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Using pure 0xygen as a propellant, the perils thereof.

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: ShowNoMercy » Mon Mar 10, 2008 8:29 pm

If I am not mistaken, N20 can be gotten for 5 dollars a pound I believe.
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 10, 2008 8:54 pm

Novacastrian wrote:I remember JSR pointing out the fact and providing a picture of a air rifle that was used with oxy, it looked a little worse for it too.


This was the launcher in question, and this is why I discouraged the use of oxygen:

Before using pure oxygen as a tank filler:

Image

After:

Image


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Unread postAuthor: daberno123 » Mon Mar 10, 2008 8:58 pm

Ahh, so my mind is not playing tricks on me after all. Thats for clearing that up Nova, and the pictures from jack were what triggered my memory also.
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Unread postAuthor: SpudMonster » Mon Mar 10, 2008 10:39 pm

Has everyone forgotten Gormanorv's Oxy-Mapp gun? Christ I feel old...

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Unread postAuthor: SpudBlaster15 » Mon Mar 10, 2008 11:02 pm

DYI wrote:That's a good idea to use N<sub>2</sub>O. Shame it isn't quite as available as oxygen. How do it's oxidising properties compare to O<sub>2</sub>? I'd think it wouldn't be as powerful an oxidiser.


In this thread, I calculated that a pure oxygen/propane mixture releases ~20% more energy than an N<sub>2</sub>O/propane mixture.

BUT, energy is not everything, as one would learn from indulging in the hobby of pyrotechnics. Note that the N<sub>2</sub>O reaction requires 82kJ/mol of energy to decompose before reacting (endothermic), so the reaction will tend to propagate more slowly. Somewhat like comparing KNO<sub>3</sub>/Al flash powder to KClO<sub>4</sub>/Al flash powder. Given stoichiometry, the KClO<sub>4</sub>/Al mixture will burn hundreds of times more rapidly on account of the fact that KClO<sub>4</sub> decomposes exothermically, which means it releases energy as it liberates oxygen, propagating the reaction throughout the fuel/oxidizer mass, while KNO<sub>3</sub> requires substantial heating before it will give up its oxygen.

Since I have never taken a chemistry class in my life, and I am quite tired today, I could very well be missing some other property that adds "effectiveness" to an oxidizer. If I think of something, I will add it to this post.
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Last edited by SpudBlaster15 on Tue Mar 11, 2008 1:02 am, edited 1 time in total.
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Unread postAuthor: CS » Mon Mar 10, 2008 11:11 pm

SpudMonster, that is the one I was refering to in my post. That gun was posted a long time ago. It was on the SpudTech archives, when SpudTech was still around.
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Unread postAuthor: jrrdw » Tue Mar 11, 2008 6:06 am

pimpmann22 wrote:Well if you haven't heard of the hysteria surrounding pure O2... well your retarded.
(Hysteria - rightfully so)

Everytime someone mistakenly uses the term "oxygen" for "air" we will get about 5 people that pounce on the oxygen hysteria subject - and just how retarded the person is for using it.

I call only recall 1 or 2 situations in which pure O2 was used for a launcher. The one I recall specifically it seemed as if the operator used reasonable safety precautions.

One area I'd like to see pure O2 used is in a higher ROF combustion. The oxygen would circumvent the "venting" ordeal. Just dreaming...


The part that bugs me is the lit cigarette inhale and gasp that should have been paid attention to here. Most people don't even think of safety, generally just worry about getting away if it blows up. Hysteria, no, I don't see anybody flipping out. I hope you don't consider asking for a exact answer hysteria, if so, you got the wrong idea.
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Unread postAuthor: D_Hall » Tue Mar 11, 2008 9:36 am

DYI wrote:That's a good idea to use N<sub>2</sub>O. Shame it isn't quite as available as oxygen. How do it's oxidising properties compare to O<sub>2</sub>? I'd think it wouldn't be as powerful an oxidiser.

It's not as strong an oxidizer; that's a given.

But it's still pretty good, a lot better than air, and the safety issues are trivial in comparison.

As for a "real world" example of it's abilities? It was good enough to get SpaceShip 1 to space (Nitrous was the oxidizer used in SS1's rocket). Oh, and there's all the car people. :)
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Unread postAuthor: CS » Tue Mar 11, 2008 11:42 am

Really don't want to hash out my word usage on a public forum, but....

"Hysteria is a diagnostic label applied to a state of mind, one of unmanageable fear or emotional excesses." - Wikipedia

If not already identified by the italized portion - I was using "hysteria" in the sense of emotional excess. Basically "oh noes !!!11!1!!!1" in forum terms.

I have been active on these forums for over 3 years, so I naturally pick up on things that annoy me. (History repeats itself near daily on this forum)
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Unread postAuthor: jrrdw » Tue Mar 11, 2008 5:06 pm

"Really don't want to hash out my word usage on a public forum, but...."

but.... I like that, but....I see what you mean now. I've all ways taken the word "hysteria" loosly. Like someone running down the street with their arm flaleing above their head screeming their heads off.

I remember seeing that cannon also, it's a nice one!

"I have been active on these forums for over 3 years, so I naturally pick up on things that annoy me. (History repeats itself near daily on this forum)"

I must really get under your skin....
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Unread postAuthor: judgment_arms » Tue Mar 11, 2008 8:44 pm

pimpmann22 wrote:(History repeats itself near daily on this forum)

Indeed… just how may topics to the effect of “my sprinkler valve doesn’t work” are there?

Quick question:
Does mixing pure oxygen with propane/MAPP/acetylene make it less volatile, or do people just run degreaser through there cannon before filling it with an oxy- mixture?

Another thing, has any body considered using hydrogen peroxide, you’d have to atomize it somehow I’m sure, but it worked for the V2 and a whole slew of other rockets.
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Unread postAuthor: D_Hall » Wed Mar 12, 2008 12:00 am

pimpmann22 wrote:(History repeats itself near daily on virtually every Internet forum)


Fixed your post.
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Unread postAuthor: DYI » Wed Mar 12, 2008 10:01 am

I don't think that the pressure of oxy-mixes that most people use really requires careful cleaning before each shot. I have done some testing on the matter, and even at 60 psi, I couldn't get paraffin wax, wood, ethanol, or oil to react. It is by all means possible at oxygen tank pressures, but it seems rather unlikely at the kind of pressure we're likely to put in a hybrid before we ignite it.
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Unread postAuthor: jrrdw » Wed Mar 12, 2008 6:32 pm

DYI wrote:I don't think that the pressure of oxy-mixes that most people use really requires careful cleaning before each shot. I have done some testing on the matter, and even at 60 psi, I couldn't get paraffin wax, wood, ethanol, or oil to react. It is by all means possible at oxygen tank pressures, but it seems rather unlikely at the kind of pressure we're likely to put in a hybrid before we ignite it.


Kinda shoots the first post down in flames, doesn't it?
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Unread postAuthor: Novacastrian » Thu Mar 13, 2008 3:39 am

Someone HAS to photoshop this pic...
http://www.spudfiles.com/forums/files/o ... n2_978.jpg
I mean look at the possibilities, pitty i am a dumb ass otherwise i would do it myself. :D :roll:
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