GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: antithesis on May 30, 2021, 10:48:54 PM
-
Ok now I know I am pretty well remembered for some strange ideas when I am looking to solve a problem...and Bob and company are the first place In the gauntlet of feasibility I use to put these to the test. Let's see what happens .
First anyone who is familiar with the kral puncher platform feel free with your thoughts.
I plan on installing a lane or huma in tube reg on this rifle. I already upgraded to the 330cc mega tube to help offset some of the lost fill volume. I don't need a TON of power here, so I am going with a reasonably small regulator plenum.
These valve bodies have one gauge port and opposite side a burst disc. I am in talks to get a plenum can made to thread into the gauge port, supplementing the regulated air volume.
My question now becomes since the air supply is perpendicular to the main plenum space and will be feeding pretty close to the poppet at 90 degrees, could this pose any problems with flow to the poppet, or could this be relatively ineffective at maintaining air pressure coming from a different direction? Is there any way that this could be optimized by opening the bottom of the port , or can anyone point out any immediate problem they see with this idea, other than the fact that I'll be putting a hole in a plastic stock?
-
In Evanix that gauge port has small like 1.5-2mm orifice that turns back towards the front of the gun. It would be a very poor air route and size for plenum extension. It could be different in Krals though.
-
In Evanix that gauge port has small like 1.5-2mm orifice that turns back towards the front of the gun. It would be a very poor air route and size for plenum extension. It could be different in Krals though.
Well this one appears to do a 90 straight in. However the port isn't much more than you describe. I have room I can use to open it up a bit. Let's suppose I could get up to .20 or so. Or better yet let's be hypothetical and say I could open it up more (dont worry I'm not).
Let's throw all pertinent model specific information to the side at this stage and say a .25 hole feeding into regulated airspace 90 degrees to the rest of the plenum air.
rkr that is however the kind of thing I will be considering if I pass the physics section of the test...thank you I need as much information as I can use
-
I think you should state your power goal. At 12 fpe most anything will work as the existing plenum is enough. At 100 fpe, well let's just say I have damaged a depinger with only one 4.5mm hole in it.
-
I think you should state your power goal. At 12 fpe most anything will work as the existing plenum is enough. At 100 fpe, well let's just say I have damaged a depinger with only one 4.5mm hole in it.
Ok that's fair. In .22 I am aiming at 30-35 ftlbs. I am not aiming for more power but rather better efficiency, lower reg set and keeping as much full pressure fill volume as possible. I'm going to try to accomplish this with a reg set hopefully 1.5-1.7k. Max fill on these tubes is 2900 according to kral, I am not uncomfortable with 3k even. A in tube reg is going to cost me no less than 30cc post install and I want to make the most out of the other 300cc.
-
Generally, you want the air inlet from the plenum to be larger than the throat of the valve, so that the air can get into the valve faster than it can get out.... I had two 90 deg. turns in a .25 cal Disco pumper, with a valve arranged like this....
(https://hosting.photobucket.com/albums/oo221/rsterne/Millenium Pumper/.highres/IMG_2725.jpg?width=1920&height=1080&fit=bounds) (https://app.photobucket.com/u/rsterne/a/2b6b9a8f-bf4c-41f4-8426-985eaf5ed6aa/p/e7038a69-fc75-456a-9c98-ca07478e7789)
The 16 gr. CO2 cartridge had an internal volume of about 20 cc, added to the 7 cc in the valve and gauge port, for a total of 27cc.... However, it fed into the very front of the valve, just behind the check valve, and a long ways from the poppet.... the valve seat is about in the middle of the rear valve half.... That gun could reach 40 FPE at 1500 psi, and shoot efficiently at 30 FPE at that pressure, with a 20" barrel.... The passages from the CO2 through the gauge port and into the valve were 1/4" however, which is bore-size for a .25 cal....
Bob
-
Think of it as pressure rather than air flow, The smaller reservoir is supplementing the pressure in the main reservoir. Everything else works the same as before.
-
Think of it as pressure rather than air flow, The smaller reservoir is supplementing the pressure in the main reservoir. Everything else works the same as before.
That was essentially what I was hoping to accomplish, just to keep the average pressure of the air up enough. I know laminar or axial flow is more or less out the window....so its probably the biggest matter now to try to open up that port some. It is a 10x1 thread at about 8mm deep. How much do you think I could comfortably open it up to? Leave maybe a 2mm ledge for the gasket to sit on? It's not a tapered thread and I am hoping I can avoid a sealing nightmare
-
Generally, you want the air inlet from the plenum to be larger than the throat of the valve, so that the air can get into the valve faster than it can get out.... I had two 90 deg. turns in a .25 cal Disco pumper, with a valve arranged like this....
(https://hosting.photobucket.com/albums/oo221/rsterne/Millenium Pumper/.highres/IMG_2725.jpg?width=1920&height=1080&fit=bounds) (https://app.photobucket.com/u/rsterne/a/2b6b9a8f-bf4c-41f4-8426-985eaf5ed6aa/p/e7038a69-fc75-456a-9c98-ca07478e7789)
The 16 gr. CO2 cartridge had an internal volume of about 20 cc, added to the 7 cc in the valve and gauge port, for a total of 27cc.... However, it fed into the very front of the valve, just behind the check valve, and a long ways from the poppet.... the valve seat is about in the middle of the rear valve half.... That gun could reach 40 FPE at 1500 psi, and shoot efficiently at 30 FPE at that pressure, with a 20" barrel.... The passages from the CO2 through the gauge port and into the valve were 1/4" however, which is bore-size for a .25 cal....
Bob
I want to say I remember you building that....is that co2 a threaded cartridge?
I know this one may be reaching a little close to diminishing returns but if it can help me reduce the necessary reg pressure by maybe 200-300 lbs for equivalent performance I'd be happy. I don't know how high to set my expectations I'm just doing what I can to create a favorable atmosphere to make it happen. It may look a tiny bit ugly but on the upshot at least I'll have a reg gauge too
And just as pertinent info after we discussed it this should be a 20cc plenum, itll probably just be a matter of how effectively it feeds the main chamber
-
Yes that is a threaded CO2, and soft soldered into the brass gauge fitting (after threading in) to seal it....
A 10x1 mm thread has an 8.5mm minor dimension, I think you could seal it on a 2mm edge, as you say, and that leaves a 4.5mm hole.... That is probably similar to your port diameter on a .22 cal, so it should work fine.... Having the flow impinge on the side of the poppet would I think cause turbulence there..... that may or may not cause a problem.... By definition, to keep the pressure inside the valve up, requires flow out of the plenum.... If the hole linking them was too small you would see a pressure drop at the valve seat during the shot, compared to a larger hole, but certainly not as much drop as with no plenum....
Bob