WTC Vent Valve problems

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  • llangston1
    Lieutenant
    • Sep 2013
    • 84

    WTC Vent Valve problems

    I am having problems getting my vent valve on my old (1996) WTC 3 that goes with my Skipjack sub. I replaced to original vent that had the rubber washer on the adjusting screw with the newer design with the flapper and round headed adjusting screw. I can't seem to get this thing adjusted correctly. If I raise the screw so that the valve is closed at neutral (when powered) and no bubbles escape then after several vent blow cycles the little flapper gets pushed to the side and opens the vent completely. I usually have to remove the vent to reorient that flapper so it will seal. If I lower the screw then at neutral servo I get a small stream of bubbles that I can stop if I move the emitter trim switch to the far left (max blow). If I place the trim switch in the middle I get the small stream of bubbles and if I move it to the far right (vent) it will open the vent. Never had any issues with the old style valve but it was destroyed/lost years ago when I switched to this newer designed valve.
  • RCSubGuy
    Welcome to my underwater realm!
    • Aug 2009
    • 1768

    #2
    Just for others interested, here is what I had replied to Leo when he emailed me directly on this topic:



    Dave's current iteration of that valve has been in play now for years and there have been probably a hundred cylinders put out with them employed with no issues. It's possible that the geometry is slightly different between the new SubDrivers and your old WTC, but I don't know that it would be significant. There are many points of adjustment in that linkage, any of which can make a big difference in the performance of the valve:

    1.) wheel collars on linkage shaft
    2.) bend of the linkage arm at its pivot point
    3.) adjustment screw at the valve


    It sounds like you've tried #1 and #3. You could play around with the bend in the arm, changing the angle from, 90 degrees, for example, to something like 91 or 92 (opening up the bend). This will not change the geometry of the screw interaction with the vent valve, but will affect how tightly it seats at the same given position of the servo.

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    • llangston1
      Lieutenant
      • Sep 2013
      • 84

      #3
      I finally got the valve properly adjusted. What I had to do was add a small nut that I could tighten it up against the brass lever. This basically stiffened up the adjustment screw attachment to the actuation lever enough to allow me to adjust the screw the right amount. The vent appears to be working now. Without the nut that screw head position could wobble around slightly and if it went too far it would push the vent flapper to the side and open the vent. The sub is working pretty good right now. I need to adjust the boat's overall trim so it's not so tail high underwater. I drilled some small holes to let any trapped air out of the tail cone but I may need to cut out some of the rear foam. I need to get it in a larger deeper pool to really test it out.

      Comment

      • llangston1
        Lieutenant
        • Sep 2013
        • 84

        #4
        Here is a short video of the first tests of the resurrected Skipjack sub. So far so good.

        Comment

        • llangston1
          Lieutenant
          • Sep 2013
          • 84

          #5
          to he who shall not be named; where did all your Cabal reports that used to be on the Caswell site go? Are they located on some other public site?

          Comment

          • trout
            Admiral
            • Jul 2011
            • 3545

            #6
            My link to them is gone.......I can't upload because the PDF is ~8megs and the limit is 6 something MB.
            PM me and I can email it to you.
            Peace,
            Tom
            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

            • llangston1
              Lieutenant
              • Sep 2013
              • 84

              #7
              So with this particular sub is it desirable to keep the top of the sail near the surface with a full ballast tank or just let it sink and control the depth with ballast gas? If I should keep it near the surface I fear it’s going to take a bunch of foam and I am worried there isn’t enough room between the WTC and hull. I probably need some small lead wts in the tail to make it submerge on an even keel.

              Comment

              • trout
                Admiral
                • Jul 2011
                • 3545

                #8
                With a full ballast tank the top of the sail should be above the surface. From what I am seeing a little bit of foam just forward of the sail at the top of the hull may correct the nose heavy and lift needed. You have room.
                Click image for larger version

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                Very cool to see new life into your sub!
                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

                • llangston1
                  Lieutenant
                  • Sep 2013
                  • 84

                  #9
                  Here is my latest sea trial with foam attached with rubber bands. It has about 1/2” of the sail above the surface at full ballast. Now to figure out how to get all that foam inside the hull. There is not much room between the WTC and outer hull up front of the sail.

                  Comment

                  • trout
                    Admiral
                    • Jul 2011
                    • 3545

                    #10
                    Since this foam is for submerged trim, you will attach the foam high in the hull 9above water line). If your surface trim is fine with it, then you can put it below the surface of the water. Well done on trimming it!
                    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

                    • llangston1
                      Lieutenant
                      • Sep 2013
                      • 84

                      #11
                      I wasn’t really able to cut those blue foam blocks Thin enough to fit inside the hull and not prevent the WTC from going up inside when closing it up. It’s not the best but I was able to slice ip a large white styrofoam cup so it would fit inside that decreasing diameter of the forward hull. I makes the submerged trim pretty good but the surface trim could be higher. Oh well I can live with this for now.

                      Comment

                      • RCSubGuy
                        Welcome to my underwater realm!
                        • Aug 2009
                        • 1768

                        #12
                        I have quite a few Cabals downloaded. I need to find the time to create a dedicated page on my site and upload them all.

                        Number 832 on the to do list...

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