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The "BEAST" ~ Propane Bazooka

Built a combustion cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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The "BEAST" ~ Propane Bazooka

Unread postAuthor: STHORNE » Fri Mar 21, 2008 10:54 am

Hello fellow spudders. This is my first advanced combustion (to an extent). I bought all the pvc brand new (yes, it's dwv, i know), otherwise everything else was salvaged from junk around the house (propane meter, fan, piezo, etc.) so don't critique how i set it all up, it's all i had lol, and it works just fine. I got some pics, vids, and specs of the gun.

So far I have only used potatos and empty "Liquid Nails" containers (fit 2" barrel perfectly). Sorry no damage pics yet, only distance.

And yes, i know...i need a paint job, but between my job and school, i really don't have time to tape everything off and give 'er a coat or two, but i did do a really nice job on the primer/cement (can't see it). Anyway, enjoy.

Questions and Comments always welcome.

EDIT: I bought pressure rated pvc pipe and sleeved the chamber/barrel with it, resolving the whole "what if it blows up" ordeal. So now you can enjoy the cannon for what it is and stop bickering about the whole dwv deal lol.

This is the exact shot described/showed in the picture at the bottom of the page. And after seeing the recoil this thing puts off, there's no way I'm shooting it off my shoulder at anything past 25psi (in the video, it was set at 30 psi cause the propane tank was almost empty). You should see it at 60 psi, it flies back probably a foot, even with sand bags
[youtube]http://www.youtube.com/watch?v=WjXL0PSePLQ[/youtube]
sorry about the poor quality of the video. Last time i use youtube...
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Attachments
shotfireddistance.JPG
This was a shot fired on a day with 4mph winds and it was about 38 degrees F. The video is currently being uploaded.
propaneinjectionsystem.JPG
homemade propane meter (sorta ghetto). The calculator said to use 15" long piece of 1/2" pipe at 60 psi, but i used 30" of 1/4" tubing instead and usually keep it at around 45 psi.
propaneinjectionsystem.JPG (37.41 KiB) Viewed 3683 times
propaneinjectionandfanbox.JPG
propane injection system and fan box
piezoignitionhandle.JPG
custom piezo ignition handle (excuse the duct tape, i plan on covering it with shrink wrap, and making a custom handle to encase it all to make it less noticeable).
piezoignitionhandle.JPG (19.78 KiB) Viewed 3683 times
Ignitionspark.JPG
ignition spark gap (not bad for a piezo)
Ignitionspark.JPG (11.03 KiB) Viewed 3683 times
fanpowerbox.JPG
fan power box
fanpowerbox.JPG (25.83 KiB) Viewed 3683 times
specs.JPG
Specs of the Gun without barrel/s (if any of you are wondering)
specs.JPG (22.04 KiB) Viewed 3683 times
bazookaonshoulder.JPG
watch out, I'm loaded and ready for action!
bazookaonshoulder.JPG (31.37 KiB) Viewed 3683 times
Wholegunandbarrels.JPG
1) The bazooka
2) Interchangeable GB barrel
3) Interchangeable 1.5" barrel
Wholegunandbarrels.JPG (29.96 KiB) Viewed 3684 times
Last edited by STHORNE on Wed Apr 02, 2008 6:55 pm, edited 9 times in total.
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Unread postAuthor: Fnord » Fri Mar 21, 2008 11:15 am

Bah... it isn't easter yet.
I actually didn't have a clue if it was easter today or even what day it was so naturally I just checked the Google logo.

Anyway I would paint it black/red trim. The distance is really good for a shorter barrel. Your CB is crazy though.
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Unread postAuthor: STHORNE » Fri Mar 21, 2008 11:18 am

_Fnord wrote:Bah... it isn't easter yet.
I actually didn't have a clue if it was easter today or even what day it was so naturally I just checked the Google logo.

Anyway I would paint it black/red trim. The distance is really good for a shorter barrel. Your CB is crazy though.



Lol, I'm just saying happy easter in advance because i might not be on the next couple days.

I know the C:B ratio is messed up but i didn't have enough money atm to buy a longer section for the barrel, so i had to settle for 4ft :( . I plan on either upgrading this cannon or just making a steel hybrid.
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Unread postAuthor: Jared Haehnel » Fri Mar 21, 2008 11:44 am

Go for the longer barrel you'll have a lot more power, but over all a nice gun and I like how you showed the distance. Nice work!!! 8)
The shoulder mount was vary nice idea...
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Unread postAuthor: STHORNE » Fri Mar 21, 2008 11:47 am

thanks lol. i got the map from http://www.maps.live.com.

and the shoulder mount i thought up on the spot when i went to buy pvc lol
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Unread postAuthor: pizlo » Fri Mar 21, 2008 12:48 pm

Very inovative, and seems like a great gun.
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Unread postAuthor: SpudFarm » Fri Mar 21, 2008 1:14 pm

wow i like your gun :)
you should build a steel hybrid you don't know how fun it is to put a buckshot of lead deep inside a two by four and then hear them smash into the steel backstop and become dust :P
and yeah a really clean gun yu got there :)
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Unread postAuthor: daberno123 » Fri Mar 21, 2008 4:18 pm

Great gun you've got there, I especially like the DANGER: HOT sticker on the chamber. I look forward to seeing some damage shots.
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Unread postAuthor: SpudFarm » Fri Mar 21, 2008 4:45 pm

give us some damage with the GB barrel dude :)
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Unread postAuthor: Ragnarok » Fri Mar 21, 2008 5:19 pm

The calculator said to use 15" long piece of 1/2" pipe at 60 psi, but i used 30" of 1/4" tubing instead and usually keep it at around 45 psi.

Those are totally different volumes of propane. The calculator gives a volume of 193 cc, the volume you have is around 72cc.
The different pressures you're throwing around, aren't going to get the best results. There is a perfect fuel ratio of 4.19% propane by volume, and surely you're not actually hitting it.

I'd like to say it's a nice launcher, but I have a gripe with it - I know people will disagree with me on whether this is acceptable - it uses unrated parts.
Combustion or not, unrated parts are not completely safe. You just need to search youtube to see dozens of cannons (combustion, mostly spray n' pray - for which many people will tell you that unrated parts are acceptable for) that have shattered or ruptured from pressure. I'm not saying that it's guaranteed to explode, but I personally wouldn't really want to use it.

The design itself is fine, if with rather interesting proportions and ratios, but I can't give it a real thumbs up because of my safety concerns.

I'm going to sound like an old grump by the time I'm done, but I'm also a little wary of your range measurements. Particularly with a tree line in the way, it would be very hard to actually find where a round actually landed. Would you care to elucidate on the matter?

However, if you're happy with it, that's the main thing, and don't let my ramblings affect how you feel about it.
At the very least, it shouldn't be too hard for you to find that perfect propane mix and get the real power out of it. Just don't stand too close.
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Unread postAuthor: SpudFarm » Fri Mar 21, 2008 5:48 pm

i am not 100% agree with you rag.. if he shoots protectiles that don't got an uber tight fit there is no really high pressure in that chamber..

i said to him over msn that i would have stuck to GB and no tight fiting ammo ..

you can see at DYI's cannon at 500psi the barrel holds up nice
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Unread postAuthor: bigbob12345 » Fri Mar 21, 2008 5:53 pm

Quite nice
I havnt read the other posts so i dont know if they have mentioned this but it really needs a longer barrel. I would say 10ft minimum for the golfball barrel but even longer would be better. With a chamber that large you could even add on a 3in barrel. that would give you much higher muzzel energy and wouldnt require as long of a barrel for a good CB.
And it looks familiar. Is it that gun that you were wanting to make pnuematic.
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Unread postAuthor: STHORNE » Fri Mar 21, 2008 6:05 pm

Ragnarok wrote:I'd like to say it's a nice launcher, but I have a gripe with it - I know people will disagree with me on whether this is acceptable - it uses unrated parts.
Combustion or not, unrated parts are not completely safe. You just need to search youtube to see dozens of cannons (combustion, mostly spray n' pray - for which many people will tell you that unrated parts are acceptable for) that have shattered or ruptured from pressure. I'm not saying that it's guaranteed to explode, but I personally wouldn't really want to use it.



In the original post, i said
I wrote:I bought all the pvc brand new (yes, it's dwv, i know)

and i know the.."risk" I'm taking using dwv parts but since I'm keeping it at relatively low pressures, I'm not concerned. Most of the people on youtube are idiots and either use way too much, or don't properly prime/cement there fittings.
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bigbob12345 wrote:Quite nice
I havnt read the other posts so i dont know if they have mentioned this but it really needs a longer barrel. I would say 10ft minimum for the golfball barrel but even longer would be better. With a chamber that large you could even add on a 3in barrel. that would give you much higher muzzel energy and wouldnt require as long of a barrel for a good CB.
And it looks familiar. Is it that gun that you were wanting to make pnuematic.




I wrote:I know the C:B ratio is messed up but i didn't have enough money atm to buy a longer section for the barrel, so i had to settle for 4ft Sad . I plan on either upgrading this cannon or just making a steel hybrid.

and yes, I originally planned on making it a pneumatic but decided not to because of the parts being dwv.
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Unread postAuthor: Ragnarok » Fri Mar 21, 2008 6:27 pm

sthorne wrote:In the original post, i said
I wrote:I bought all the pvc brand new (yes, it's dwv, i know)

and i know the.."risk" I'm taking using dwv parts but since I'm keeping it at relatively low pressures, I'm not concerned. Most of the people on youtube are idiots and either use way too much, or don't properly prime/cement there fittings.

You seem a little confused. More fuel doesn't equal more power. In fact, too much usually means no power at all. I would assume you knew that, but from your posts, it doesn't quite seem that way.

Your propane cannon is easily capable of more pressure than the cannons people use on Youtube. Often the failures I see on Youtube are not joints blowing apart, but the launcher actually doing an impression of an M67 grenade.
That's no mark of poorly made joints, but of the pipe being over loaded.

Mind you, I suspect that if I go on, this will degenerate into a useless argument, so I'll leave it... for now.
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Unread postAuthor: DYI » Fri Mar 21, 2008 6:30 pm

but since I'm keeping it at relatively low pressures


I've got to wonder how safe it is for you to be playing with something that you have little to no understanding of, especially when it's made of such dubious materials.
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