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mini hybrid win!

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 22, 2010 2:02 am

I had done some testing here, the fragments were flying fast enough to penetrate beer can.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Unread postAuthor: ilovefire » Mon Nov 22, 2010 2:17 am

thats impressive, but not all that surprising, i mean you dont just expect all that lead to just stop dead still :lol:
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 28, 2010 4:45 am

Tried a shotgun round using a plastic marker cap as a sabot, guess what happened :roll:

[youtube]http://www.youtube.com/watch?v=k8tpUs2X8jE[/youtube]

As you can see the sabot fragments made it to the target first, followed by the lead shot that was obvious not very energetic, having only the gas blast to push it along...

Here's what's left of the sabot:
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Unread postAuthor: ilovefire » Sun Nov 28, 2010 6:23 am

ha ha ha what about making a cup out of layered aluminium foil, not sure if it would work but i think its worth a try
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Unread postAuthor: Labtecpower » Sun Nov 28, 2010 7:28 am

never had anything like it with my piston cannon....
I would think that a plastic cup should be strong enough to survive the blast :roll:
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Unread postAuthor: saefroch » Sun Nov 28, 2010 11:39 am

I see a good application for a solid steel sabot...
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 28, 2010 11:54 am

saefroch wrote:I see a good application for a solid steel sabot...


Actually, a 12 gauge shotgun sabot would be perfect, fits nicely in the barrel and can take the 12-15,000 psi the firearm generates - I just don't have any around at the moment.
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Unread postAuthor: jackssmirkingrevenge » Wed Dec 01, 2010 1:21 pm

The hybrid R&D persists, I made a new chamber for a 0.75" barrel, this time just over three times volume of my previous one at 90mL. Tried it out at 6x and it was louder than the smaller one at 12x, which already exceeds tolerable noise levels for an urban environment, so I decided to make a suppressor to see what extent I can reduce the noise. It's a pretty basic design with 2 expansion chambers, but the suppressor tube is 100mm diameter drain pipe which gives it a total volume of over 5 litres :D currently curing, will probably test it tomorrow.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Unread postAuthor: Fnord » Wed Dec 01, 2010 2:32 pm

100mm diameter drain pipe... 5 liters


?!

How long is the barrel again?

Properly designed, a five liter silencer should be good for anything up to and including a stealth hand-grenade. I know the other one you made didn't do much, but if this doesn't work you must be doing it wrong :P

Did you back the epoxy plugs with anything, to avoid fragmenting them when that pressure wave hits? They look pretty thin in the diagram.

Also, how do you intend to aim a .75" bore with a drainpipe in the way?
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Unread postAuthor: JDP12 » Wed Dec 01, 2010 2:45 pm

Looks awesome!! Can't wait to see the pictures.

Fnord... you could add a sight along the suppressor, or paint a line along the top of the suppressor to aim down, or if you really wanted to, add a laser sight to the tip of the suppressor.
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Unread postAuthor: jackssmirkingrevenge » Wed Dec 01, 2010 2:57 pm

Fnord wrote:How long is the barrel again?


Around 75cm

Properly designed, a five liter silencer should be good for anything up to and including a stealth hand-grenade. I know the other one you made didn't do much, but if this doesn't work you must be doing it wrong :P


The one I made for the mini wasn't exactly well made in the sense I was concerned about losing power so the porting was fairly limited. A "proper" suppressor would look something like this one ;)

Did you back the epoxy plugs with anything, to avoid fragmenting them when that pressure wave hits? They look pretty thin in the diagram.


Some very rough calculations for say a 5 litre suppressor + barrel and 100mL chamber generating 1000 psi, worst case scenario if you plug the muzzle it's not going to generate more than 20 psi, so I'm not too worried. Besides it's not just epoxy, I threw inthis filler, the result is incredibly tough and the plugs are over 1cm thick. The pipe wall thickness is only 1.5mm so it's not the plugs that are the weakest point anyway.

Also, how do you intend to aim a .75" bore with a drainpipe in the way?


This is more of a test rig so aiming is not really a concern.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Unread postAuthor: JDP12 » Wed Dec 01, 2010 3:07 pm

Is there a name for this filler, or perhaps a substitute one could use?
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Unread postAuthor: jackssmirkingrevenge » Wed Dec 01, 2010 3:16 pm

JDP12 wrote:Is there a name for this filler, or perhaps a substitute one could use?


This is the stuff.

There are other improvised options for thickening up epoxy though, in the past I've used sawdust or even talcum powder.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Unread postAuthor: Fnord » Wed Dec 01, 2010 3:46 pm

er... fiberglass?
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Unread postAuthor: jackssmirkingrevenge » Wed Dec 01, 2010 4:20 pm

Fnord wrote:er... fiberglass?


...as a wrap, but not as a filler, right?
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