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hybrid cartridge protoype without burst disk

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: al-xg » Mon Sep 19, 2011 3:01 pm

The Delrin would still have to withstand the 28x starting pressure.

Threaded Delrin just doesn't seem right :D Although an added 50% thread length would look safer somehow.

It seems the reduced ring surface aera works quite well. With the last drawing you could do the smaller "O" ring with a stepped bore to prevent too much compression, would be nice if it worked without though.

Oh and this came up on the French forum:
http://www.airmunition.info/index.html

Not very powerful, but still pretty cool.
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Unread postAuthor: jackssmirkingrevenge » Mon Sep 19, 2011 3:19 pm

al-xg wrote:The Delrin would still have to withstand the 28x starting pressure.


Maybe I can cup it, as attached?

Threaded Delrin just doesn't seem right :D Although an added 50% thread length would look safer somehow.


I know what you mean, but it's such a small bore...

It seems the reduced ring surface aera works quite well. With the last drawing you could do the smaller "O" ring with a stepped bore to prevent too much compression, would be nice if it worked without though.


Hmmm... interesting thought.

Oh and this came up on the French forum:
http://www.airmunition.info/index.html

Not very powerful, but still pretty cool.


*cough* ;)

Labtecpower wrote:But I see you had sealing problems..


... mostly due to a poorly sealing fill rig it seems, nothing to do with the cartridge design.

LOL @ the rage comic :D

POLAND_SPUD wrote:lol that reminds me of one occasion when I was going to suggest caseless (more like GP-25 granades than this) ammo on one occassion but then I realized you want flying brass dammit!


:D

This is a 9mm variation, quite interesting - the AUPO designed for the Benelli CB-M2

It's the flying brass Labtecpower was suggesting ;)
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Unread postAuthor: al-xg » Mon Sep 19, 2011 4:17 pm

Is that for sealing or for holding together ? I was referring to POLAND's full Delrin cartridge suggestion.

I reckon the first drawing was OK, I'd just have a longer thread on it, I guess the next test will tell :)

Ah well, a bit behind on my Spudfiles reading it seems... wow what's up with the post dating !? The first post of that topic is dated 2007 :?
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Unread postAuthor: jackssmirkingrevenge » Mon Sep 19, 2011 4:59 pm

al-xg wrote:Is that for sealing or for holding together ? I was referring to POLAND's full Delrin cartridge suggestion.


Hmmm... I'm sure a rifle sized Delrin cartridge with reasonably thick walls could take a couple of hundred psi safely... but still, not brass ;)

I reckon the first drawing was OK, I'd just have a longer thread on it, I guess the next test will tell :)


You know, this one with the hole for the pins drilled off-centre to avoid the spark jump issue should be fine, it can be a single pin too.
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Unread postAuthor: al-xg » Thu Sep 22, 2011 9:49 am

Oh, I meant to post this the other day, but was at work and forgot.
Image

Part sizes are a bit random (fat o-ring :D), the bore is .22 though.

Oh and that front section is meant to be threaded, not sure what I did there.

Edit: Oh and I meant to make the O-ring compression stop a bit longer.

Also Edit: I meant to drill a couple of holes in the srew in brass bit, to be able to unscrew it, with a handy custom tool ?
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Unread postAuthor: jackssmirkingrevenge » Thu Sep 22, 2011 12:21 pm

Looks great but unless you use thread tape... or have I missed something?
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Unread postAuthor: al-xg » Thu Sep 22, 2011 12:57 pm

Yeah no tape would be better. Tapered thread? Or O-ring on the brass or Delrin ring. The delrin plug should seal depending on the fit but I guess an o-ring or rubber washer could be used.

...or just drop the compression stop and use a closer to bore size cartridge like the last prototype.

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Unread postAuthor: jackssmirkingrevenge » Fri Sep 23, 2011 2:53 am

al-xg wrote:Yeah no tape would be better. Tapered thread? Or O-ring on the brass or Delrin ring. The delrin plug should seal depending on the fit but I guess an o-ring or rubber washer could be used.


Image

A groove in the delrin ring should allow it to act like a parachute seal.

What is critical is that the pressure drop on the outside of the fill rig should be dramatic. At the moment I'm just using the fill schrader, I'm wondering if I should add an exhaust valve, or perhaps an adjustable pop-off that automatically drops the pressure once the desired mix number is achieved.

edit: speaking of polymer cartridges, looks what cropped up on TFB: http://extremepolymer.blogspot.com/2011 ... -case.html
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Unread postAuthor: al-xg » Fri Sep 23, 2011 11:13 am

3 way valve + regulator + syringe -> automated syringe metering :)

Oh and while I'm at work...
Image
Some more useless 3D. I just like using the program :)

Obviously the O-ring wouldn't be used with the cup. (that sounds worse than I thought)
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Unread postAuthor: POLAND_SPUD » Fri Sep 23, 2011 11:54 am

that sounds worse than I thought

two spudgunners (al-xg + jsr) and one cup
yikes :?

3 way valve + regulator + syringe -> automated syringe metering
not a new concept - I've seen two guns that used it

What is critical is that the pressure drop on the outside of the fill rig should be dramatic
Been there (I understand you're referring to the fact that detents need to reach a given minimal pressure to work correctly)

Get a 1/8" QEV and a 3 way
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Unread postAuthor: al-xg » Fri Sep 23, 2011 12:03 pm

Could one not just chuck a spring in there?
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Unread postAuthor: POLAND_SPUD » Fri Sep 23, 2011 12:21 pm

Could one not just chuck a spring in there?
to keep the ammo pressed against the oring ??
hmm you might be right
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Unread postAuthor: al-xg » Fri Sep 23, 2011 12:57 pm

Between the ring and the check valve, coil diameter close to the cartridge ID. Fair point with keeping the projectie in place though, I guess one just has to keep the cartridge pointing down while filling.
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Unread postAuthor: jackssmirkingrevenge » Fri Sep 23, 2011 11:44 pm

al-xg wrote:Some more useless 3D. I just like using the program :)


Which one is it by the way?

two spudgunners (al-xg + jsr) and one cup


You need some new material ;) (and I managed to find that with spudfiles search :P :D)

I guess one just has to keep the cartridge pointing down while filling.


... rather while emptying the rig, this is what I've been doing.

Could one not just chuck a spring in there?


Better to add one time complexity to the fill rig than complicated every cartridge, this is how I see it:
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Unread postAuthor: al-xg » Sat Sep 24, 2011 3:25 am

... rather while emptying the rig, this is what I've been doing.


Oh yeah I keep forgetting the whole cartridge goes in.

Which one is it by the way?


SolidWorks, very user friendly, probably my preferred choice for CAD now.

this is how I see it:


Weren't you meant to be venting the filling chamber on disconnecting the schrader ? :?

You should use some sort of quick release plug, or even just an o-ringed threaded cap.

Maybe a large version of one of these schrader connectors:
<img src="http://www.jerzeecustoms.com/images/GaugesTire/EZ-02%200-100%20Tire%20Pressure%20Gauge%20001.jpg" width="300" height="200">
to hold the plug in.
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