Continued working on my low pressure launcher concept with a new design still using PVC components. The pressure vessel is now doubled in volume with the use of 40mm pipe. Instead of using a powered ball valve, this design incorporates a modified sprinkler valve. This is state of the art for spud gun launchers.
So much simpler designing and packaging the launcher with the bonus of threaded fittings so different pressure vessels and barrels can easily be changed. Pressure testing revealed the brilliance behind this valve. Works at my max pressure (150-160 psi ) with minimal bleed down even after 10 mins. Trigger works perfectly at all times , being whisper quiet at lower pressures.
For initial testing I am using the barrel of my first launcher with the addition of a threaded fitting. This makes the design take down with assembly taking only seconds.
My first test shots were with a new nail dart design using a extra layer of tape and some hot glue for reinforcement. Performance was excellent. Even with only 20 psi darts pierced 12mm ply. Any pressures over 60 psi saw the darts buried to the head. Stopped tessting at 90 psi as the nails were close to shooting clean through the ply. Darts were moving at killing velocities and the danger of richochets was all to real.
Am hoping this design is a large improvement in performance over my first launcher. Will keep developing and testing with the aim of exceeding 200 joules.
Built a dedicated breech loading barrel for my pneumatic launcher. A improvement over my first attempt, this one being much neater giving 3 more inches of barrel for a total of 38 inches. Testing gave very interesting results. At lower pressures speed was up by 50 to 100 fps. The larger volume of the pressure vessel really helps at sub 100 psi. As the pressure got closer to my max (160 psi) the advantage diminished speed peaked at 725 odd fps. A decent improvement of 40 fps over the original breech loader. Energy is up slightly to a nasty 85 joules. With a longer barrel able to use the extra air volume a fair bit more speed could be generated.