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Suppressor baffle design - single assembly

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: jackssmirkingrevenge » Sun Jan 30, 2011 11:32 pm

Hotwired wrote:Dainty little tubes as on a small calibre rifle are not going to do much.


Thank you!

Hotwired wrote:So multiply by 50 = 1500 cc / 1.5 litres :wink:


That's the rough rule of thumb, but really "as big as you're willing to live with".

Quick question: has anyone tried using wipes in an air rifle suppressor?


I have done some experiments in the past, mainly using bicycle inner tube that would be perforated by the passage of the projectile at exit end of the suppressor, and they do have a significant effect when it comes to sound reduction, however there are two major downsides:

- they have a significant effect on power, particularly when used with "marginal" devices such as commercial CO<sub>2</sub> pistols.

- they have an even bigger effect on accuracy.

The Welrod pistol for example used wipes and was extremely effective, yet was intended to be used at "same room" range, so effective sound suppression was much more important than accuracy, and a reduction in power was also beneficial given the fact that the 9mm round was potentially supersonic.

The De Lisle Carbine of the same era was intended for a range of several hundred meteres, so accuracy was important, and fired the naturally subsonic 45 ACP round, and therefore didn't use wipes.
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Unread postAuthor: Zeus » Sun Jan 30, 2011 11:46 pm

Once my hybrid is completed, I'll do some experiments with reasonable mixes ~10x.

I have some ideas involving easily replaced wipes and very large volume, I'll see if one has any advantages over another.
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/sarcasm, /hyperbole
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Unread postAuthor: FighterAce » Mon Jan 31, 2011 5:43 am

Totally forgot about sketchup :D

This is what I had in mind...

Image

Milling out a club shape along the entire length of the baffle.... and then sleeving it into another piece of Al pipe. I calculated the volume for 10x45cm baffle is about 2000cc :D
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“The combined synergy of a man and rifle is matchless.
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the art of knowing how to make the rifle an extension of the
body all equate to the ultimate synthesis of man and machine.”
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 31, 2011 6:44 am

Looks good, but far too much of the volume is taken up by the baffle material in my opinion if you just repeat the above pattern. I would suggest for the next pattern turning the cylinder 90º and boring another "club" shape in the opposite direction, in such a manner that they mesh together, and repeat. If the outside of the cylinder were a tube and opened out it would look something like this:
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Unread postAuthor: FighterAce » Mon Jan 31, 2011 7:16 am

Something like this?

Image


Note how big of a hole that leaves between the separate cube shapes. Shouldn't there be a hole, slightly larger then the barrel ID, separating the different "chambers" in the baffle?

Image
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 31, 2011 7:37 am

FighterAce wrote:Note how big of a hole that leaves between the separate cube shapes. Shouldn't there be a hole, slightly larger then the barrel ID, separating the different "chambers" in the baffle?


In this case one "chamber" is covered by the two meshed opposing club shapes, I pictured them being closer together. That means that the one in my diagram would have three separate chambers.
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Unread postAuthor: FighterAce » Mon Jan 31, 2011 8:02 am

Yeah that sounds more effective :D

Man how the hell do you calculate the volume of such shape??
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 31, 2011 8:49 am

FighterAce wrote:Man how the hell do you calculate the volume of such shape??


Make it then fill it with water ;)
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Unread postAuthor: FighterAce » Mon Jan 31, 2011 9:34 am

What about the materials? Maybe machine a polyetheline bar with the club pattern and then sleeve it with an aluminum pipe?

I can't think of anything lighter...
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 31, 2011 9:55 am

To be honest, I still don't see the practical benefits of this layout over a conventional baffle stack as I had done here for a pneumatic, but I think I understand the appeal.

Yes, some kind of synthetic polymer seems to be the best material to make it out of in terms of being light while still able to resist the blast of air coming out of the muzzle.
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Unread postAuthor: FighterAce » Mon Jan 31, 2011 12:00 pm

Thats the thing... blast coming from the muzzle... I'm hoping all these sharp corners and bends will trap as much of the air as possible...

I tell you what... when I make this suppressor I'm gonna make one baffle your way... and then compare the 2 :D
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 31, 2011 12:35 pm

FighterAce wrote:I tell you what... when I make this suppressor I'm gonna make one baffle your way... and then compare the 2 :D


It would be perfect if you could make a test unit which could allow different baffle arrangements to be inserted in a sleeve, it would give a measure of how baffle shape affects noise for the same length and diameter.

I don't mind being proved wrong in the interest of progress :)
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Unread postAuthor: saefroch » Mon Jan 31, 2011 2:59 pm

Fighterace wrote:Man how the hell do you calculate the volume of such shape??
It's actually possible if you know the radius of each circle and how much they overlap. You add together the circles, then subtract the area of overlap.

Image
To find the area of overlap, fit a triangle into each black region. The red region is another convenient triangle. Then by using the length of one of the longer sides of those triangles and the radius of one of the circles, you can determine the last bit remaining by calculating the area of a sector, then fitting in a triangle from the center of a circle to the boundaries of the arc and subtracting that, you have the remaining bit. Multiply that by 6 and add it to the area of the 3 congruent triangles fitted into the black regions and the triangle fitted into the red region, and you have the area of overlap.

If you're going to go through all of that already, I'd just assume that the volume of each is just that area times the thickness of the pipe :roll:.

Probably more work than its worth, I suggest using JSR's method, but you did ask :D.
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Unread postAuthor: jakethebeast » Mon Jan 31, 2011 4:03 pm

do i see win XP pro x64? :D
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Unread postAuthor: FighterAce » Mon Jan 31, 2011 4:42 pm

saefroch wrote:To find the area of overlap, fit a triangle into each black region. The red region is another convenient triangle. Then by using the length of one of the longer sides of those triangles and the radius of one of the circles, you can determine the last bit remaining by calculating the area of a sector, then fitting in a triangle from the center of a circle to the boundaries of the arc and subtracting that, you have the remaining bit. Multiply that by 6 and add it to the area of the 3 congruent triangles fitted into the black regions and the triangle fitted into the red region, and you have the area of overlap


Or you can get some millimeter paper, draw it and count the squares! :D

btw. Its actually x32.. my pc sucks... don't let the Zune theme fool ya
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The steadiness of hand, the acuity of vision and finally
the art of knowing how to make the rifle an extension of the
body all equate to the ultimate synthesis of man and machine.”
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