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How to choose a dive module ?

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  • How to choose a dive module ?

    I am interestd in buying and building an rc submarine and I already have experience in rc models. My problen is that I don`t know what type of balast or subdriver module to buy. I know that there are 3 types of subdriver modules ( SAS ballast system / OTW diving modules / and dive cylinders made by ENGEL in germany )
    I would like that my submarine can stay balanced underwater also when is not moving ( so thet I can regulate the depth only with the balast)
    What type of dive sistem can do this ? and what are the characteristics of the others?

    I also saw in videos a picture of a nice rc foxtrot class submarine is it still avaitable ? and where can I find it ?
    I hope there are not too much questions

    best regards

  • #2
    The Engle piston-pump type WTC is what you want for precise control of buoyancy. Second choice for your stated need is the OTW module. The SubDriver ballast sub-system only operates with the ballast tank fully flooded or empty, so can not manage model displacement incrementally like the others you mentioned.

    The FOXTROT you saw is not available at this time.

    Never too many good questions. Fire away. Just don't ask stupid questions and we'll get along fine.

    Resident Luddite


    • #3
      It's a actually very difficult to achieve neutral density in water regardless of the system you use. Why?

      Two main reasons.

      1. Water refraction makes it very difficult to judge if the boat is moving up or down at a slow rate. If the water is choppy or anything less than crystal clear, you don't stand a chance.
      2. Water density will vary within the same pool/pond etc. Perfect trim at one point can be negative or positive at another.

      Thus to get a boat to hover accurately underwater generally requires some kind of automation. This is out there , but it has to be tuned to the specific boat- so we're talking complexity and cost. Even then the ballast system will be shuttling about and the boat will have a margin of error for accurate depth.

      All that so you can look at something motionless underwater- why not just tie a brick to a bit of rope and chuck that in the drink, cheaper and less to go wrong.

      Most model submariners will trim a boat so that with the tanks flooded the boat is just a few grams buoyant (e.g. less than 1% of overall displacement). Then you just require a whiff of throttle to remain underwater.

      Do yourself a favour and keep things simple to start with, otherwise you risk no boat, no money and a chip on your shoulder.
      Last edited by Subculture; 11-25-2019, 04:58 AM.
      Time to DIVE IN!


      • #4
        The "perfect hover" feature is one that I get questions on most frequently, and it bugs the hell out of me. Other than the cool factor of hovering close to shore and poking the guy beside you to watch, what's the point? Real subs don't do it (at least not often). I suppose if you've engineered missile release, we're talking about an appropriate feature, but of course if that's the case, you have the engineering chutzpah to rig up working weapons, so getting a hover is a piece of cake, right?


        • #5
          And as a word of warning to Ubootkommandant and anyone else who thinks that they'll get faster responses by spamming the entire forum with the same question... I'll warn you once. Do it again and I'll send you kicking your lunch pail down the road.


          • #6
            I like piston systems. Not because of the hover factor (although I like doing that), it is another technical feature that makes this hobby fun. I can park my sub on the bottom and do reconnaissance or grab a lunch and come back up to PD or surface (or any combination). it is also great for trimming a submarine to see how it handles completely submerged. If I was to give an analogy, some people get a V-8 Hemi engine and never use the power it offers or some get a fancy car, say a Porsche or Maserati, why? It has four wheels like all other cars, an engine (like the V-8 Hemi with more power than most use), and gets you between point A and B. You can’t use the speed (legally) and it costs so much more than a Toyota Camry. But people still do buy them. I do not put them down for doing that nor minimize the joy they get for running a well crafted vehicle like that. I do not think we should do that for the bubbleheads that do run piston systems. There are large groups in Europe and other countries that use pistons and a splattering of those here in the U.S. that do as well. It is another aspect of our wonderful hobby. Have I gotten that perfect hover, at times I have, in fact I have a video of one time, it looks like a still picture. Fun (for me).
            If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.


            • #7
              I wasn't putting down the piston system at all. Quite the contrary, I think they're a great solution for some boats. My issue was the infatuation that some people have with the boat's ability to hover. That feature is not unique to piston tanks. I've hovered successfully tons of times with pump-based systems (which are also exceptionally precise) and with the SAS system (though admittedly a bit trickier).

              I'm basically saying that unless you have a boat that will be launching weapons from a static depth, the feature is not overly useful other than the "ooohhh. aaaahhhhh" factor.


              • #8
                Ahhh, I get it. Still if I ever get to the east coast with a sub with a piston system and get to run with David, you better believe I am going to rib him as I hover in place while he is madly dodging obstacles! As a side note, I am playing with an idea of a piston system for a Revell Gato. It is vapor ware until I get it made, but on paper, I think it will work.
                A piston is definitely not the only way to hover. The bladder system in a TT Neptune SB-1 has gotten there, but is tougher for me and much harder to replicate. The beauty of a piston is the ability to replicate a particular attitude consistently. You got a SAS system to? You are da MAN, I have not been able to.
                If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.


                • #9

                  Resident Luddite


                  • #10

                    Resident Luddite