Making a pcp valve that has a greater than 50% "theory" max power.
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Making a pcp valve that has a greater than 50% "theory" max power.
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Topic: Making a pcp valve that has a greater than 50% "theory" max power. (Read 7715 times))
K.O.
Eternally Tinkering
GTA Senior Contributor
Posts: 7111
yes
Real Name: Kirby
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #20 on:
October 12, 2018, 01:36:45 PM »
Well I would think the dump valve would make the most power with a chamber like Lloyd used for the over 2000 fps shots... I believe it will have the fastest beginning flow and creates a de Laval nozzle as the round travels down the Loooong Barrel... The biggest prob would be to dump the charge without impeding the air flow...
also have some
LIGHTNING
in a bottle ideas for a timed raise of the energy state/temp of the gas..
Capacitor in the stock; leads in the chamber..?
?
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The Great Northwest, United States, Washington
rsterne
Member 2000+fps Club
Bob and Lloyd
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Posts: 26920
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Real Name: Bob
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #21 on:
October 12, 2018, 02:47:30 PM »
Kirby, a dump valve would need a HUGE volume to keep the pressure drop as the bullet travels down the barrel to similar values as a conventional timed valve.... If you used a 300 cc dump valve, then the pressure profile would be the same as a timed valve that stays open until the pellet exits and then closes if the plenum/reservoir was 300 cc.... The difference is that with a barrel volume of 20 cc (.25 cal @ 25" long), with the timed valve you would use 20 cc of HPA, while with the dump valve you would use all 300 cc.... In both cases if you started with 3000 psi, the pressure would have dropped to just over 2800 psi when the pellet exits the muzzle....
If you used a dump valve of 20 cc, so that you used the same amount of HPA as the dump valve.... the pressure when the bullet reaches the muzzle would only be 1500 psi....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
K.O.
Eternally Tinkering
GTA Senior Contributor
Posts: 7111
yes
Real Name: Kirby
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #22 on:
October 12, 2018, 03:28:26 PM »
yes but a sudden sharp rise from 3500 psi (or what ever) that ruptures a burst disk... brought on by the heat of an electrical discharge (lightning) in in the chamber... is only limited by the % of absolute temp rise in chamber temp you can cause... 50 % rise in temp 50% rise in pressure/energy state... well sort of,,, Van der Waals constant/equation would apply...
http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/waal.html
that would bring down the size of chamber needed and thereby up efficiency compared to the timed valve..
«
Last Edit: October 12, 2018, 03:44:13 PM by K.O.
»
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rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26920
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #23 on:
October 12, 2018, 07:33:38 PM »
and once you factor in the energy of the "spark" required to raise the temperature of the air enough to, say, double the power?.... I couldn't even begin to guess what the efficiency (output / input) might be.... When you think about it, 50% is pretty good, many machines only get to 30% or so.... Car engines are 20-40%....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
shorty
Expert
Posts: 1936
yes
Real Name: Tim
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #24 on:
October 14, 2018, 11:43:22 AM »
Yes I pull my hair out and talk to myself
but, this seems to be the only thing on my mind lately.
So, what I am hearing is that a conventional valve can produce the same amount of energy as a balanced (or semi balanced ) valve as long as they are opened up big enough.
And,
The balanced valve/semi balanced valve just makes opening easier and designed properly, can aide in closing it just as fast.
I would guess that unless the valve your building is for .22 and less, there is probably no reason to use a balanced/semi balanced valve due to the poppet/throat ratio for full bore porting (unless you like extremely low cocking force and ultra light hammers).
I ran the numbers for .25 cal and you would need a throat of a minimum of .285" with a .125" stem. Now that would be hard to crack at 3000psi
I counldn't sleep last night and woke at 4am. I knew I should have went back to bed but stayed up till 6am making drawings. The drawings got boring so I headed out to the garage to try and turn something out. 3 cups of coffee later.
It would never work as is because I was just messing around ( been a long time since I turned out some parts ). But, I had an idea and went to work.
I would say it's kind of like cothran style for balancing and kind of like cobra tech for closing and kind of like "me" being able to fit into a marauder valve with the least work.
The piston diameter is less than the poppet sealing (balancing). The piston has a hole through it from the poppet sleeve to the center of the piston with another hole to allow for HPA to enter (air spring - closing force).
I would think it would create a bell curve since the valve is semi-balanced similar in the way the SS valve works.
I also didn't feel like making a new poppet right now so the sleeve ID at the poppet head is a press fit. I would imagine if these 2 contact points were lapped, they would seal similar to how the poppet seals to the throat/valve seat.
I could also imagine the piston being threaded the same as the valve cap for alignment and ease of assembly.
Like I said, I was just messing around on the lathe and in no way trying to copy or steal someones idea/ideas. I was just trying to make the idea in my head into a couple parts.
Would love to hear some thoughts on the parts though. Maybe your comments will help me either change direction or think about it some more.
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Palm Coast, FL
MJP
Member 4400+Fpe Club
GTA Senior Contributor
Posts: 2136
I'll make it real. For me.
Real Name: Marko
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #25 on:
October 15, 2018, 07:59:25 AM »
So now you just need to test it, how much is the closing force, or balancing force?
Testing what works is fun, assembled it and shoot.
Marko
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Finland
Impossible just takes a little bit longer to achieve.
If an engineer is not presented with a suitable problem, they will create their own!
shorty
Expert
Posts: 1936
yes
Real Name: Tim
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #26 on:
October 15, 2018, 06:09:43 PM »
Marko,
I am gonna take that as a go ahead and do it. Thank you. I am looking to make a new insert for the marauder valve with a .285" throat and fit the balancing act in it.
I have some other ideas for the bolt.
The piston looks like a good idea to keep things tiny in the .5" area.
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Palm Coast, FL
shorty
Expert
Posts: 1936
yes
Real Name: Tim
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #27 on:
October 16, 2018, 07:01:06 PM »
Just have to share how these parts came out when coated. Just beautiful.
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Palm Coast, FL
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26920
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #28 on:
October 16, 2018, 07:22:29 PM »
Tim, how does the air get into the front of the valve?....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
shorty
Expert
Posts: 1936
yes
Real Name: Tim
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #29 on:
October 16, 2018, 07:32:06 PM »
It doesn't yet. I will be making v2 of this design very soon as V1 was just playing around. But, ever since I got to hold the parts in my hand i figured a bunch out.
I am thinking of shortening everything down and use the valve cap as the retainer. Mill out the sides of the piston for air to get into the valve.
So really all you have to do is hog the valve out to .5", pop this piston in and screw the valve cap on to hold it in place.
It's coming.... I have the idea but have not made the parts yet to explain it yet.
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Palm Coast, FL
shorty
Expert
Posts: 1936
yes
Real Name: Tim
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #30 on:
October 16, 2018, 07:35:02 PM »
I really want to have a .285" throat for the full bore porting and don't feel like making a poppet. I am wondering if a bulldog poppet will suffice and if I can get one from crosman on the cheap.
Otherwise,
I will be ordering some Peek.
Got to admit though, that's a nice ceramic coating huh. So pretty.....
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Palm Coast, FL
MJP
Member 4400+Fpe Club
GTA Senior Contributor
Posts: 2136
I'll make it real. For me.
Real Name: Marko
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #31 on:
October 17, 2018, 04:19:14 AM »
Quote from: rsterne on October 16, 2018, 07:22:29 PM
Tim, how does the air get into the front of the valve?....
Bob
Sssshh don't tell him everything
Logged
Finland
Impossible just takes a little bit longer to achieve.
If an engineer is not presented with a suitable problem, they will create their own!
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26920
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #32 on:
October 17, 2018, 12:31:54 PM »
I must be missing something here.... Please correct me if I am wrong....
The "piston" (front part with O-ring) has a hole drilled from the back part way up, and then a cross hole connected to that.... This means that the pressure inside the poppet chamber (formed by the tube pressed onto the poppet) is the same as the pressure inside the rest of the valve, right?....
When the valve is closed, the total force holding the poppet closed would therefore be exactly the same as if you used a poppet with the same sealing diameter.... If you removed the piston, nothing changes in regard to the opening force required, because the piston is surrounded on all sides by the same air pressure....
What am I missing, Tim?....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
MJP
Member 4400+Fpe Club
GTA Senior Contributor
Posts: 2136
I'll make it real. For me.
Real Name: Marko
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #33 on:
October 17, 2018, 01:46:53 PM »
Wow, now I noticed that too,
Not going to work I'm afraid.
You need to breath that port in to atmosphere, not in to tank pressure if tou want balancing.
Marko
Logged
Finland
Impossible just takes a little bit longer to achieve.
If an engineer is not presented with a suitable problem, they will create their own!
shorty
Expert
Posts: 1936
yes
Real Name: Tim
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #34 on:
October 17, 2018, 06:50:06 PM »
To be serious Bob. What your missing is that I am trying and your not. I like the "it ain't gonna work" thing but jezz, come on. Put some of your experience into it. Damnnn.
MJP,
Thank you for for the push and bread crumbs.
I have learned alot lately doing this (money work and play time work).
V2 was made today but darn, I really need a mill.
Please keep in mind, that a marauder tube or any crosman tube has a double o ring gauge port right before the valve on the HPA side for venting to atmosphere.
Not only that, I don't see an SS valve venting to atmosphere and yet people claim it reduces cocking cracking force. Tell me how that works ?
To me,
I can buy a cothran valve, Cobra valve, or SS valve but, it's just like you guys said, it's how big you can open the valve and still crack it open. I'd rather figure how out to do that instead of buying and possibly change a few things.
Please feed the ideas. This seems to be my only hobby besides work and family.
V2 is now enclosed in the valve body and uses the valve cap as a retainer.
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Palm Coast, FL
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26920
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #35 on:
October 17, 2018, 07:25:20 PM »
Yeah, Tim, I tell you it won't work and I'm a jerk.... Marko says the same thing and he's a good guy.... Seriously?.... Give your head a shake, man.... Obviously I was right to drop out of this thread the first time....
Let us know when you get it all figured out and working.... 'cause you sure don't want to listen when I tell you there is a problem and why.... You want us to design it for you, and yet aren't interested in hearing about it when our experience sees problems....
Bob
«
Last Edit: October 17, 2018, 07:44:58 PM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Rob M
GTA Senior Contributor
Posts: 6304
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #36 on:
October 17, 2018, 11:32:32 PM »
balanced valve
by
murphyrobert9
, on Flickr
heres my partially balanced valve , the stem is not balanced so the pressure on the sliding piston minus the stem ( area - area) is the % balanced.. It will take years to explain it , I did build it.. with a 1/8th stem sealed to the body, and the sliding piston being .625 , the valve was roughly 75 % balanced .. a few issues were closing force after the pressure drop in the tube , that number would be very low.. Another problem, the piston only aligns with the TP for a split second , NOT GOOD>. its a bad design , but it was a majority balanced valve
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Louisiana
Rob M
GTA Senior Contributor
Posts: 6304
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #37 on:
October 17, 2018, 11:36:08 PM »
balanced 2
by
murphyrobert9
, on Flickr
full pic.. the tiny weep hole would be key to the design.. also , the rear of the valve carried the oring to seal the stem , much like a vigilante valve design.. id love to find the pic of the built valve , ill keep looking
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Louisiana
Rob M
GTA Senior Contributor
Posts: 6304
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #38 on:
October 17, 2018, 11:40:17 PM »
heres the stem.. you can see how it sealed to the inner valve body
stem balanced
by
murphyrobert9
, on Flickr
Logged
Louisiana
Rob M
GTA Senior Contributor
Posts: 6304
Re: Making a pcp valve that has a greater than 50% "theory" max power.
«
Reply #39 on:
October 17, 2018, 11:44:48 PM »
im looking more at compact qev designs that are rear vented with a balanced piston.. getting them to repeat under constant feed pressure is the trick.. I have not tested in this regard yet, but I do think its the way to go in regard to offsetting complex pocket machining.. just my opinion.
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Louisiana
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Making a pcp valve that has a greater than 50% "theory" max power.