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"valveless" cartridge concept

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Unread postAuthor: Fnord » Wed Nov 10, 2010 1:09 pm

It's good to see you finally got it working, though it sounds as though some large marine mammal is purging its blowhole in the background :)

How much air leakage are you seeing?
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Unread postAuthor: jackssmirkingrevenge » Wed Nov 10, 2010 1:38 pm

Labtecpower wrote:Maybe you could remake it with some durable materials?


As stated earlier, this is just a proof-of-concept model, my intention is to make a neater version now that I proved the idea works.

How much air leakage are you seeing?


I suppose it sounds worse than it actually is (remember that air flowing down the remote line makes noise even through a completely sealed connection), I have 3 more cartridges curing so in a couple of hours I'll be able to do before and after measurements of paintball tank pressure to calculate air usage for a 5 round burst.
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Unread postAuthor: Ragnarok » Wed Nov 10, 2010 2:07 pm

... Oh I see. It's taken me ages to work out what the extra unfired cartridge was doing. I thought it was just there to test the feeding - clever.

(Yeah, you probably said earlier, but I equally probably missed it.)
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: Brian the brain » Wed Nov 10, 2010 4:03 pm

As stated earlier, this is just a proof-of-concept model, my intention is to make a neater version now that I proved the idea works.


You mean you're finally ready to move on to the next stage? :D
I thought all your contraptions were proof of concept items....


It would be nice to see a finished version of this thing, before someone else runs off with the idea...

My compliments buddy... the flying cartridges look supercool on high speed.

Oh Rag...I understand they aren;t exactly super-cooled, although cooled slightly from the decompression.. :roll:
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Wed Nov 10, 2010 6:21 pm

Oh WIN!!!!

[youtube]http://www.youtube.com/watch?v=cB1JzDdWlMc[/youtube]

5 round mag dump full auto, 420 and 210 frames per second (though granted the latter video only made it to 4 rounds because the thing fell over :roll:

I wanted to make some better videos (and some target ones because dammit, this is a BBMG, not a cartridge launching machine) but the thing stopped working, there seems to be some kind of obstruction in the barrel so I'm going to hack it off :)

edit: it seems there was lead buildup at the breech where the projectiles enter the barrel, something to keep in mind for my next design.

Have another 5 round burst, at 1000 frames per second it seems almost painfully slow...

[youtube]http://www.youtube.com/watch?v=lFOB1Sk7Jek[/youtube]

Brian the brain wrote:You mean you're finally ready to move on to the next stage? :D
I thought all your contraptions were proof of concept items....


Good point ;) but in this case, since the focus is not only what the launcher does to the target but how it actually works, you'd want something a bit more presentable.

One interesting thing, after the first burst there was a distinct smell of burnt propellant, WTF I thought then it clicked that whatever residue that was left in the cartridges after they were last fired from a firearm had been blown out :)

As to air consumption, compare the gauge (on a 48 cubic inch tank regged down to 800 psi) before and after firing 5 rounds:
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Unread postAuthor: MrCrowley » Wed Nov 10, 2010 7:31 pm

FINALLY! A project of yours that wont end up in the "If it doesn't work you can always hit them with it" pile :D

I'm surprised how fast you've managed to get it to cycle, what ROF do you have in mind for the final version? How many cartridges do you plan on making?

This is a seriously cool piece of equipment though, good stuff! :)
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Unread postAuthor: POLAND_SPUD » Wed Nov 10, 2010 8:59 pm

what ROF do you have in mind for the final version?
I don't think that it has to be set. Put a flow control valve there and you've got adjustable ROF
If he decides to use a pressure washer (which technically is a proportional valve) as the trigger it can be work pretty much like the trigger on styer AUG and TMP
pulling the trigger halfway produces semi-automatic fire, pulling the trigger all the way to the rear produces fully automatic fire


Though in this case it would be more like 'semiauto and/or short bursts and/or fullauto at low ROF'
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 11, 2010 12:33 am

MrCrowley wrote:A project of yours that wont end up in the "If it doesn't work you can always hit them with it" pile :D


Nice subtle reference there, Boris :P :D

I'm surprised how fast you've managed to get it to cycle, what ROF do you have in mind for the final version?


I like it as it is, as our Polish comrade mentioned it's impressive on full auto but slow enough for a careful trigger pull to give you only one shot, like the M3 grease gun.

I don't think that it has to be set. Put a flow control valve there and you've got adjustable ROF


That's pretty much the idea, and this is feeding directly from the remote line adapter which has very poor flow, so it has the potential to shoot much faster in terms of rate of fire with a better valve.

One thing I've noticed from the high speed footage is that the cartridges don't pop off at the same, rate, my guess is it depends on the orientation of the cartridge when it is chambered, ie to what extent one of the cartridge ports is in line with the feed port.

How many cartridges do you plan on making?


There's nothing to it, just glue a seal in the mouth, drill a couple of holes and polish it by spinning on a drill, so as many as I need :)
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Unread postAuthor: Brian the brain » Thu Nov 11, 2010 2:20 pm

there seems to be some kind of obstruction in the barrel so I'm going to hack it off



The barrel IS the obstruction...at least if you want to move around with this thing.You should always hack it off... :D

But more seriously...you probably need enough barrel length to build up the blowback required to cycle the system...
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Gun Freak » Thu Nov 11, 2010 4:55 pm

Brian the brain wrote:But more seriously...you probably need enough barrel length to build up the blowback required to cycle the system...

I think his earlier test showed that even without a barrel the cartridge could eject itself.
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 11, 2010 11:53 pm

Gun Freak wrote:I think his earlier test showed that even without a barrel the cartridge could eject itself.


That was with the hybrid cartridge, sadly with the current barrel length of 2 inches this pneumatic model won't cycle.

But more seriously...you probably need enough barrel length to build up the blowback required to cycle the system...


Adding a detent seal at the breech would probably allow it to cycle even with no barrel, but finding the right pop-off pressure would be critical as it might eject the cartridge before the projectile clears the seal.
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