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The Big Bang...

Built a combustion cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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The Big Bang...

Unread postAuthor: iPaintball » Thu Mar 08, 2007 6:23 pm

I had just recently resurrected (sp) my old combustion cannon and turned it into more of a salute cannon by hacking the barrel down to about 3" and stuffing it with a sock before every shot. (pretty dang loud) Today was different though. I decided to try acetylene gas (produced by calcium carbide/water) to spice things up a bit. BOY was I in for a surprise... I had just cleared the chamber of spent propane when I remebered an article I read saying how energetic acetylene was, so I put some water in the chamber, threw in some carbide rocks, and pressed the switch on my stun gun. HOLY @#%&! The cannon shot back about 10 feet (it was on the ground) and a huge pressure wave that almost blew my eardrums out smacked me in the chest. An implausibly loud BOOM reverberated through the air and I heard screaming children and barking dogs. Take it from me, DON"T USE ACETYLENE GAS FOR A FUEL IF YOU ARE IN A RESIDENTIAL AREA!
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Unread postAuthor: Bluetooth » Thu Mar 08, 2007 6:43 pm

People have said that thousands of times. BTW there's a spellcheck there for a reason!!!!
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Unread postAuthor: chaos » Thu Mar 08, 2007 6:53 pm

ACETYLENE NEEDS O2. to get the energy you said you had, you would have needed an oxygen rich atmosphere in your chamber. does calcium carbide in water split the oxygen molecules of the H2O as well as give off the acetylene? What is you gun made of?

peace
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Unread postAuthor: risto » Thu Mar 08, 2007 7:16 pm

we used to make oxygen-acetylene bombs out of old 2 liter bottles...

it seemed way too dangerous to ever put in a potato gun however, and yes, that topic did come up with my friends.
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Unread postAuthor: spudthug » Thu Mar 08, 2007 9:39 pm

isnt there something about using solid propellents in the rules???well anyway this is most likely going to be deleted because
1. its in combustion showcase....
2. your using solid propellents
3. its and iditic kind of post its been posted like 100 times read before you post
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Unread postAuthor: MrCrowley » Thu Mar 08, 2007 10:18 pm

spudthug wrote:isnt there something about using solid propellents in the rules???well anyway this is most likely going to be deleted because
1. its in combustion showcase....
2. your using solid propellents
3. its and iditic kind of post its been posted like 100 times read before you post


Who's the idiot now :P Just joking. The topic poster is though and needs to read the damn rules before even thinking of posting ever again.
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Unread postAuthor: Hotwired » Fri Mar 09, 2007 5:38 am

spudthug wrote:isnt there something about using solid propellents in the rules???well anyway this is most likely going to be deleted because
1. its in combustion showcase....
2. your using solid propellents


1. It IS a combustion
2. So you think calcium carbide is a propellant?
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Unread postAuthor: chaos » Fri Mar 09, 2007 6:06 am

it is actually not solid propellant because it is not burning a solid fuel and as hotwired wrote it is a combustion therefore it is in the right place i see nothing wrong with this because it is using a gas as a propellant???
wat is so wrong with this? its just another way of using acetylene just not out of the cylinders of an oxy tortch

peace
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Unread postAuthor: CpTn_lAw » Fri Mar 09, 2007 8:33 am

this potato canon is made of PVC like any other simple combustion? If so, you can be very thankful to someone upthere, not letting you die with piece of PVC in your body.
However, acetylene produces an extreme pressure peak. It's sometimes more powerful than hybrid systems at low mixes...i would feel a lot safer to use acetylene in a metal combustion.
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Unread postAuthor: iPaintball » Fri Mar 09, 2007 7:05 pm

Okay, first, chaos is right. The calcium carbide is definitely NOT a solid propellent. It just produces acetylene gas, which is a gaseous propellent! So don't be stupid and try to tell me the rules! *cough* MrCrowley and spudthug *cough* And second, about his being in the cannon showcase, I'm new and I really don't know my way around the forum very well... Jeez!
By the way chaos, the oxygen in the air was plentiful enough to combust like that. ie carbide cannons...
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Unread postAuthor: Scope » Fri Mar 09, 2007 9:40 pm

If you introduce calcium carbonate with water in a sealed container you would be breaking apart oxygen from both the calcium carbonate and the water... this would mean it would produce an oxygen rich environmentc... not pure oxygen but it would raise the levels...
calcium carbonate (CaCO3) + Water(H20) = Acetylene(C2H2)
this means that byproducts of producing C2H2 would be Calcium (Ca) and Oxygen (O2).... Actualy a good amount of oxygen... i could tell you how much if i balanced the equation... but im to lazy right now.. if anyone wants i will
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Unread postAuthor: chaos » Fri Mar 09, 2007 10:08 pm

ok well yer scope answered my question about the oxygen environment thing. acetylene burns no were near as well in a plain air environment as it does in an oxygen rich environment, you may not have realized this but as scope has pointed out it was in an oxygen rich environment by bringing the oxygen to a higher percentage, you had a more explosive mixture.
And as CpTn_lAw said if this cannon was pvc be thankful you are not dead.please do not try this again if it is pvc.

peace
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Unread postAuthor: judgment_arms » Fri Mar 09, 2007 10:50 pm

You should rig that thing up as an anti-theft devise. With that loud of a boom you’ll have all the cops in a five mile radius converging on your house in seconds. How many showed up that time?
If nothing else you’ll scare the crap out of the thief, giving the cops an easy trail to fallow!
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Call me "Judge", it's easier to type.

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Unread postAuthor: willarddaniels » Fri Mar 09, 2007 11:22 pm

Acetylene can combust in up to a 70% mixture with air. So you can forget about the O2-rich envrionment, acetylene will go in just about any situation. That is the main reason you need to be careful - it is unstable.
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Unread postAuthor: chaos » Sat Mar 10, 2007 12:06 am

willarddaniels wrote:Acetylene can combust in up to a 70% mixture with air. So you can forget about the O2-rich envrionment, acetylene will go in just about any situation. That is the main reason you need to be careful - it is unstable.


yes exactly. but what i was trying to say was it was an enriched environment and that it could be very dangerous in a pvc cannon.
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