Questions.
In the search for ultimate power…
I’ve produced a few valves now, the most powerful of which was able to give a .22 21-grain pellet 1150fps with a Blod spring and 22mm of spacers behind a 100g hammer and a fill of 3000psi through a 24″ barrel. My current valve gives a max of 1050fps with all the above the same except for needing 30mm of spacers. With 10mm of spacer the best I can get is 750fps.
On the Condor with it’s power-wheel, could somebody please tell me what the wheel-settings equate to in terms of spacers at both it’s lowest and highest settings? And also some fps numbers with 21-grain pellets would be helpful.
The last question…does the air-volume in the components between the tank and the breech affect performance appreciably? In other words, which gives best performance, a low-volume stem or a high-volume stem? That also affects the weight of the stem, which I’m thinking may also be hindering performance. The longer the stem the greater it’s mass and volume.
Any insights will be gratefully received. 😀
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You can never have enough power 😆 If you choose to use It or not Is a different matter. Like cars, It’s always nice to have something that can shift when needs be 🙂
Walter….
Mine did. Don’t know how but I;ve had them deform too. The 45 degree shoulder bit on top has opened out.
Valve seal on the right has opened out…
Fuck knows what happend to this one but that stem Is pushed In all the way??
2 stroke expansion chambers utilize sound to form waves of higher or lower pressure. They have to be timed properly and work at only a bit more or less than atmospheric. I would hazard a guess and say that they wouldn’t work in this application due to the very high pressures already in the workspaces when the valve opens. Also, sound waves have a hard time turning certain corners, which is the basic principle behind every ldc, but doesn’t work well in the airgun’s valve or breech.
The breech diam is kept to a minimum so not to waste air from each valve blow. It’s more dead space that must be pressurized each time a pellet is fired. But from the valve perspective, the larger the diameter of the valve stem the better, obviously, to improve flow rates through the stem. And orifice turbulence probably has a lot to do with it as well, down the stem just after the seal. Which is why different types of seal bases (with the same size seal surface) can and do affect flow rate.
aloha,
walt
Ah, that’s interesting, and I’ve been wondering about it. Previously I was profiling my seals so they were hemi-spherical. I figured giving the smallest point of contact between the seal and aperture offered the best performance. Then I saw the seal on Blod’s was completely flat and made the one on my current valve the same. I’ve assumed the force acting upon it largely negates any difference in the seal’s diameter.
Soon as I take delivery of the 3mm lock-nuts I’ll open the valve and change the seal back to a profiled item and see what result that garners.
Lang, nice looking project.
2 stroke expansion chambers utilize sound to form waves of higher or lower pressure. They have to be timed properly and work at only a bit more or less than atmospheric. I would hazard a guess and say that they wouldn’t work in this application due to the very high pressures already in the workspaces when the valve opens. Also, sound waves have a hard time turning certain corners, which is the basic principle behind every ldc, but doesn’t work well in the airgun’s valve or breech.
The breech diam is kept to a minimum so not to waste air from each valve blow. It’s more dead space that must be pressurized each time a pellet is fired. But from the valve perspective, the larger the diameter of the valve stem the better, obviously, to improve flow rates through the stem. And orifice turbulence probably has a lot to do with it as well, down the stem just after the seal. Which is why different types of seal bases (with the same size seal surface) can and do affect flow rate.
aloha,
walt
Current state. The barrel comes up about 2/3rds of the way inside the silencer and it’s baffled for only half of it’s length. Doesn’t silence particularly well as a result.
Pah, shite. 839fps at 32.8fpe. Seems odd, shouldn’t the fpe been higher than for a 21-grain (which come in at 50fpe)?
30-grain Eley Wasp next…
666fps, 20.73fpe.
Duh, twat, forgot to enter the pellet-weight into the chrony. 😆
Ok, 30-grain PD get’s 45fpe for 830fps.
40 grain swaged bullets at 1075fps for 102fpe in .257
50 grainers make 125fpe IIRC……
Very impressive. 😀
Ah, that reminds me, I have some 30-grain .22 piledrivers. Testing time!
28 grains at 1160 for 85fpe in .22
40 grain swaged bullets at 1075fps for 102fpe in .257
50 grainers make 125fpe IIRC……
pop out and pop new one in……. easy peasy
so why are you making this valve again???? :):):)
Not always, I’ve had seals kicked to the side, Damaged seals needing me to order new ones which Is a PITA 😆 I think Lang’s idea Is great…. but needs more power 😉 🙂
If the tank has no lower than the minimum shooting pressure inside there is no way for the valve head to slip out of the way.
Langs method is indeed a good one
BTW with my valve and stem system I can use the same valve body, same valve head and get from 10fpe to 466fpe in a range of calibers from .177 to .458 :):):)
Walter….
What fpe are you getting with a .22 and .25?
If I wasn’t restricted by the need to have interchangeable heads I could implement a much more radical design and probably increase the power significantly. A totally one-piece stem & head would be the way to go I suppose, ultra-short and a max OD of 8mm.
pop out and pop new one in……. easy peasy
so why are you making this valve again???? :):):)
Not always, I’ve had seals kicked to the side, Damaged seals needing me to order new ones which Is a PITA 😆 I think Lang’s idea Is great…. but needs more power 😉 🙂
If the tank has no lower than the minimum shooting pressure inside there is no way for the valve head to slip out of the way.
Langs method is indeed a good one
BTW with my valve and stem system I can use the same valve body, same valve head and get from 10fpe to 466fpe in a range of calibers from .177 to .458 :):):)
Walter….
pop out and pop new one in……. easy peasy
so why are you making this valve again???? :):):)
They do? 😕 First I’ve heard of it, and of all the pics I’ve seen I’ve not seen one such as you describe.
with the judisious use of a flat blade screwdriver the stem pops out to allow another to be installed.
All the stems are a friction fit into the Delrin head and can be exchanged.
Now having said that what you have made is better for changeing the tophats out.
Walter….
pop out and pop new one in……. easy peasy
so why are you making this valve again???? :):):)
Not always, I’ve had seals kicked to the side, Damaged seals needing me to order new ones which Is a PITA 😆 I think Lang’s idea Is great…. but needs more power 😉 🙂
Well, a higher max-power would be nice (for the Yanks and their 9mm stuff etc), but for .22s and .25s anything above around 950fps and you start to lose accuracy (pellets de-stabilize). The bigger issue is having to have 30mm of spacers to hit 1000fps, I’ve had 1150fps on 22mm of spacers with previous designs.
pop out and pop new one in……. easy peasy
so why are you making this valve again???? :):):)
They do? 😕 First I’ve heard of it, and of all the pics I’ve seen I’ve not seen one such as you describe.
pop out and pop new one in……. easy peasy
so why are you making this valve again???? :):):)
Not always, I’ve had seals kicked to the side, Damaged seals needing me to order new ones which Is a PITA 😆 I think Lang’s idea Is great…. but needs more power 😉 🙂
The stem’s ID is 6mm, going into a 6mm tophat/head. The stem goes into a 10mm ID hole (inside the valve-body), and there’s about 10mm of space between the stem and the aperture that leads into the bottle. The bore in the stem is 35mm long. So between the aperture and the breech there is 10mm of 10mm-ID space, then 35mm of 6mm bore in the stem and 14mm of 6mm bore in the head. It’s a fair old distance. 😆
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at 1,000 psi a Talon valve has 75 pounds force holding it closed/in position
so a little push fit stem to head will not dislodge it.
the crooked one was likely assembled poorly from the getgo. a sharp edge on the stem could shear a sliver of plastic out of the way and end up crooked.
walter….