Page 5 of 6

Posted: Sat Mar 31, 2007 1:35 pm
by FeLeX
Scope, it is perfect mix of the bat. Ask your chemistry teacher. I still dont understand why make hills out of moles.

Posted: Sat Mar 31, 2007 3:52 pm
by boilingleadbath
Well, there are two situations that can occur that could disrupt the mixture:
1) You could use a binary salt or such as an electrolyte... which would give you, I think, Cl<sub>2</sub> in your oxygen... and less oxygen than you'd expect, because some of it'd be used to form chlorates. (again, I'm fuzzy on electrolysis chemistry)
Yeah, this is easy enough to avoid, but it's worth mentioning anyways.

2) You could use a electrode material other than a noble metal/noble metal oxide/such, which could react with your oxygen... vastly reducing the quantity produced. (A similar situation can probably occur with the hydrogen, but I don't know of it)
Again, not that hard to solve - my understanding is that even 316 stainless handles electrolysis with NaOH electrolyte - but worth mentioning.

Now, we note that both of these are easier than metering oxygen, so it's probably a stupid idea to forgo them in favor of manual metering.
*****************

Anyway, my question of <i>why</i> you guys want to use H2-O2 remains, considering it'll give you about the same amount of pressure as air-propane, and so shouldn't be much more powerful than your typical gun with a good ignition system.
(ok, the O2-H2 gun way provide pressure for a longer distance... but I'm not sure)

I've heard it suggested that the "shock wave" (which I suspect won't form) adds immense amounts of velocity.
Although I doubt this, I'll shut up if the guy with the 6mm H2-O2 airsoft gun repeats his penetration test <b>without</b> a barrel; that is, with the pellet taped over a hole in the chamber.

If you guys are correct, the projectile should still preform well.
If you think that the pellet moves enough before the shock wave reaches it that it's not in front of the hole anymore (I admit, it's fairly probable), feel welcome to preform a miniature of the latke chamber:barrel ratio tests, looking for abrupt acceleration.

Posted: Sat Mar 31, 2007 8:33 pm
by Insomniac
I suppose that you have a point there, but hydrogen and oxygen is the perfect fuel for a 'carbide cannon' type gun. It is easier and cheaper than acetylene and the shockwave would make it a helluva lot louder than air-propane.

Posted: Sat Mar 31, 2007 11:57 pm
by Scope
I just like the thought of it cuz its so simple...
plus its fun... no metering...


I wanna seperate it because its mores flexible... cannons arent the onlything i wanna use this for...

its always intresting making somethin from nothing

Posted: Sun Apr 01, 2007 12:02 am
by singularity
well the reason im making it is becuase i want a gun that runs of water and whats cooler than hydrogen gun. when the gun is complete it will have a built in electrolysis machine so i can got any where hook up a car battery pour in some water and ill have every thing i need to fire. that way i wont need to pay for propane and worry about that hole 4% mix thing

Posted: Sun Apr 01, 2007 12:04 am
by FeLeX
boilingleadbath wrote:Well, there are two situations that can occur that could disrupt the mixture:
1) You could use a binary salt or such as an electrolyte... which would give you, I think, Cl<sub>2</sub> in your oxygen... and less oxygen than you'd expect, because some of it'd be used to form chlorates. (again, I'm fuzzy on electrolysis chemistry)
Yeah, this is easy enough to avoid, but it's worth mentioning anyways.

2) You could use a electrode material other than a noble metal/noble metal oxide/such, which could react with your oxygen... vastly reducing the quantity produced. (A similar situation can probably occur with the hydrogen, but I don't know of it)
Again, not that hard to solve - my understanding is that even 316 stainless handles electrolysis with NaOH electrolyte - but worth mentioning.

Now, we note that both of these are easier than metering oxygen, so it's probably a stupid idea to forgo them in favor of manual metering.
*****************

Anyway, my question of <i>why</i> you guys want to use H2-O2 remains, considering it'll give you about the same amount of pressure as air-propane, and so shouldn't be much more powerful than your typical gun with a good ignition system.
(ok, the O2-H2 gun way provide pressure for a longer distance... but I'm not sure)

I've heard it suggested that the "shock wave" (which I suspect won't form) adds immense amounts of velocity.
Although I doubt this, I'll shut up if the guy with the 6mm H2-O2 airsoft gun repeats his penetration test <b>without</b> a barrel; that is, with the pellet taped over a hole in the chamber.

If you guys are correct, the projectile should still preform well.
If you think that the pellet moves enough before the shock wave reaches it that it's not in front of the hole anymore (I admit, it's fairly probable), feel welcome to preform a miniature of the latke chamber:barrel ratio tests, looking for abrupt acceleration.
Well the reason I used it because I used it on a mini and its easier to meter it this way because all you do is just turn the machine on thats it.
I think it would be pretty useless for a standard size cannon.

Posted: Mon Apr 02, 2007 1:26 pm
by jimmy101
Ya know, you can buy a hydrogen / oxygen generator from Estes....

Or, do it the way I think the Estes system does, couple volts from some C batteries, steel (zinc plated?) electrodes, sodium ascorbate or sodium citrate as the electrolyte (and base).

<a href="http://www.estesrockets.com/products.ph ... 876">Estes Hydrogen powered rocket</a>

Somewhere I think I have a copy of the patent...
<a href="http://www.freepatentsonline.com/682084 ... >patent</a>

Posted: Wed Apr 25, 2007 3:18 pm
by meatballs
how many shots could you get out of the car battery? any idea how much power you'd take to generate enough hydrogen for one shot?

Posted: Wed Apr 25, 2007 3:24 pm
by singularity
no idea my generator uses a computer psu, as for how much hydrogen used depends on the chamber. i have finally gathered the pieces to make a simple hydrogen prototype, i plan on testing it on the week end. its got a 3/4 by 3in chamber and a 1/8 barrel, ill post it once i have confirmed it works

Posted: Fri Apr 27, 2007 7:01 pm
by yuandrew
This was labeled Hydrogen/Oxygen combustion cannon. The car starting in the background cylinders was used for ignition.

[youtube][/youtube]

Posted: Fri Apr 27, 2007 10:53 pm
by meatballs
Good luck with the prototype, cant wait to hear what happens. what are you using for the barrel on the prototype?

Posted: Mon Apr 30, 2007 6:41 pm
by Shadowscion
Does anyone think this would work? Ive been messing around with electrolysis for a while now and I want to have a fun(loud) time this 4th of July without spending tons on fireworks.

This isn't what I would make it look like, as it isn't to safe set up the way the picture is. I would most likely have a hose setup running the hydrogen and oxygen into the bucket with a quick connect on the electrolysis chamber so I could disconnect it and bring it away when firing.

Posted: Tue May 01, 2007 11:27 am
by jimmy101
Shadowscion: What you've drawn will work. The fuel / oxidizer ratio will be off since the bucket starts out with 20% oxygen in it but it should still ignite without any problems. You are just going to let the excess gases "burp" out from the bottom of the bucket?

Don't forget to disconnect the generator from the bucket before igniting! You'll have an explosive gas mixture in the generator and pipe, don't want the flame running back up the pipe into the generator.

You will want to have the largest electrode surface area as you can get, and you want them as close together as possible (but no closer than the typical bubble size for your particular choice of electrolyte). Both of those factors affect the current flow, which controls the rate of gas formation.

You probably already know this, but Drano and other drain cleaners make pretty good electrolytes (they contain NaOH or KOH). The higher the concentration the electrolyte is the faster you'll generate gas. But, concentrated NaOH, KOH etc. is corrosive and dangerous. If you do something wrong you run a real risk of spraying the area (and you) with the caustic solution.

Sometime people use Epsom salts (Magnesium sulfate) as the electrolyte. Much safer. You can get a pound or two at most grocery or drug stores for a couple bucks.

Salt (NaCl) can be used also but it will generate chlorine gas which is pretty toxic. Chlorine gas is an oxidizer just like oxygen. Indeed, Cl<sub>2</sub> is a stronger oxidizer than oxygen. You will loose some of the Cl<sub>2</sub> to hypochlorous acid (Cl<sub>2</sub> + water) but your setup has excess oxidizer anyway so that probably isn't a problem. But again, Cl<sub>2</sub> is pretty dangerous stuff, toxic and explosive.

Have you seen this site;
Big ass water bottle launched like a water rocket using H<sub>2</sub> and O<sub>2</sub> generated in the bottle itself. Check out "Dean's Benchtop" (http://www.et.byu.edu/~wheeler/benchtop/hydropyro.php), the definitive page on electrolysis powered water rockets.


Play safe.

Posted: Thu May 10, 2007 6:14 pm
by spudzinger
ARE YOU RETARDED??????HYDROGEN AND OXYGEN ARE EXPLOSIVE!!!!!!IF YOU WERE TO MAKE IT DONT MAKE IT OUT OF STEEL BECAUSE THE HYDROGEN BURNING WILL CREATE METHANE OUT OF THE CARBON IN THE STEEL AND WILL THIN YOUR BARREL. OK, enough with the capslock. Anyways, if you were to be stupid enough to do it put the chamber inside a like cement block for safety. Point is, dont do it. Even though I dont know you I dont want to hear about you one the news or here about being killed while doing it. Call me a party pooper if you want I dont care Spud

Posted: Thu May 10, 2007 6:18 pm
by Shadowscion
Way to over-react.