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3D Printing Submariens and Sub Components

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  • #16
    Originally posted by He Who Shall Not Be Named View Post

    Raise the c.b. higher over the c.g. More fixed ballast low, more buoyant foam up high. That will reduce the torque roll.

    David
    Hi David!

    I was wondering if the blue foam addition high in the hull might be the answer! My question to you is what is the c.b.? I understand the c.g. and I am just about on with the weights that I added to the center of the keel. If my thinking is correct, I would add the blue foam in equal amounts in the upper hull over the c.g.!?

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    Thanks for your advice and help David!

    Rob

    "Firemen can stand the heat"

    Comment


    • #17
      Originally posted by RCJetDude View Post

      Yes it is my first RC sub. I have wanted one for years. A Nautilus is on my bucket list. I spent a lot of time trying to make sure the hull seam was as minimal as possible. I used the Evercoat Rage recommended by Bob in one of his videos and it worked out great. Printed in PLA+, sanded and primered 3X. The new MSD looks like it should work exceptionally well in the boat. I have learned a ton on this build. I know 3D printing has its limitations but it has allowed me the opportunity to get started. I am a long time foam EDF flyer and am well versed on the effects of sun on a model so I am no stranger to it. My scum line is really too prominent so I may try to re-do it. Less is more but it was my first ever attempt. I have a line on the mold for a big Typhoon which may be my first fiberglass hull project. I hope to lay it up soon. Was it difficult to trim your boat? Did you use foam in the upper hull?
      Hi Steve,

      Hope it was OK to use your name!? I got it off your profile! My boat did trim out somewhat, but it still needs some help with ballast set up. The torque from the screw when I throttle up to high causes the boat to torque roll. As suggested by David Merriman, I need to add some foam in the upper hull to help correct this issue! It does make sense to me! Still got a lot to learn!!

      Rob

      "Firemen can stand the heat"

      Comment


      • #18
        I did have an issue with a slight leak through the water proof on/off switch!

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        I have reprinted another end cap, and designed and printed a containment box for the new switch. I has a threaded top with a rubber seal. This should solve the leak problem..

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        Rob

        Firemen can stand the heat"

        Comment


        • #19
          Originally posted by rwtdiver View Post

          Hi David!

          I was wondering if the blue foam addition high in the hull might be the answer! My question to you is what is the c.b.? I understand the c.g. and I am just about on with the weights that I added to the center of the keel. If my thinking is correct, I would add the blue foam in equal amounts in the upper hull over the c.g.!?

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          Thanks for your advice and help David!

          Rob

          "Firemen can stand the heat"
          By, 'equal amounts', you mean equal amount of force (a pound of feathers takes up a lot more volume than a pound of lead).

          The following applies to 'wet-hull' type model submarines, but applies for the most part to dry-hulls as well though with that type you can only change the weights position as the displacement is fixed by design.

          c.b.= center of buoyancy. The c.b. is the nexus of all the buoyant forces the vessel exerts as a consequence of its immersion in the fluid -- in this case a liquid. The force of buoyancy is a consequence of the weight of the water displaced.

          Buoyancy is a force whose vector points up. A submarine (unless its sitting on the bottom) changes its weight and displacement to maintain equality between the two forces, gravity and buoyancy. The magnitude of the gravity and buoyant forces will change, but they will change equally. That's how you achieve either surfaced trim, or submerged trim.

          Any vessel (regardless of the fluid it resides within) becomes statically stable when the c.b. is above and in line with the c.g. The greater the distance (moment arm) between these two points of force, the more statically stable becomes the vessel. In a submarine you increase that moment arm by lowering the c.g. (more fixed weight down low), and raising the c.b. (more buoyant foam up heigh, but no higher than the waterline). The trick is to match the two forces, i.e. produce one pound of weight, and counter it with one pound of buoyant force. Equal amounts of force. The net trim has not changed, but the vessel is much more stable about the roll and (to a much lesser extent) pitch axis. Most submarines can not dynamically produce rolling force and rely exclusively on static stability to maintain an upright condition -- that's why they are subject to the unwanted effects of propeller torque, sail-roll, and boundary-layer shearing (snap-roll).

          More fixed weight down low. More buoyant foam up high.

          https://youtu.be/2O8gTIr4lys

          David
          "... well, that takes care of Jorgenson's theory!"

          Comment


          • #20
            OMG!! David!

            I think I VERY BASICALY understand what you just wrote above!! Between the two (weights and Foam) you add a little here and take away a little there. Trail and error seems to be quite profound here for me!

            I really have so much more to learn and comprehend about this hobby! Thank you very much for taking your time to explain the c.b. principal! Waite till I show this to some of my old RC flying friends!

            Rob

            "Firemen can stand the heat"

            Comment


            • #21
              You distilled it most succinctly, Rob. Trial and Error as to amounts and placement of weight and buoyant foam.

              Bottom line: Increase the vertical distance between c.g. and c.b. and the vessel becomes more statically stable about the roll and pitch axis.

              David
              "... well, that takes care of Jorgenson's theory!"

              Comment


              • #22
                Well crap! My tub isn't long enough to float my boat so I can trim it. Now I have more incentive to get the pool running again.

                Comment


                • #23
                  [QUOTE=RCJetDude;n137374]Well crap! My tub isn't long enough to float my boat so I can trim it. Now I have more incentive to get the pool running again.[/QUOTE

                  LOL. We all have our Crosses to bear (err …. deer). Clean that pool and get back into the game. Man! I've heard some lame excuses before, but … Damn!


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                  David
                  The Horrible
                  Last edited by He Who Shall Not Be Named; 03-28-2020, 05:04 PM.
                  "... well, that takes care of Jorgenson's theory!"

                  Comment


                  • #24
                    [QUOTE=He Who Shall Not Be Named;n137375]
                    Originally posted by RCJetDude View Post
                    Well crap! My tub isn't long enough to float my boat so I can trim it. Now I have more incentive to get the pool running again.[/QUOTE

                    LOL. We all have our Crosses to bear (err …. deer). Clean that pool and get back into the game. Man! I've heard some lame excuses before, but … Damn!


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                    David
                    The Horrible
                    David is right!! Use the pool!!

                    Comment


                    • #25
                      RCJetDude, for your Futaba T9CAP look around for Futaba module FP-TJ-FM as they are already 75mhz. Also look around for Futaba Synthesized module PK-FSM. It will let you use any 75mhz freq on your T9CAP, please note the PK-FSM will only work with single conversion receivers. I was able to buy a few 8 channel 75 mhz receivers off a hobby shop in china. They are tiny little things, 33mm by 22mm by 12mm. They work great on my Futaba Robbe F-16, FC-28, T7CAP, T8UAF, T9CAP Super and Vex. All at 75mhz. Yea I know I got to many radios lol. I also sent a few receivers and TX modules to Radio South a few months ago, he is pretty quick. Mostly FP-TK-FM modules with FP-R148DF and FP-R148DP receivers for better retuning to 75mhz. My current projects are a new Engel U177 1/45 scale sub. I also bought the optional upgrade kit with the late war decking and conning tower from modellbau-wikinger. To get that sub shipped to the US in its close to 7 foot long box was a very tearful moment for my bank account. I also have three 3D printed subs I am working in Fusion 360. it just takes time which I just never have, so it slow going.

                      other David

                      PS, Been reading stuff in this forum for a long time. Just never open my mouth before. That maybe a good thing or a bad thing
                      Last edited by Sinksalot; 03-28-2020, 11:41 PM.

                      Comment


                      • #26
                        [QUOTE=He Who Shall Not Be Named;n137375]
                        Originally posted by RCJetDude View Post
                        Well crap! My tub isn't long enough to float my boat so I can trim it. Now I have more incentive to get the pool running again.[/QUOTE

                        LOL. We all have our Crosses to bear (err …. deer). Clean that pool and get back into the game. Man! I've heard some lame excuses before, but … Damn!


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                        David
                        The Horrible
                        It's a bit too early to open the pool here but I have started. The pump/filter went out last year so I ordered a new one.

                        Comment


                        • #27
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                          just got a new test tank today.......or puppy pool.
                          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


                          • #28
                            Originally posted by trout View Post
                            Click image for larger version Name:	6CE0941E-3461-4CF2-B75A-C3EA9962389F.jpeg Views:	0 Size:	64.6 KB ID:	137383
                            just got a new test tank today.......or puppy pool.
                            I've thought of that too...

                            Comment


                            • #29
                              Originally posted by Sinksalot View Post
                              RCJetDude, for your Futaba T9CAP look around for Futaba module FP-TJ-FM as they are already 75mhz. Also look around for Futaba Synthesized module PK-FSM. It will let you use any 75mhz freq on your T9CAP, please note the PK-FSM will only work with single conversion receivers. I was able to buy a few 8 channel 75 mhz receivers off a hobby shop in china. They are tiny little things, 33mm by 22mm by 12mm. They work great on my Futaba Robbe F-16, FC-28, T7CAP, T8UAF, T9CAP Super and Vex. All at 75mhz. Yea I know I got to many radios lol. I also sent a few receivers and TX modules to Radio South a few months ago, he is pretty quick. Mostly FP-TK-FM modules with FP-R148DF and FP-R148DP receivers for better retuning to 75mhz. My current projects are a new Engel U177 1/45 scale sub. I also bought the optional upgrade kit with the late war decking and conning tower from modellbau-wikinger. To get that sub shipped to the US in its close to 7 foot long box was a very tearful moment for my bank account. I also have three 3D printed subs I am working in Fusion 360. it just takes time which I just never have, so it slow going.

                              other David

                              PS, Been reading stuff in this forum for a long time. Just never open my mouth before. That maybe a good thing or a bad thing
                              Other David,

                              Glad you came aboard! It's nice to know there are others starting to use this building process! I know 3D Printed Subs are not as yet up to the high standards as set forth from builders like David Merriman, Tom, Bob Martin, "SUB" Ed, and many others using the tried and true traditional building methods! But over time as 3D Printers improve and new kinds of filaments come to the market place, then we will see some real solid submarines being built! But for now we just have to deal with special sealers, primers, paints, and adhesives to get these subs in the water!

                              Rob

                              "Firemen can stand the heat"

                              Comment


                              • #30
                                Todays update:

                                I installed the on/off from the ESC into a 3D fabricated box that is mounted on the end cap.

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                                Put it all together, dumped it into the pool and it checked out NO LEAKS!

                                As you know I fabricated my WTC using 3D Printed parts, this included the end caps. I purchased the O-rings from amazon and used a product called Magic Lube ll on the rubber seals. At this point in time I was unable to 3D print an end cap that was perfect enough to seal up tight enough to the cylinder, even with the rubber seal and lube to prevent a total leak proof system, it did not work. I used Z-Proxy finishing resin to seal the end caps inside and out and this stopped the water penetration through the PLA at 100% infill.

                                I came up with my solution to totally seal my 3D Printed WTC! And it works great. I sealed up the WTC, weighted it down and put it into my pool at about 3 foot of water for 3 to 4 hours and I am happy to say, I did not have one drop of water inside the cylinder! :-))

                                Here is what I did to make the final seal!

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                                I know this comes NO WHERE CLOSE to a David Merriman SD/MSD designed system! But for a totally 3D printed WTC it works!! (bailing wire & duct tape)

                                I will be using this WTC in both the Redoutable and the Astute submarines as surface runner application only. Now that I have a total water tight WTC, dynamic diving will be next!

                                Rob

                                "Firemen can stand the heat"
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