looking to fuel my monster cannon

[F.E.A.R._Sniper]

yes i've been teasing you guys with talk about my monster cannon every now and then. I want to put pictures up really badly but because I am in the military and only get to work on it when i go home (except for the small parts I can work on in my barracks room) i have to wait for another 2.5 weeks before i can get you guys some pics.

now on to my question:
This bad boy is huge, damn nigh 6 feet long at least 2 and a half feet wide. I wanna know what my best option for fueling would be. I know there is always the trusty ones propane, hairspray, mapp gas, butane and such but lately electrolysis has caught my eye. What I wanna know is, which of these is the most powerful or is there an even more powerful substance to fuel my cannon? I had thought about the possibility of a small mix hybrid and using epoxy or something to reinforce the chamber.

what should i do to fuel my gun?

edit:ok just to clarify THE BARREL ISN'T ATTACHED YET, I AM LOOKING FOR THE BEST WAY TO HOOK INTO THE CROSS WYE BEFORE I PERMANENTLY MOUNT IT.

if any of you have suggestions for the best way to mount a barrel onto a 4" cross wye then let me know

[starman]

Propane or MAPP will be the easiest, safest, quickest, cheapest fuel. It sounds like you have a fairly large chamber there so electrolysis (hydrogen) will be slow and awkward getting fueled up. Also corralling and making safe hydrogen will be a challenge.

Hybridizing your cannon will be much more straight forward with propane for MAPP. These fuels will also be plenty powerful.

[DYI]

damn nigh 6 feet long at least 2 and a half feet wide

With a barrel that short in relation to its bore size, you'd better have a strong chamber, and a really energy-dense fuel. Assuming that the bore is 30", that's an L2.4. Even with a fuel as energy dense as nitrocellulose, the performance would be rather poor. For gaseous fuels at low pressures, well...

If you are indeed sticking to low pre-ignition pressures (below 15psig or so) oxygen/acetylene mix is as good as it gets for readily available gases, but also prone to detonation. The same goes for oxy/hydrogen (though it isn't quite as powerful). If there's no burst disk, a fast burn like those fuels provide (assuming you can prevent them from reaching DDT) is beneficial. If a burst disk is going to be used, then oxy/MAPP is likely your best choice, because it's almost as powerful as oxy/acetylene, and quite a bit more so than oxy/hydrogen.

There is a good reason that propane and MAPP are by far the most common fuels in combustion guns.

[F.E.A.R._Sniper]

ok just to clarify THE BARREL ISN'T ATTACHED YET, I AM LOOKING FOR THE BEST WAY TO HOOK INTO THE CROSS WYE BEFORE I PERMANENTLY MOUNT IT.

if any of you have suggestions for the best way to mount a barrel onto a 4" cross wye then let me know

[jimmy101]

ok just to clarify THE BARREL ISN'T ATTACHED YET, I AM LOOKING FOR THE BEST WAY TO HOOK INTO THE CROSS WYE BEFORE I PERMANENTLY MOUNT IT.

if any of you have suggestions for the best way to mount a barrel onto a 4" cross wye then let me know

Common FEAR, you know better than to post a lame-ass question like this. A little more info would be helpful.

PVC? Stainless steel? Paper towel carboard tubes?

Removeable barrel important?

[vovka351]

... hydrogen will burn faster then the other gasses. But I was recently thinking of acetylene dissolved in acetone. 250 liters of acetylene gas at room temperature will dissolve into one liter of acetone, imagine how energy dense you could get your fuel.

[F.E.A.R._Sniper]

yeah, it's all pvc so far. I was hoping to have a removabl barrel but that isn't super important. I wanted something a little more complex and badass than just having a 90* coming up out of the cross wye to mount the barrel on. I was thinking of maybe putting a sanitary tee up top with a clean out cap on the end facing me and the barrel going out the other end so I could make it a breech loader but I have also thought some on making a revolver cylinder or a semi-auto style (not to be confused with pure semi auto) action to make it a semi- fast action repeater

[Lentamentalisk]

ummm... you are trying to take a 30" wide chamber, and connect it to a 4" barrel? Can you specify what you are doing? draw us a diagram or something?

If that is the case, I hope you are looking for some place to buy a 28 foot long barrel...

How are you expecting to find a reducer from 30" to 4" inch?

I don't doubt that you can figure these things out, I am just trying to understand your situation.

[psycix]

You mentioned electrolysis, and by that I see you are considering hydro and oxygen mixtures, but know that hydrogen does not give more pressure then propane, it just burns faster, and tends to detonate instead of deflagrate (especially in large chambers and mixed with oxygen). Hydrogen will quickly induce DDT and rip your monster cannon to monster shreds.

I would say, use propane or mapp, and maybe in a 2x mix or so, and use alot of spark gaps.

[F.E.A.R._Sniper]

aight thanks for the info psycix.

without it i may have went and did something bad

[psycix]

But, what are the dimensions of the gun actually?
There seem to be some misunderstandings.
What is your chamber diameter and length? And your barrel's?

[mark.f]

Well, since most PVC of these large dimensions I've seen is DWV, I would recommend only a 1x mix, using propane or some other safe fuel.

[psycix]

Indeed.
SCH80 wall thickness may sound like a sturdy pipe, but when the pipe diameter is one foot, its just a thin, flimsy wall which can't have alot of pressure.
As diameter increases, wall thickness should increase proportionally, and then even with such a thick wall, you can run no more then a 1x mix safe.

Also remind, that when a normal combustion fails, you may get hit by a piece of PVC and get hurt; when a gun with a big chamber of of one foot diameter fails, so big are the consequences too and you may get hit by a whole chunk of pvc and get hurt by alot more.