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New to the forums - my 2nd cannon

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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New to the forums - my 2nd cannon

Unread postAuthor: Boom_erang » Fri Apr 25, 2008 2:44 pm

Hello spudders! I'm only about a month into this whole thing, but I've built my 2nd cannon and I'm having a blast, so to speak!

This is PVC, with a 4" by 16" chamber, and a 4' by 2" barrel, with suppressor. Since building this one last weekend, I've learned that the suppressor should not have holes in the outer jacket, so I'll be changing that out probably this weekend. The suppressor could probably use more internal volume to be effective, but it helps a little bit.

The ignitor is a CharBroil piezoelectric starter, with a solid wire extending the rear terminal to be a spark plug. It's mounted in a "trigger" position on the "handle" of the big T, and is positioned very near the center of the chamber. It is very effective, and fires every time as long as the gun is properly fueled.

For fuel, I use Static Guard, although I've tried AquaNet and it works, too, but not as effectively. Static Guard takes about a 1/2-second spray into the chamber for an excellent ignition.

Here's a YouTube video showing a little bit more about this, including some shots fired with it with my dad in his backyard.

http://www.youtube.com/watch?v=g2wdYk431hs

I look forward to exchanging ideas and learning a lot from you veterans!

Next project: a mini

-B[/url]
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Combustion Potato Cannon Mark II, with 4" x 16" chamber, 4' x 2" barrel.
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Unread postAuthor: potatoflinger » Fri Apr 25, 2008 2:56 pm

Wow, nice gun, I really like the desert camo paint job :thumbright:
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Unread postAuthor: SpudFarm » Fri Apr 25, 2008 3:02 pm

yead that has to be a blast! :D
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Unread postAuthor: biggsauce » Fri Apr 25, 2008 3:15 pm

Hey, nice cannon. I really like the paint and the suppressor look 8)
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Unread postAuthor: jrrdw » Fri Apr 25, 2008 3:41 pm

Nicely done, Boom_erang! Unfurtuneitly my computer is having a few problems downloading rite now, so I will have to watch the video later, I'm looking forward to it. Nice write up also.

Welcome to Spudfiles, two thumbs up!
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Unread postAuthor: Boom_erang » Fri Apr 25, 2008 5:06 pm

Thanks for the comments, guys. As I've been reading the forums, I've been learning about the 0.8:1 C:B ratio as being more effective than the 1.5:1 I've been using. Back to the drawing board! I can probably shorten the chamber on this one, but it's always good to start fresh. These things are so inexpensive to build that it's just plan fun to build a new one. I'll have to read up a bit more about the metered propane, though. Looks like a good solution.

By the way, I forgot to mention the paint I use. Krylon makes "Super-flat" camouflage paint that sticks pretty well to plastic. I got the tan, and the dark brown to make desert camo.

-B
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Unread postAuthor: OuchProgramme » Fri Apr 25, 2008 6:29 pm

Nice supressor :)

0.8/1 is the suggested ratio, but some prefer aethestically pleasing cannons more than preformance.
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Unread postAuthor: Lentamentalisk » Fri Apr 25, 2008 7:07 pm

The C:B ratio would be better named the B:C ratio. It is more a suggestion as to how large of a barrel you should have for a specific chamber. Decreasing you chamber size will lower the power you get, but you could instead increase the barrel length to get more power.
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Unread postAuthor: Boom_erang » Sat Apr 26, 2008 1:04 am

Lentamentalisk,

Understood. I'm just trying to optimize the gun for a given barrel size and also make it manageable and reasonably quiet. Seems that although reducing chamber size may reduce power, too big of a chamber wastes that power anyways in muzzle flash and "bang".

Did some work on the gun tonight, actually. ended up making a whole new chamber at 8" and the barrel is slightly shorter at 40". Also working on a better suppressor with more volume. Pictures to come once I've painted it and all that... and tested it.

-B
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PC 2.5 Updated with new video

Unread postAuthor: Boom_erang » Sat Sep 06, 2008 4:39 pm

So far this has been a very reliable gun, even though it's only a spray 'n' pray. I was hoping to also get some footage from a different day off of my brother's cell phone, but I haven't figured out how yet. Maybe he can email it to me...

http://www.youtube.com/watch?v=v4LecJvP81I

-B
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Unread postAuthor: SpudFarm » Sat Sep 06, 2008 4:44 pm

not more to say than, heck i like this gun!

good job!
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Unread postAuthor: rp181 » Sat Sep 06, 2008 4:57 pm

nice paintjob.

If you ever decide to go metered propane, ide suggest building another one with pressure rated fittings.

Allaround nice cannon =).
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Unread postAuthor: iPaintball » Sat Sep 06, 2008 5:45 pm

Very nice cannon and great paint job. This puts my second cannon to shame :( One comment about the suppressor, you will notice a very significant drop in sound output without the holes in the shroud. Remember, a suppressor's job to to keep the sound inside, not let it out. Again, very clean build and i look forward to seeing more from you in the future.
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Unread postAuthor: starman » Sat Sep 06, 2008 6:37 pm

Boom_erang wrote:I've been learning about the 0.8:1 C:B ratio as being more effective than the 1.5:1 I've been using. Back to the drawing board! I can probably shorten the chamber on this one
-B


It's a little more efficient but only by a few percentage points. 1.5:1 is actually a reasonable compromise for a 1.5" barrel and a chamber size you have. A 5' 1.5" barrel is about the longest practical for a handheld inline combustion cannon like yours. It will give you slightly more but noticable performance.

This is a nice spray and pray cannon. I like your paint job and obvious effort to get it right. Next time use couplers and reducer bushings and avoid the DWV fittings.

Good job!!
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Unread postAuthor: Boom_erang » Sat Sep 06, 2008 8:44 pm

Thanks, guys! This gun performs pretty well for what it is... I've been reading up in my US Plastics catalog and McMaster web site on the fittings, etc., so my next one will be all pressure rated. I've learned a hell of a lot on this site, by the way. Many of the cannons here are just stunning!

A couple of comments. This gun started out with a 4"x18" chamber, and 48" barrel. The original suppressor had holes in the outer jacket, and was smaller in diameter. I've made a lot of changes since then! The chamber is now nly 8.5 inches long, and the barrel is 42", the holes in the barrel are larger, and the suppressor is larger with no holes in the outer jacket. Overall, the gun is more compact, and is quieter, although not by much. My original 3"x18" chamber with 48"x1.5" barrel gun is actually quieter than this, but too long to cart around. Plus, I like the impact of the 2" projectile...

I'm still learning (hopefully we all are) so thanks again for the comments.

-B
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