Is it a water bottle or a gun?

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.
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pneumaticcannons
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Sat Aug 06, 2011 8:40 pm

This is my first combustion cannon and I thought, why make it the same as the rest when it can be unique. And given the freedom of desighn with combustions due to the lower operating pressures, I decided to disguise it as a water bottle
:lol:
When it comes to internals it's a basic combustion. Here some specs:

Chamber: water bottle
Style: coaxial
Barrel: 1/2 inch Thai pvc (I live in thailand)
Ignitor: grill lighter piezo
Main propellant: spray on deodorant

Some Pics:
Image

In the Chamber:Image

Layout:
Image
The gun has a barrel knife and is breech loaded.

The piezo:
Image
The piezo just broke and Ill be redoing the whole backside when I get a new one

The Video: enjoy
:shock:
[youtube][/youtube]
You may notice that I close the top of the bottle when I fire it. This is so the pressure builds up inside before firing and it creates a loud BANG!
Hey I just unghettofied the entire backside of the gun after leaving the thing in a closet for 4 months. Here it is:)

From this:
Image

To this:
Image

Me pressing the piezo now concealed neatly within the gun:
Image

tutorials up!
Last edited by pneumaticcannons on Sun Nov 06, 2011 4:30 am, edited 6 times in total.
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Gun Freak
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Sat Aug 06, 2011 9:05 pm

YOU LIVE IN THAILAND OMG THAT IS AWESOME!!!
okay.
Nice job! Pretty original :D
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pneumaticcannons
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Sat Aug 06, 2011 9:23 pm

Gun Freak wrote:YOU LIVE IN THAILAND OMG THAT IS AWESOME!!!
okay.
Nice job! Pretty original :D
yea and i come back home to the states in summer and winter. Whats not awesome is the pvc here lol. nothing is pressure rated and its all blue
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Gaderelguitarist
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Sat Aug 06, 2011 10:13 pm

Very clever. I doubt you need to leave the lid of the bottle on as you fire, but that would ruin the illusion.

Whats with all the tape on the bottom?
so many muchness
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pneumaticcannons
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Sat Aug 06, 2011 11:15 pm

Gaderelguitarist wrote:Very clever. I doubt you need to leave the lid of the bottle on as you fire, but that would ruin the illusion.

Whats with all the tape on the bottom?
your right, I don't need the cap on but it gives me a very big increase in power. It acts kinda like a burst disk on a hybrid except its re-usable
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Mr.Tallahassee
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Sat Aug 06, 2011 11:53 pm

I guess it's the principle that a combustion process being contained accelerates the process. That's why burst disks boost power so well. It also explains how hybrids are so scary powerful. :shock:
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Gaderelguitarist
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Sun Aug 07, 2011 2:10 am

The combustion is already contained if the spud is cut on the end of your barrel, meaning that the round acts as your burst disk. The reason burst disks provide such tremendous results is that they allow the pressure to build up and then rapidly be discharged, instead of gradually build up in a more conservative setup. Hybrids are powerful because they reach much higher pressures than a standard combustion.
so many muchness
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pneumaticcannons
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Fri Aug 12, 2011 5:05 am

Gaderelguitarist wrote:The combustion is already contained if the spud is cut on the end of your barrel, meaning that the round acts as your burst disk. The reason burst disks provide such tremendous results is that they allow the pressure to build up and then rapidly be discharged, instead of gradually build up in a more conservative setup. Hybrids are powerful because they reach much higher pressures than a standard combustion.
the cap acts as a bust disk doing exactly what you said about the pressure building up an then rapidly being released. The only difference is that the "disk" is infront of the round and that instead of air making the pressure the combustion procces is.
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jackssmirkingrevenge
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Fri Aug 12, 2011 6:04 am

Nice little project and good to see another Exilim owner on spudfiles ;)
hectmarr wrote:You have to make many weapons, because this field is long and short life
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pneumaticcannons
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Fri Aug 12, 2011 11:24 am

jackssmirkingrevenge wrote:Nice little project and good to see another Exilim owner on spudfiles ;)
yes I do love my little Exilim. I should have some high speed vids of my co-ax soon. :wink:
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pneumaticcannons
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Thu Aug 25, 2011 9:59 am

Gaderelguitarist wrote:Very clever. I doubt you need to leave the lid of the bottle on as you fire, but that would ruin the illusion.

Whats with all the tape on the bottom?
The tape is the mark of ultra ghettoness lol. btw I just re-did it. Looks nice now
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pneumaticcannons
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Fri Sep 09, 2011 10:27 pm

I guess it's the principle that a combustion process being contained accelerates the process. That's why burst disks boost power so well. It also explains how hybrids are so scary powerful.
ya. When i built this, at first i never used the cap but after realizing it was virtually a reusable burst disk i tried it and will never go back to using it without. though im still sometimes to scared to push the cap on all the way because of the fear of it exploding :?
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Sat Sep 10, 2011 12:21 am

Thats pretty cool. Its like a 1x flap-piston hybrid.
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pneumaticcannons
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Sun Sep 11, 2011 5:19 am

Moonbogg wrote:Thats pretty cool. Its like a 1x flap-piston hybrid.
I guess it is. I never actually thought of it that way. i didn't even know the what a flap piston hybrid was until now. :) [/i]
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