Help me make a Non-projectile combustion BANG! cannon.

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
SemperSpud
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Tue Dec 26, 2017 10:36 pm

Hello SpudFiles.

I've made a couple of spudguns in the past, but now i'm trying to create a "Spudgun" just for a loud bang!

This is what i came up with so far.

I would like to go with a "standard" PVC design, like the most common builds.
A screwcap-end, sleeves and a reducer from a large to smaller diameter, but with a shorter "barrel" to make the gasses expand more at the muzzle (i might add a muzzle brake to divert the gasses to the sides for visual and sound altering effects).
For the combustion chamber i'm thinking of using 3 pieces of 110mm sleeves adding up to around 300mm in length, and some 50mm pvc pipe as a barrel.
My fuel and ignition will come from a MAPP/Propane blow-torch.

Now i've read something about Burst-disks, but i don't really want to go that way because i would like to be able to fire in rapid succession (Squeeze trigger to fill chamber with gas, fully press to ignite).
Also the torch mixes Air/fuel before the nozzle, and the burst-disks seal off the chamber so the pressure in the chamber will make the gas leak out of the torch where the air is added.

So instead of a burst-disk, would i be able to take a reducer to make the end of the barrel a smaller diameter? for example 50mm to 32mm. This in theory should increase the pressure, and forces the gasses to exit the muzzle at a higher velocity. Resulting in a louder bang. amiright?

Basically that is what i've come up with, and truth be told i'm just making an educated guess here.

So if anyone might have some knowledge to share, suggestions and/or (other) idea's to add, please let me know (It might even prevent me from building something that possibly wont even produce the results i'm after. The louder the better :thumbright: . ).

Thank you.
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farcticox1
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jackssmirkingrevenge
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Thu Dec 28, 2017 7:03 am

You might want to look at propane powered "bird scare cannons" that basically do what you would like to achieve - repeated blasts with no projectile.
hectmarr wrote:You have to make many weapons, because this field is long and short life
SemperSpud
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Sat Dec 30, 2017 12:33 am

Thanks great stuff. That Exhaust cannon is sick!

And my brother just bought a bird scare cannon. ( they are called "Cherry cannons" here because they are mostly used for Cherry plantations.

Tomorrow i'm going to glue together my design.

I will let you know how it went next year....

Have a great new years eve all...
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