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sub build competition entry

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  • sub build competition entry

    I wish to submit my concept sub model for the 2013 Build a Boat Competition.
    Build info:
    Boat Name: SSBN Harpoon
    Length: 36"
    Beam: oal 5.37", hull 3.60"
    Weight: 3.2 lbs.
    Scale: 1:144
    Construction summary:
    The boat hull is made of wood sealed with two coats of epoxy. The framework is made of Poplar hobby wood. The skin is a Revell Ash hobby plywood 1/32" thick. The whole structure is held together by JB Weld epoxy. The hull is split horizontally to allow access to the propulsion system. The upper half forward end is inserted into the nose socket then the aft end is aligned to a vertical support to guide and hold it and a latch holds it down. No tools needed. Metal (aluminum, brass, or steel) are strategically placed where needed to protect and reinforce critical parts.
    Some unique features of the design:
    Use of the velocity tube to hold the rudder.
    Method of holding/locating the SD in the lower half of the hull: metal hoop clips latched to metal insets in the lower hull.
    Using a cable to actuate the rudder.
    Using two torpedo shaped major ballasts to level and set the boat upright. Fine tuning of buoyancy is by adding small nuts or washers in the hull where a magnet holds it in place.
    Extensive use of canards. forward, aft, keel and lower hull corners.
    Oversized propeller, 7 Schimitar shaped blades for low rotation speed.
    Oversized rudder to permit responsive turning.
    Click image for larger version

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  • #2
    Some very interesting ideas. For example, the use of a cable to actuate the rudder and how you fine tune the buoyancy. Do you have some pictures to show how you did it. I once used a cable inside a plastic tube to operate forward dive planes.



    • #3
      I used a brass tube formed with gentle bends and a picture hanger wire as the inner cable. the brass or even aluminum tubes are from hobby center of my local Merrit Ace Hardware. the picture hanger wire is from home depot. I epoxied the magnet coupling to the actuator end, the rudder end took a small tube to adapt it to a threaded rod for my rudder clevis (courtesy of a discarded R/C airplane). both ends of the outer tube are supported/braced and an oversized hole on the hull allowed fine tunning the position. I later patched this hole for a better cosmetic fit. I will take pictures and post it.


      • #4
        the buoyancy was dealt with in two steps.
        1. the major ballast to keep it upright and horizontal was achieved by attaching at the outside bottom of the hull two torpedo like steel rods. they are held by home made clips. the clips allowed axial movement of both rods to find the balanced position. I of course reduced the guess work by trying it first using rubber bands to get close to the attachment points. to arrive at the rod size, I played with bolts and nuts to find the weight I needed. then I calculated the equivalent length of the rod after I decided what diameter looks nice. the first size was too long. I tried several diameters till I found a reasonable length. my intention is to disguise these external ballasts as missiles or torpedoes slung under the hull just like fighter airplanes. since I do not have a lathe, the rod end received a ball pen cover to give it a pointed look. to protect the pair of "torpedoes" I installed a pair of cannards (fins) on either side. these (plus a third aft fin) also allowed the sub to be able to stand on a surface with out the support cradle I made.
        2. for the zero buoyancy fine tunning, a magnet inside the hull held washers, nuts, or cut rods determined by trial and error. the torpedoes are readjusted to hold the boat level in this process. the zero buoyancy is set with the sail about 1/2" above the water. diving below this depth is by the dynamic method. there are two forward planes and two aft planes that controls this action.
        I will take pictures and post it.


        • #5
          Is this yours?

          Make it simple, make strong, make it work!


          • #6
            Originally posted by redboat219 View Post
            Yes. That was one of the early test runs. Since then I have improved my operating skill in running the boat. I will make a better video.


            • #7
              Click image for larger version

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ID:	84207Here are pictures. the home made cable to actuate rudder and the primary or major ballast system disguised as torpedoes slung under the forward end of the hull. There is a pair of fins out board of the ballasts to protect it and serve as a support together with the 3rd fin located aft. the ballasts are steel rods. It can be slid fore-aft to level the sub.


              • #8
                Very clever, thanks for the pictures.



                • #9
                  Updated pictures of my SSXN submarine version Harpoon class. Showing the WTC now pressurized to improve moisture or water intrusion. This is a RECABS-R system. Also shown is my system diagram.


                  • #10
                    Your diagram doesn't show.

                    Anyway, interesting wtc set up. Can you elaborate more about the green "pressure indicator."

                    What happened to the air containment you had in the stern? Are you now using the whole wtc as the pressure tank?
                    Last edited by redboat219; 02-28-2017, 08:23 PM.
                    Make it simple, make strong, make it work!