I'm interested in model submarines and looking for advice..

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  • salmon
    Treasurer
    • Jul 2011
    • 2340

    #16
    If I understood Ralph correctly, that a piston is run either fully empty or fully filled, I have a different view with regards to a piston tank (although there are some systems that is done - most are proportional now). If I misunderstood (and that happens to me) ignore my statement LOL. My Walrus, it uses a piston tank, does not run fully filled when submerged (currently at 55% it it just barely buoyant). At fully filled I am at the bottom of the lake (which is cool in shallow and clear water) The goal is to get where last 25% is used to get to various degrees of buoyancy submerged (I am being taught) at 75% the sail should be kissing the surface of the water. This gives you plenty of positive buoyancy if you need it for emergency and enough to adjust your depth. I adjust the piston to get my sub to run at a particular depth. The piston set to full empty and the sub will sit at waterline. I bring it to 56% filled and the sub will just start to dip below the surface. Fill it completely and I am at the bottom of the pond. It is a true static diving system. The Walrus ran for 3 hours and still had power left when we called it quits that day (it was a maiden run). The Akula II will have the same control if you set it up that way. Two people I have utmost respect for and decades of knowledge and experience, both have the Akula II and it runs amazingly well. They can sit still and the scope will be out of the water just sitting there.
    Here is a photo of my Walrus (not painted) with two other piston subs each sitting at their own depth.
    Click image for larger version

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    If you want a WWII type sub, Bob also sells a setup for a Bronco model's Type XXIII.

    You asked about which goes deeper, the joke is, they both will go to the bottom. However, most people run at a periscope depth or 1-2 feet under the surface. both systems will go the same depth, it is radio signal that makes the difference. You mention running in a pool with viewing windows (cool), if the pool is chlorinated heavily you might not get below a few feet, but if it is not heavily chlorinated you can go much deeper. I am not sure the exact depth 75MHz will penetrate a clear water lake. I ran my Gato in a pool that was at my mother-in-law's community pool and could go to 8' with no issues (most days). When they would bump up the chlorine, sometimes just being at the far side of the pool barely submerged would cause the sub to do an emergency rise.

    I, like you, enjoy the older subs. So, I understand the appeal of the WWII subs or older. I would be a hypocrite to say do not build an older sub for your first sub. Whatever you choose, you will have a ton of support here. There is not a wrong answer really. It is your choice. You will learn no matter which way you go. For me, I am loving all the different systems I have played with. Each has its merits and each has it's own quirks. However a well balanced and setup submarine is a joy to play with.
    Last edited by salmon; 07-27-2017, 05:13 PM.
    If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

    Comment

    • Ralph --- SSBN 598
      Junior Member
      • Oct 2012
      • 1417

      #17
      Scott,
      You being new to submarines RC, you may not know the major plays in the building and design.
      Bob the Builder is one of those major players and I am glad he has joined in on this thread.
      Bob can answer direct questions on the VII you're interested in.
      He has built a few and I believe his company makes one of the available kits.
      He also has many videos on his building of various boats.

      Comment

      • thor
        SubCommittee Member
        • Feb 2009
        • 1479

        #18
        The sad fact of the matter is that there really is not an 'easy' entry level model for those new to the hobby. Some are easier than others, but none are easy. I think the Thunder tiger sub is probably the closest.

        If you do go the Gato route keep in mind that the model was never intended for R/C. It is a display model that has had conversion components manufactured to adapt it to R/C.

        In my experience 3 months is a VERY aggressive time table to build that boat. Please look on the forum for the build threads and you will get a good idea as to what you are getting yourself in for.

        Perhaps consider the 1/48th Type VII by Arkmodel. That boat was designed from the outset as an R/C model and is quite robust. It, also, builds into a gorgeous model.

        Whatever you decide, we here in the SubCommittee welcome you aboard and stand ready to assist no matter what your choice may be.
        Regards,

        Matt

        Comment

        • Ralph --- SSBN 598
          Junior Member
          • Oct 2012
          • 1417

          #19
          Tom, you are correct about having more piston than needed to surface and submerge.

          The Akula II has a piston that is right at the minimum limit.
          To have the boat submerge and be just a little negative so it will go down to the bottom leaves little to get the boat up to full surface waterline.
          In trimming to get my boat to be slightly negative in submerge trim, I had to give up full waterline by about 3/16'.
          This is fine because in the water, unless you know this, all looks good.

          I would have like a little bigger tank.
          I do have the proportional control over the ballast tank.
          I run with the decks awash as I prepare to dive.
          I then run at periscope depth.
          I stop forward motion and play with sitting on the bottom at about 3 feet. (same place your photo shows your boat with the other two)

          My Tx does not show what percentage of control input I have put in.
          I have to count clicks and I am still learning how many clicks gives me how much dive.
          This is all part of the process of running any boat.
          New boat or new captain on a boat, it takes time to know the boat and how it operates.

          I had problems controlling the Akula II the first time out.
          I had set up the Tx controls to work like my Skipjack thinking it would make it easier to learn.
          How ever it turned out, it made it worse because on the Skipjack, I use the sail planes to control depth while running
          Akula does not have sail or bow planes that are operational and I used the piston to control depth in conjunction with the stern lanes.
          This cause me to use the incorrect control to get the wanted reaction on the boat.
          I have since change the controls at the Rx to make the Tx control input do they same action on both boats.
          Just not using the same equipment on the boat end.
          ======================

          Comment

          • JWLaRue
            Managing Editor, SubCommittee Report
            • Aug 1994
            • 4281

            #20
            So...pistons, and the full vs. empty discussion. Note this is my personal experience and preference that I am stating.

            For my piston-based boats I trim them out so that a 100% full piston will place the boat on the bottom. What this does is provide me an ability to do a certain amount of on-the-fly submerged trimming. I find this to be quite handy when running in different bodies of water where the specific gravity (density) differs due to the amount of dissolved compounds (pool chlorine vs. fresh water ponds, etc) Since the piston system allows for precise, repeatable control over the amount of water allowed into the piston, once I know where on the control slider I get the correct submerged trim, I'm good to go for the day and I do not ave to fidget with the ballast system to achieve the correct trim. No need to bring extra lead and/or floatation foam for the daily sub outing.

            The pump, gas, and RCABS systems do not allow for the same level of repeatable control. Well, except for completely full or empty.

            -Jeff

            p.s.: In my collection of R/C subs, I have all of the above ballast types.
            Rohr 1.....Los!

            Comment

            • Ralph --- SSBN 598
              Junior Member
              • Oct 2012
              • 1417

              #21
              Trim can be a trick thing.
              I build and trim my boats in my shop out back.
              Once I get them trim, it does not mean they are trimmed at the pond.
              As Jeff said, I too like more ballast than the boat needs so I can compensate for the changes I see at the pond.

              I am not concerned by the chemical make up of the water as much as I am that I built and trim at 3000' above sea level and the pond I run in is at 300' above sea level.
              I do have small ballast weight I can add and remove to make quick weight changes.
              I remake the periscopes and other masts out of brass tubing and rod.
              They all have a different weight so I can change the boat's trim by using different combinations of masts.
              I don't worry about the surface trim, I fill the ballast tank and look at the submerged trim.
              If the boat stays with the top of the sail or a mast above the water, I can add more masts.
              If the boat goes to the bottom too fast, I can remove a mast or two.

              I did this with the Akula II piston system and I also did that with my internal balloon ballast boat.
              I trim the boat a little high when surfaces because I can trim on sight by adding a little water in the ballast tank and if I fill the ballast tank the boat will go negative.

              I use to trim my boats with about 1/4" of the sail above the surface when the tank was full but that did not give me the control I wanted static dive.

              I just finished, this morning a modification to my Skipjack safety tank to allow more than needed water volume.
              In the water trimming will take place tomorrow morning.
              I will be removing some of the dead weight lead ballast to get above surface waterline and there is plenty of volume available to go negative.
              ------------------
              Jeff, I have the same collection of ballast systems.
              Started a gas system when Freon was still used, RCABS, Pump with internal ballast tank and now piston.
              The completely empty to completely full ballast tanks may be that all my boats are nukes, except the first one, which was just a for fun shark fin with no body.

              I like the old boats, I just haven't got to the point I want to build a boat with all that detail.

              Comment

              • bob the builder
                Former SC President
                • Feb 2003
                • 1367

                #22
                A bit off topic, but I just wanted to say that this is a great thread so far, everyone. Getting into subs can be a daunting thing for the uninitiated, and information like this helps people take the initiative to "get their feet wet" much faster than they might otherwise.

                Carry on!


                Bob
                The Nautilus Drydocks - Exceptional Products for the World of R/C Submarines - www.nautilusdrydocks.com

                Comment

                • sam reichart
                  Past President
                  • Feb 2003
                  • 1325

                  #23
                  I can speak for the quality of the Type VII Arkmodel kit. If you are looking for good scale and it has to be an older sytle boat, this is a great choice. If you want to go nuts with the detailing, add the photoetch set to it. Either way, it will build out to a nice looking, decent sized model. You will have to do less fabrication that the Type XXIII from Bronco. As Matt mentions above, the Gato, the Type XXIII and the Revell VII or IX are display models first, and have to be modified to make them robust enough to run. The Arkmodel was designed for R/C.
                  That being said, newer hulls like the Skipjack, the Permit, the LA class and the Alfa can also be built up and running pretty quickly. But the older boats have the cool details.

                  Comment

                  • cdivine
                    SubCommittee Member
                    • Mar 2010
                    • 166

                    #24
                    Got any pictures of this project. We consume pictures like Cheese Danish. By the pound.

                    Comment

                    • Guest

                      #25
                      If the piston tank system is of interest, then you really ought to take a good long look at the R&R module.

                      This gives you a twin piston tank system, so no concerns about a shifting centre of gravity, and as the system is a removable cylinder, you are free to move it from boat to boat.

                      Price is extremely competitive with other systems and it will give you the very best control of trim.

                      The linked gallery shows the types of model fitted out with this system, as you can see, quite varied.

                      R & R Model Engineering welcomes you to our website. Please feel free to take a look around at our products, all of which have been custom designed and built to make your entry into the fascinating world of operating a model submarine as easy as possible. From a basic dynamic dive module to a full blown static dive system, operating torpedoes, up to a fully built, ready to go boat, R & R can supply you with exactly what you need. We can provide you with a kit to build, if you wish to construct your own boat; all the parts you will need to complete the kit with the minimum of fuss; and, most importantly, free and impartial advice.


                      For hull types, my personal preference is GRP hulls. They do cost a lot more than injection moulded polystyrene/ABS hulls, but they're far stronger and easier to repair the inevitable dings and scrapes you'll pick up when using the boat.

                      OTW produce a great range of very nice boats, especially a lot of older designs with the detail you crave. They also supply some very nice modules based on water pump systems, although I prefer the piston tank modules from R&R.

                      A blend of R&R module with OTW hull is very nice match indeed and would give you a superb performing and looking boat.



                      I believe the OTW hulls are also available from Bob Martin.

                      Comment

                      • scottyk
                        Junior Member
                        • Jul 2017
                        • 12

                        #26
                        Great information on here guys thanks for sharing the info! That Arkmodel looks to be a nice designed sub and a little quicker and nicer than converting a plastic model over and not a lot more cost added. Just curious where are you guys purchasing these from? and is there a certain size WTC these are designed for? I assume that would be covered in the instructions but I know sometimes the chinese stuff is lacking in that area.

                        Comment

                        • scottyk
                          Junior Member
                          • Jul 2017
                          • 12

                          #27
                          I found this website "the actual Arkmodel website is blocked here at work"



                          They seem to offer the sub kit and various components for the sub such as WTC kits in various levels of assembly. but the descriptions are horrible you cannot tell whats included or anything. Anyone happen to have experience with these WTC's or piston kits they offer?

                          Comment

                          • salmon
                            Treasurer
                            • Jul 2011
                            • 2340

                            #28
                            Try looking at: https://www.rc-submarine.com/product...n-1-48th-scale
                            They are in the USA and great company to deal with.
                            If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

                            Comment

                            • SubtechRC
                              SubCommittee Vendor Member
                              • Feb 2017
                              • 77

                              #29
                              .....and the rest of us poor schlubs make stuff too...
                              Best Regards,

                              Matt

                              sigpic

                              Comment

                              • salmon
                                Treasurer
                                • Jul 2011
                                • 2340

                                #30
                                Yes Matt, you do. Do you sell the Arkmodel kit? If so, I was not aware and I am sorry for not mentioning you.
                                If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

                                Comment

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