American Air Arms

predator-pellets

Neil Clague Air Strippers, Shrouds and LDCs

windmeister-ad

Wicked Air Rifles - Flex

Marmot Militia Machine Works

Author Topic: Building a better balanced valve  (Read 2241 times)

oldpro

  • Hero Member
  • *****
  • Posts: 1132
    • View Profile
Building a better balanced valve
« on: July 29, 2017, 11:36:38 AM »
 Balanced valves in PCPs are great things, especially in high powered PCPs.  The basic idea is that some of the high pressure reservoir air is prevented from pressing on the head of valve poppet, and thereby reduces the amount of hammer strike that is needed to knock the valve open. There are already some good balanced valves of many different designs out there, and each has its strengths and its weaknesses.  It is not too hard to build a balanced valve that works, but building one that works well definitely IS difficult.

This is a variation on one of Travis's valves, the Cobra Valve, I believe.  He and I chatted at the Fun Shoot in May in KY, and he scratched out a napkin sketch of a valve with two different o-ringed internal diameters that created varying pressure differentials within the valve.  This reduces the amount of force that is needed to open the valve, so you don't need 2 hands to cock a high powered airgun.  But the dual diameters within the valve also "somewhat" control the closing timing of the valve.  This has a big affect on the air efficiency of the valve.

Shortly after the fun shoot Travis gave me one of his valves, and I replaced the guts of it with this dual diameter poppet.  The valve body and seat and snap ring and retainer  all remained the same, though.

Testing started on a .22 M-Rod and was going so-so, but nothing earth shattering.  I was about to give up but Travis was more optimistic so I tried changing some of the passage diameters within the valve. Bingo! That did it.  The number of variables with 2 internal diameters and 2 internal passages make it difficult to assess the success or failure of each iteration, but after a while trends start showing.

The valve is now pretty close, but it can always be made better.
The test bed is a Marauder Gen 1 rifle with a P-Rod pistol grip and trigger group. The hammer and spring are stock.
It has a 23" .308 barrel, and for testing, the reservoir volume has been reduced to 120ccs.  That makes it easier to measure pressure changes and therefore, air usage and air efficiency.

The first set below, Set number 22, is this new valve shooting 45.8 lead round balls in the .308 barrel.
All shots were taken at 2300 psi, and between each shot the gun was refilled to 2300psi and the hammer spring was adjusted. This was done to measure the power and the air efficiency at various hammer strikes. The valve proved to be fairly powerful and efficient over a full range of power levels.

The new valve produced 97 FPE at 1.26 fpe/cuin air efficiency, down to 50fpe at 1.80 efficiency. The required hammer force was much lower than stock.

The second set, Set number 23, is with a stock valve, with exhaust port opened slightly, and the remainder of the setup identical to set 22.  For comparable hammer strikes, the stock valve produced 59 FPE at 0.76 efficiency, down to 47FPE at 1.03 efficiency.

Even though this isn't an apples to apples comparison,  the new valve is almost twice as efficient with air usage compared to a stock valve. Twice the power for the same amount of air. More to come.

==========
Darn, guess I've been asleep at the wheel. Just realized i need to pay Photobucket $400 a year to be able to display the hundreds of images I've uploaded to their site. I will try and find a way to display the chart that goes with this post tomorrow.  Sorry.
Lloyd


  • Mount Shasta Ca.

oldpro

  • Hero Member
  • *****
  • Posts: 1132
    • View Profile
Re: Building a better balanced valve
« Reply #1 on: July 29, 2017, 11:40:48 AM »
 Here are some charts that may help answer questions that will arise from this new valve.
  • Mount Shasta Ca.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1217
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Building a better balanced valve
« Reply #2 on: July 29, 2017, 11:49:56 AM »
Nice to see the wraps are FINALLY off this new and exciting ART/Sikes Balanced Valve.... Travis sent me one of the original Cobra valves, and in my high-power builds I was less than excited about the results.... While Scott and Travis were achieving some spectacular efficiency numbers with low to medium powered builds, my rip-snorting guns didn't see the efficiency gains, or the lighter hammer strikes.... For my new 6mm build I hope to do this winter, I therefore planned to use a Cothran valve, and that meant I would have to adjust the power level solely by adjusting the regulator setpoint pressure.... It also meant that off regulation, or off tether, the first shot would be the fastest, with a declining shot string to follow.... I really needed a Balanced Valve that would be tunable with hammer strike, and produce a bell-curve when unregulated.... but there were simply none that were Commercially available, and the designs I had seen, or come up with, were too difficult for me to build with my meager machining skills and equipment....

Without giving away the farm, this new valve uses a stepped poppet with two different diameters, one to seal the seat, and the other to counterbalance the force holding the valve against that seat.... However, it is very different in concept to anything I have seen before, and although I have been privy to the design and testing for a while, I have yet to lay my hands on one (hint, hint).... I have carefully analysed the design, and I can see no pitfalls, either in the concept, or in producing them.... Kudos to Travis for the original idea, and to Lloyd for the development work.... I think this may just lead us to a whole new generation of Balanced Valves that could be made as replacement items for many existing PCPs.... and the concept should have far-reaching implications for future PCP development.... Imagine the ability to use MUCH larger ports, while reducing the cocking force required.... and yet still maintain the ability to tune the valve with hammer strike, in addition to pressure, and get a solid bell-curve.... Not only that, but I think that maybe, just maybe, I can make my own version of it (for my own use), and hopefully thereby add to the body of knowledge surrounding it....

I wish Travis and Lloyd all possible success in furthering this new and exciting valve design, and obtaining Patent protection for it.... Yes, gentlemen, it's THAT good !!!

Bob
  • Coalmont, BC

Alan

  • Hero Member
  • *****
  • Posts: 1308
  • Set the example... Don't be one!
    • View Profile
    • Mobile Amateur Radio
Re: Building a better balanced valve
« Reply #3 on: July 29, 2017, 12:07:58 PM »
The on-going discussion about balanced valves is proof positive why this airgun site is a head above the others. Yes, some of the data appears here and there, but where else can you get all of the information in one spot? Kudos to all.
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

Christopher

  • Sr. Member
  • ****
  • Posts: 322
    • View Profile
Re: Building a better balanced valve
« Reply #4 on: July 29, 2017, 10:03:23 PM »
Sounds like pretty exciting stuff.  Bad as I hate to I guess I'll volunteer to be a beta tester :P I'm starting to sound like Monkeydad now ;D

Chris
  • dead end road KY

Monkeydad1969

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1857
    • View Profile
Re: Building a better balanced valve
« Reply #5 on: July 29, 2017, 11:47:38 PM »
Sounds like pretty exciting stuff.  Bad as I hate to I guess I'll volunteer to be a beta tester :P I'm starting to sound like Monkeydad now ;D

Chris

You haven't even scratched the surface. ::)
  • Aurora, Colorado
Joe the P-Dawg Slayer!!!!!

Alan

  • Hero Member
  • *****
  • Posts: 1308
  • Set the example... Don't be one!
    • View Profile
    • Mobile Amateur Radio
Re: Building a better balanced valve
« Reply #6 on: July 30, 2017, 05:20:20 AM »
Chris, you have to remember what Joe does for living. I'm convinced the chemicals are doing a number on him, by just looking how long his arms are!
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

Christopher

  • Sr. Member
  • ****
  • Posts: 322
    • View Profile
Re: Building a better balanced valve
« Reply #7 on: July 30, 2017, 10:50:24 AM »
Travis, on a Mrod breech will we need to drill out the hole for the transfer port? Or any other mods to take full advantage of the valve's "breathing"?

Alan,
Chemicals???!....I'm beginning to understand now....

Chris
  • dead end road KY

Monkeydad1969

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1857
    • View Profile
Re: Building a better balanced valve
« Reply #8 on: July 30, 2017, 03:37:56 PM »
Chris, you have to remember what Joe does for living. I'm convinced the chemicals are doing a number on him, by just looking how long his arms are!

Long and huh?  Long enough to snatch you up and stick you into a tin of pellets.
  • Aurora, Colorado
Joe the P-Dawg Slayer!!!!!

oldpro

  • Hero Member
  • *****
  • Posts: 1132
    • View Profile
Re: Building a better balanced valve
« Reply #9 on: August 02, 2017, 06:30:41 PM »
  As promised I ran a few strings today when I could devote time to it and This is the first string on a WARP .25 with WAR valve(conventional) filled to 3K using a 13ci tank and ninja regulator. I made NO attempt to make any adjustments just put gun together set conventional spring set up in (no TSS/SSG) and locked down adjuster for comparison to ART/Sikes valve. Ran string and made note where it came off regulator(reg at 2K). Came off Regulator at shot #26
 
Contact photo
Attachments

    csvfile.csv (~1 KB)
    Show options

Message Body
Created: 08/02/17 01:19 PM
Description: Warp .25
Notes 1: 3k run reg at 2k
Notes 2: 15" barrel NO Tuning
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 34.00
Temp: 91 °F
BP: 29.97 inHg
Altitude: 0.00
#          FPS  FT-LBS      PF
35    760      43.61    25.84
34    750      42.47    25.50
33    744      41.80    25.30
32    741      41.46    25.19
31    729      40.13    24.79
30    737      41.01    25.06
29    731      40.35    24.85
28    747      42.13    25.40
27    739      41.24    25.13
26    736      40.90    25.02
25    728      40.02    24.75
24    730      40.24    24.82
23    730      40.24    24.82
22    729      40.13    24.79
21    729      40.13    24.79
20    730      40.24    24.82
19    732      40.46    24.89
18    727      39.91    24.72
17    732      40.46    24.89
16    721      39.25    24.51
15    724      39.58    24.62
14    721      39.25    24.51
13    721      39.25    24.51
12    725      39.69    24.65
11    722      39.36    24.55
10    725      39.69    24.65
9    721      39.25    24.51
8    725      39.69    24.65
7    724      39.58    24.62
6    718      38.93    24.41
5    711      38.17    24.17
4    716      38.71    24.34
3    712      38.28    24.21
2    713      38.39    24.24
1    680      34.92    23.12
Average: 727.4 FPS
SD: 13.5 FPS
Min: 680 FPS
Max: 760 FPS
Spread: 80 FPS
Shot/sec: 0.0
True MV: 727 FPS
Group Size (in): 0.00


Ok now second string the ONLY change is replacing conventional valve with ART/Sikes valve and surprising to me it came off reg at exact shot count as above shot #26
 
Created: 08/02/17 03:42 PM
Description: Warp 25
Notes 1: 3k run 13ci reg at 2K
Notes 2: 15" barrel NO tuning
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 34.00
Temp: 95 °F
BP: 29.96 inHg
Altitude: 0.00
#          FPS  FT-LBS      PF
35    793      47.48    26.96
34    790      47.12    26.86
33    798      48.08    27.13
32    794      47.60    27.00
31    801      48.45    27.23
30    802      48.57    27.27
29    801      48.45    27.23
28    793      47.48    26.96
27    785      46.53    26.69
26    782      46.18    26.59
25    783      46.29    26.62
24    793      47.48    26.96
23    785      46.53    26.69
22    785      46.53    26.69
21    783      46.29    26.62
20    782      46.18    26.59
19    790      47.12    26.86
18    782      46.18    26.59
17    784      46.41    26.66
16    785      46.53    26.69
15    784      46.41    26.66
14    790      47.12    26.86
13    788      46.89    26.79
12    787      46.77    26.76
11    789      47.01    26.83
10    786      46.65    26.72
9    783      46.29    26.62
8    781      46.06    26.55
7    788      46.89    26.79
6    777      45.59    26.42
5    775      45.35    26.35
4    771      44.89    26.21
3    774      45.24    26.32
2    782      46.18    26.59
1    775      45.35    26.35
Average: 786.3 FPS
SD: 7.6 FPS
Min: 771 FPS
Max: 802 FPS
Spread: 31 FPS
Shot/sec: 0.0
True MV: 786 FPS
Group Size (in): 0.00


 Then I filled gun again still with ART/Sikes valve and this time I decreased the spring 1 turn took three shots and decreased it 1/2 shot then took three more and decreased it again 1/2 turn and again and again then last three I turned it in 4.5 turns.

Created: 08/02/17 05:42 PM
Description: warp .25
Notes 1: 15" barrel Reg at 2K
Notes 2: adjusted run
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 34.00
Temp: 92 °F
BP: 29.93 inHg
Altitude: 0.00
#          FPS  FT-LBS      PF
18    840      53.28    28.56
17    843      53.66    28.66
16    840      53.28    28.56
15    560      23.68    19.04
14    552      23.01    18.77
13    555      23.26    18.87
12    601      27.27    20.43
11    595      26.73    20.23
10    593      26.55    20.16
9    636      30.54    21.62
8    634      30.35    21.56
7    627      29.68    21.32
6    654      32.30    22.24
5    658      32.69    22.37
4    657      32.59    22.34
3    703      37.32    23.90
2    702      37.21    23.87
1    702      37.21    23.87
Average: 664.0 FPS
SD: 94.1 FPS
Min: 552 FPS
Max: 843 FPS
Spread: 291 FPS
Shot/sec: 0.0
True MV: 664 FPS
Group Size (in): 0.00
  • Mount Shasta Ca.

oldpro

  • Hero Member
  • *****
  • Posts: 1132
    • View Profile
Re: Building a better balanced valve
« Reply #10 on: August 02, 2017, 08:00:49 PM »
If you looked at the above chart and your not excited you should be lol
  • Mount Shasta Ca.

Christopher

  • Sr. Member
  • ****
  • Posts: 322
    • View Profile
Re: Building a better balanced valve
« Reply #11 on: August 02, 2017, 08:55:48 PM »
Just comparing apples to apples here.

Conventional valve:
39.9 fpe avg
1.16 fpe/ci eff.

ART/Sikes valve
46.6 fpe avg
1.35 eff.

That's a 17% increase in power and 16% in efficiency. Yep, I'm excited  :) Thanks for sharing and keeping us updated.

Chris
  • dead end road KY

oldpro

  • Hero Member
  • *****
  • Posts: 1132
    • View Profile
Re: Building a better balanced valve
« Reply #12 on: August 02, 2017, 09:21:01 PM »
 Actually its close to 18% but at a higher FPE/FPS so the actual percentage is much higher. The gain is 18% and 60FPS at the same pressure range and shot count , Massive!!!
« Last Edit: August 02, 2017, 09:23:07 PM by oldpro »
  • Mount Shasta Ca.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1217
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Building a better balanced valve
« Reply #13 on: August 02, 2017, 09:27:13 PM »
Yep, that about sums it up.... but take a look at one thing.... With the stock valve, the gun is operating way down on the downslope for a regulated PCP.... You can tell that by how far the velocity climbs below the setpoint.... By shot 35, it has climbed to 760 fps (~30 fps) and looks like it is still climbing.... This indicates that if the hammer strike was increased, the velocity of the entire string would increase, giving more power.... It is very likely that the air use would increase as well, of course.... The gun is operating a long ways below the velocity plateau....

With the ART/Sikes valve, because it is much easier to open, the same hammer strike opens the valve further and for longer, which increases the velocity and energy.... The gun is operating closer to the knee of the curve, which you can see because the blip in velocity after the setpoint isn't as great, and peaks at only shot #30 (instead of still increasing to or past #35).... This explains the increase in velocity and FPE, it is occurring from less hammer energy being wasted in opening the valve, so more is available to create useful lift and dwell.... which means more power.... The gun is operating closer to the velocity plateau....

This leaves us with the increased efficiency of the ART/Sikes valve to ponder.... How can it create more power on the same amount of air?.... The first question that comes to mind for me is.... how do the port sizes (the ability of the two valves to flow air) compare?.... I would like to know what the velocity is at the plateau (ie the maximum velocity at that pressure) for both valves, to properly assess where in their operating ranges the two tunes are.... Please don't misunderstand me, this isn't intended as a criticism.... I just want to understand more about the parameters of this great new valve.... For this to be an apples to apples comparison, the two valve need to have identical port sizes, IMO.... and maybe they do?....

Bob
  • Coalmont, BC

oldpro

  • Hero Member
  • *****
  • Posts: 1132
    • View Profile
Re: Building a better balanced valve
« Reply #14 on: August 02, 2017, 10:07:03 PM »
 The two valves are identical in every way except the balanced poppet. TP .250 and valve throat .280 in both valve. Bob both valves are identical to the valve I sent you except for the balanced valve poppet design of the ART/Sikes valve. Hope that helps.
  • Mount Shasta Ca.