Lethal low pressure launcher

Discussion in 'Crazy contraptions' started by tomfreds66, Mar 19, 2016.

  1. tomfreds66

    tomfreds66 Member

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    Air guns and air powered launchers are quite topical at the moment. There seems to be quite a few air rifle enthusiasts on the forum. With Jorge getting great results using high pressure air to power his arrow launcher I thought it would be challenging and fun to build something using relatively low pressure air. I will be restricted to sub 150 psi courtesy of my bicycle pump.
    As a teenager I worked shifts in a pvc pipe factory. With access to all manner of pipes and fittings, not to mention unrestricted high pressure air, you could imagine the mischief that took place.
    Last weekend I glued together a very basic pressure vessel out of 25mm pvc pipe around 500mm long. A ball valve and a tyre valve completed the job. The barrel is a 15mm pipe 1 meter long attaching via a reducing fitting. Roughed out a ply lever to work the valve and I had a working test rig.
    This rig is basically a blow pipe on steroids. All my testing was done with 80 psi. Ammo was to be cheap nails with a tape cone stuck on. From the first shot the nails would bend on impact every time. I switched to 75mm and 100mm hardened concrete nails to solve the issue. Testing was done indoors at around 5 to 6 meters range. No problem penertrating 12mm ply, and speed was impressive. Next tested were 150mm nails weighing nearly 30 grams. They hit hard, too hard actually. The unbraced ply was being flung around upon impact, bending the nails as they flew off. Some 19mm pine was clamped in the vice and easily pierced from 3 meters. The final shot was a full power test with the 100mm nail into the clamped pine. Went in and bent !!!!!! the hardened nail.
    Will test other ammo options then start on a build.
    Envisage a breach loader fully enclosed with a quick opening valve and trigger.
     

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  2. bigdh2000

    bigdh2000 Administrator

    I will probably never get into this type of building myself but you, Jörg and BoyTonStu sure keep me entertained with the fun and excellent science of these things.
     

  3. RickOchet

    RickOchet New Member

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    I have a large divers bottle for a pcp rifle.
    These threads could corrupt my innocent little mind soooo easily!
     
  4. TheNewSlingshotGuy

    TheNewSlingshotGuy AKA- "The Raccoon"

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    Holy cow! Im interested in seeing the chrony results. Do you plan on shooting some steelballs out if it?
     
  5. tomfreds66

    tomfreds66 Member

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    Tried some different projectiles today shooting what I had lying around in the work shop.
    Marbles work with wadding and achieve very serious velocities.
    Paint balls are a perfect fit for this bore size. Using max pressure ( 140-150 psi) move with insane speed.
    Who would have thought that with a bit of cloth tape you could turn 1/2 lead balls into giant air gun pellets. Worked like a charm with decent speed at 80 psi.
    Field points work fine but tend to bounce of hard surfaces.
    The Bodkin point projectile was plain scary. Was a bit concerned about 25 grams of steel richocheting indoors. No concerns, flew perfectly and hit damn hard even at 80 psi.
    I don't think I will have any problems getting this launcher into the lethal category.
    Have a few construction ideas and will post future progress.
     

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  6. Arturo Borquez

    Arturo Borquez Administrator

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    very cool ! ... another projectile I like, easy to do and cheap are steel rods, I cut them from threaded bars ... nastier :cool:
     
  7. tomfreds66

    tomfreds66 Member

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    Put together a working test rig after trying a couple of different configurations. Very crude and absolutely rough workmanship.
    Hot glued and screwed ply and pvc. Trigger is basic rolling nut turning ball valve powered by 25-30 pounds of TBS tube.
    Trigger works great, very quick action and opens valve completely. A few safe low pressure test shots with paint balls at 60 psi were going to fast to see. Must be getting 350 fps plus easily.
    Shooting the duct tape darts showed just how well the trigger worked. At any pressure over 40 psi the tape cones would crumble from the shock of the of air release. The heavy Bodkin dart worked fine up to 60 psi when the breach would blow off even with reinforcing tape.
    Will continue to tinker with test rig and projectiles and try to get some chrony results.
     

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  8. bigdh2000

    bigdh2000 Administrator

    Awesome but we need videos man.
     
  9. tomfreds66

    tomfreds66 Member

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    Had time and enough light to launch a few paint balls over the chrony this afternoon.
    The results were startling and more than a little scary.
    Starting with 60 psi easily cracked 440 fps.
    80 psi got me to over 500 fps.
    Going to 100 psi gave me over 550 fps !!!
    The paint balls were going fast enough to penertrate a exercise mat set up as a splatter shield.
    With a weight of around 3.5 grams these paint balls are hitting with nearly 50 joules of energy.
    Am really astounded at the performance achieved with very modest air pressure so far.
     

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  10. seppman

    seppman Folding-Ladder Expert

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    Crazy!!!! Please find some more time! And hit the record button on the cam accidently! :)
     
  11. TheNewSlingshotGuy

    TheNewSlingshotGuy AKA- "The Raccoon"

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    :eek: :eek: :eek:
    I didn't know paintballs could withstand that kind of velocity! Get some ballistic gel to simulate what that would do to someone in a paintball match!
    And you have got to try 1/2 in steel balls with wadding.
     
  12. tomfreds66

    tomfreds66 Member

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    TNSSG suggested I try shooting some 1/2 inch steel ball with the air launcher. The bore was too large for this ammo size, but 15mm steel, similar diameter lead and marbles fitted nicely with the right size patch. Loading was down the muzzle with a makeshift ramrod till seated just forward of the breach. At 100 psi the marbles were zipping out at serious speed. The metal balls had good speed as well. Had tested my pressure vessel and pump and discovered both were good for 150 psi. Wanted to see what speed the rig was capable of at higher pressures. Going above 110-120 psi caused the ball valve trigger to bind resulting in scary hang fires or not rotating at all. It would seem that my wheel lock is too small in diameter to get sufficient leverage to overcome the force on the ball valve at higher pressures. Still is fun and entertaining to shoot even with these limitations. Have a few ideas I want to try. Want to get some more chrony results with different weight projectiles to see how many joules this beast can produce.
     

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  13. bigdh2000

    bigdh2000 Administrator

  14. tomfreds66

    tomfreds66 Member

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    Gave the 15mm steel a go today with 100 psi at 7 meters against unbraced 12mm ply. Great impact, so close to smashing through, would have no problem penertrating if clamped solid.
    Solved my dart issues too. Some large caulking nozzles trimmed to size with a blob of hot glue to retain a 75mm nail. Will pierce 19mm pine to the head with only 60 psi. These are great fun with serious penetration at only 40 psi.
    The best was yet to come. Weighed up a bodkin point with lead and fitted a nozzle to make a 30 gram hard hitting projectile. Shot at 100 psi the bodkin not only went straight through a 19mm pine board, but snapped it length ways. This round is definitely a man stopper!
     

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  15. onnod

    onnod Im from Holland, isnt that weird?

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    A caulking nozzle? That's so smart! I used to make my homemade airgun arrows out of the next size of pvc down and wrapped the nails in tape untill they fit, this is much better :)
     
  16. tomfreds66

    tomfreds66 Member

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  17. TheNewSlingshotGuy

    TheNewSlingshotGuy AKA- "The Raccoon"

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    how many FPS were you getting with the steelballs?
     
  18. BeMahoney

    BeMahoney Builder of things

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    This made me smile!

    Sikaflex is from around here!

    .. and sold in Australia! :)


    Cheers to down under - The home of Lord OilBurner ;)


    Be
     
  19. tomfreds66

    tomfreds66 Member

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    Was going to start on a new launcher designed to overcome the limitations of my test rig. Even went as far as to get a bunch of pipe and fittings from the hardware store. Having a good look at my launcher I saw a quick and easy solution to the valve binding issue. A larger lock wheel in the shape of a cam gives around 2 1/2 times more leverage to open the ball valve. Works perfectly even at over 140 psi pressure. Hard to tell, but I think the operation of the valve is slower. How this will effect performance remains to be seen. Will more pressure compensate for slower release of air volume, or are other factors at work. Only testing will answer this.
    Came up with a new concept for launching 50 ish caliber lead. Simply hot glued a nozzle to the lead ball to make sabot/pellet hybrid. Not wanting to waste the left over part of the nozzle I found it fits in a 25mm pipe. Anyone for a 4 bore air gun?:D That would be a build.
    Am dying of curiosity to see how the rig performs, as soon as possible I will be having a comprehensive chrony session to find out.
     

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  20. bigdh2000

    bigdh2000 Administrator

    Dude, you're nuts. No wonder you fit in around here.