a product to perform

At this time Mike is hitting his sources up for the pump-motor and already he's found some good candidates.

Andy and others have suggested using small spun copper spheres (think: toilet float) for the ballast tank, and we'll look for quantity sources for those. I like that type tank: the sphere is ideal in shape to resist the considerable pressure the tank will be subjected to as it's crammed with trim water. And the sphere is the best package to jam into a cylinder/typical submarine hull.

A proposed installation scheme would go like this: the pump-motor and its controller, as a unit, within the forward dry space of the SubDriver cylinder. The small trim tank sphere in the ballast tank, at the center of rotation. the line between pump and tank running through the forward access bulkhead, running external of the cylinder, entering the main ballast tank through an open flood-drain hole or dedicated trim system manifold block, and into a nipple at the bottom of the trim tank sphere. The water inlet-outlet side of the pump runs between the pump-motor unit and a port within the forward bulkhead.

The system, as envisioned at this time, is only suitable for use in SubDriver's sized 3.5 and larger in diameter -- that's an assumption -- it all depends on the size of the pump-motors Mike finds out there in China-land.

For the record (Aquadeep, you listening?): This, like so many gadgets that come out of my shop, originated as an idea formulated by others. I have not invented a thing here. The idea for this type trim system has come from guys who have given of their talents and minds, freely, in pursuit of a hobby, over the years.

This game is a business to Mike and me. However, it's a business that would not be possible without the free and heartfelt enthusiasm and participation of those who have advanced the state-of-the-art. Mike and I want to make it clear that we acknowledge and appreciate the talents and practical observations offered by you guys in the field. Thank you. We stand on the shoulders of those who came before and who currently advance the Craft. Guys like: Norbert, Johann, Andy, Skip, John, Joel, Brian, Kevin (the good one), Dan, Greg, Lee, the Dave's, Bob, George, Art, Mike, Rick, and the other movers-and-shakers in the game.

(There are unaccomplished idiots in this game too, but if you look hard enough the above guys drown out the drivel dished out by the morons who today reside on many of the forums. All you have to do is cherry-pick the good info from the crap. I've learned how. Many of you have too. But so many newbies are being led astray by the bad information out there on the Net; bad information originating from guys who present themselves as experts, but who have not built/assembled and operated a single r/c submarine!).

David,

Cool.
Jim's trials here over the weekend went very well. His test beds are a converted Robbe U boat and 1/72 LA for using a toilet cystern float tank.

What I am amazed by this is the LA which is a fairly big sub in that scale utilised a 100mm sphere tank the volume is: 523ml where V = 4/3(pi x r^3),
r=50mm = 5 cm.

Jim estimates the tank fills to only around 60%. On my calcs above that is only 314ml or if you like 11.07 ounces. So I amazed that such a small quantity of ballast positioned right on the centre of rotation is enough to take the boat from proper surfaced trim down. Can this be right???

I do hope this does goe well - the biggest problem I have found is pump longevity.

The other issue Jim has grappled with is control - he uses a currently a servo that engages microswitches - Fwd / Reverse on the pump and when the pump is in reverse the release of the valve happens in union with reverse.
Was thinking could this set up use one of Kevin's units.

I hope to have photos soon, Jims's sending me the pump and valve and various toilet cystern floats in 80mm / 100 mm and 120mm.

So much for me ending experimenting and settling on gas - spose I can atleast tick off RCABS as been there done that! My curiosity will kill me one day!

[He Who Shall Not Be Named]

You guys are doing great work. Keep it up. And a big thank you to Jim over there.

Don't get too excited about the relatively small volume of variable ballast getting the LA to designed waterline all by itself -- Those boats require less than 15% reserve buoyancy.

The system will not get a modern Soviet attack or SSBN to anywhere near its designed waterline -- those boats having between 30-40% researve buoyancy.

The LA (and other American attack and SSBN boats) is the exception to the norm.

[Slats]

You guys are doing great work. Keep it up. And a big thank you to Jim over there.

Don't get too excited about the relatively small volume of variable ballast getting the LA to designed waterline all by itself -- Those boats require less than 15% reserve buoyancy.

The system will not get a modern Soviet attack or SSBN to anywhere near its designed waterline -- those boats having between 30-40% researve buoyancy.

The LA (and other American attack and SSBN boats) is the exception to the norm.

Ok - great info.

To clarify is something like what I have sketched below, what you had in mind?




I.e. Are you keeping the vent / snort function of the free flooding ballast tank that the trim tank sits within? This way (unlike the system Jim and I have and are playing with), you get away with a smaller sphere tank, which you use only to adjust trim and get completely under where the free flood vented tank and snort just take you from waterline perhaps to decks awash?

OR are you heading for something like the system below - which is more or less what Jim is testing right now?
I have used this setup for more than a decade except I have never employed a sphere as a tank. Whilst the sphere is a good idea for pressure I have doubts, given what you just wrote about reserve bouyancy that the sphere will hold enough volume of water to dive all manner of boats down. My Collins for example has around 30% reserve bouyancy. In previous systems the tank has been PVC pipe and PVC endcaps glued together with PVC pressure cement. Baffles inside I find do a very good job. In fact I have never observed in the boats trim sloshing about, but getting back to my concern about these systems (using just the one tank sealed under pressure), is that the pumps work very hard, even though they are on for but a few seconds, and I have found after a while they quit on you.
key to all this is finding a good pump.



Below is a further variation I have used - again baffles in the tank - but in this system the tank is vented by a float valve. This means the initial pump in phase takes you to decks awash with the tank vented and not under pressure. The final pump in phase is pressurised as the water level already in the tank seals off the vent using a ball float valve. The pump works not as hard this way compared to a non-vented tank and you get more water in the tank. You can still make incremental trim changes under pressure and surface from being fully submerged.




J

[Slats]

Ps...apologies for the poor resolution of the diagrams above - they are drawn bigger than that but for some reason why uploaded they compress down.
J

[He Who Shall Not Be Named]

Alternative A

[Slats]

I like it David, I like it a lot.

This way you keep parts comon to your current investment and R&D in production i.e. the bulk head with servo mounted in it for the vent, and the established snort system. Very smart indeed. Logically The rear motor end cap tray and snort connection are unaffected too. You also minimise the work the water pump to the sealed tank does, by sharing the load through the free flood / snort system - smart. A very clever variation on a theme, using proven parts too.

By putting the new pump onto the front bulkhead, should you have a need to service it or indeed throw the pump out and replace it - it simply pops off the front end.

Too often if I blew a pump on my old setup I'd have hours of surgery due to poor design around access - it was a bit like removing a whole engine and gear box from a car to change a tyre- least I learnt something.

Do I want to play guinea pig to this new system, given my order of 2 new 3.5" single shaft twin motor setups? - you bet I do. I'll flick you an e-mail of the other stuff I will buy (like the vent servo end cap) etc. If Jim's pump and valve aren't up the job, if I mount these were you intend it will be an easy upgrade later on.

J

[Subculture]

If you're using a peristaltic pump, will you be running the pump in the wet? That way if the tubing splits, it won't flood your forward compartment. Also the water will help lubricate the moving parts.