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Silencers, Who has them?

A place to ask general spud cannon related questions.
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do you think silencers are...

STUPID
2
18%
OK, but not wrth the trouble
1
9%
AWESOME!
8
73%
 
Total votes : 11
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Unread postAuthor: sputnick » Mon Dec 15, 2008 6:07 pm

I mean, that i have had many weeks this semester filled with work and projects, but just recording 2 shots then mixing them together and repeating can be done in under half an hour.
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Unread postAuthor: raptorforce » Mon Dec 15, 2008 8:05 pm

Lentamentalisk wrote:steel wool is used in situations where hot gases are involve, because it aids in cooling them. As every spudder should know, if you cool a gas, it contracts, so there is less of an explosion. That is why we can never hope to silence a pneumatic as much as a combustion, because there is still there sheer volume of gas to deal with. Steel wool will do next to nothing in a pneumatic, other than possibly make a little turbulence.

does this still apply for a pneumatic gun
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Unread postAuthor: sputnick » Mon Dec 15, 2008 8:08 pm

Dont listen to that guy, he's 100% wrong about the mechanics of a silencer.
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Unread postAuthor: Lentamentalisk » Mon Dec 15, 2008 8:17 pm

I don't know what you are talking about. I said what applies to what... Of course the parts in which I was mentioning pneumatics apply to pneumatics...
Though there seem to be other opinions out there.
Here is the discussion I had with Sputnick, some what edited and all:

Sputnick wrote:That is actually wrong. Steel wool does not cool the gasses to reduce noise. and any contraction would not reduce the explosion in the maybe 0.1 seconds that the hot gasses flow through. Not only the time, but steel wool would not have a high enough capacity for heat to make a contraction of any noticeable difference.

I am not entirely sure what the steel wool does to the gasses, but i can tell you for certain that it is not there to cool them.


Lentamentalisk wrote: It does cool the gases. If you use steel wool that is too fine, it will catch fire, meaning that it did absorb heat. Also, although may not have a huge heat capacity, remember that with the amount of gas we are dealing with, the steel wool has probably 10 to 100 times the mass (I don't feel like doing the math) so that is not a big deal. Also, the temperature differences we are dealing with are incredible, so the energy transfer will happen very quickly.

Lastly, I have used steel wool baffles in a rocket I made, to protect the parachute from the hot ejection gases. If you don't know what that is, it is basically a black powder charge, directed up the body tube, that without wadding (or a baffle made of steel wool in this case) it will melt your parachute into a little plastic lump.


Sputnick wrote: Something catching on fire does not mean that it absorbs heat. Wood will catch fire, but no sensible person would use wood as a heat sink.

Of course steel wool DOES absorb heat, but enough to contract gasses and silence a weapon.

If that were true, then how come silencers with baffles or other not-so-conductive material work so efficiently?

As for the rocket gasses, i would imagine you use it to STOP the flow of gasses, because it is less flammable than paper, and still light. I would not believe you if you told me it filters the flaming gas and cools them, because now your two stories do not add up, because that would mean that the gas in the rocket would contract, and would be ineffective for launching the chute.

Contracting gasses do not contract the the point that an explosion is avoided. If that were the case, then explosions would not happen in the arctic.

The conductivity and heat retention of steel would is debateable and variable, but whatever the case, they are not the main silencing material in a silencer.
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Unread postAuthor: STHORNE » Mon Dec 15, 2008 8:30 pm

lol, settle down you 2...
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Unread postAuthor: Lentamentalisk » Mon Dec 15, 2008 8:34 pm

Naw, were good. I always get a little less mellow in my PMs I guess...
We are in agreement as to the main purpose of a silencer (or should I really be saying suppressor :) ) which is to give the gases a place to expand.

The real question is as to whether a ton of steel wool packed into the suppressor would provide enough surface area, for a long enough time, with a great enough heat transfer rate, to make a difference.

I think we need some of our engineers with degrees out here...
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Unread postAuthor: Ragnarok » Mon Dec 15, 2008 8:37 pm

Right on cue, a person who's working for his engineering degree.

sputnick wrote:Dont listen to that guy, he's 100% wrong about the mechanics of a silencer.

Actually, Lentamentalisk is mostly in the right here. Pneumatics, combustions and powder burners all have different suppressing requirements (I am loathe to use the word silence), so they cannot be considered one and the same.

Pneumatics require de-pressurization and slowing of the gasses.
Combustions require cooling of the gases.
Firearm suppressors ideally need both.

Steel wool is thermally conductive, and has a relatively high mass compared to the combustion gasses, so it does indeed absorb heat quickly, making it viable for use in a combustion to moderate it.

The reason steel wool is not used in regular firearm suppressors is that even if firearm gasses were cooled to room temperature, they would still have considerable volume (like pneumatic gasses do), rendering cooling alone moot.

For a firearm, rapid expansion of the gas is therefore a more solid option. This both reduces pressure, and due to the fact that decompression of a gas reduces its temperature, hits both points at the same time.

The same principle can be applied to both pneumatics and combustions to have a moderating effect - however the low pressures, high temperatures and low masses of combustion gasses make the use of a heavy (for fine wools will absorb enough heat to exceed their ignition temperature, and catch alight) steel wool to absorb heat an additional option to save on suppressor volume.

The same short cut is not viable in either pneumatics or powder burners.
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Unread postAuthor: sputnick » Mon Dec 15, 2008 8:58 pm

I would have to disagree with you, Heat absorbtion is not an effective means of suppression. Even if it is somehow a viable means of reducing noise, which I highly doubt, then it would be completely inefficient, because then the heat from the previous shot would be absorbed into the steel wool, making it less effective with every consecutive shot until given time to cool (me not knowing how long that would be not since I do not make combustion guns or make suppressors for them) but I imagine it would be considerably long seeing as the wool is kept in a confined area with hot gasses.

So I will admit, the evidence does seem to be compiled against me,

but I stand by my say that it is likely not a well designed means of suppression, especially since the other silencer designs are effective on ALL guns, and have almost no loss of suppression when heated.

Thanks everyone for being so involved with this, this has been a really insigtfull conversation

I look forward to more in the future :wink:
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Unread postAuthor: Ragnarok » Mon Dec 15, 2008 9:13 pm

sputnick wrote:Even if it is somehow a viable means of reducing noise, which I highly doubt, then it would be completely inefficient, because then the heat from the previous shot would be absorbed into the steel wool, making it less effective with every consecutive shot until given time to cool.

Due to high area/volume ratio of steel wool, the wool will be long since cool enough by the time you've loaded again, so any loss of subsequent shot suppression will be unnoticeable to even the trained ear.
It's a perfectly viable method for a combustion. The only potential flaw is someone using a wool that's too fine.

especially since the other silencer designs are effective on ALL guns

O...kay. Are you saying that even though this method could be used to greater effect on a combustion than the other methods, it should be discarded because it won't work for non-combustions?

That's like saying "Don't use a sledgehammer to knock down that wall. Use this clawhammer instead, you can use it to bash in nails, pull out nails, lever apart pieces of wood, AND brain puppies*."
*To give an example of a task for which a hammer could be used, if you REALLY wanted.

Sure, good for more tasks, but not as good for the one at hand.
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Unread postAuthor: sputnick » Mon Dec 15, 2008 9:36 pm

I am not dismissing it, and your example is not at all accurate. other silencers are not some kids toy, they are VERY effective, and more universal. You say it like I am substituting effectiveness for interchangeability.

And by the way, since you seem to really want to keep going with this,

I would debate that it is not heat being absorbed that is suppressing it, it is once again just gasses disipating in the silencer. If you really wanted to test that, then use an empty silencer tube, and use it as a mold to form an ice block, then use that as a silencer for a spudgun. no holes, no expansion room. just pure cooling.

If that wont prove my point, i dont know what will
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Unread postAuthor: STHORNE » Mon Dec 15, 2008 10:06 pm

both good arguments. you should make a new debate thread for it and not get off subject with this one lol.
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Unread postAuthor: sputnick » Mon Dec 15, 2008 10:10 pm

its my post, and thread, i think if anyone I have the right to continue this debate,

no offense sthorne
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Unread postAuthor: STHORNE » Mon Dec 15, 2008 10:39 pm

no, i meant...

didn't know you wanted to continue with the debate in the same thread. my bad.

1200 posts :o
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Unread postAuthor: Xxplosive42o » Mon Dec 15, 2008 10:47 pm

Ragnarok supports my design concept - great minds think alike :wink:

Funny thing is, I made my version (pictured earlier in the thread) and it worked beyond satisfactory. I ALSO built an identical one using NO steal wool and NO vent holes on the aft end where the expansion chamber was. Just baffles that draft the pressure into the expansion chamber (exactly like a firearm suppressor) .

Would you like to know the results?... Well the one using steel wool was exponentially quieter. It's a simple design; It contains all elements of a firearm silencer but it also has a dense section of steel wool in the expansion chamber to dissipate some of hot combustion gasses. In addition to that quality, it displaces the jetstream of blowback gasses and slows the pressure before exiting the vent holes. That is my out-take of my silencer design and it has proven successful to me.

It is obvious many people will hold different opinions on the matter of how it exactly works, but why not just settle on its effectiveness.
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Unread postAuthor: Ragnarok » Mon Dec 15, 2008 11:11 pm

That assumes ANYONE has the right to continue the debate. The moderators may get on this if it gets too long.

sputnick wrote:I would debate that it is not heat being absorbed that is suppressing it

For an atmospheric combustion, as heat is the only source of pressure, get rid of the heat, and you have no pressure.
That fact doesn't apply to hybrids, pneumatics or firearms, so it may sound odd to you, but I assure you, it can work.

Your ice suppressor wouldn't work because ice is neither thermally conductive enough or high enough surface area to achieve meaningful heat transfer rates. Also, the change in temperature from using ice in place of something at room temp. is small (a couple of percent at the outside) compared to the thousands of degrees the combustion gases have.
Just adding something cold does not necessarily cool anything by any real degree.

Steel wool has a very high surface area. One gram of 0.2mm diameter steel wool (0.2mm is just a generic figure that sounded about right of a heavy wool. I can't remember what actual sizes are suitable for combustion suppression) has 26 square centimetres of surface area, a little over 4 square inches.
Compare that to a solid steel sphere of the same mass. A hair under a 1/4" in diameter, it has a surface area of just 1.24 sq. cm, or a fifth of a square inch.

The wool's large area (and low diameter) leads to HUGE heat transfer rates (of approaching thousands of times that of the sphere), which can sap considerable temperature from the gasses very quickly, and makes it both a workable and effective technique as a subsitute for raw volume in a combustion suppressor.
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