shut-off valve suppressor

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jackssmirkingrevenge
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Wed Feb 22, 2012 1:27 am

Following this conversation and considering Brian's input, here's a concept for a suppressor that uses a free floating ball of larger diameter than the bore to trap the expanding gasses after the projectile has left the muzzle, thus offering the benefits of the captive piston design without the engineering difficulties that implies.

It should be effective for both combustion or pneumatic type launchers, and as long as the ball doesn't make a completely airtight seal with the endcap, it should reset automatically by gravity.

Here's how I imagine the firing sequence working, some gas leakage is inevitable but I would surmise that the small volume involved would be inconsequential to the report, and an elongated projectile as shown in the diagram would probably give it a better chance of success than a spherical one:
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pneumaticcannons
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Wed Feb 22, 2012 5:05 am

Tip it upside-down and... :D but other than that it looks like it could work... However, if the ball gets sucked up before the projectile gets to it because of the Venturi effect, it probably wouldn't be so pretty :shock:
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Technician1002
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Wed Feb 22, 2012 5:23 am

Not shown in the diagram is the air the projectile pushes. A possibility exists the air flow prior to projectile arrival could move the ball into the path.
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pneumaticcannons
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Wed Feb 22, 2012 5:56 am

How about this?

Just seems to have less things that can go wrong. I wouldn't bother making any of the seals airtight though, since it's a suppressor we're talking about and the built up air has got to be released sometime...
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jackssmirkingrevenge
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Wed Feb 22, 2012 6:38 am

pneumaticcannons wrote:Tip it upside-down and... :D
Thought about that, the area where the ball rests could be enlarged in such a way that no matter what the orientation, the ball is clear of the projectile path.
However, if the ball gets sucked up before the projectile gets to it because of the Venturi effect, it probably wouldn't be so pretty :shock:
Not shown in the diagram is the air the projectile pushes. A possibility exists the air flow prior to projectile arrival could move the ball into the path.
A very minor possibility, wouldn't you say? Given the fact that the barrel is open-ended and ported?
How about this?


I'm willing to try the ball idea first, it tickled my "keep it simple" senses. Ordered some ping pong balls off eBay for some big bore testing but I'd really like to try it with a 5.5mm barrel for lead pellets and a 6mm BB as a stopper.

If it works as well as I hope it would, a bigger hybrid is definitely on the cards...
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Zeus
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Wed Feb 22, 2012 6:41 am

JSR, my isthisagoodidea sense is tingling, aren't ping pong balls hollow and rather weak? I recall smashing a few in some overzealous table tennis matches.
/sarcasm, /hyperbole
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jackssmirkingrevenge
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Wed Feb 22, 2012 6:59 am

Zeus wrote:JSR, my isthisagoodidea sense is tingling, aren't ping pong balls hollow and rather weak? I recall smashing a few in some overzealous table tennis matches.
Yeah, but they're also very light, and fit in well with my general "underengineered" build ethic :)

I don't expect them to take a full 15x hybrid firing but they should be ok for lower pressure testing.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Wed Feb 22, 2012 8:32 am

jackssmirkingrevenge wrote:as long as the ball doesn't make a completely airtight seal with the endcap, it should reset automatically by gravity.
The check ball could be cross-drilled to ensure a small amount of gas bleed, thus preventing the possibility of an airtight seal.
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Brian the brain
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Wed Feb 22, 2012 12:58 pm

or a small notch could be taken out of the ..ehm..barreltip porthole ..thing..

anyway..having the barreltip stick out a mm or so inwards would be enough to prevent the BB rolling onto it..
I doubt a pingpongball would be a good idea though.
I would say a marble should do the job.
Here's why:

My second build ever, well..the upgraded version... was a ballvalve launcher.
The ballvalve lead up to a 22mm Tee, into wich I coaxed the 15mm barrel.
( BV coming in from the bottom)
the opposite side was capped off as a breechloader.
I put a piece of hose over the barrel and dropped a marble into the Tee.
then I made a bolt that would slide inwards to break the seal of the marble after the shot.

I managed to get up to 15 shots out of that little launcher, from a single fill.
This was pre-SF..

This idea will most likely work just as well in an airtrap silencer.
As long as there is enough flow coming from the airchannel below.

It's probably not all that critical.
We might have to experiment with the ideal location of the portholes and baffles, but that's about it.

So...please JSR...wip up a quick prototype to end the discussion.. :D
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Wed Feb 22, 2012 1:10 pm

Better then ping-pong balls would be the hollow plastic golf balls (or foam depending on the application) sealing a 1.5" barrel. The dimples or the open cell foam would allow air to seep through
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al-xg
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Wed Feb 22, 2012 2:17 pm

Why would the ball rise up ? Unless the chamber gets pressurised just as the projectile is passing, the pressure forces are balanced after it passes, in fact the pressure is likely to be higher on top of the ball.
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mark.f
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Wed Feb 22, 2012 3:53 pm

al-xg wrote:Why would the ball rise up ? Unless the chamber gets pressurised just as the projectile is passing, the pressure forces are balanced after it passes, in fact the pressure is likely to be higher on top of the ball.
Bernoulli's Principle.
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al-xg
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Wed Feb 22, 2012 4:16 pm

Yeah but that would only be significant after the projectile has left the barrel and the air can rush out, it seems the drawing intends that to happen a lot sooner.
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battlelava
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Wed Feb 22, 2012 4:24 pm

What would the end plug be made out of epoxy? How well would that hold up depending on the pressure and if it has to be made precisely might be hard to get all the venting holes to a proper size. Just my 2 cents (not that I know much on the subject or material)

Edit:: what about a direct impregnation system to push the ball up and have it delayed by reducing the size maybe
Last edited by battlelava on Wed Feb 22, 2012 4:56 pm, edited 1 time in total.
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mark.f
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Wed Feb 22, 2012 4:37 pm

al-xg wrote:Yeah but that would only be significant after the projectile has left the barrel and the air can rush out, it seems the drawing intends that to happen a lot sooner.
If the projectile is pushing a column of air before it, the ball bearing would most likely be drawn upwards by the differences in pressure, as tech mentioned before.
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