compressed air lung... with theory for gatling gun

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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trollhameran
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Mon Jun 16, 2008 12:48 pm

Im looking for ways that i could make a sort of lung that is filled with compressed air and then it can "breathe" the air out into a chamber and then "breathe" it back in emptying the chamber again. Can anybody think of a way i could do this?
Last edited by trollhameran on Tue Jun 17, 2008 11:51 am, edited 1 time in total.
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Carlman
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Mon Jun 16, 2008 12:51 pm

syringe type piston inside chamber

basically imagine you chamber as a syringe with a water bomb balloon filled with air on end.
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trollhameran
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Mon Jun 16, 2008 1:07 pm

hmm that could work, i would like it to empty automatically though so would that work with this
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Carlman
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Mon Jun 16, 2008 1:12 pm

maybe if you said what the project at hand was i would be able to help you more

how big of a chamber?
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trollhameran
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Mon Jun 16, 2008 1:35 pm

Basically im trying to make a small piston that moves back and forward to turn a small wheel. The chamber will probably be around 6 inches long and made of 1 1/2 pvc
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psycix
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Mon Jun 16, 2008 4:04 pm

Ah your making some sort of piston engine?
Get a pump, and ruin the check-valve and seal off the intake.
Those foot pumps people use to pump up air matresses when they're on holliday would be the easiest to do it with.
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trollhameran
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Mon Jun 16, 2008 4:23 pm

Yep thats right, going to see if i can get it to work then maybe work on a bigger version to power a go kart or something.

Thats a brilliant idea psycix, theres a shop in town that sells them for like a pound
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psycix
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Mon Jun 16, 2008 4:37 pm

It might be somewhat hard to get the timing right I think.
You will need to suck/blow exactly at the right times.
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trollhameran
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Tue Jun 17, 2008 1:15 am

I was thinking probably the best way to do it would be to have a 3 way solenoid valve and have one port with the air supply attached to which is used to fill the piston, then another port leaving the chamber so that you can switch between fill and empty in quick succession, maybe even using a computer to operate the valve so you can get perfect timing on it and also change the speed of it to effect the speed it moves
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Tue Jun 17, 2008 1:20 am

trollhameran wrote:Basically im trying to make a small piston that moves back and forward to turn a small wheel. The chamber will probably be around 6 inches long and made of 1 1/2 pvc
Why not just make a straight copy of a CO<sub>2</sub> motor?

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*stares at animated diagram* fork in hell, do I see the mechanism for a full auto pneumatic? *ponders*
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trollhameran
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Tue Jun 17, 2008 1:49 am

I had never seen how a CO2 motor worked before now but that does look like a pretty good/simple way of doing it, i had originally thought of doing it something like that but I couldn't work out how to stop the flow to let the piston go back up, but now I know.

I have no doubt your mind can figure out an auto mechanism from that diagram, I think i have an idea to but its not full auto
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Tue Jun 17, 2008 2:09 am

If I'm not mistaken this is how the compressed air motors that power Air Hog model aircraft work.

With a bit of ingenuity, one could make a pneumatically powered gatling gun - the crankshaft would drive the rotating barrels and through cams, the reloading mechanism, while the projectiles would be fired by the air exhausting from the piston...

Looking at the mechanism though, it's essentially similar to my last (largely unsuccesful :roll: ) attempt at an auto-piston design, where the moving piston alternates between opening the valve and releasing the air, but the crank is substituted for a spring. If they can make it work in those little motors, maybe a bit of fine tuning is all the system needs as it's theoretically feasible.

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The difference is that in the interest of power, I added a "pop-off" element to the design:

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Perhaps eliminating this element and following the first design would give the concept a better chance of practical success. Food for thought :)
hectmarr wrote:You have to make many weapons, because this field is long and short life
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trollhameran
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Tue Jun 17, 2008 6:18 am

i have come up with a design for a gatling gun which i think will work, it is very similar to what you posted but it has a different loading system and it uses a crank from the piston to turn the barrels. Im in college at the moment, but i will post drawings when i get home.
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trollhameran
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Tue Jun 17, 2008 11:47 am

I have uploaded a pic of my design for a gatling gun using this idea, basically the valve design is the same as the first animation you put up of the co2 motor, the crank will be attached to a sprocket with a small amount of teeth on it, which will then be connected to another sprocket which will be sideways to the first one with the number of teeth on the first sprocket times the number of barrels, so that for each full turn of the sprocket on the crank, the second sprocket will only turn enough to line up the next barrel with the airline. The barrels will be mounted inside the second sprocket so that the sprocket doubles up as a way of holding the barrels in place.

Using this method i believe that with the correct timing I should be able to get the piston to move past the air exit hole at the same time as a barrel lines up with the air exit hole, so that every time a barrel is lined up, air is expelled out of it.

Each barrel will have a break cut into it about 2 inches long and will then have a semi circle sleeve over it so that there is a breach hole which is slightly bigger than the barrel size, this is so that i can have shells made of the same pipe as the barrel, which will contain the ammo, and then when the air is expelled the ammo shoots out but the shell stays in the barrel. The barrels will also have a peg sticking out each end of the breach hole both on the left hand side which will be used to catch the shells and pull them into the barrel. The shells themselves will be quite a loose fit in the breach hole to allow easy entry and exit, they will be held together by fishing line in a sort of bullet belt style, this is so that once the first shell is loaded, the whole belt will follow the barrels around and a shell will be pulled into the barrel one at a time as the barrel reaches 11 o clock, then the shell will be fired at 12 o clock then drop out of the barrel at around 4 o clock, allowing a new shell to be loaded once the barrel reaches 11 o clock again. To explain the way is works simply, imagine a chain going around on a bike, each link on the chain would be a shell and each tooth on the sprocket would be a barrel.

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psycix
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Tue Jun 17, 2008 2:29 pm

WOW good thinking!
Attaching a gattling gun to the engine axle and the air vent to the barrels would make a very simple made gattling gun.
Now how to load the projectiles?
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