To hell with single shot testing, couldn't wait to try it out with pellets
Ten round bursts using unmodded 0.22" (5.5mm) airgun pellets in a 6mm barrel at 100 psi, firing at a 0.5mm (0.02") thick aluminium plate target. The second video is with a greater flow into the chamber and therefore greater rate of fire.
Basically it's this valve coupled with this magazine, simple but effective
edit: update 07/04/2009
Here it is with the hopper and BBs as ammo, not 100% reliable but good enough. Note how the rate of fire decreases progressively as the pressure in the compressor goes down. Target was a plastic box.
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Here's the hopper and valve firing:
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Unfortunately with the smaller calibre power is down from what it had been with pellets, here's what happened with the 0.5mm aluminium plate, most rounds failed to penetrate it - no video though, too many BBs flying back at my face but with 450-850 psi on tap eventually it should be a blast, literally
Posted: Fri Apr 03, 2009 10:41 am
by sniper hero
wow
post a pic of the gun !
and tell something about pressure and range
this is really amazing
Posted: Fri Apr 03, 2009 10:48 am
by jackssmirkingrevenge
sniper hero wrote:post a pic of the gun !
Nothing to see really, it's the valve I made attached to a barrel and tee magazine
and tell something about pressure and range
pressure is about 7 bar, range for now is accross my garage floor
Posted: Fri Apr 03, 2009 11:16 am
by Brian the brain
This looks to be what you were after all this time..
Congratulations!!!!
So I was pretty close with the Snapvalve huh....
I'll give it another go soon..
Posted: Fri Apr 03, 2009 11:28 am
by jackssmirkingrevenge
Brian the brain wrote:This looks to be what you were after all this time.
Indeed, you should see the size of my grin at the moment
So I was pretty close with the Snapvalve huh....
Always - I think there are two key design elements to keep in mind for a reliable design:
1) The piston seat must be significantly bigger than the outlet to the barrel, to ensure that the piston chamber fills with pressure faster than it can empty and the piston has time to actually pop
2) The piston must be significantly wider than the piston seat, in order for there to be enough area for the pressure to act on and overcome the spring strength.
Remember this is at only 7 bar, imagine what you could do with 30!
I'm asking the Easter bunny for a fridge compressor!
Posted: Fri Apr 03, 2009 11:28 am
by ALIHISGREAT
its got a fair bit of power for 100psi, how long is the barrel?
Posted: Fri Apr 03, 2009 11:35 am
by jackssmirkingrevenge
ALIHISGREAT wrote:its got a fair bit of power for 100psi, how long is the barrel?
About 36 inches. This by the way was with the barrel held against the valve, and the magazine blocked with my finger leaking air all over the place, so once everything's sealed up the power potential is higher
Posted: Fri Apr 03, 2009 11:46 am
by ALIHISGREAT
jackssmirkingrevenge wrote:
ALIHISGREAT wrote:its got a fair bit of power for 100psi, how long is the barrel?
About 36 inches. This by the way was with the barrel held against the valve, and the magazine blocked with my finger leaking air all over the place, so once everything's sealed up the power potential is higher
ahh so its relatively long, that explains it!
Posted: Fri Apr 03, 2009 12:18 pm
by SPG
FINALLY !!!!!
What range is this shot at ?
Posted: Fri Apr 03, 2009 12:24 pm
by dewey-1
jackssmirkingrevenge wrote:
Brian the brain wrote:This looks to be what you were after all this time.
Indeed, you should see the size of my grin at the moment
I bet it is a real shite eating grin too!
Does this mean you will be changing your avatar soon?
Congrats on your longtime endeavor to success!
Posted: Fri Apr 03, 2009 12:32 pm
by jackssmirkingrevenge
SPG wrote:FINALLY !!!!!
What range is this shot at ?
A couple of metres
As to the blowback bolt, I don't think I'm going to try it with this one to be honest, at 100 psi the power is marginal and I think it would lose too much energy cycling.
The next step I'm considering is buying one of these and hooking it up to a properly made pop-off valve. I've made some friends in the stainless steel welding business through work, I reckon if I got some *shock horror* standard parts together I could have one made at a reasonable price - then there would be power to spare and the world would be my proverbial oyster
dewey-1 wrote:Congrats on your longtime endeavor to success!
Thanks, it means a lot
Posted: Fri Apr 03, 2009 1:05 pm
by mark.f
Congratulations. Maybe you could stop clogging up the pneumatic cannon discussions already. kidding
Looks like a pretty effective feed. No double/triples/streams of ammo per shot. Looks like friction can be a good feeding aid...
Posted: Fri Apr 03, 2009 1:21 pm
by jackssmirkingrevenge
mark.f wrote:Maybe you could stop clogging up the pneumatic cannon discussions already. kidding
I know, I know, I have made a bit of a fuss of this personal crusade... but see! there ARE viable alternatives to 1,304,874 round per second cloud BBMGs
Posted: Fri Apr 03, 2009 1:32 pm
by Carlman
Good work mate! I'm glad ypu got er working, now kick it in the gut and lets see what she can really do!
Posted: Fri Apr 03, 2009 2:09 pm
by POLAND_SPUD
so.. that's it ?? I was expecting something more impressive...
but with 450-850 psi on tap eventually it should be a blast, literally 
