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Suppressors Rotary Baffles - Opinions, Has It Been Done, Is it worth the effort

zenbiker

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Full Member
Minuteman
Nov 15, 2009
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Charlottesville, Virginia
I have read here and there about suppressors theoretical ( I believe it was theoretical) using turbine-like baffles that would rotate on bearings, possibly ceramic. The bullet would pass through the bearing center; the turbine assemblies would press on to the outer diameter of the bearing. A central shaft supported by the endcaps would support the baffle assembly. Still working out in my head the entire mechanism, but I know it can be one. The glaring thought I have is this: if it is such a good idea, why don't one of the major manufacturers make one?


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Cost.
I like your idea of converting all that pressure into kinetic energy instead of just heat.
 
Ohh, field windings! Then you can charge your iPhone while shooting. On a serious note, neat idea, gotta be expensive and don't turbines need tight tolerances to be efficient?
 
Yea, I'd imagine most of the reasons they have for not trying a particularly method would have to do with cost that and in the event that it doesn't show any marked improvement over current designs then they'd be stuck with a really expensive worthless prototype.
 
For a moderately easy way to get turbines. What about turbos with junk bearings. They are the right shape, made for high heat and just happen to have a hole in them already. I'd want the intake side for weight but the exhaust side for heat. Just a thought. Be weird to hear a rifle spool down.

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Wouldn't all the carbon build up eventually freeze up the bearings?
 
For a moderately easy way to get turbines. What about turbos with junk bearings. They are the right shape, made for high heat and just happen to have a hole in them already. I'd want the intake side for weight but the exhaust side for heat. Just a thought. Be weird to hear a rifle spool down.

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Thanks: I've been trying to design this based on readily available parts, and a source for turbines readily availale has escaped me until your post. They are made to operate in high heat/high stress conditions under high duty cycles, so designing a baffle to protect them against the muzzle blast would then be the an easy step. I only have one Form 1, so I want to consider a few designs before I commit to one.


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Wouldn't all the carbon build up eventually freeze up the bearings?

All suppressors need regular carbon removal o maintain optimal performance. immersion in a carbon removal agent such as SLIP 2000 Carbon Killer in an ultrasonic cleaner is routine in LEO and military subgun suppressors; even if a bearing did seize, the turbine should still be a pretty effective bafffle. If I used this design, I'd want to be able to remove the endcaps to clean the baffle/ turbine stack. Comments? Any turbo service techs out there?


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All suppressors need regular carbon removal o maintain optimal performance. immersion in a carbon removal agent such as SLIP 2000 Carbon Killer in an ultrasonic cleaner is routine in LEO and military subgun suppressors; evev if a bearing did seize, the turbine wold be a pretty effective bafffle. If I used this design, I'd want to be able to remove the endcaps to clean the baffle/ turbine stack. Comments? Any turbo service techs out there?


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The bearings in a turbo are housed in the Centre housing rotating assembly and are oil lubricated completely separate of where the exhaust gases are. At least if everything is working right they are.

The hole through the turbine wheel is just for a bolt to hold it all together. You would need to open up that hole or used thrust bearings on either side with the stack under compression by the end caps.

I'd have to think about how I would go about it. Just thought they might work in this application. Plus junk small turbos can be found cheaply

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That would be quite a large can if you are looking at salvaging turbines from turbos. With that said, you could probably make your own turbines, as I don't see the super tight tolerances being a major factor in a turbine for suppressor use. Most modern turbo's turn at a rate well above 100,000 rpm's for a sustained length of time. For the purpose of your suppressor, it's going to spin off of a single burst of pressure and immediately wind back down.

I also think salvaged turbo turbines would be a bad bet because of their design. They are tapered, in that the outside diameter has a wider "fin" surface, due to the natural dynamics of the airflow being forced to the circumference of the turbine housing. What you would want to look at for a suppressor design is something that is more uniform across the entire fin surface.
 
I could be way off the mark here, but isn't this essentially what OSS is accomplishing, only using a fixed turbine muzzle break that channels expelling gases?

Forgive me, as it am not an engineer, just seems similar, maybe I'm picturing the op wrong in my head.


Who is John Galt?
 
I have read here and there about suppressors theoretical ( I believe it was theoretical) using turbine-like baffles that would rotate on bearings, possibly ceramic. The bullet would pass through the bearing center; the turbine assemblies would press on to the outer diameter of the bearing. A central shaft supported by the endcaps would support the baffle assembly. Still working out in my head the entire mechanism, but I know it can be one. The glaring thought I have is this: if it is such a good idea, why don't one of the major manufacturers make one?


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Interesting project. Answer: Cost, durability, usability to name a few.

Lots of obstacles to overcome. Keep us up to date on how it turns out. Tagged.
 
OK, from Google-gu, it seems we are looking for a "open impeller", often used in pumps, with at least a 1/2" center hole. These appear to be ready made baffles if made out of the right material. And, as previously stated, I dont know that they need to rotate, although that would reduce any torquing from parabolic vanes. Still looking for the right one.


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Zen I applaud you for making a thought provoking post.

Posts like these are why this is a great site.
 
Just a hunch, but I don't think it would do anything. There is so little time to impart any energy to the impellers that very little energy would be transferred. I could be wrong, though. Also sounds very complex and difficult to keep running.
 
I don't think turbo chargers use bearings, they use bushings. I might be wrong here but most turbos spool up to something like 30,000 rpm. Bearings that can handle that much speed would be insanely expensive. I can't imagine a can being much different, if the gas leaves the muzzle at 6,000 to 7,000 fps it would instantly over speed your bearings. Just my .02 I'm not trying to be a buzz kill.
 
I don't think turbo chargers use bearings, they use bushings. I might be wrong here but most turbos spool up to something like 30,000 rpm. Bearings that can handle that much speed would be insanely expensive. I can't imagine a can being much different, if the gas leaves the muzzle at 6,000 to 7,000 fps it would instantly over speed your bearings. Just my .02 I'm not trying to be a buzz kill.

They do use bearings. Both journal bearings which you're speaking of and ball bearings depending on the turbo. Also the rpms range is much higher than youre thinking. 80k-100k +.

However the bearings as set up in the turbo would not work. I was only suggesting using the exducer. suitable workable bearings may be difficult to find reasonably priced though.

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I think the most important consideration you may have missed, is that the orientation of spinning turbines in the baffle stack would change after every shot, into an infinite variety of combinations. To me, this would make shot to shot velocity and POI shift incredibly inconsistent and completely unpredictable. Might be workable for a sub gun or a bullet hose, but as a precision rifle can, I think it's a non starter. Also, why? You haven't really articulated a particular problem with static baffles your solution would solve.
 
I think the most important consideration you may have missed, is that the orientation of spinning turbines in the baffle stack would change after every shot, into an infinite variety of combinations. To me, this would make shot to shot velocity and POI shift incredibly inconsistent and completely unpredictable. Might be workable for a sub gun or a bullet hose, but as a precision rifle can, I think it's a non starter. Also, why? You haven't really articulated a particular problem with static baffles your solution would solve.

You bring up an excellent point, but bullet will have exited the suppressor before any movement occurs of the turbines. The orientation of the baffles after each shot is a very insightful point; the use of precision balanced turbines would hopefully render the point moot:; look at the balance of spinning compressors is a jet turbine. I believe that in a precision turbine suppressor stack, the myriad of possible turbine positions would e irrelevant, though I grant you that testing is the only real way to be certain. Furthermore, as to their use in subguns or even rapid fire strings of semiauto fire where the turbines don't come to rest before the next shot, or worse, undergo rotational acceleration as the turbines "spool up" with each successive shot, The suppressor will become less efficient in dampening the sound because less of the expanding gas energy of each successive shot is needed to overcome the inertia of the turbine stack, allowing each successive shot to become louder and louder, although still quieter than the native muzzle blast. Let me add that shot-to shot carbon fouling would probably limit turbine speed, possibly temporarily stopping turbine rotation altogether util the unit is cleaned.

As to why? Look at the goal of suppressor baffles: slowing of the expanding gases, creation of turbulence, and dissipation of the muzzle blast as heat through the exterior walls of the supressor. If the design of open turbines is compared to the average baffle stack, it is evident that turbines would create more turbulence in the same suppressor size. Adding the inertia of movable turbines robs the muzzle gas of more
heat energy as some of that heat is very quickly converted to kinetic energy required to start the turbines turning. Again. in a theoretical sense, a kinetic turbine suppressor should be quieter than a static baffle stack suppressor. However, the problem I am running into is finding a source for he turbines. There does not seem to be a "Turbines R Us" supplier; my google searches so far have led me to a weird maze of Chinese, Indian, and Pakistani websites which I am having a hard time navigating. I'll end this rambling by saying that a kinetic stack turbine may be able to be made smaller to achieve the same noise reduction. All of this depends oon being able to find a readily available source of bearings at a good price point to create an "off the shelf" design that would save time at the lathe turning out baffles.

That's the best answer I can give right now, so I'll see how far I get with this hypothetical design before I proceed or bag it.

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Just a hunch, but I don't think it would do anything. There is so little time to impart any energy to the impellers that very little energy would be transferred. I could be wrong, though. Also sounds very complex and difficult to keep running.

If the impellers obstruct the gas enough, the bullet would be gone and out of the can before the suppressor starts to do its job. Static baffle suppressors do the same thing; they are obstructing and cooling gas flow long after the bullet is gone. I propose using baffles of superior design along with the addition of kinetic scavenging to make a quieter can. As far as keeping it running, I presume you mean that carbon fouling would cause the impellers to slow or stop turning, in which case you would still have a conventional "static baffle" suppressor with arguably superior baffles and comparable sound reduction.


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dangit i saw this in silencertalk where a guy built one. i cant find the dang thread right now im going to keep searching. i remember he had a video of him blowing compressed air through it.
 
I could be way off the mark here, but isn't this essentially what OSS is accomplishing, only using a fixed turbine muzzle break that channels expelling gases?

Forgive me, as it am not an engineer, just seems similar, maybe I'm picturing the op wrong in my head.


Who is John Galt?

That's exactly how I thought about it. Gas spinning around a fixed turbine, and bleeding off energy as it does.
 
Exactly


Who is John Galt?

Well, not exactly, A suppressor is an energy conversion device, changing acoustic energy into heat. The cans with turbine baffles that do not move do absolutely create a lot of turbulence, a great way to convert sound to heat; now, if those turbines could also rotate/spin, now you have added inertia/kinetic energy to the conversion process, and, along with the
turbulence, more sound is converted to heat more quickly, theoretically allowing for greater noise reduction. Spinning the turbines in the OSS cans (I need to research them) should make what I am guessing is a good can even better.

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OK, ordered a set of sealed bearings designed to be used in hot and corrosive environments with a 7/16" ID. This project is moving ahead. It will have a blast baffle/brake with a static end plate in front of it and 4 rotating baffles. Next step is sourcing the turbines to be used for the baffles.


add: fiancee half asleep beside me asked me what I was on the 'net for, told her looking for components for the suprressor. She sighed and said "why don't you just stick the barrel up a cat's ass? You know, *click*...ROWR*...."

I had to put the ipad down until the tears of laughter subsided enough to see straight.


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I followed that thread in real-time, if memory is correct the OP (from silencertalk) was banned from the site, as his IP was generated from the U.S. (not Australia). I thought the concept was neat, but too complex for my skill sets. I ended up using a Form1 to make a suppressor with K-Baffles with mouse holes...works for me...and it was simple enough for me to make with a cheap lathe.