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Tow Release Help Please

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  • Tow Release Help Please

    A few weeks back I saw a set of pictures of a home made tow release system. It was a cross bar in a brass tube with a sliding pin. A wood dowel with a ramp was slightly behind the cross pin. Try as I might I can't seem to find the post of the pictures. I've tried the search function to no avail and looked through close to 200 pictures recently posted. My new project requires a redsigned tow release system and it sure would help if I could look at the pictures again. Pretty sure I saw them in this forum, sure wished I had saved the page. Thanks in advance for any help.
    Last edited by Mark9; 12-12-2017, 04:07 PM. Reason: Grammar
    Mark

  • #2
    Hi Mark, I think you may have seen it in Michaels build tread starting with post #6
    http://forum.scalesoaring.com/forum/...rofessor/page2

    Jeremy and Ben
    SCCAAA TT TN

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    • Mark9
      Mark9 commented
      Editing a comment
      Thanks, but that is not the installation I remember seeing. I should be able to fabricate something from the pictures in my mind (seems I heard that in a song). My design will be all internal to the fuselage and contained in brass tubing. My plan is to make a proof of concept version starting this evening.

  • #3
    I can't wait to see it! Does this need some kind of external manual tool to push the loop inside the tube? I could be wrong but I can see the loop getting blocked by the cross bar at times.

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    • #4
      This is the commercially made version of what I think you want......I have the same style in my 40% K-8.......and as Michael has mentioned it can be a pain in the ass at times to get the loop inserted.
      TEAM GORGEOUS

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      • #5
        Tom, you're exactly correct that is another version of the release I wanted to manufacture for my needs. Here is what I have cobbled together over the last couple of days. The angled ramp on the forward block is hard to see. It is only dry fit and the length of the pull pin and the tube have not yet been cut. When I determine the proper length I will finish rounding the end of the pull pin.

        I also plan to silver solder a brass plate to the aft end of the tube to transfer the loads into an aircraft ply plate I will fabricate and glue to the back of the nose block. This will be done before the poplar spacer blocks and pull tube are glued in place. BTW, the balsa nose block has four light ply stringers that are inset almost to the hole the release will use as an exit. Also, may add another sleeve of tubing to fully capture the cross pin.

        I think it will work quite well. It has been tested (no load) and it threads easily and releases easily. Next I need to put about a 20-30 lb. load on it and test again. From what I expect the plane will weigh under 10 lbs. so that should be more than adequate.

        Sorry about the order of the pictures might need try another method for loading them.
        Mark

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        • #6
          Very Nice!

          Steve K

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          • ARUP
            ARUP commented
            Editing a comment
            +1 And... it looks like the cross bar is forward enough to be able to put the loop in easily!

        • #7
          Well, I now have all the components fabricated and ready for final assembly. I seem to always tackle the most difficult part of assembly of a new model first. On this one I had to totally engineer a new tow release system. Anyway,this morning I silver soldered the brass back up plate on the main tube and cleaned that all up. That portion is all prepared for final assembly. Just pull tested the release and pulling down as hard as I could it released smoothly multiple times. So, I think as they say, "I'll nail it". Just need to mix up the epoxy with colloidal silica insert in the nose and walk away.

          BTW, in the last pic it looks like the cross bar is crooked, it's not, must be the angle of the camera. Ooh, I was wrong about the nose block. When I cut away the covering I found out it is multiple layers of Asian Liteply...might as well be balsa though. The round aircraft ply plate will be in front of the brass plate to spread the towing loads into the first substantial former.
          Mark

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          • ARUP
            ARUP commented
            Editing a comment
            That looks really nice! You could even loop some CF tow around it and tie the loose ends into the fuselage nose.

        • #8
          I don't know what impresses me more, the overall design or your soldering skills! When I solder it looks like a kindergartner using a crayon for the first time!
          Member In Good Standing - "Builds Slower Than A Dead Turtle Nailed To A Fencepost" Club

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          • Mark9
            Mark9 commented
            Editing a comment
            Well, I did have to clean it up a bit. ;^)
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