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Combustion spudgun made of EU pvc

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: jackssmirkingrevenge » Tue Mar 31, 2009 3:37 am

ozoncqp wrote:This is not me or my brothers just some random rednecks :D


Love the ignition system, very... rustic :)
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Unread postAuthor: ozoncqp » Tue Mar 31, 2009 6:16 am

Ok the 75/75 union should be on the way now. 30$!
The guy got 90 and 50 mm pressure tested pipes approved for 240+ psi
And the solid glue on pvc fittings and union etc only cost 1/3 of these.
I could ofcourse skip having breechload and use the plunger, but its just cooler. And more convenient the day it misfires and gets stuck or similar.
Theres a 14day return right on the shipping atleast.

Now im having second thoughts, is this cannon an overkill ? the 90/50 would not have the same overall power i guess.
The best thing about my 110/75 is working at a fruitgrocers makes oranges close to free.
Tho a box of baking potatoes wouldn't cost more i guess.
I could allways sell this cannon to my inlaw and make a smaller version.
The friggin union is 540grams lol.
Anyways im off to make my sparkstrip-electrode-dingie.
/michael
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Unread postAuthor: ozoncqp » Wed Apr 01, 2009 5:19 pm

Ok, got all my parts.
But before im going assemble my pipes. I just want to make sure that I understood all this correctly.

My current gun is spray n'pray.
But a quick 2+2=4 made me see how cheap a propane canister is compared to hairspray, deos etc. Even if im buying the cheapest avail.
I haven't found any exact data on max PSI on the pipes im using this time. Tho i know its PP-H, flame resistant etc. I found some numbers indicating that it can stretch 800% ! before it should burst. And its atleast 2.5mm thick in the walls. I'll bet almost anything that you can run a sedan over it without it breaking.

But from what i can read, the 100-120PSI is maximum for combustion cannons. The tools available in the post I've been refereing to earlier makes close to no sense to me. But english not being my native language I might just mixup all the terms. although I'm using oranges that are hard to get into the barrel they slide easily after I gets in there. Well with a squize of a finger you can push em. And we even had a 85mm orange inserted to a 72mm barrel. It kind flew further I'd say.
I would like a metered propane system but, with a risk of having the gun confiscated by the cops one day I don't wanna make it worth a lifesaving. It shouldn't happen tho. My few neighbours thinks its funny shooting it.
And I'm not really into all the pipes, I like it clean. So im thinking of making this incredible syringe propane injection system using "speed connectors" mounted in the 2 layer part of the chamber.

Now I'm sure I'll get more power alone from adding my new powerstrip and improved fan system im working on. Heck I'll even be able to fully vent the cannon. All I would like now is the same power every time I shoot it. But would going for a propane/butane mixture blow up my gun. I cant really tell what the reply sugests back on page one.

psycix wrote:Your pipes will probably hold the pressure of a normal combustion. Just do not use acetylene or hydrogen (not because of the pressure, but because of the shockwave)


Is propane listed as "normal" combustion to you guys ? Because my cannon have done done pretty crazy stuff.

The orange 10mm bigger than the barrel.
An accidental double load. Both me and a mate loaded it with an orange.
So I thikn it looks solid enough.
Oh and does it matter if its a 40/60 propane/butane mixture? I think I read that the explosion is somewhat equal or very close. I got a few of those canisters ready to mod with a coupler.
And I'll by aiming for the 4% marker if the cannon can support it. Unless I can go all the way.
Ok I think thats me for now. I guess the reason I'm asking is theres hardly any spudgun community in denmark, our materials are different, and im pretty sure you guys knows an aweful lot about it.
I really hope that I can toss in a few cents soon.
/michael
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Unread postAuthor: inonickname » Wed Apr 01, 2009 6:46 pm

Even if the chamber is completely sealed, which is unlikely it would still hold the pressure, so it's not that crazy..

A propane/butane mix is fine, though if your metering it make sure to take to ratios of each gas in proportion so you get an accurate mix.
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Unread postAuthor: POLAND_SPUD » Wed Apr 01, 2009 9:46 pm

Love the ignition system, very... rustic


lol


@ozoncqp
you might consider using metal pipes... or even better - switching to metal and building a pneumatic... do you have a compressor ? well AFAIK most TRACTORS have in-built compressors

even a 1.5" pneumatic run at 100 psi should offer hours of fun... and I am sure you could find 2" or even 5" pipe
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Unread postAuthor: ozoncqp » Thu Apr 02, 2009 3:20 am

About the syringe metering i guess ill need a big syringe to get the 4% mix in one injection. Or i gotta work out a way to calculate the amount of gass at XXX Psi in a syringe of XXX size. Im sure theres a guide here somewhere.

Poland: Well ya but the compressor style isn't really me. Im more of a BOOM person and metal piping makes what im making now useless lol.

Ok propane/butane syringe injection it is.
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Unread postAuthor: inonickname » Thu Apr 02, 2009 3:30 am

Well it depends on the size. By the way, with a syringe don't act on pressure as you will lose it in transition from source to cannon. Calculate it by volume.

If you want a better system that works on volume and pressure, check this out. Don't both with pressure in a syringe, it wont work.
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Unread postAuthor: ozoncqp » Thu Apr 02, 2009 4:22 am

inonickname wrote:Well it depends on the size. By the way, with a syringe don't act on pressure as you will lose it in transition from source to cannon. Calculate it by volume.

If you want a better system that works on volume and pressure, check this out. Don't both with pressure in a syringe, it wont work.


Yeah but im looking at a already kinda heavy cannon.
My overkill battery i just love cause of its possibilities is 750grams, the Union is 560grams. I all so have to find its point of balance without making it chubby ;)
But then again with the fibreglass work i got in mind i might be able to semi hide the tubes and propane canister.

But if i understood this correctly (haven't really read that much about it since im still calculating the actual size i want on my cannon.) Then with my beta cannon.
Chamber size 6000ml
Barrel of 39"*2,8" Gives a 1.52 ratio
Acording to the prometer i just grabbed. Using some ½" pipes for the injection. My meter should be at 47,3 psgi and peak is 106 psgi
That should be safe.
Now with the syringe system i guess i have to measure the chamber size.
6000ml If i understand correctly i want a 4% mix. so i would take
*edit* Just used a different way to calc it.
6000*,04=240ml. My old number was 62,2 *edit*

So all i gotta do now is make a syringe that holds this amount right ?
Im kinda lost in translation lol
But im going to add 500grams to the pre-assembled cannon to see how big a difference its going to make, using the onboard.
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Unread postAuthor: POLAND_SPUD » Thu Apr 02, 2009 7:54 am

well if you are really
more of a BOOM person
then it would be good for you to know that pneumatics are usually lauder than combustion guns

switching from one material to the other is never easy but sooner or later you'd have to switch to metal for more power.... even with combustions
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Unread postAuthor: ozoncqp » Thu Apr 02, 2009 9:02 am

Hmm all the vids Iøve watched the pneumatics had a more SWUSH sound to em.

And about the metal yeah I know I'll have to switch if I want to go mapp.
But what im trying to do atm is. To create a powerful gun made of european pvc with 3 mm chamber walls. and 2.5 mm barrel walls. And I'm OK witht the spray n'prey really, the hairspray im using now is rather easy to balance. But I know that 70-80% of its flameables is propane/butane. So I could go with a modded ligther refill canister. Or with the propane injection with either syringe or onboard.

Getting rid of the gunky stuff would be nice, having the same power everytime would be nice.
And the competion in denmark regarding soudguns is really low. I know of a total of 5 who got one. Being able to impress them with the one im curently building would be fun. Even more fun would be to blow anything to oblivion where their gun would give up.
I might, if, then and when I can afford it both financial and timewise make an aluminium cannon of a hybrid monster.
*edit*
Can this be right btw?
Image*edit*

Looks like a massive amount of power in the muzzle, but im a newbie when it comes to these numbers.
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Unread postAuthor: Biopyro » Thu Apr 02, 2009 12:03 pm

Combustions definately generate the satisfying boom better for those of us who like it. Pneumatics may be louder at the same bore, but in my experience, they have a different sound. That said, I have only fired my large bore pneumatic a few times until I retired it because the piston wasn't tight enough.
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Unread postAuthor: starman » Thu Apr 02, 2009 1:36 pm

While I've found some of the HGDT numbers to be slightly optimistic, they are definitely in the neighborhood and very usable.

The sounds you get out of any cannon are based on several factors: chamber size, barrel length, ammo size and mass, fuel type, etc. Both combustion and pneumatic type can be built to be quiet or very loud, so to say that one type is "louder" than another isn't taking all these factors in to play.

However, after saying all that, averagely configured combustion cannons I have heard do tend to have a rifle crack or shotgun/cannon boom that no pneumatic I've ever heard has. While pneumatic shots can be loud decibel wise, they tend to lean more toward the thwwuump, swoosh, ppowww character.
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Unread postAuthor: ozoncqp » Thu Apr 02, 2009 2:04 pm

Well I dont know if my current is a BOOM really. It got the motar sound thump! and after .1sec the KaBlang. Followed by a rolling thunder. But ya I've been messing around with HGDT scaling the barrel and chamber. And im pretty sure that my projectiles fly faster than listed. Even with the spray 'pray. This is based on how far it goes really.
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Unread postAuthor: Biopyro » Thu Apr 02, 2009 2:11 pm

It is nearly impossible to gauge the speed of your projectile by eye, unless you regularly chrono your projectiles and (try to) look at them in flight.
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Unread postAuthor: ozoncqp » Thu Apr 02, 2009 3:09 pm

Well I'm not saying I can see how fast it travels. But I can tell how far. I know it takes power to move an object XXX range, but speed must be an important factor. And looking at some of the air I've had it gotta be faster than HGDT says.

I did just browse the entire section of combustion showcase guns. And my attention dropped on the one made by Grizzly. Same type of pipes im using. I know now that the orrange stuff is vurnable to sunlight, but takes the same pressure. And im sure what made his go boom is the frigin BIG chamber versus the what 32-40mm barrel. I can tell the barrel bends, if it broke during cold weather my guess is the impact in the "bend" on the barrel plus the stiff pipe = crack. (It gets kinda cold in lithaunia I recon)

Im not afraid mine will crack anymore. My pipes hardy curves, and it's thicking in the walls and the 40mm. I'm still figuring out if I want onboard or syringe. Both will work for me, but I'm at 25/75 in favor of the syringe.
It takes less room and to me it seems like the same amount of time used'ish.
Should be semi assembled tomorow so I can start meassuring the chamber with fluid. And figure out where to put handles, triggers etc.
/michael
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