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| jackssmirkingrevenge |
 Posted: 01/07/2008 10:02 AM Post subject: valveless launcher patent |
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aspiring machinist
Joined: 15 Mar 2007
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An interesting take on the "valveless" design (where the projectile seals the chamber) in this patent.
The red lever pushes the green pin with moves the purple projecile enough for air to get behind its base, the resultant pressure difference launches the projectile.
I believe there had been a similar design made on spudtech. The inconvenience is the need for a perfect seal and a rigid projectile.
I have come up with this (rough) deisgn a few years back on the same principle, actuated by a piston valve instead of a mechanical rod:
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| Hotwired |
| Posted: 01/07/2008 10:15 AM Post subject: |
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UK Spudgunner
Joined: 13 Oct 2006
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Hmm.
I had an idea similar to the patented design for a chain of projectiles fed into that position in semi-auto where the projectile immediately behind is the breech seal.
Too complicated to actually make.
However that design looks fine. As long as you were certain the whole system sealed perfectly.
Otherwise, as there is no safety mechanism at all, once air gets behind the projectile it fires 
Incidentally jack, doesn't your sketch look like an unneccesary complication of a coaxial piston cannon? 
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| Fnord |
| Posted: 01/07/2008 10:53 AM Post subject: |
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reenigne
Joined: 13 Feb 2007
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| I bet you wouldn't even need a piston. You could just use a blowgun to give the projectile a "tap", and full flow would kick in as soon as it started moving forward.
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| jackssmirkingrevenge |
| Posted: 01/07/2008 12:01 PM Post subject: |
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aspiring machinist
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| It would be the equivalvent of a piston valve with zero opening time and maximum flow, so if it's performance you're after then it's not an unnecessary complication.
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| ALIHISGREAT |
| Posted: 01/08/2008 17:08 PM Post subject: |
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Eternal Noob
Joined: 25 Aug 2007
Posts: 1799
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| so could i shove a projectile down the barrel and over some orings and then use somehting to push it forewards and it would be just like that design or is it a bit more complicated?
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| benstern |
| Posted: 01/08/2008 18:30 PM Post subject: |
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Looks too inconvenient to warrant constructing. Also does not look like any performance increase would be had by this design. A novelty at best. 
Oh and it is a valved design! Note: piston and exhaust valve.
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| jackssmirkingrevenge |
| Posted: 01/08/2008 22:59 PM Post subject: |
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aspiring machinist
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| benstern wrote: | | Oh and it is a valved design! Note: piston and exhaust valve. |
Ignore my design, the patent shows the projectile simply pushed forward by a lever to expose its base and fire it.
The performance advantages could be tremendous, because unlike a piston valve which is still opening after the projectile has started to move, once the base of the projectile passes the end of the barrel its the equivalent of a piston that has moved back to maximum flow in zero time.
| Quote: | | so could i shove a projectile down the barrel and over some orings and then use somehting to push it forewards and it would be just like that design or is it a bit more complicated? |
Pretty much, but getting it airtight in the first place might be a little tricky.
Have a look at the diagram, the red lever pushes the green pin with moves the purple projecile enough for air to get behind its base et voila, whoomph!
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| ALIHISGREAT |
| Posted: 01/09/2008 1:47 AM Post subject: |
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Eternal Noob
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| Quote: | The performance advantages could be tremendous, because unlike a piston valve which is still opening after the projectile has started to move, once the base of the projectile passes the end of the barrel its the equivalent of a piston that has moved back to maximum flow in zero time.
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but surely the time it takes for the ammo to move past the brach of the tee is the opening time but i suspect it will be significantly less than a piston's opening time. the one major problem i can think of for us spudders is that regular ammo would be needed, i was thinking about cylindrical air rifle pellets?
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| jackssmirkingrevenge |
| Posted: 01/09/2008 2:18 AM Post subject: |
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aspiring machinist
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| Quote: | | but surely the time it takes for the ammo to move past the brach of the tee is the opening time |
This is irrelevant, because in a piston launcher this movement doesn't exist - the actual time of firing is when the base of the projectile is in line with the breech, and unlike a piston launcher at this point the valve is already fully open. On the contrary you should get even more power, because the projectile is already moving when in a piston launcher it would be starting from a stop, you would have effectively lengthened the barrel slightly.
With a bit of work it could be made with an ammunition feed to give multiple shots, though there'd be a lot of wasted air:
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| hyperspaz |
| Posted: 03/07/2011 21:43 PM Post subject: |
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Private
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| what if you had a projectile with a groove cut into it so that it could be latched into place in the barrel, up against a o-ring (similar to how a quick connect works). then when the projectile is unlatched, it fires. this would make it much easier to get a perfect seal, right?
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| jackssmirkingrevenge |
| Posted: 03/07/2011 22:15 PM Post subject: |
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| hyperspaz wrote: | | what if you had a projectile with a groove cut into it so that it could be latched into place in the barrel, up against a o-ring (similar to how a quick connect works). then when the projectile is unlatched, it fires. this would make it much easier to get a perfect seal, right? |
Have a look through this thread
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| JDP12 |
| Posted: 03/07/2011 22:19 PM Post subject: |
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Major General
Joined: 30 Mar 2007
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| did you ever continue your experiments with a quick disconnect? it seems like a perfect option- there is no flow restriction. Obviously you're limited in your projectile size, but still. 9/16" can do some damage.
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| POLAND_SPUD |
| Posted: 03/07/2011 23:04 PM Post subject: |
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| Quote: | | what if you had a projectile with a groove cut into it so that it could be latched into place in the barrel, up against a o-ring | yeah why not, but there would be quite a lot of force acting on the latch...
I don't think there is any need to waste air with this design.... you just have to build a system that sends air into the chamber when the gun is loaded
Sounds complicated but in fact it isn't. You don't even need electronics to control that, you might as well use a simple pneumatic circuit
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| JDP12 |
| Posted: 03/07/2011 23:14 PM Post subject: |
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Major General
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| POLAND- are you still referring to the quick connect design? Couldn't you simply just make a chamber like a normal gun, fill via a ball valve or similar, and then fire it by sliding the sleeve back? Perhaps I'm on the wrong topic, but i dont see why youd need anything complex.
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| jackssmirkingrevenge |
| Posted: 03/07/2011 23:24 PM Post subject: |
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aspiring machinist
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Posts: 18061
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| POLAND_SPUD wrote: | you just have to build a system that sends air into the chamber when the gun is loaded
Sounds complicated but in fact it isn't. You don't even need electronics to control that, you might as well use a simple pneumatic circuit |
Blow forward bolt 
| Quote: | | did you ever continue your experiments with a quick disconnect? it seems like a perfect option- there is no flow restriction. Obviously you're limited in your projectile size, but still. 9/16" can do some damage. |
Not my experiments, LeMaudit's
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