MAPP gas chamber preasure help and pump action

[xbow]

Hello Spud community from Ukraine!
Last sammer i have discover this forum and make my pneumatic cannon with MAPP GAS ballon & piston valve, see attach, on foto its not finished...
If I right gas is stored in this ballon with preasure with 2,5 bar.
I use it with 6 bar ~ 85 psi.
Can this ballon take 10 bar ~ 140 psi would it be safety?
And what is maximum preasure for this ballon?

[jackssmirkingrevenge]

Welcome to spudfiles

I believe MAPP is actually stored at around 95 psi (from here), it's safe to say that as a commercial unit the cylinder ("ballon") will contain at least twice that pressure safely, so you shoul be perfectly fine with 140 psi.

Nice launcher by the way, I like the ball valve trigger especially. And the particular photo lighting and setting, it looks like an improvised weapon in a post-zombie apocalypse wasteland

[xbow]

Thanks! it's also interesting article about gas cutting for me
Will test soon and post results.
Yea, it's comletely built from stuff that I find in garage, it's GREAT idea about "post-zombie apocalypse" maybe I leave it in this style.
Thanks a lot!

[Technician1002]

Most of those disposable gas bottles have a relatively tiny passage between the valve in the tank and the tank itself. I would recommend researching on how to remove the valve and then drilling the hole larger. High pressure is kind of useless if the flow is just a trickle.

They are designed not to vent gas as the pressure rises due to a hot day. Use the pressure the gas has on a hot day such as 110F or 43.3C. Using it at 100 PSI is no problem.

[POLAND_SPUD]

greetings from poland

[xbow]

I has completely remove valve and drill bottle about 20mm diameter like the barrel, but the piston and internal parts small to shoot full power of 20 mm barrel, so i will use 10mm barrel

more dateiled full size foto

greetings neighbor

[Technician1002]

The full size photo is very nice. It shows the added fill valve and new outlet connection very nicely.

[jackssmirkingrevenge]

My new wallpaper, cheers

[nature-boy]

"post-zombie apocalypse" maybe I leave it in this style.

Definitely! Don't ever paint it! I really like the look of it, that picture is like art and really creates a atmosphere.
...btw... Have you got a car, because I think I found the perfect vehicle to carry it around...

ok, back to topic: Do you plan on making it breech-loaded, or leave it muzzle-loaded? If you do so I think a pump-action would fit the theme very well.
And I wonder that nobody told you yet, that you have a really BIG chamber/tank/balloon for your barrel, especially if you put on the 10mm barrel.
What is not a bad thing, but it literally screams for multiple shots, at least in my opinion.
You would just have to add a smaller chamber and a ball-valve between the "balloon" and that smaller chamber (-> long nipple)

[Crna Legija]

"post-zombie apocalypse" maybe I leave it in this style.

Definitely! Don't ever paint it! I really like the look of it, that picture is like art and really creates a atmosphere.
...btw... Have you got a car, because I think I found the perfect vehicle to carry it around...

hey my cars not for sale

[xbow]

My new wallpaper, cheers

WOW Thanks))

nature-boy
Thanks! that car is awsome) my friend work in truck service there lots of rusty metal, will make some photoshoots with cannon)

I really want to make it multipe shoot. I'm thinking about pump-action with cartridge clip (3 or 5 bullets depends on air capacity)and while it reload bullet small chamber will fill air from big chamber. Maybe it be "chamber in chamber"... i've got some drawings with this ideas, i'll complete them and post little later.
Thanks!

[xbow]

I find 3d model that i have made some time ago, add some parts and animation, the 3rd part shows how air fills small chamber and whole system work.

Any suggestions will be great!

[youtube][/youtube][/youtube]

[jackssmirkingrevenge]

That looks like it would work great, and there will be plenty of air for a three shot magazine at least.

Also, I think I realised why I like this launcher so much - it's the spudgun equivalent of an automotive rat rod

Many rat rods appear unfinished, with primer-only paint jobs. Satin or matte black and other flat colors are also common. Other finishes may include “natural patina” (the original paint with rust and blemishes intact), a patchwork of original paint and primer, or bare metal with no finish at all in rusty or oiled varieties, honoring the anti-restoration slogan that "it's only original once". Many rat rods also have free hand pinstriping done by the owners with a pinstriping brush. Contrary to tastes of many car builders, rust is often acceptable and appreciated by a rat rodder.

Function over form FTW!

[al-xg]

I would suggest making the barrel return spring external, you could reduce dead volume and improve flow.

If you can live with bolt action instead of pump action you could, have the barrel as a simple tube (no breach) and have it lock back in firing position. The projectile would be stripped backwards from the magazine.

Or I guess you could keep the pump action and have a simple tube barrel by making the barrel fixed and moving the sleeve. But that wouldn't reduce the dead volume.

[xbow]

jackssmirkingrevenge Yea, you right, it really looks like hot rod))
al-xg thx for advise, using external spring will better reduse losing of air and power.

Heh... my progect goes to be long time to built I has not much free time now... little later I will create new topic for discussion and work in progress information.