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1/48 G7 Torpedos

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  • Did a little bit of experimenting in the shop today. Was able to make a quick test prototype holder for the cartridge style poppet valve. The outlet for it is 3D printed. It slides over the 13/32” OD K&S brass tubing that the poppet valve inserts into. The 3D printed outlet has a very tight almost press fit over the brass tubing. The design keeps the poppet valve cartridge from being pushed out of its tube from the pressure it is holding back. Works get with zero leaks tested at 85psi.

    Also made a small air reservoir tank to hold the volume of air needed to push the floating piston inside the torpedo tube to just short of the tube’s muzzle. One end of the tank connects to the poppet valve holder. The other end of the tank uses a one way ball style check valve. Charging the tank was tested two ways. First was by the shop air compressor that was set at 85psi and the other method was using a 100ml Syringe.

    I chose to use a check valve instead of a Shradder valve because I wanted to see how well it would work for charging the tank by simply slipping a hose over a the full tube that is connected to the check valve on the tank. The upside to this is the connection is quick and takes up very little room and the fill tube connection can be placed anywhere in the model. The downside to using an unsprung or floating ball style check valve is the valve will have equaled pressure on both sides of it and won’t seal until pressure on the inlet side of the valve is suddenly released cause the valve to slam shut.

    Now that the a testing prototype for the poppet valve holder and reserve tank were finished I could move on to connecting them to a launch tube to see if would send the floating piston inside the launch tube far enough, and quick enough with out launching the piston out the muzzle.

    Success!!! Charging the Reservoir tank with either the shop compressor or the syringe yielded the same performance results. Once the poppet valve was pressed the floating piston would shot down the tube and stop just short of the muzzle.

    Charging the system with the syringe is simple. Draw the syringe back to 100ml. Connect the tubing from the syringe to the hard line coming from the check valve by sliding it on about 3/16” of an inch. Squeeze the syringe like hell until the clear tube blows off the end of the hardline and Voilą that tube’s system is ready.

    I decided to load the tube with a torpedo to see how it worked compared to earlier tests, launching the tubes with the syringe. Wow! I should’ve probably gave that torpedo more room to travel cause now it’s in the repair shop for major repairs....

    Click image for larger version

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    It was a good day of testing and the theory of this part of the design yielded positive results. If I decide to pursue this design, I now have a good baseline to work from.



    • [QUOTE=Monahan Steam Models;
      I decided to load the tube with a torpedo to see how it worked compared to earlier tests, launching the tubes with the syringe. Wow! I should’ve probably gave that torpedo more room to travel cause now it’s in the repair shop for major repairs....
      Nick [/QUOTE]

      LOL-without water to dampen the force-I'll bet it will travel! I used to shoot cut off pencils eraser end out for dry tests. You need to change that name to "Monahan Engineering" Great Info here. Real Progress also.


      • Ha! Yeah after that test I spent the rest of the day launching pens at the mrs. She was not impressed to say the least... When I do contract engineering work, I do it under Monahan engineering. The Monahan steam models handle dates back to when I had a company under that name producing miniature live steam engines for Rc model boats. Started and operated a few companies before and after that. Those engines and steam plants are on every continent which is kinda surreal. Got to meet a lot of awesome folks from around the world during that time. Every day was like Christmas at that job. I’d design a part, wrote the code for it to be made on the multi axis cnc machines and then test it that same day.

        In the evenings or butt crack of dawn, got to chat with folks from all around the world and help them on their projects. Lots of really awesome people from all sorts of backgrounds. I always joked, I used the most advanced technology to make antiquated technology. I didn’t care. I was having fun and could make you anything you could dream of. Those were the days. Now I just want to tinker in the shop. Hell, I planted a lawn just so I could be that guy that says get off my lawn but that hasn’t happened yet. Till then I’ll mess with designing things that I think are neat and try to share that experience in hopes to help others.


        • Now that's a backstory!