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electro-pneumatic full auto design

Posted: Sun Sep 23, 2007 12:42 pm
by jackssmirkingrevenge
Following the lack of success of my blow forward experiments, I've decided to try a different approach. The breech is attached to a shaft and is free to rotate, and also has a cutaway. Ammo is fed from the top, air from the bottom, and the rotating hole alternately feeds air and ammo into the barrel. This is a bit of an old concept, SPG had done some work on it on spudtech but nothing concrete had come out of it.

The prototype's being built, I'll keep you posted with the progress.

Posted: Sun Sep 23, 2007 12:52 pm
by Hubb
Sealing may be a problem but you could probably get it to work right. Also, it seems that the barrel will have to be an exact fit for your ammo or that rotating piece may jam against the next round.

Besides, is there anything you can't do (besides post first in almost every thread)?

Posted: Sun Sep 23, 2007 1:17 pm
by iPaintball
I can tell this is gonna look sweet. Just make sure you use o-rings and plenty of lube. Again, anotherfull auto design. Stop being so creative! :D

Posted: Sun Sep 23, 2007 1:21 pm
by jackssmirkingrevenge
I'm relying on the tight fit to minimise leaks to a tolerable level.

With epoxy you can do anything :) here's the breech curing, I basically made a cardboard mould and pored the epoxy in. The rotating bit has been cut too.

Posted: Sun Sep 23, 2007 1:27 pm
by HaiThar
I actually have a fully automatic electric airsoft gun that works just like the one you are suggesting...but it's fed in through a spring loaded magazine.

Posted: Sun Sep 23, 2007 1:29 pm
by spanerman
waiting with baited breath for this one!!

Posted: Sun Sep 23, 2007 1:31 pm
by Gepard
What's to stop you just drilling a hole through the wall of a BV? Then just hook the BV up to a motor.....

Might be half as efficient but should have the same effect with less hassle surely? And you could use the second blast to propel it further....

Posted: Sun Sep 23, 2007 1:31 pm
by jackssmirkingrevenge
HaiThar wrote:I actually have a fully automatic electric airsoft gun that works just like the one you are suggesting...but it's fed in through a spring loaded magazine.
are you sure it doesn't work like this?

Image
Gepard wrote:What's to stop you just drilling a hole through the wall of a BV? Then just hook the BV up to a motor.....

Might be half as efficient but should have the same effect with less hassle surely? And you could use the second blast to propel it further....
Fnord illustrated the idea in this post, SPG had drawn up similar plans on Spudtech. My problem with the ball valve idea is too much drag that would require a very powerful motor to work, but if you're willing to live with that it would certainly work very well.

The great thing about using a motor is that the rate of fire is infinitely variable by altering the revs per minute.

Posted: Sun Sep 23, 2007 1:38 pm
by HaiThar
actually now looking back...it wasnt either. It was just electric... :oops:

Posted: Sun Sep 23, 2007 1:41 pm
by Gepard
Ahh thought it'd seen it somewhere - can't you lube it up?

What sort of ROF you trying to get?

Looks good though - you tape up the sides?

Posted: Sun Sep 23, 2007 1:58 pm
by jackssmirkingrevenge
I don't know how effective lube would be. It would certainly make a good design for a full auto marble gun, the valve would be extremely efficient (because the marble would drop into the valve and fire only when the valve was fully opened) but the motor needed to drive it would have to be along the lines of a cordless drill.

I'm aiming for a ROF of around 2-3 rounds per second, to give the "dakka dakk dakka" machinegun effect as opposed to the hosepipe "braaaap" that strafers do. The aim here has always been lower rate of fire but more power per shot.

The box is made from an old airfix sopwith camel box hehe (you can just see the "world war I" script), the tape is used to keep the box together and the edges are then sealed up with glue to contain the epoxy.

Posted: Sun Sep 23, 2007 2:24 pm
by windshrike
Jackssmirkingrevenge,
you'll do anything to achieve the dakka dakka dakka you've been humming for so long, won't you?

Posted: Sun Sep 23, 2007 2:31 pm
by jackssmirkingrevenge
every man has a holy grail :)

Posted: Sun Sep 23, 2007 2:37 pm
by iknowmy3tables
no offense man but this is starting to sound like the frequently thought of rotating breech and valve design that we know doesn't work well,
http://www.spudfiles.com/forums/my-firs ... t4566.html
only diffrence is your kinda making the ball valve which might work but really I've seem you make some crazy stuff but machining such a thing is a feat I don't think any of us can do with basic machining tools

Posted: Sun Sep 23, 2007 11:06 pm
by jackssmirkingrevenge
no offense man but this is starting to sound like the frequently thought of rotating breech and valve design that we know doesn't work well
I know the idea has been floating around for years but this is a somewhat different take which I'm fairly confident will work well. It should be ready for basic testing in a few days, watch this space :)