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Combustion or Pneumatic

A place to ask general spud cannon related questions.
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Unread postAuthor: squeaks » Wed Dec 13, 2006 6:39 pm

hydrogen? Weak? I don't think so. I'd like to see that vid 'cause I find it hard to beleive.
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Unread postAuthor: joannaardway » Thu Dec 14, 2006 4:02 am

In my days of pyromania (I'm a recovering addict), I found that Oxygen/Hydrogen mixes were very powerful.

Back to the point: If mobility is your number one concern, and you hate bike pumps, then a combustion is your only real option (propane metering preferable).

However, you will almost certainly fail to get the same power that some pneumatics can offer.
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Unread postAuthor: CpTn_lAw » Thu Dec 14, 2006 7:58 am

squeaks wrote:hydrogen? Weak? I don't think so. I'd like to see that vid 'cause I find it hard to beleive.


it has an explanation at the molecular level. hydrogen is a very light atom. compared to butane or propane, it is very light. the combusion of hydrogen is very quick, so it detonates more than it burns. the peak is obtained a few miliseconds after the ignition. With propane, the peak is obtained when the projectile is already going down the barrel. burning propane results in braking the molecular chain, causing new materials to be generated and, heat as an energy emission result.(Joule effect) with hydrogen, you get heat, but a lot less result materials
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Unread postAuthor: frankrede » Sat Dec 16, 2006 5:59 pm

CpTn_lAw wrote:
squeaks wrote:hydrogen? Weak? I don't think so. I'd like to see that vid 'cause I find it hard to beleive.


it has an explanation at the molecular level. hydrogen is a very light atom. compared to butane or propane, it is very light. the combusion of hydrogen is very quick, so it detonates more than it burns. the peak is obtained a few miliseconds after the ignition. With propane, the peak is obtained when the projectile is already going down the barrel. burning propane results in braking the molecular chain, causing new materials to be generated and, heat as an energy emission result.(Joule effect) with hydrogen, you get heat, but a lot less result materials

Wow, I never knew that.
He knows what hes talking about.
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Unread postAuthor: CpTn_lAw » Sun Dec 17, 2006 11:51 am

the video can be found here: http://video.google.fr/videoplay?docid=-6095931018136671323&q=spudgun

read the explanation on the right.
I don't know if I'm right Frankrede, but i'm studying physics at university and i managed to make an easy explanation of the process.
I have to change bit what i said.
Hydrogen is an atom, where as propane and butane are molecules : alcanes. propane has a carbon chain at the third place of the molecule's carbon atom: CH3.
butane, is globally similar, but the carbon chain is a the fourth position.
You learn that in Terminal here in france (last year of highschool)

Hydrogen combustion gun could be devastatingly powerfull if it was pressurized. but then again, it would be even more devastating if you reached the DDT point....
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Unread postAuthor: squeaks » Sun Dec 17, 2006 12:20 pm

hey, I can't view the site, computer blocks it. Do you think you can save it to your computer and post it as a download or something?
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Unread postAuthor: CpTn_lAw » Sun Dec 17, 2006 12:54 pm

mmmh, i don't think so....
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Unread postAuthor: frankrede » Sun Dec 17, 2006 2:16 pm

Why would google video be blocked?
Cautious parents or schools proxy?
Go to proxify.com then use the proxy to view the website.
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Unread postAuthor: SpudBlaster15 » Sun Dec 17, 2006 2:37 pm

Hydrogen gas is not an atom, it is a diatomic molecule, H2. Propane is an aliphatic alkane, with the structure C3H8. Hydrogen gas does in fact yield higher performance due to the faster burn rate of a stoichiometric mixture of hydrogen and atmospheric air, but simplicity as a molecule is not the only factor that can influence the performance of a fuel. For example, acetylene yields higher performance than hydrogen gas, yet an acetylene molecule is 13 times heavier. This is because of:

1. The considerable energy stored in the carbon/carbon triple bond
2. The combustion products (CO2 has a much lower heat of vaporization than H2O)

I dont suggest using hydrogen or acetylene in a spud gun.
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Unread postAuthor: CpTn_lAw » Sun Dec 17, 2006 2:49 pm

no one in fact told dihydrogen. everyone thought it was simply hydrogen H put in a closed chamber then lit.
I've done experiments with H2 in an electrolysis (electrolyse in french) and we had fun lighting it!
If you saw the video you have seen by the way the potato leaves the barrel very slowly compared to normal spudguns...
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Unread postAuthor: SpudBlaster15 » Sun Dec 17, 2006 3:05 pm

What? Are you trying to say that there is a form of hydrogen gas that is not diatomic? If so, I suggest you start doing some reading before posting again.
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Unread postAuthor: CpTn_lAw » Sun Dec 17, 2006 3:13 pm

lol no, there is some misunderstanding! i wasn't speaking of hydrogen in its gaz form.
then again, that is a bit off topic...for the pneumatic question, i suggest you go here http://video.google.fr/videoplay?docid= ... 7196203759

this is my latest spudgun. 150 psi of air...very portable.
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Unread postAuthor: SpudBlaster15 » Sun Dec 17, 2006 3:48 pm

I know that you were not talking about hydrogen gas, you were talking about a hydrogen atom. I simply attempted to explain to you that a reference to hydrogen in its atomic form did not fit the context of your post.
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