For your consideration: a .051 kiloton thermonuclear hand grenade. Just kidding, it has a burst disc.
Background - This is part of an overall larger project that has been in the back of my mind for a couple years now which is to design a stacked tube blowback semiautomatic paintball pistol that actually works. I always wanted an Ariakin pistol as a kid and since acquiring a Delta .68 and reading up on the PT Extreme is is clear to me that these are paperweights. The main problem with the Delta .68 (aside from it's obscene .700" bore) is the cup seal where the 12 gram CO2 cartridge interfaces with the inlet port. It's overly complicated for its size with several tiny parts that are easily lost forever in the carpet or the grass. This wouldn't be such a nuisance if not for the fact that the cup seal eats orings. The oring is located in an internal bore groove which seals around the neck of the 12 gram. It is a huge pain to replace. Since the marker has no regulator it stops firing before exhausting all of its CO2 and it vents when you disconnect the spent cartridge. This effectively freezes and pulverizes 70 durometer orings. 90 durometer urethane orings stand up to the discharging CO2 better but since they don't stretch as much it takes more force than I can comfortably generate with my hands in order to seat the cartridge, forgot trying to do that while being shot at. A very cleverly designed paperweight.
Refillable Cartridges - I got to thinking that maybe one way to improve the marker would be to use a larger co2 cartridge. It wouldn't necessarily solve the cup seal problem but fewer cartridge changes would reduce wear on the orings. That's when I stumbled across refillable co2 cartridges - a top half and a bottom half that threads together in the shape of a 12 gram made from stainless steel with a small charging port that can interface with a co2 tank with an adapter. It seemed like a cool concept and then I thought, "couldn't I just fill that with 800 psi of compressed air from a standard tank regulator?" There seemed like a lot of ways that could go wrong but the concept clicked like a light bulb - A Small Refillable High Pressure Air Tank.
Enter The SRHPAT - (I don't know how to phonetically pronounce that). I know what you're thinking - "You'll put your eye out when that fancy aluminum pipe bomb goes off in your hand, kid." Which is fair, but this is an oil quenched and tempered 4340 pressure vessel and that is a 7.5k burst disc; this is a 4.5k tank. In all actuality, this tank could be made from normalized 4340 and would still have a favorable factor of safety. It's somewhere between 4 and 50 depending on material selection and on how you calculate your safety factors, but I do intend to hydrotest as well as destructively test a percentage of the batch. The tank has an internal volume of approximately 1.40 cubic inches. Using a factor of 15 shots / cubic inch at 4.5k - that's twenty one shots per fill or two ten round tubes.
Also, that's not a regulator, it's a poppit valve. The adults in the room are probably nervously shifting in their seats right about now trying to decide if I'm serious or if this is a very long winded and elaborate joke. In all honesty, I don't have a solid enough conceptual understanding of regs to design a micro-regulator that would fit within the size envelope of this project while maintaining a twenty shot capacity which would be machinable with commercially available tooling. Filling the tank from the same port that air releases from would also have been really tricky to design with a regulator. I would feel more comfortable designing an internal regulator for the marker where I would have more space for it.
Since there is no pressure gauge this tank does not conform to OSHA standards, however, where applicable, it adheres to basic ASTM standards for pressure vessels and assuming it is hydrotested properly, it has a burst disc which will give way long before the tank does. And before the burst disc fails at 7.5k all the seals are gonna fail at 5k, I didn't double them up. That said, I don't think I would sell you one. This is meant to be the technological innovation (I can hardly use the word innovation, this is the airsmith equivalent of a cudgel) that enables my semiauto pistol design to work and remain within its acceptable size envelope. With a more traditional air system I would have been comfortable casually selling units to the public, but this is first and foremost and has always been a "crate of good guns for the field" project. When viewed through the lens of "this fleet of markers only gets unlocked during the occasional invite-only private game of responsible folks and people I consider friends and will only be pressurized under my direct supervision" my insurance agent's hair probably stays attached to his head a lot longer. If you're interested in your own "crate of good guns for your field" feel free to call me; I can be surprisingly budget friendly.
At the end of the day, this is a turbine blisk for a Pratt and Whitney F135 jet engine. It requires the same material traceability and certs. It requires the same process control and heat treat documentation. It requires the same metallurgical testing and dimensional inspection, and before a person is ever playing paintball with this tank I'm gonna bolt one down in the heaviest steel flange I can find and fill it with pressurized fluid until it stops being a pressure vessel.
Anyway, thank you for coming to my Ted talk, please tear this design to shreds in the replies - or if you have any suggestions for how to improve it at all, even if you're just spitballing ideas, please do help me out.
P.S. - This is a hollow bore cylinder with threaded features and an endcap and technically meets the legal definition of a suppressor. That being said, I don't think anyone makes a .09 caliber bullet and who the hell takes the time to oil quench and temper their absurdly heavy 4340 beer can? I digress. Hey does anyone know which form I have to fill out to legally posses an eight ball of Plutonium 239 and a tea cup full of lithium duteride?
Background - This is part of an overall larger project that has been in the back of my mind for a couple years now which is to design a stacked tube blowback semiautomatic paintball pistol that actually works. I always wanted an Ariakin pistol as a kid and since acquiring a Delta .68 and reading up on the PT Extreme is is clear to me that these are paperweights. The main problem with the Delta .68 (aside from it's obscene .700" bore) is the cup seal where the 12 gram CO2 cartridge interfaces with the inlet port. It's overly complicated for its size with several tiny parts that are easily lost forever in the carpet or the grass. This wouldn't be such a nuisance if not for the fact that the cup seal eats orings. The oring is located in an internal bore groove which seals around the neck of the 12 gram. It is a huge pain to replace. Since the marker has no regulator it stops firing before exhausting all of its CO2 and it vents when you disconnect the spent cartridge. This effectively freezes and pulverizes 70 durometer orings. 90 durometer urethane orings stand up to the discharging CO2 better but since they don't stretch as much it takes more force than I can comfortably generate with my hands in order to seat the cartridge, forgot trying to do that while being shot at. A very cleverly designed paperweight.
Refillable Cartridges - I got to thinking that maybe one way to improve the marker would be to use a larger co2 cartridge. It wouldn't necessarily solve the cup seal problem but fewer cartridge changes would reduce wear on the orings. That's when I stumbled across refillable co2 cartridges - a top half and a bottom half that threads together in the shape of a 12 gram made from stainless steel with a small charging port that can interface with a co2 tank with an adapter. It seemed like a cool concept and then I thought, "couldn't I just fill that with 800 psi of compressed air from a standard tank regulator?" There seemed like a lot of ways that could go wrong but the concept clicked like a light bulb - A Small Refillable High Pressure Air Tank.
Enter The SRHPAT - (I don't know how to phonetically pronounce that). I know what you're thinking - "You'll put your eye out when that fancy aluminum pipe bomb goes off in your hand, kid." Which is fair, but this is an oil quenched and tempered 4340 pressure vessel and that is a 7.5k burst disc; this is a 4.5k tank. In all actuality, this tank could be made from normalized 4340 and would still have a favorable factor of safety. It's somewhere between 4 and 50 depending on material selection and on how you calculate your safety factors, but I do intend to hydrotest as well as destructively test a percentage of the batch. The tank has an internal volume of approximately 1.40 cubic inches. Using a factor of 15 shots / cubic inch at 4.5k - that's twenty one shots per fill or two ten round tubes.
Also, that's not a regulator, it's a poppit valve. The adults in the room are probably nervously shifting in their seats right about now trying to decide if I'm serious or if this is a very long winded and elaborate joke. In all honesty, I don't have a solid enough conceptual understanding of regs to design a micro-regulator that would fit within the size envelope of this project while maintaining a twenty shot capacity which would be machinable with commercially available tooling. Filling the tank from the same port that air releases from would also have been really tricky to design with a regulator. I would feel more comfortable designing an internal regulator for the marker where I would have more space for it.
Since there is no pressure gauge this tank does not conform to OSHA standards, however, where applicable, it adheres to basic ASTM standards for pressure vessels and assuming it is hydrotested properly, it has a burst disc which will give way long before the tank does. And before the burst disc fails at 7.5k all the seals are gonna fail at 5k, I didn't double them up. That said, I don't think I would sell you one. This is meant to be the technological innovation (I can hardly use the word innovation, this is the airsmith equivalent of a cudgel) that enables my semiauto pistol design to work and remain within its acceptable size envelope. With a more traditional air system I would have been comfortable casually selling units to the public, but this is first and foremost and has always been a "crate of good guns for the field" project. When viewed through the lens of "this fleet of markers only gets unlocked during the occasional invite-only private game of responsible folks and people I consider friends and will only be pressurized under my direct supervision" my insurance agent's hair probably stays attached to his head a lot longer. If you're interested in your own "crate of good guns for your field" feel free to call me; I can be surprisingly budget friendly.
At the end of the day, this is a turbine blisk for a Pratt and Whitney F135 jet engine. It requires the same material traceability and certs. It requires the same process control and heat treat documentation. It requires the same metallurgical testing and dimensional inspection, and before a person is ever playing paintball with this tank I'm gonna bolt one down in the heaviest steel flange I can find and fill it with pressurized fluid until it stops being a pressure vessel.
Anyway, thank you for coming to my Ted talk, please tear this design to shreds in the replies - or if you have any suggestions for how to improve it at all, even if you're just spitballing ideas, please do help me out.
P.S. - This is a hollow bore cylinder with threaded features and an endcap and technically meets the legal definition of a suppressor. That being said, I don't think anyone makes a .09 caliber bullet and who the hell takes the time to oil quench and temper their absurdly heavy 4340 beer can? I digress. Hey does anyone know which form I have to fill out to legally posses an eight ball of Plutonium 239 and a tea cup full of lithium duteride?
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