Airgun sound moderator with polymeric acoustic baffles
View Patent ↗An airgun moderator employing a stack of acoustic baffles fabricated from fibrous polymeric felt, which degrades in the presence of gunpowder combustion temperatures, thereby providing an effective airgun sound moderator that us ineffective as a firearms silencer.
1. An airgun sound moderator assembly for attachment to an airgun having a barrel that defines a bore axis, the barrel fixed to a frame member, and having a moderator engagement fitting adjacent a muzzle end thereof, comprising:
an elongated housing having an interior profile, and having an airgun engagement fitting at a first end, and having a moderator muzzle cap at a second end, and wherein said airgun engagement fitting is selectively attachable to the airgun moderator engagement fitting;
a stack of acoustic baffles comprised entirely of plural acoustic baffles located adjacent to one another, and within said elongated housing between said airgun engagement fitting and said moderator muzzle cap, and wherein
said plural acoustic baffles are each fabricated from a fibrous polymer felt comprised of aromatic rings in polymeric chains that yield stiffness and resist deformation of said plural acoustic baffles so as to endure repeated compressed air pressure blasts, and which inherently defines a polymer softening temperature and a polymer melting temperature, both of which are below three hundred degrees Celsius, such that said plural acoustic baffles will rapidly deteriorate if exposed to gunpowder combustion products and temperatures, rendering the airgun sound moderator assembly unsuitable for use as a firearms silencer, and wherein
each of said plural acoustic baffles are substantially planar, having a thickness in the range of 0.5 to 4.0 centimeters, with an outer profile that at least partially conforms with said interior profile of said elongated housing, and each having a bore hole formed therethrough, which is aligned with the bore axis when said airgun engagement fitting is engaged with the moderator engagement fitting.
2. The assembly of claim 1 , and wherein:
said fibrous polymer felt is fabricated from polyethylene terephthalate fibers.
3. The assembly of claim 2 , and wherein:
said polyethylene terephthalate fibers are substantially heterogeneous in size, and said plural acoustic baffles are thermally cut from sheet felt material, which fuses the cut edges to thereby enhance rigidity.
4. The assembly of claim 1 , wherein the moderator engagement fitting is fixed to the airgun frame and internally threaded, and wherein:
said airgun engagement fitting is externally threaded for selective attachment to the moderator engagement fitting.
5. The assembly of claim 1 , wherein the airguns discharges a projectile of predetermine caliber, and wherein:
said plural acoustic baffles comprise a first portion of baffles interleaved with a second portion of baffles, and wherein
said first portion of baffles have round boreholes having a first diameter that is larger than said predetermined caliber, and said second portion of baffles have a second bore hole size that is greater than said first diameter.
6. The assembly of claim 5 , and wherein:
said second bore hole size is cut to reveal a zigzag edge profile.
7. The assembly of claim 5 , and wherein:
said second bore hole size is cut to reveal an undulating edge profile.
8. The assembly of claim 1 , and wherein:
a portion of said plural acoustic baffles are cut such that said outer profile reveals a concave scalloped edge.
9. The assembly of claim 1 , and wherein:
a portion of said plural acoustic baffles are cut such that said outer profile reveals a castellated edge.
10. An airgun sound moderator assembly for insertion into an airgun having a barrel that defines a bore axis, the barrel located within a frame member by a barrel support member, the frame member having an interior profile and enclosed at a muzzle end by a muzzle cap, comprising:
a stack of plural acoustic baffles, comprised entirely of plural acoustic baffles located adjacent one another, and locatable within the frame between the barrel support member and the muzzle cap, and wherein
said plural acoustic baffles are each fabricated from a fibrous polymer felt comprised of aromatic rings in polymeric chains that yield stiffness and resist deformation of said plural acoustic baffles so as to endure repeated compressed air pressure blasts, and which inherently defines a polymer softening temperature and a polymer melting temperature, both of which are below three hundred degrees Celsius, such that said plural acoustic baffles will rapidly deteriorate if exposed to gunpowder combustion products and temperatures, rendering the airgun sound moderator assembly unsuitable for use as a firearms silencer, and wherein each of said plural acoustic baffles are substantially planar having a thickness in the range of 0.5 to 4.0 centimeters, with an outer profile that at least partially conforms with the interior profile of the frame member, and each having a bore hole formed therethrough, which is aligned with the bore axis when inserted into the airgun frame.
11. The assembly of claim 10 , and further comprising:
a baffle spacer disposed between the barrel support member and said stack of plural acoustic baffles to thereby provide separation between the barrel and said stack of plural acoustic baffles.
12. The assembly of claim 10 , and wherein:
said fibrous polymer felt is fabricated from polyethylene terephthalate fibers.
13. The assembly of claim 12 , and wherein:
said polyethylene terephthalate fibers are substantially heterogeneous in size, and said plural acoustic baffles are thermally cut from sheet felt material, which fuses the cut edges to thereby enhance rigidity.
14. The assembly of claim 10 , wherein the airguns discharges a projectile of predetermine caliber, and wherein:
said plural acoustic baffles comprise a first portion of baffles interleaved with a second portion of baffles, and wherein
said first portion of baffles have round boreholes having a first diameter that is larger than said predetermined caliber, and said second portion of baffles have a second bore hole size that is greater than said first diameter.
15. The assembly of claim 14 , and wherein:
said second bore hole size is cut to reveal a zigzag edge profile.
16. The assembly of claim 14 , and wherein:
said second bore hole size is cut to reveal an undulating edge profile.
17. The assembly of claim 10 , and wherein:
a portion of said plural acoustic baffles are cut such that said outer profile reveals a concave scalloped edge.
18. The assembly of claim 10 , and wherein:
a portion of said plural acoustic baffles are cut such that said outer profile reveals a castellated edge.
19. A method of fabricating an airgun moderator assembly, including a stack of plural acoustic baffles comprised entirely of the plural acoustic baffles located adjacent one another, which are for insertion into an airgun having a barrel fixed to a frame member that defines a bore axis, and having a moderator engagement fitting adjacent a muzzle end thereof for attachment of an elongated housing having an interior profile, and having an airgun engagement fitting at a first end, and having a moderator muzzle cap at a second end, and wherein said airgun engagement fitting is selectively attachable to the airgun moderator engagement fitting, or for insertion of the plural acoustic baffles into an airgun having a barrel located within a frame member by a barrel support member, the frame member having an interior profile and enclosed at a muzzle end by a muzzle cap, thereby enabling location of the stack of plural acoustic baffles within the frame member between the barrel support member and the muzzle cap, the method comprising the steps of:
selecting a substantially planar sheet of fibrous polymer felt comprised of aromatic rings in polymeric chains that yield stiffness and resist deformation so as to endure repeated compressed air pressure blasts, and within the thickness range of 0.5 to 4.0 centimeters according to its inherent polymer softening temperate and polymer melting temperature, which are both less then three hundred degrees celsius, such that the polymer will rapidly deteriorate if exposed to gunpowder combustion products and temperatures, and according to the fibrous polymer felt rigidity, thereby providing structural rigidity below the polymer softening temperature, and rendering the airgun sound moderator unsuitable for use as a firearms silencer;
cutting the plural acoustic baffles from the sheet of fibrous polymer felt, wherein each of the plural acoustic baffles have an outer profile that at least partially conforms with the interior profile of the elongated housing or the interior profile of the frame member, and each having a bore hole formed therethrough, which is located to align with the bore axis of the airgun, thereby moderating the acoustic impulse emitted by the airgun upon discharge of a projectile.
20. The method of claim 19 , and wherein:
the fibrous polymer felt is fabricated from polyethylene terephthalate fibers.
21. The method of claim 20 , and wherein the polyethylene terephthalate fibers are substantially heterogeneous in size, and further comprising the step of:
thermally cutting the plural acoustic baffles from sheet of polymer felt, thereby fusing the cut edges and enhancing rigidity.
22. The method of claim 19 , wherein the airgun discharges a projectile of predetermine caliber, and wherein:
said cutting step further includes cutting a first portion of the plural acoustic baffles and cutting a second portion of the plural acoustic baffles;
interleaving the first portion and second portion of the plural acoustic baffles, and wherein
the first portion of baffles are cut with round boreholes having a first diameter that is larger than the predetermined caliber, and the second portion of baffles are cut with a second bore hole size that is greater than the first diameter.