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Double barrelled 3x hybrid

Unread postPosted: Thu Jul 19, 2012 2:08 pm
Author: spudamine
This is yet another of my completely un-planned cannons, seeing a pack of these on the shelf:
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I was intrigued and couldn't resist the dual temptations of alcoholic beverage and a novel preesure vessel. The lager was unexceptional but I liked the aluminium bottles, the necks were about the right size for a 1/2" tap so I thought what the hell and a few weeks later this was sitting on my work bench:

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I'm not really into pneumatics these days so my first though was a straight up combustion, however the power would have been puny through the 1/2" orifice, so I thought I'd add a few x :)
Of course this brought up the obvious problem of the beer bottles exploding so they were sleeved with aluminium tube which was cross-bolted at the end and filled with wire mesh and hot glue. This gave me a chamber sufficiently safe up to about 3x, enough for some fun.To finish off I thought I'd give it two independently firing barrels and chambers. Finally hybrids are noisy beasts so barrel shrounds / suppressors were mandatory.

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Ignition is by two BBQ piezo units, one actually came out of my old barbecue which had rusted to bits (the rest gets shot in the video). The electrodes were tricky due to the wall of the chamber not really being thick enough to take a thread, i used an M8 mylon bolt with channels dremmeled down the side for enamelled winding wire electrodes, all tapped and epoxied in.
As i was determined not to buy anything for this project i didn't bother with proper unions for the burst disks, just used some pipe fittings epoxied together. This worked well although the rotating barrels gave poor accuracy (who cares, it's a shotgun)
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For metering I tried JSR's syringe technique which worked flawlessly, ignition first time. I've fired this thing a lot and it's not failed to ignite the mixture a single time. It just goes to show you don't need a hundred pressure guages attached to a hybrid to get it too work, one on the pump is sufficient (for low mixes/small chambers anyway).
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This is probably my favourite damage pic, this was only 1mm steel but the projectile punched a perfect full bore disk out of the target.

And finally the damage vid :D


Unread postPosted: Thu Jul 19, 2012 2:49 pm
Author: al-xg
Wow, quite an impressive canon and video there !
Looks like that will be quite popular.

Unread postPosted: Thu Jul 19, 2012 3:05 pm
Author: AircannonSweden
Looks very good :)

Unread postPosted: Thu Jul 19, 2012 3:23 pm
Author: killerbanjo
Oh damn that is VERY sexy!!! Nice work mate :D

Unread postPosted: Thu Jul 19, 2012 9:37 pm
Author: POLAND_SPUD
yet another so I got drunk and thought... :D

Unread postPosted: Fri Jul 20, 2012 1:29 am
Author: jackssmirkingrevenge
:shock:

Wow, just wow. This is everything I believe in! Hybrid, syringe fuelling, epoxy thrown in, full bore finned darts.... Brilliant!

Your "shotgun" sabots seem to be letting you down though, looks like they're coming apart in the barrel and not transferring all the energy to the projectile.

What do the suppressors look like internally?

Glad to see you using a syringe, I believe that manometric metering is something that puts a lot of pneubs off when building a hybrid, this is much easier and cheaper to set up.

Excellent work as always!

Unread postPosted: Fri Jul 20, 2012 1:32 am
Author: MrCrowley
jackssmirkingrevenge wrote:I believe that manometric metering is something that puts a lot of pneubs off when building a hybrid, this is much easier and cheaper to set up.
Na, it's definitely volumetric (excluding syringe metering)! :D

No one really uses manometric metering anyway :(
But there's one fixed pressure for each gas at each mix regardless of chamber size. No need to measure your chamber volume with water. All you need is one accurate 0-15PSI gauge and one normal 0-150PSI gauge.

That being said, I love the ingenuity of this cannon. Naturally, I wouldn't have said that if it weren't a hybrid. Good job :P

Unread postPosted: Fri Jul 20, 2012 1:36 am
Author: jackssmirkingrevenge
MrCrowley wrote:All you need is one accurate 0-15PSI gauge and one normal 0-150PSI gauge.


Think of how many big syringes you could buy for the price of those ;)

Unread postPosted: Fri Jul 20, 2012 7:42 am
Author: DYI
All you need is one accurate 0-15PSI gauge and one normal 0-150PSI gauge.


Or one really accurate 0-5000psi gauge... :lol:

That's an interesting use of beer bottles. It's nice to see people just "throwing together" hybrids - with proper construction, they really are very simple. Four years ago, this would've been yet another 1X combustion gun.

Unread postPosted: Fri Jul 20, 2012 7:54 am
Author: mark.f
Girls, girls, you're both very pretty. :P

Excellent job Spudamine. The bottle chambers seemed to be a little more trouble than they're worth but the double barrelled design is awesome. Not something I've seen in a hybrid yet.

Unread postPosted: Fri Jul 20, 2012 2:13 pm
Author: spudamine
Thanks for all the comments guys.
What do the suppressors look like internally?

They're a bit primitive really, just some holes drilled in the barrel near the muzzle and the outer chamber filled with wire wool and sealed, I'm not convinced they're doing a lot but I didn't want to have to build two complex suppressors.

The bottle chambers seemed to be a little more trouble than they're worth

They're the reason this cannon exists but I did find myself thinking I could have swapped them out for paintball tanks for a rather sweet 10x :)
Still it worked out rather nicely, even with all the reinforcement they have a nice strength to weight ratio.

Unread postPosted: Fri Jul 20, 2012 11:43 pm
Author: jackssmirkingrevenge
spudamine wrote:They're a bit primitive really, just some holes drilled in the barrel near the muzzle and the outer chamber filled with wire wool and sealed, I'm not convinced they're doing a lot but I didn't want to have to build two complex suppressors.


Sometimes it's hard to judge the performance of a suppressor, but even a crude one will take the edge of the muzzle "crack".

They're the reason this cannon exists but I did find myself thinking I could have swapped them out for paintball tanks for a rather sweet 10x :)


A certain crazy French forum member took paintball bottles to 40x :D

Still it worked out rather nicely, even with all the reinforcement they have a nice strength to weight ratio.


I would probably be comfortable taking them to 5x at least, but then again I'm not known for launchers that don't spread their parts around in a violent manner :D

Unread postPosted: Sat Jul 21, 2012 1:26 am
Author: spudamine
A certain crazy French forum member took paintball bottles to 40x

Alas said crazy frenchman also has a nice field to shoot in, not a garage attached to the side of his house :(

I was going to take it up to 4x but I first found a 60ml syringe, then calculated the required fuel volume as something like 60.2ml, which I consider fate :)

Something strange i've noticed about this cannon, the right barrel appears to be consistenly more powerful than the left. for example look at the .177 pellet shot into the plywood, on the left barrel only one pellet makes it through, the right just blows a big hole through. I've also had two misfires on the left (ignition but failiure to burst the disk) and none on the right.
This is particularly odd as the two chambers, barrels and burstdisk holders are identical. The only potential difference is the ignition :?:

Unread postPosted: Mon Sep 03, 2012 5:38 am
Author: hawktalk
stunning creation, its very shiny 8)

Unread postPosted: Tue Sep 04, 2012 10:19 am
Author: PotatoEnemy17
Awesome Cannon, Kinda reminds me of when I built a cannon with water bottles - oh wait that one turned in to a bomb, oops! It looks pretty ergoomic :P