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Tank will be vented to the surface via a mast I reckon.
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John Slater
Sydney Australia
You would not steal a wallet so don't steal people's livelihood.
Think of that before your buy "cheap" pirated goods or download others work protected by copyright. Theft is theft.
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You'd have to rely on positive buoyancy or if that was lacking, due to a leak or caught in weeds etc. a back-up system to bring you to the surface.
I don't know if the latter is being fitted.. The system is being built for another member, who purchased an old Eden models Ohio (now Sheerline). These early Eden Ohios used a Craycraft dive module, which was based on a design by Nick Burge.
The dive modules were among the most expensive and elaborate I've seen produced for the hobby market. They had a small twin cylinder compressor on board which sucked air out of the central ballast tank and stored it under pressure in the forward compartment of the dive module. Probes mounted in the tank detected when the water level reached about 80% of the volume and cut the current to the compressor to prevent it sucking in water and flooding the boat.
The system worked well enough but had a few caveats- the air bubble in the tank is compressible, as the tank is vented at the bottom. This results in a boat that gets heavier as you dive deeper.
Also the air sucked out of the ballast tank is very humid. This air is stored in the same area as the compressor servo controlled valve, electronics for controlling the pump etc. Electronics and water isn't a very good mix.
In practice there are a lot of these systems doing good service out there. Most submariners rarely dive beyond a couple of feet, and the electronics seem to hold out well against the humid atmosphere.
However better systems exist, and as the module in the Ohio was in need of a minor refit, it was decided to try a different system.Last edited by Subculture; 02-21-2009, 07:54 AM.Comment
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Andy mentioned Nick Burge.
Now, there was an r/c submarine inventor and builder of the First order. He was truly one of the innovators and talents in the field!
On that thread (and you'll have to excuse me if I get some of the spelling wrong here) I present a few more notables in the field:
Brother Otto, Dave Weeks, Dave Manley, Mike Dorey, Ray Mason, Bob Dimmick, Dave Welch, Skip Assay, Norbert Bruggen, Ron Pierrot, myself, Art Meyer, Matt Thor, and others.
Significant people who invented or have refined the devices, produced the hull kits. People who have advancement the game of r/c model submarining.
My success in the field is due, in no small part, because of the things I learned from others; I stand on the shoulders of those who came before me and to those today who are my peers.
No genius works in a vacuum.
David,Last edited by Kazzer; 02-22-2009, 05:59 PM.Who is John Galt?Comment
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John Darnell and Steve Warner really should be mentioned here. John Darnell produced the first truly affordable kits for those wishing to enter into model submarines here in the UK. His hulls are still produced, now by Models by design.
Steve Warner is really the main modelmaking arm of OTW. He stays out of the limelight, but he is the man responsible for the hull masters.Comment
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Aspirated, Pumped Tank
Subculture,
The Ohio ballast tank you showed is called an Aspirated Pumped Tank similar to the one Norbert Bruggen discussed in his book Model Submarine Technology. Basically it's a rigid fixed container fitted with an open vent tube at the top. At the bottom is a flood valve, which when opened allow water to flow in from the outside. To surface a pump forces the water out and air is sucked in through the vent tube.
The crucial disadvantage here is: if you operate the pumps while the boat is submerged only water flows in through the vent pipe instead of air; and the tank just stays full.
In the Subcommittee Report Carter Kaplan used a small reversible airplane fuel pump together with a vented tank on his Revell 1/200 George Washington RC conversion.Last edited by redboat219; 02-22-2009, 11:47 AM.Make it simple, make strong, make it work!Comment
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No ballast system is 100% perfect, you have to decide what imperfection(s) you can live with.Comment
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I have prepared a document explaining the main ballast systems which can be downloaded from the Caswell web page. There are some diagrams too.
Support Center » Downloads » R/C Modeling Files » Pro's and con's of Ballast Systems
Stop messing about - just get a Sub-driver!Comment
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Exactly! Now, if we bear this in mind, why would you design something to go out of sight? Being a newbie at this, I have found that sometimes these 'clever folks' often over-design and over-engineer the problems, making construction and operation extremely difficult.
It was brought home to me when I operated my D&E Skipjack for the first time. A 4 ch radio, no forward planes and no gas in the tank, I was able to dive and surface at will on the move. If the boat stopped, it would surface. (Very comforting!) I never vented the ballast tank.The sail/forward planes were set horizontal and were not hooked up to a servo.
It gave me my much needed practice time.Stop messing about - just get a Sub-driver!Comment
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Agree - yes we don't tend to go much deeper than PD.
But - I do like gas fitted too - Got to remember that a positive ballasted boat using dynamic forces to go under can sometimes not pop back up as we like should the boat go deeper enough - which can happen due to glitch or operational error. Not too much of an issue in the pool, but in blue water ops (like a lake) it can be.
JJohn Slater
Sydney Australia
You would not steal a wallet so don't steal people's livelihood.
Think of that before your buy "cheap" pirated goods or download others work protected by copyright. Theft is theft.
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Exactly!
And John's observations (derived from practical, real-world experience -- you newbee's listening?!) are the same ones that drove me to finally integrate the two real-world (most American submarines do this) methods of emptying a ballast tank: the normally used low pressure blower, taking advantage of surface air to force the water out of the ballast tank; and the gas blow to get the boat to the surface -- if need be.
Sure, there are other ways to change the displacement/weight of the boat to achieve surfaced and submerged trim: squeeze bags, belows, variable geometry WTC's, pistons, water pumps, reactive chemicals, and the like. All with unique and often burdensome hardware, electronics, and plumbing.
But I've found for efficiency, simplicity, reliability and achievement of task -- employing the minimum of on-board volume, complexity, and electricity -- the LPB-gas ballast system to be the best means of managing ballast water, even in the smallest r/c submarine.
Just like the real thing.
When I operate in deep water, I want the gas sub-system aboard.
You guys keep ***** this dog! For decades I've seen this debate: "what is the best ballast system". Jesus H ******! ... the debates over. Move on already!
Stop posting this useless navel-gazing bull-**** and build something!
David,Last edited by He Who Shall Not Be Named; 02-22-2009, 09:06 PM.Who is John Galt?Comment
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Aha! I see the new auto-sensor is working well! Now if only I can figure out the 'infractions and punishments' system. We can have some wonderful punishments, like keelhauling, flogging, cat 'n nine tails, two bricks surgery (my favorite), eye gouging, the rack and a few other medieval routines. Oh! I almost forgot, hanging from the yard-arm.
I'll just keep adding these morsels to the sensor system each time anyone uses them, or tries to by-pass the system, until you won't be able to read a thing.
Just behave boys, we have women and children on board! And you Merriman! Do you want me to have a little chat with Ellie?Last edited by Kazzer; 02-23-2009, 12:28 PM.Stop messing about - just get a Sub-driver!Comment
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ELLIE!
We need a little chat!!!!!!!
(just watch him collapse like the Armadillo Man in the Capital One advert!)
Armadillo man clipStop messing about - just get a Sub-driver!Comment
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