Hector,Thanks for your detailed reply. Would it be rude to inquire the name of your company? How does one apply for a job there I fully get that spring air rifles are more efficient than SSPs. That for higher FPE applications, the "springer" (adiabatic compression) efficiency advantage makes for a smaller, potentially lighter, and lighter cocking airgun. So, if optimizing springer efficiency is the business path, you may already be implementing some of the ideas expressed below:I recently bought two cheap refurb Gamo Big Cat gas-ram "springers". The plan is to cut off the barrel hinges and mount the two cylinders face to face. Then, have a TP in the middle with a Marauder style breech and barrel on top. I may replace the gas springs with steel (oh the vibration). This would be in order to use the space inside each piston ID to house an attached steel tube, holding tungsten shot. The OD of the inner steel tubes become spring guides.The reason for the above is that springers loose efficiency in the form of piston bounce: Doubling up the swept volume will tend to make that bounce much worse (worst, if we assume the same caliber as the single power unit had). The combined piston velocity will also make the air pressure spike much quicker and much higher; possibly to the point of blowing the pellet skirt up in a ridiculous manner. So, by adding some weight to the pistons to slow down their end of stroke velocity a little, and by disconnecting the mass in the form of a shower of tungsten pellets, the efficiency robbing piston bounce can be greatly reduced. This, while the two "heavy" pistons cancel each other's inertia. Tungsten shot should be more gentle as a "deadblow hammer", than a single tungsten slug per piston. However, tungsten slugs with very light o-ring friction to hold them against gravity may behave in a more predictable manner, for the best vibration cancellation.I can also see how ramming the air into a small "plenum" leading to the TP could help: Such a plenum would have a volume perhaps one or two percent of the combined piston swept volume: The effect would be to reduce the peak air pressure to a level the pellets can handle. And, in combination with a reed valve at the entrance of this little plenum, restore efficiency otherwise lost, by preventing air from back-flowing, that would normally follow the bouncing pistons.If this were a ground up design, I would consider making the bulk of the receiver tubing from aluminum. Using steel inserts for wear and to handle high pressure air only where such loads exist. As it is, just the receivers of the two Gamos would weight over 8 lb. That is OK for a testbed, but would add up to a 12 lb wood stocked rifle. And that is twice as much as the lower target weight point for a sporter. Now, my goal with such a Frankenstein is .22 PCP level FPE, without exceeding 30 lb peak cocking force; probably done in two steps; or with a windlass, like a crossbow...Airguns are a hobby for me. If I were in the business, I would not be sharing the above. Not that I assume to have actually suggested anything you haven't heard before, or though of yourself. As the holder of over a dozen US patents, I know that virtually any "new idea" I come up with has been thought of before. Rather than disappointment, I see that as validation
Hector,Thanks for your detailed reply. Would it be rude to inquire the name of your company? How does one apply for a job there I fully get that spring air rifles are more efficient than SSPs. That for higher FPE applications, the "springer" (adiabatic compression) efficiency advantage makes for a smaller, potentially lighter, and lighter cocking airgun. So, if optimizing springer efficiency is the business path, you may already be implementing some of the ideas expressed below:I recently bought two cheap refurb Gamo Big Cat gas-ram "springers" to splice together. My goal is a .22 "Frankenrifle" that delivers PCP level FPE, without exceeding 30 lb peak cocking force. Cocking would probably be done in two steps; or with a windlass, like a crossbow...The plan is to cut off the barrel hinges and mount the two cylinders face to face. Then, have a TP in the middle with a Marauder style breech and barrel on top. I may replace the gas springs with steel (oh the vibration). This would be in order to use the space inside each piston ID to house an attached steel tube, holding tungsten shot. The OD of the inner steel tubes become spring guides.The reason for the above is that springers loose efficiency in the form of piston bounce: Doubling up the swept volume will tend to make that bounce much worse (worst, if we assume the same caliber as the single power unit had). The combined piston velocity will also make the air pressure spike much quicker and much higher; possibly to the point of blowing the pellet skirt up in a ridiculous manner. So, by adding some weight to the pistons to slow down their end of stroke velocity a little, and by disconnecting the mass in the form of a shower of tungsten pellets, the efficiency robbing piston bounce can be greatly reduced. This, while the two "heavy" pistons cancel each other's inertia. Tungsten shot should be more gentle as a "deadblow hammer", than a single tungsten slug per piston. However, tungsten slugs with very light o-ring friction to hold them against gravity may behave in a more predictable manner, for the best vibration cancellation.I can also see how ramming the air into a small "plenum" leading to the TP could help: Such a plenum would have a volume of perhaps one percent of the combined piston swept volume: The effect would be to reduce the peak air pressure to a level the pellets can handle. And, in combination with a reed valve at the entrance of this little plenum, restore efficiency otherwise lost, by preventing air from back-flowing, that would normally follow the bouncing pistons.If this were a ground up design, I would consider making the bulk of the receiver tubing from aluminum. Using steel inserts for wear and to handle high pressure air only where such loads exist. As it is, just the receivers of the two Gamos would weight over 8 lb. That is OK for a testbed, but would add up to a 12 lb wood stocked rifle. Just the barrel-less powerplant would already exceed my preferred weight point for a sporter. Airguns are a hobby for me. If I were in the business, I would not be sharing the above on an open forum. Not that I assume to have actually suggested anything you haven't heard before, or though of yourself. As the holder of over a dozen US patents, I know that virtually any "new idea" I come up with has been thought of before. Rather than disappointment, I see that as validation EDIT: I found you at Connecticut Custom Airguns. I am sure people pester you for a job all the time. How many try to sell you product ideas, or do incidental consulting?
Thanks for your continued interest and replies! All replies are useful.In the little over 1 week we have been discussing this, there are now more than 5000 shows of interest, of which a little under 90, ended in a post, of which less than 10 are negatives.Sure there are a lot of details to work out. And possibly we can come up with something that satisfies the majority. Because "you can't win'em all", it's just human nature.One thing for sure is that we will try to avoid Whiscombe's errors. And our own past errors, also!The technology and physics of the system are more than fascinating, and the new manufacturing technologies open so many doors.We'll have a better feeling about whether this becomes a project or not after IWA (March).Thanks again!HM
Seriously though, I've wondered about integrating shock absorbers into the stock...The shock absorbers would only allow the barrel and action to move in a straight line front and back. Kind of like how a howitzer works.
Hector,I will even put my money where my mouth is and give you/Diana a $100 deposit! -Y
Quote from: Mossonarock on February 05, 2019, 10:48:27 AMSeriously though, I've wondered about integrating shock absorbers into the stock...The shock absorbers would only allow the barrel and action to move in a straight line front and back. Kind of like how a howitzer works.Tim,This thread is about a spring air rifle that uses the Giss system. The Giss system has a mass of equal weight to the piston, that moves in coordinated manner, in the opposite direction of the piston at the instant of firing. This does a very good job of cancelling vibration and "recoil". Hence, no additional shock absorbers or other damping parts or materials would be required...
Recoil-less Spring-Piston Airgun?Ideas, comments, and pro-positive suggestions welcome.TIA! HM
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