GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Motorhead on February 11, 2018, 03:01:51 PM
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Kudos go to Travis Whitney as the brainchild of the tech we have been reading about but having little being shared on specifics .... AKA: Cobra Valve etc.
With an ok by Travis to let out what some have been privileged to know about and further the R&D & proof of concept I shall in my own words & pictures share what Cobra tech actually is 8)
What we are talking about is in essences an AIR SPRING that is a semi sealed plunger sealed via o-ring that replaces a PCP valve poppet spring / and or the poppet too if designed as such.
At some point in design a vent hole is created to allow air into the plunger/tube space, while also be used to control the Escape of air during the shot cycle. ( This we will cover shortly )
** All versions DO contain a small spring that only needs to be strong enough to overcome stiction of the o-ring and get poppet to contact seat so an empty gun can be filled.
HERE: the first generation based upon the working of the WAR valve with it replaceable seat assembly.
* First 3 picture a WAR valves poppet Cobra modified.
What we have happening is the PRESSURE within the valves HP side or with a regulated guns plenum is allowed to enter the tube and bear against the back of poppet giving the basic same exerted force even if tube was not in place.
Difference being as the shot happens pressure drops all around the head of poppet while open and air is flowing past, a conventional poppet becomes less effected by the pressure exerted that was keeping it closed and somewhat hangs in the flow driven back to the seat & sealing by sail effect, pressure differential & a spring.
In "Cobra" we KEEP nearly all the pressure valve had within it before shot contained within the tube. So as valve opens and pressure drops around the poppet we keep nearly all the driving force of the pressure around the area of the poppet intact sending the valve closed SUBSTANTIALLY faster !!
* Another benefit being with the increased pressure on poppet at closing given by the cobra chamber, hammer BOUNCE is greatly reduced as we have found out.
** The SIZE of the vent hole allows for some bleed off of pressure from within tube and is the TUNING that we hear about using JET sizing we'll cover shortly ;)
Next 2 pictures are a design twist where the previous tube was attached to poppet and cap/vent o-ring was fixed in valves end cap, we have the o-ring on poppet and the tube / end cap are fixed.
This valves poppet I build for Theoben / RAW based valves that have very limited space between valves seat & end cap.
Last 3 pictures a SELF CONTAINED cartridge type unit that was fitted between plenums intake port and an unmodified poppet ( Daystate bottle gun in this instance )
Air in this one comes in at larger end, side vents into valves inner body via 4 radial ports. intake to the tube is the red straw piece down inside. Force exerted expands plunger against poppet.
Clever stuff and IT WORKS !!!
In recent months Travis along with Jefferson State Air rifles has come out with the ART/ SIKES "SS" valve that is a ballanced valve and another tech all its own ... BUT STILL uses "Cobra" tech to speed up the closing cycle. Also where we now hear about JET TUNING ;D Here the LAST picture in series is the business end of an SS valve showing said jet as it controls the exit bleed off of the containment tube within ;)
As for that wild hammer ... one of my R&D lightweights that got into the pic 8)
As to the JET or air bleed on simpler designs becomes important because in the testing confirmed among R&D testers valves closing become nearly Violent !! being so dang fast the poppet head is hammered into the seat damaging poppets delrin head. * Peek helps here a bunch ;) So we use the vent to help balance the dwell of valve because as noted paragraph previous, valve closes so dang fast you simply cant get valve to dwell long enough to get any power without use of a massive heavy hammer & spring set up to counter the Cobras effect. Finding a good compromise in vent hole size allows use of previous hammer & spring combos yet still takes advantage of a faster closing poppet and air savings from reduced dwell.
So there ya have it if following along & understanding ... I'm sure thread will get plenty of Q's, so ask away ;)
Scott
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Subscribed, I was wondering about this but dared not ask :D
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Cool stuff for sure and way over my head. When can we buy an "ALLINONE" valve with a regulator? Kinda of a Ron Popeil type system. LOL
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Wizardry I say!
Lol... jk.... very cool stuff indeed.
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Now my mind is spinning up on some of the nuances of the design known and its variables ... here a few ;)
We gain LAMINAR flow now along side tube without the air headed towards seat tumbling around return springs coils ... Nice !!
The tubes area can be made Less than or Greater than the diameter of poppets head. Doing so decreases or increases the effective area and force the contained pressure exerts upon the poppet trying to close it.
The stroke of poppet from on seat to max lift is all we need to allow for in the sliding fit of plunger & tube no matter the design in use.
*We don't want the limits of slip less than stroke of poppet or the hammer will drive the tube over end cap and seize it there :P ... but also want the best laminar flow by keeping the lumps and bumps of profile smooth down its length if practical to do so.
The basic principle of the design has near limitless configurations that can be made up to fit many PCP's & has in my case been applied to these guns so far ...
WAR WarP #1
Daystate MK-3 #2
RAW TM-1000 #3
Taipan Mutant #4
Marauder Gen 1 #5 X2
BSA Scorpion #6 X2
AirMax PP700 #7
Kral Puncher Breaker #8
Industry QB-79 #9
Hatsan AT-44 #10
Daystate Airwolf #11
Along with some other odd ball guns ...
Many times due to SPEED in which the poppet is driven back to the seat the material of poppets head may become no longer viable & PEEK may become required to increase life.
* Changes in sealing surface shape or overlap, sealing margin can also be made using OEM poppet or something custom.
Thats it for now ... sure more will come up.
;) Scott
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subscribing
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it's an air compression spring in place of the metal coil return spring....
yeah i bet it can close with some serious force.....
cylinder nternal compression combined with external pressure drop....
and with light weight material it not just fast but holy cats fast too....
you bet that vent is a tuning concern!!!
Formula 1 car valve tech in your air rifle anyone?
beautiful...just beautiful
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Travis installed a Cobra valve in my Flex .30 along with a regulator. All this stuff is way above my head but the results are amazing.
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Very interesting, and thank you for sharing.
I am subscribed and I hope to learn from this discussion.
By chance,
are there any illustrations / animations of its function(s) in motion ?
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Wait... Wait.
...The basic principle of the design has near limitless configurations... been applied to these guns so far ...
RAW TM-1000 #3
Industry QB-79 #9
;) Scott
Have prototype (or one-off) valves been made for these rifles?
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Wait... Wait.
...The basic principle of the design has near limitless configurations... been applied to these guns so far ...
RAW TM-1000 #3
Industry QB-79 #9
;) Scott
Have prototype (or one-off) valves been made for these rifles?
Personal guns ... One offs
My TM used at the Nats had one similar to shown but also had a custom valve in there with it.
My QB same thing sorta ... 3mm valve stem went to .125" using a Peek head & modified seat shape.
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After reading through this thread my head is hurting a bit, being on my third valve of Travis design, and having taken all three apart, their design is making more sense to me.
I'm following this thread to learn even more.
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Subscribing as well.
Cool stuff.
Mike
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So is the JSA SS valve considered a better alternative to the Cobra?
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So is the JSA SS valve considered a better alternative to the Cobra?
I'm not sure ( but pretty confident ) the Cobra valve was the past WAR valve with the Cobra tech similar to 1st example shown. The SS valve is a new beast all together being a Balanced valve with cobra tech.
The SS balanced version opens with less hammer strike , weight of hammer, spring energy etc ....
Honestly in terms of power there both going to be similar tho will require far different hammer strike energy and cocking force to run at the same power level.
My WarP uses the WAR valve with Cobra tech and makes more than enough power for .177 /.20 / .25 cal pellet duty.
** Please correct me if I am mistaken tho :-\
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Ss valve sounds nice if it allows for less hammer strike and cocking force. With my warp having only 12" .25 barrel it takes quite a whack to even make 35fpe and isn't the lightest bolt I've used. I'll be looking into a new valve in the near future. Thanks Scott for the info.
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Are you sure about the LAMINAR flow thing? I know what you are describing when you call it laminar, but I think it's a wrong word for it. With the pressure differences inside a pcp airgun, I think all flow past the valve will stay turbulent. Or have you calculated the Reynolds number to determine it laminar?
I have a marauder cobra valve and it's like the 1st example shown. Or almost the same.
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Are you sure about the LAMINAR flow thing? I know what you are describing when you call it laminar, but I think it's a wrong word for it. With the pressure differences inside a pcp airgun, I think all flow past the valve will stay turbulent. Or have you calculated the Reynolds number to determine it laminar?
I have a marauder cobra valve and it's like the 1st example shown. Or almost the same.
Its a huge reduction in turbulent flow and increase in Laminar . The air is now passing down the sides of the cobra tube and moving under the poppet quite smoothly compared to smashing into the top of the poppet creating a huge disturbance in flow. I have high speed air flow data stored somewhere on my hard drive I will dig it up.
http://www.pilotfriend.com/training/flight_training/aero/images/29.jpg (http://www.pilotfriend.com/training/flight_training/aero/images/29.jpg)
https://www.google.com/imgres?imgurl=https://www.cfdsupport.com/OpenFOAM-Training-by-CFD-Support/sketch-laminar-flow-turbulent-flow.png&imgrefurl=https://www.cfdsupport.com/OpenFOAM-Training-by-CFD-Support/node275.html&h=768&w=842&tbnid=aapQO3pX_cC_BM:&tbnh=183&tbnw=200&usg=__-EScy_mNgCQ9ZipHCI3wff5KjZk%3D&vet=10ahUKEwjp_PLxnKHZAhUmBsAKHYF9ArMQ_B0IkQEwCw..i&docid=ZNCx5vdL49vApM&itg=1&client=firefox-b-1&sa=X&ved=0ahUKEwjp_PLxnKHZAhUmBsAKHYF9ArMQ_B0IkQEwCw (https://www.google.com/imgres?imgurl=https://www.cfdsupport.com/OpenFOAM-Training-by-CFD-Support/sketch-laminar-flow-turbulent-flow.png&imgrefurl=https://www.cfdsupport.com/OpenFOAM-Training-by-CFD-Support/node275.html&h=768&w=842&tbnid=aapQO3pX_cC_BM:&tbnh=183&tbnw=200&usg=__-EScy_mNgCQ9ZipHCI3wff5KjZk%3D&vet=10ahUKEwjp_PLxnKHZAhUmBsAKHYF9ArMQ_B0IkQEwCw..i&docid=ZNCx5vdL49vApM&itg=1&client=firefox-b-1&sa=X&ved=0ahUKEwjp_PLxnKHZAhUmBsAKHYF9ArMQ_B0IkQEwCw)
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air flowing along a tube with a coil spring in the tube's center
versus
air flowing along a tube with another tube in it's center...
valve head fit inside center tube...
hmmmmm...much smoother flow to the valve...
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air flowing along a tube with a coil spring in the tube's center
versus
air flowing along a tube with another tube in it's center...
valve head fit inside center tube...
hmmmmm...much smoother flow to the valve...
Yes it really keeps the air velocity up and the air piston closes the valve very fast. It can close it so fast no amount of hammer spring can make it open far enough to make power so the orifice size is crucial to the tune.So take the Cobra and then make the orifice adjustable then also make a balanced piston inside the cobra chamber and you have a valve that’s easy to open and extremely efficient and tunable like nothing around that is the new SS valve pioneered by my self and Lloyd SS. Most of the Cobra tech was developed by myself and S Schneider, Scott has applied it to more guns then anyone and it even helped him win the National title. Lots of R&D has been done by GTA members and no other websites can even come close to the advancements we’ve done here among friends.
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oh yeah....i got the program on the vent as soon as i understood it's a gas ram that starts out at reservior pressure ...
i have been building a series of project guns as my basic knowledge grows and I'm in the planning stages of an attemp at 100fpe in a QB platform using .30cal 51gr pellets at 940fps.....I contacted Bob and he was generous with advice and a thread referral that were spot on what i wanted to know even though i didn't know that was what I wanted to know...and even more than that covered 3 or 4 follow up questions i hadn't asked yet...
so much for short story long....the end is.....bore diameter ports for power production and a super fast valve for air conservation tuned to the gory edge might get there if i can get enough reservior area at the valve and the streamlined spring concept ought kick up the flow rate.....the vent gives tuneablity
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I have a war Cobra valve in my 22 marauder. It's paired with a Huma regulator set at about 2100 psi. As some of you may know from my other posts, I've been having major consistency issues. While it is more efficient compared to my stock valve at the same power level, the trade off for me, has been consistency. Keep in mind this is a sample size of 1. Even without the regulator, the stock valve is more consistent for me.
With a regulator, mine cannot use a light weight hammer in conjunction with a free floating system (TSS, short 262 spring, etc). Mine currently uses the hill hammer with stock spring and about .25 inch of preload on the hammer spring. ES is about 35fps. It was about 17fps with the stock valve, hammer, spring, regulator. With the war Cobra valve, regulator, hill hammer free floated, ES was 150+ feet. Again, this is a sample size of 1. Take it with a grain of salt.
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I have a war Cobra valve in my 22 marauder. It's paired with a Huma regulator set at about 2100 psi. As some of you may know from my other posts, I've been having major consistency issues. While it is more efficient compared to my stock valve at the same power level, the trade off for me, has been consistency. Keep in mind this is a sample size of 1. Even without the regulator, the stock valve is more consistent for me.
With a regulator, mine cannot use a light weight hammer in conjunction with a free floating system (TSS, short 262 spring, etc). Mine currently uses the hill hammer with stock spring and about .25 inch of preload on the hammer spring. ES is about 35fps. It was about 17fps with the stock valve, hammer, spring, regulator. With the war Cobra valve, regulator, hill hammer free floated, ES was 150+ feet. Again, this is a sample size of 1. Take it with a grain of salt.
As with ANY PCP be it regulated or not, is finding at any desired power / speed setting where it is operating in respect to it's bell curve potential. If or when the balance of hammer weight, stroke of hammer, strength of hammer spring & pressure as primary contributors are skewed extremely one way or the other and not sorta in the middle ranges your going to get funky operation & instability.
Now add in a "Cobra" air spring which can / has such strong influence on the valves dwell cycle and things can really go wonky !!!
Knowing folks love to self tune, read How-Too threads, Buy hop-up parts based upon someones elses tuning tech and then MARRY this Mix & Mis-match group into what is thought to be the best of all worlds so it has to work great configuration.
In theory all these parts have merit used somewhat within the parameters of the original tuning but don't always work together as one might expect.
In my own R&D of valving ( That I keep to my self mostly ) I too have hit speed bumps being stumped that the combo in the gun is not performing or working well at all.
With all we know, think we know & info shared freely out there on the web to read the modern PCP is still being figured out as more tech gets used within them.
YES the rabbit hole keeps getting deeper !!
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Something seems off with consistency issues with your WAR Cobra valve. Just ran 2 guns through the chrony a week or 2 ago one a buddies .25 I was getting setup and one my personal WARP and both have very good consistency.
Created: 02-05-2018 05:52:41 PM
Description: .25 Mrod
Notes 1: 130bar reg set (too low)
Notes 2: Cobra valve
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 25.390
Altitude (FT): 0.0
Temp: 54 °F
BP: 30.04 inHG
Shots
# FPS FT-LBS PF
27 851 40.84 21.61
26 851 40.84 21.61
25 846 40.36 21.48
24 851 40.84 21.61
23 848 40.55 21.53
22 848 40.55 21.53
21 847 40.45 21.51
20 847 40.45 21.51
19 849 40.64 21.56
18 849 40.64 21.56
17 846 40.36 21.48
16 848 40.55 21.53
15 852 40.93 21.63
14 852 40.93 21.63
13 847 40.45 21.51
12 847 40.45 21.51
11 849 40.64 21.56
10 852 40.93 21.63
9 849 40.64 21.56
8 846 40.36 21.48
7 850 40.74 21.58
6 850 40.74 21.58
5 848 40.55 21.53
4 849 40.64 21.56
3 848 40.55 21.53
2 848 40.55 21.53
1 847 40.45 21.51
Average: 848.70
StdDev: 1.88
Min: 846
Max: 852
Spread: 6
True MV: 848.99
Shots/sec: 0.15
Group Size (IN): 0.00
Created: 02-02-2018 06:47:01 PM
Description: .30 WARP COBRA
Notes 1:
Notes 2: reg set 2400psi
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 44.750
Altitude (FT): 0.0
Temp: 47 °F
BP: 30.10 inHG
Shots
# FPS FT-LBS PF
44 807 64.72 36.11
43 808 64.88 36.16
42 807 64.72 36.11
41 808 64.88 36.16
40 811 65.37 36.29
39 813 65.69 36.38
38 814 65.85 36.43
37 810 65.20 36.25
36 812 65.53 36.34
35 808 64.88 36.16
34 810 65.20 36.25
33 811 65.37 36.29
32 808 64.88 36.16
31 807 64.72 36.11
30 812 65.53 36.34
29 813 65.69 36.38
28 812 65.53 36.34
27 813 65.69 36.38
26 807 64.72 36.11
25 815 66.01 36.47
24 817 66.34 36.56
23 815 66.01 36.47
22 812 65.53 36.34
21 808 64.88 36.16
20 812 65.53 36.34
19 814 65.85 36.43
18 812 65.53 36.34
17 811 65.37 36.29
16 812 65.53 36.34
15 811 65.37 36.29
14 815 66.01 36.47
13 817 66.34 36.56
12 811 65.37 36.29
11 812 65.53 36.34
10 817 66.34 36.56
9 814 65.85 36.43
8 815 66.01 36.47
7 811 65.37 36.29
6 809 65.04 36.20
5 814 65.85 36.43
4 817 66.34 36.56
3 817 66.34 36.56
2 815 66.01 36.47
1 806 64.56 36.07
Average: 811.82
StdDev: 3.15
Min: 806
Max: 817
Spread: 11
True MV: 812.09
Shots/sec: 0.07
Group Size (IN): 0.00
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Something seems off with consistency issues with your WAR Cobra valve. Just ran 2 guns through the chrony a week or 2 ago one a buddies .25 I was getting setup and one my personal WARP and both have very good consistency.
Created: 02-05-2018 05:52:41 PM
Description: .25 Mrod
Notes 1: 130bar reg set (too low)
Notes 2: Cobra valve
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 25.390
Altitude (FT): 0.0
Temp: 54 °F
BP: 30.04 inHG
Shots
# FPS FT-LBS PF
27 851 40.84 21.61
26 851 40.84 21.61
25 846 40.36 21.48
24 851 40.84 21.61
23 848 40.55 21.53
22 848 40.55 21.53
21 847 40.45 21.51
20 847 40.45 21.51
19 849 40.64 21.56
18 849 40.64 21.56
17 846 40.36 21.48
16 848 40.55 21.53
15 852 40.93 21.63
14 852 40.93 21.63
13 847 40.45 21.51
12 847 40.45 21.51
11 849 40.64 21.56
10 852 40.93 21.63
9 849 40.64 21.56
8 846 40.36 21.48
7 850 40.74 21.58
6 850 40.74 21.58
5 848 40.55 21.53
4 849 40.64 21.56
3 848 40.55 21.53
2 848 40.55 21.53
1 847 40.45 21.51
Average: 848.70
StdDev: 1.88
Min: 846
Max: 852
Spread: 6
True MV: 848.99
Shots/sec: 0.15
Group Size (IN): 0.00
Created: 02-02-2018 06:47:01 PM
Description: .30 WARP COBRA
Notes 1:
Notes 2: reg set 2400psi
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 44.750
Altitude (FT): 0.0
Temp: 47 °F
BP: 30.10 inHG
Shots
# FPS FT-LBS PF
44 807 64.72 36.11
43 808 64.88 36.16
42 807 64.72 36.11
41 808 64.88 36.16
40 811 65.37 36.29
39 813 65.69 36.38
38 814 65.85 36.43
37 810 65.20 36.25
36 812 65.53 36.34
35 808 64.88 36.16
34 810 65.20 36.25
33 811 65.37 36.29
32 808 64.88 36.16
31 807 64.72 36.11
30 812 65.53 36.34
29 813 65.69 36.38
28 812 65.53 36.34
27 813 65.69 36.38
26 807 64.72 36.11
25 815 66.01 36.47
24 817 66.34 36.56
23 815 66.01 36.47
22 812 65.53 36.34
21 808 64.88 36.16
20 812 65.53 36.34
19 814 65.85 36.43
18 812 65.53 36.34
17 811 65.37 36.29
16 812 65.53 36.34
15 811 65.37 36.29
14 815 66.01 36.47
13 817 66.34 36.56
12 811 65.37 36.29
11 812 65.53 36.34
10 817 66.34 36.56
9 814 65.85 36.43
8 815 66.01 36.47
7 811 65.37 36.29
6 809 65.04 36.20
5 814 65.85 36.43
4 817 66.34 36.56
3 817 66.34 36.56
2 815 66.01 36.47
1 806 64.56 36.07
Average: 811.82
StdDev: 3.15
Min: 806
Max: 817
Spread: 11
True MV: 812.09
Shots/sec: 0.07
Group Size (IN): 0.00
I agree something is up, it performed very well just a few weeks ago with the same reg pressure, war cobra, 44 gram MDS hammer, stock spring with 1/8 preload. Ive taken it apart about 20 times the last few weeks to try to figure out what's wrong. O ring is good. Valve doesn't bind. Who knows. It works now with my current setup. I'm gonna leave it unless it goes crazy again
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So is the JSA SS valve considered a better alternative to the Cobra?
I'm not sure ( but pretty confident ) the Cobra valve was the past WAR valve with the Cobra tech similar to 1st example shown. The SS valve is a new beast all together being a Balanced valve with cobra tech.
The SS balanced version opens with less hammer strike , weight of hammer, spring energy etc ....
Honestly in terms of power there both going to be similar tho will require far different hammer strike energy and cocking force to run at the same power level.
My WarP uses the WAR valve with Cobra tech and makes more than enough power for .177 /.20 / .25 cal pellet duty.
** Please correct me if I am mistaken tho :-\
Does the Cobra valve require less hammer strike/cocking force than the original WAR valve to shoot the same speed?
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Something seems off with consistency issues with your WAR Cobra valve. Just ran 2 guns through the chrony a week or 2 ago one a buddies .25 I was getting setup and one my personal WARP and both have very good consistency.
Created: 02-05-2018 05:52:41 PM
Description: .25 Mrod
Notes 1: 130bar reg set (too low)
Notes 2: Cobra valve
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 25.390
Altitude (FT): 0.0
Temp: 54 °F
BP: 30.04 inHG
Shots
# FPS FT-LBS PF
27 851 40.84 21.61
26 851 40.84 21.61
25 846 40.36 21.48
24 851 40.84 21.61
23 848 40.55 21.53
22 848 40.55 21.53
21 847 40.45 21.51
20 847 40.45 21.51
19 849 40.64 21.56
18 849 40.64 21.56
17 846 40.36 21.48
16 848 40.55 21.53
15 852 40.93 21.63
14 852 40.93 21.63
13 847 40.45 21.51
12 847 40.45 21.51
11 849 40.64 21.56
10 852 40.93 21.63
9 849 40.64 21.56
8 846 40.36 21.48
7 850 40.74 21.58
6 850 40.74 21.58
5 848 40.55 21.53
4 849 40.64 21.56
3 848 40.55 21.53
2 848 40.55 21.53
1 847 40.45 21.51
Average: 848.70
StdDev: 1.88
Min: 846
Max: 852
Spread: 6
True MV: 848.99
Shots/sec: 0.15
Group Size (IN): 0.00
Created: 02-02-2018 06:47:01 PM
Description: .30 WARP COBRA
Notes 1:
Notes 2: reg set 2400psi
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 44.750
Altitude (FT): 0.0
Temp: 47 °F
BP: 30.10 inHG
Shots
# FPS FT-LBS PF
44 807 64.72 36.11
43 808 64.88 36.16
42 807 64.72 36.11
41 808 64.88 36.16
40 811 65.37 36.29
39 813 65.69 36.38
38 814 65.85 36.43
37 810 65.20 36.25
36 812 65.53 36.34
35 808 64.88 36.16
34 810 65.20 36.25
33 811 65.37 36.29
32 808 64.88 36.16
31 807 64.72 36.11
30 812 65.53 36.34
29 813 65.69 36.38
28 812 65.53 36.34
27 813 65.69 36.38
26 807 64.72 36.11
25 815 66.01 36.47
24 817 66.34 36.56
23 815 66.01 36.47
22 812 65.53 36.34
21 808 64.88 36.16
20 812 65.53 36.34
19 814 65.85 36.43
18 812 65.53 36.34
17 811 65.37 36.29
16 812 65.53 36.34
15 811 65.37 36.29
14 815 66.01 36.47
13 817 66.34 36.56
12 811 65.37 36.29
11 812 65.53 36.34
10 817 66.34 36.56
9 814 65.85 36.43
8 815 66.01 36.47
7 811 65.37 36.29
6 809 65.04 36.20
5 814 65.85 36.43
4 817 66.34 36.56
3 817 66.34 36.56
2 815 66.01 36.47
1 806 64.56 36.07
Average: 811.82
StdDev: 3.15
Min: 806
Max: 817
Spread: 11
True MV: 812.09
Shots/sec: 0.07
Group Size (IN): 0.00
I agree something is up, it performed very well just a few weeks ago with the same reg pressure, war cobra, 44 gram MDS hammer, stock spring with 1/8 preload. Ive taken it apart about 20 times the last few weeks to try to figure out what's wrong. O ring is good. Valve doesn't bind. Who knows. It works now with my current setup. I'm gonna leave it unless it goes crazy again
I would look at the hammer and not the valve. Looks like a typical hammer binding issue.
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So is the JSA SS valve considered a better alternative to the Cobra?
I'm not sure ( but pretty confident ) the Cobra valve was the past WAR valve with the Cobra tech similar to 1st example shown. The SS valve is a new beast all together being a Balanced valve with cobra tech.
The SS balanced version opens with less hammer strike , weight of hammer, spring energy etc ....
Honestly in terms of power there both going to be similar tho will require far different hammer strike energy and cocking force to run at the same power level.
My WarP uses the WAR valve with Cobra tech and makes more than enough power for .177 /.20 / .25 cal pellet duty.
** Please correct me if I am mistaken tho :-\
Does the Cobra valve require less hammer strike/cocking force than the original WAR valve to shoot the same speed?
It has a smaller or lighter return spring but the piston does close it fast so its pretty much a wash. So not by much
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Thanks Travis, I thought I had read somewhere that it did but they might have been talking about the smoothness of the MDS hammer or the SS valve.
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Thinking this thread & subject has been buried long enough .... Shameless bump to get the info out there to a new audience.
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Thinking this thread & subject has been buried long enough .... Shameless bump to get the info out there to a new audience.
I dont think people quite understand whats taking place in the thimble or understand how it helps. Might need to make a video or something.
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Somewhat a double post ... but don't shoot the messenger :-[
here is a recent addition in the evolution of the devise with pictures being worth more than words ... the concept should be clear as mud ;D
https://www.gatewaytoairguns.org/GTA/index.php?topic=149519.msg1525979#msg1525979 (https://www.gatewaytoairguns.org/GTA/index.php?topic=149519.msg1525979#msg1525979)
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I AM going to do this on my Flash, just to see if I can gain some noticeable efficiency. It ain't bad on the gun now(1.4), but I'm not against getting up higher for sure. That 1.4 efficiency is at 30fpe, and it is regulated. I'm able to get 3 magazines per fill(36 shots). It took a lot of warranty voiding to get there, so what's a little more ;) I like working on this gun, because it is so simple, and lite. I tried once to get the cobra working, but I failed on the venting I think... I hope to get around to version 2 this weekend. I will update with pictures, of course :D
On a side note: I may try to get one of you guys(Travis or Scott) to machine a barrel for it soon? I'm thinking an 18" LW on it sure would be nice. The good thing is these barrels should be easier to machine than some of the other Hatsan barrels.
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Scott, somehow I missed this thread.... Thanks for the great explanation and pics.... When the COBRA tech valve first came out, Lloyd and I looked at it and quickly realized it didn't have any "balancing" effect, so I really never even gave it a second look.... Travis sent me one to try, and I never found any advantage when installed in one of my "high powered" (and therefore high dwell) PCPs.... Travis told us it was much easier to open, but then later discovered that was because the MRod valve used a very strong valve spring, and it was eliminating that which reduced the hammer strike required.... I understood the idea that there was less turbulence, and possibly less "sail" effect on the poppet, which would increase the dwell, allowing a slightly lighter hammer strike, but I never "got" what Travis was talking about regarding the valve closing faster and saving air until I read your excellent explanation, comparing the COBRA cylinder to an "air spring".... THAT's when it finally sunk in what was happening.... ::)
If we look at using a large vent in the front, and lots of flow into the inside of the valve body, in theory there is no change to the valve operation, because the pressures in all regions (reservoir/plenum, valve body, and poppet chamber) would be the same.... Other than getting rid of turbulence around the valve spring and the head of the poppet, the valve should operate the same (and that is what I found occurring at "maximum" power)…. However, once you restrict the front of the poppet chamber with a small jet, just like in the SS valve, things change.... I still don't understand the exact mechanism why, but as you reduce the jet size, the air in the poppet chamber appears to increase in pressure from compression by the poppet, which increases the rate of the "air spring", and limits the poppet lift, reducing dwell.... It's like using a very light spring when the valve is closed, but a heavier spring during the shot cycle, at least that appears to be what is happening....
I'm sure that cleaning up the flow around the poppet head helps as well, but I'd like to hear your opinion on the above.... Have I finally "got it?".... ;D
Bob
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Bob, thanks for that. I was just catching up on this over the last couple of days and that matches my understanding as well except you helped me connect the sail effect to it.
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I have an original prototype Cobra valve. It's difficult to crack open much past a 2000psi set point even with the one pound valve spring it has and using a heavy hammer spring, but boy is it efficient. I'm not sure how the latest/current Cobra valves perform. Mine has no jet capability.
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The Cobra valve is actually easier to open but has such a short swell it takes more hammer energy to get up to a high power level so it feels like it’s harder to open. The Cobra chamber acts like a Air spring so when the valve opens the pressure drop around the poppet head isn’t there allowing the valve to dwell long instead the high pressure is trapped inside the poppet driving the valve closed as the pressure drops around the outside of the Cobra chamber. Also this helps reduce hammer bounce and also allows for very low pressure tubes.
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Bob,
In a nutshell ..... Controlled pressure differential.
The area within valves internal space has a pressure drop as flow heads out towards the pellet. The confines of the "Cobra tube" holds most of the pressure bearing down on the poppet while it was closed ... So the valve poppet once open now keeps a much more even pressure attempting to close it independent of what flow and pressure drop is happening OUTSIDE the tube.
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The area within valves internal space has a pressure drop as flow heads out towards the pellet.
If I understand how flow works, and assuming the inlet area of the valve is greater than the exhaust area (and it always should be)…. there should be virtually no pressure difference between the exhaust port, and the area surrounding the poppet (at the seat), and the area surrounding the Cobra tube (or the valve spring), and the plenum/reservoir.... at the point the air reaches the pellet and it starts to move.... Don't forget, when the valve first opens, the pellet is stationary, and the air molecules are moving randomly at ~ 1650 fps.... so it only takes about 0.05 mSec for the air to travel that ~1" to the pellet, and for the pressure in the exhaust ports to reach reservoir pressure, during which time there is virtually NO flow volume (the HPA just fills the exhaust port, transfer port and chamber), and certainly that small amount of HPA (~1cc) needed to pressurize the porting system can easily get into the valve during that time period through the large holes in the front of the valve....
For there to be more pressure inside the Cobra tube than outside it, there must be something "holding back" the air from moving into the valve body, in the area surrounding the poppet chamber.... I think it much more likely that the poppet moving forward into the Cobra poppet chamber, increasing the pressure there by compressing the air, is a more likely scenario.... I think that is why using a smaller "jet" on the front of the Cobra poppet chamber increases the pressure inside it during the shot cycle.... and thereby reduces the dwell....
As I said before, I don't fully understand the process, but I think it likely that a pressure increase inside the poppet chamber is more likely than a pressure decrease outside it.... certainly in the first part of the shot cycle, anyways.... During the latter part of the shot cycle, when the flow velocity through the seat is high, then the lack of a "sail effect" on the poppet, and less turbulence because of the lack of valve spring, may indeed be playing a part.... but again, if the inlet into the valve is larger than the exhaust there should be almost no pressure differential upstream of the poppet (except that caused by the Cobra inlet jet containing the increased pressure from the poppet compression inside the poppet chamber)....
Whatever the actual mechanism, when used to reduce lift and dwell (as opposed to a high power application)…. it seems that "Cobra Tech" works, and that is what is important.... I suspect using a jet to tune the SS valve for similar applications works in the same way.... but with the added benefit of a balanced valve to reduce the hammer strike required....
Bob
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The area within valves internal space has a pressure drop as flow heads out towards the pellet.
As I said before, I don't fully understand the process, but I think it likely that a pressure increase inside the poppet chamber is more likely than a pressure decrease outside it.... certainly in the first part of the shot cycle, anyways.... During the latter part of the shot cycle, when the flow velocity through the seat is high, then the lack of a "sail effect" on the poppet, and less turbulence because of the lack of valve spring, may indeed be playing a part.... but again, if the inlet into the valve is larger than the exhaust there should be almost no pressure differential upstream of the poppet (except that caused by the Cobra inlet jet containing the increased pressure from the poppet compression inside the poppet chamber)....
Whatever the actual mechanism, when used to reduce lift and dwell (as opposed to a high power application)…. it seems that "Cobra Tech" works, and that is what is important.... I suspect using a jet to tune the SS valve for similar applications works in the same way.... but with the added benefit of a balanced valve to reduce the hammer strike required....
Bob
A "Point" and an important one at that is .... We're using these primarily in REGULATED guns where there is indeed a pressure loss within the valves interior & plenum.
And is where at the end of the shot cycle the residual pressure kept mostly intact WITHIN the Cobra chamber is indeed higher as valve is closing and only equalizes upon valve shutting and regulator bringing the plenum back up to the set pressure.
My bad ... oups :-\
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Okay, here's my current interpretation of it on my flash(which pretty much uses an AT44 valve). I know the vent location isn't ideal, but that is what I have to work with right now. It is a .31 vent(1/32). I used a poly o-ring on the PEEK piston attached to the top of the valve pin. I haven't tested it yet, other than 5 shots over the chrony to see where the fps was. It is running about 30fps slower than before, so that makes me think it is closing faster as would be expected.
If it turns out not to work, I will acquire a WD40 tube, and a brass screw holding it to the spring retainer. That way, I can drill out the brass screw to run the WD tube through it. This is just preliminary, so I don't know if I'll need to do that yet or not.
The screw attaching the cobra tube to the spring retainer has an o-ring on it which seals that side of the tube. I tested the sealing without the vent and no spring in there by pushing the valve piston in. It pushed back out without the spring, so I know it is sealing at lower pressure at least. I'll update when I get to run some full strings.
I know the valve looks nasty, but it isn't. For some reason Hatsan painted the brass valve assembly, and that is the black paint flaking on the threads...
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Yes, with a 1/2 cc per FPE plenum, you may be getting a 20% drop in pressure inside the valve during the shot.... That, plus a rise in pressure due to the poppet compressing the air inside the poppet chamber could give you a 30-50% pressure differential, depending on the volume of that chamber and the lift of the valve....
Bob
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Yes, with a 1/2 cc per FPE plenum, you may be getting a 20% drop in pressure inside the valve during the shot.... That, plus a rise in pressure due to the poppet compressing the air inside the poppet chamber could give you a 30-50% pressure differential, depending on the volume of that chamber and the lift of the valve....
Bob
That is almost exactly what I stated earlier.
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Yeah, I'm a little slow on the uptake, Travis.... :-[
Bob
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LOL Bob! Your still the best .
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I’ve ordered a pile of mikuni carb jets ranging from .020 to .045” for eBay as a kit . I hope to be installing a cobra tube in my highly strung BT65 and get rid of the anti hammer bounce device . It’s going to need some creativity to cram it all in the Vale housing something like rallyshark did with his AT44. Yet another project on the go .
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I’ve ordered a pile of mikuni carb jets ranging from .020 to .045” for eBay as a kit . I hope to be installing a cobra tube in my highly strung BT65 and get rid of the anti hammer bounce device . It’s going to need some creativity to cram it all in the Vale housing something like rallyshark did with his AT44. Yet another project on the go .
If only I had as much tools and time, as I do creativity,lol! I'm betting I'm going to need to drill out the screw holding the cobra tube in place, so I can run the vent out the end of the spring retainer. I don't think I'll get as good of a pressure differential at the vent's current placement. I can't wait to see what you come up with on the BT! Maybe you'll come up with something I can use ;)
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It's nice to see more momentum on this one, with more folks applying it to more platforms. it will be some time before I'll be able to contribute more to the information base due to other life distractions at this time.
BTW, if you need a smaller jet size you can always solder it up and drill it out--brass is easy to solder. That's how I created an assortment of Cobra jets between .020 and .080" An assortment of micro sized drill bits comes with most pin vises. If your drill won't chuck tiny bits, here is a helpful hint---- The chuck on a dremel's flexible shaft will hold bits down to .020", perhaps even smaller.
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My first attempt. This is my gauntlet valve, up until now it had factory porting. Now it's .233 bore with the cobra mod.
Once I get the SSG done I'll give it a go!
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My first attempt. This is my gauntlet valve, up until now it had factory porting. Now it's .233 bore with the cobra mod.
Once I get the SSG done I'll give it a go!
Perfect gun to try it on. I would try it Cameron before SSG so you know what percentage each device contributed
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My first attempt. This is my gauntlet valve, up until now it had factory porting. Now it's .233 bore with the cobra mod.
Once I get the SSG done I'll give it a go!
Perfect gun to try it on. I would try it Cameron before SSG so you know what percentage each device contributed
I have such a hard time not doing things all at once. Luckily the SSG I like to put together are
very simple to install after removing the rear tube cap and the spacer.
Maybe I'll shoot it with the new valve then drop in the SSG.
Cam
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My first attempt. This is my gauntlet valve, up until now it had factory porting. Now it's .233 bore with the cobra mod.
Once I get the SSG done I'll give it a go!
Perfect gun to try it on. I would try it Cameron before SSG so you know what percentage each device contributed
I have such a hard time not doing things all at once. Luckily the SSG I like to put together are
very simple to install after removing the rear tube cap and the spacer.
Maybe I'll shoot it with the new valve then drop in the SSG.
Cam
It's like he's teasing us! LOL! Shoot it already :D I have to finish a massive photo edit, before the end of the weekend, or I'd do a string myself...
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Okay, I did a test on the version I posted above, and it is a no go :( I actually lost shot count, so something isn't working. Looks like I'm going to have to work on getting that vent outside of the valve itself as Scott has suggested. That means I'm going to have to drill out a brass screw to run it out of the spring retainer I think. I will try and update, when I get to this week hopefully.
I suppose it is possible the o-ring on the peek piston isn't sealing, but I'm pretty sure it is. Do you guys think a double o-ring groove is a bad idea on the piston? I figure that will make darn sure it seals.
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If there is the slightest drag on the oring and the inside of the brass tube is smooth, the oring should be sealing. You could test this by temporarily putting some silicon grease on the oring. Could there be a leak elsewhere else in your cobra assembly?
Once the Cobra is working you should notice it both in shot cycle and velocity. You should have to lean on the hst a little more to get the velocity back to where you were previously tuned .
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Having the tubes vent WELL INSIDE the valves internal space will IMO require you to use a very small vent size. I would start down in .020" range or smaller. ( * wire drill sizes from the 60-80 sets )
because of the large pressure drop within the valves body the captive pressure within the tube gets sucked right out if vent is too large & effectively has the valve act as if a MUCH lighter poppet spring is in place which would cause valve to over dwell somewhat if indeed a heavy poppet spring was in place previously.
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If there is the slightest drag on the oring and the inside of the brass tube is smooth, the oring should be sealing. You could test this by temporarily putting some silicon grease on the oring. Could there be a leak elsewhere else in your cobra assembly?
Once the Cobra is working you should notice it both in shot cycle and velocity. You should have to lean on the hst a little more to get the velocity back to where you were previously tuned .
I'm pretty sure it is sealing, especially on the other end of the tube. The way it's put together makes it darn near impossible to leak on the non piston end.Having the tubes vent WELL INSIDE the valves internal space will IMO require you to use a very small vent size. I would start down in .020" range or smaller. ( * wire drill sizes from the 60-80 sets )
because of the large pressure drop within the valves body the captive pressure within the tube gets sucked right out if vent is too large & effectively has the valve act as if a MUCH lighter poppet spring is in place which would cause valve to over dwell somewhat if indeed a heavy poppet spring was in place previously.
I feel like this is what is going on. That vent is right in the air path inside the valve, so it would make sense that it would pull the air out of the cobra tube. I did pick up some of the tiny drill bits yesterday, so I'll have them if needed. I'm going to attempt getting the vent relocated first though.
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Just replying to keep up with this valve's development. May also need to order when they are up for sale.
Casey
P.S. I have a couple of potential uses, have you made anything close for the Air Force valve in bottle type guns yet? And I have a 30 cal Disco tubed gun, that may get switched to an M-Rod tube and breech with the same barrel,so that may be a better candidate for this valve.
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Just replying to keep up with this valve's development. May also need to order when they are up for sale.
Casey
P.S. I have a couple of potential uses, have you made anything close for the Air Force valve in bottle type guns yet? And I have a 30 cal Disco tubed gun, that may get switched to an M-Rod tube and breech with the same barrel,so that may be a better candidate for this valve.
It is NOT a new type of valve ..... only a miens of closing the poppet for reduced dwell. Adaptation to existing valve platforms is more it's use at this juncture. Tho the JSA / SS valve does incorporate the tech.
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Mike D, have you made any more progress on the cobra install on your P15?? I'm really curious to see if you made any headway there.
Sadly, I've made almost no headway. I made changes to have it vent outside of the valve body, into the regulator plenum. I drilled out the screw that secures the tube to the cobra chamber, and inserted a tube from a small Triflow bottle. A #68 bit is a very snug fit in that tube, so the vent is right at .031. All I managed to accomplish was needing my HS turned up,lol! I'm pretty sure the cobra spring is working, given the fact that I had to increase the HS to reach the same velocity. I gained a couple of shots from my last attempt, but I still can't beat my best tune with a conventional valve spring set up.
Just thinking out loud here, but I think it would work better with a higher reg set point. Right now, it is at 125 bar. I wonder if turning it up to 130-135 bar will increase the effectiveness of the cobra tech. That would likely give a larger pressure differential between the tube and the rest of the valve. Of course, the extra pressure would make the valve close faster too. I feel like I'm just at the point of diminishing returns with it right now. A larger plenum sure wouldn't hurt either, but I'm only working with a 165cc cylinder before the regulator.
Either I'm missing something, or the cobra tech just isn't the best option for a .22 Flash at 30fpe. Any input or advice is most definitely welcome from anyone that wants to chime in! I made the cobra tech work in the gun, but it may be better suited for a lower power tune in this case? Currently, I'm thinking I'm at the point of going back to a conventional valve spring for this gun.
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Mike D, have you made any more progress on the cobra install on your P15?? I'm really curious to see if you made any headway there.
Sadly, I've made almost no headway. I made changes to have it vent outside of the valve body, into the regulator plenum. I drilled out the screw that secures the tube to the cobra chamber, and inserted a tube from a small Triflow bottle. A #68 bit is a very snug fit in that tube, so the vent is right at .031. All I managed to accomplish was needing my HS turned up,lol! I'm pretty sure the cobra spring is working, given the fact that I had to increase the HS to reach the same velocity. I gained a couple of shots from my last attempt, but I still can't beat my best tune with a conventional valve spring set up.
Just thinking out loud here, but I think it would work better with a higher reg set point. Right now, it is at 125 bar. I wonder if turning it up to 130-135 bar will increase the effectiveness of the cobra tech. That would likely give a larger pressure differential between the tube and the rest of the valve. Of course, the extra pressure would make the valve close faster too. I feel like I'm just at the point of diminishing returns with it right now. A larger plenum sure wouldn't hurt either, but I'm only working with a 165cc cylinder before the regulator.
Either I'm missing something, or the cobra tech just isn't the best option for a .22 Flash at 30fpe. Any input or advice is most definitely welcome from anyone that wants to chime in! I made the cobra tech work in the gun, but it may be better suited for a lower power tune in this case? Currently, I'm thinking I'm at the point of going back to a conventional valve spring for this gun.
How big is the valve throat and the od of the poppet? And what power are you shooting now? I believe I see and issue with your set up
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I'm going by memory here, so I could be off. The valve throat is around .360-ish, and the poppet is probably around .225-ish? It is essentially the same as an AT44 valve. Tell me what you're thinking Travis!? I NEED input :D
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Neither number is correct you can’t have a poppet smaller than the throat and the throat would be insanily huge. I would check them
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Neither number is correct you can’t have a poppet smaller than the throat and the throat would be insanily huge. I would check them
Hahaha! I was thinking about the inside diameter of the valve housing,lol. The valve seat is made of PEEK opened up to .200(throat) and the poppet/valve pin is .225-ish. Sorry about that :-[
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Neither number is correct you can’t have a poppet smaller than the throat and the throat would be insanily huge. I would check them
Ok now what’s the caliber and what FPE are you set at?
Hahaha! I was thinking about the inside diameter of the valve housing,lol. The valve seat is made of PEEK opened up to .200(throat) and the poppet/valve pin is .225-ish. Sorry about that :-[
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.22 at 28-30fpe. It only has a 17.75" barrel too.
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Ok Donny heres the problem i see its a matter of flow restriction you have a small valve being pushed to its limmits so you have to dwell it long to make the power your getting this means using the cobra tech will yield very little to no use to your set up and likely will have negative effects. i would open up the power train to breath better before going forward(exhaust port. TP. BP etc.) When i seen the pics of the valve poppet I knew right away this was likely a no go. The only way to make it work would be to put a short stiff spring inside the Cobra chamber,
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Mike D, have you made any more progress on the cobra install on your P15?? I'm really curious to see if you made any headway there.
Sadly, I've made almost no headway. I made changes to have it vent outside of the valve body, into the regulator plenum. I drilled out the screw that secures the tube to the cobra chamber, and inserted a tube from a small Triflow bottle. A #68 bit is a very snug fit in that tube, so the vent is right at .031. All I managed to accomplish was needing my HS turned up,lol! I'm pretty sure the cobra spring is working, given the fact that I had to increase the HS to reach the same velocity. I gained a couple of shots from my last attempt, but I still can't beat my best tune with a conventional valve spring set up.
Just thinking out loud here, but I think it would work better with a higher reg set point. Right now, it is at 125 bar. I wonder if turning it up to 130-135 bar will increase the effectiveness of the cobra tech. That would likely give a larger pressure differential between the tube and the rest of the valve. Of course, the extra pressure would make the valve close faster too. I feel like I'm just at the point of diminishing returns with it right now. A larger plenum sure wouldn't hurt either, but I'm only working with a 165cc cylinder before the regulator.
Either I'm missing something, or the cobra tech just isn't the best option for a .22 Flash at 30fpe. Any input or advice is most definitely welcome from anyone that wants to chime in! I made the cobra tech work in the gun, but it may be better suited for a lower power tune in this case? Currently, I'm thinking I'm at the point of going back to a conventional valve spring for this gun.
Donny-- unfortunately I have nothing more to add at this time. Hurricane Michael had been a distraction, my parents live in St Joe Beach and were displaced by the storm......thank you for continuing to share your efforts and findings. Hopefully I'll get back to testing sometime in upcoming months.
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My first attempt. This is my gauntlet valve, up until now it had factory porting. Now it's .233 bore with the cobra mod.
Once I get the SSG done I'll give it a go!
Perfect gun to try it on. I would try it Cameron before SSG so you know what percentage each device contributed
I have such a hard time not doing things all at once. Luckily the SSG I like to put together are
very simple to install after removing the rear tube cap and the spacer.
Maybe I'll shoot it with the new valve then drop in the SSG.
Cam
Cam how did it turn out?
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Donny I had a quick look at my BT65 valve and I think the volume inside the valve is too small . That is unless you move the cobra tube to the outside and thread it into the spring retainer. This would mean much longer valve stem or a two piece that looks like a dumbbell . This could allow for a much bigger diameter tube and would help with shortening the dwell.
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Subscribed, I was wondering about this but dared not ask :D
I’m probably missing what’s right in front of my face but I can’t figure out how to subscribe to a thread??? Many times I have wanted that option including this time. Can anyone tell me what I’m missing? Thanks.
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Subscribed, I was wondering about this but dared not ask :D
I’m probably missing what’s right in front of my face but I can’t figure out how to subscribe to a thread??? Many times I have wanted that option including this time. Can anyone tell me what I’m missing? Thanks.
Dave, click on the "Notify" to subscribe to a thread then click "ok" in the pop-up You will then receive an e-mail notification on new post.
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Subscribed, I was wondering about this but dared not ask :D
I’m probably missing what’s right in front of my face but I can’t figure out how to subscribe to a thread??? Many times I have wanted that option including this time. Can anyone tell me what I’m missing? Thanks.
Dave, click on the "Notify" to subscribe to a thread then click "ok" in the pop-up You will then receive an e-mail notification on new post.
Thanks.
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Ok Donny heres the problem i see its a matter of flow restriction you have a small valve being pushed to its limmits so you have to dwell it long to make the power your getting this means using the cobra tech will yield very little to no use to your set up and likely will have negative effects. i would open up the power train to breath better before going forward(exhaust port. TP. BP etc.) When i seen the pics of the valve poppet I knew right away this was likely a no go. The only way to make it work would be to put a short stiff spring inside the Cobra chamber,
Boooo, not what I wanted to hear,lol! No, I figured as much already with my testing. I knew it was likely a no go when all I was achieving was the need to increase the HS. The Cobra isn't meant for this gun, unless at a lower power level maybe(or on a .177). If I had a lathe, I could fix that small poppet issue, but... Trust me when I say, everything is opened up as far as I can safely take it. It can do 60fpe with that short barrel in .22, so it is breathing quite well. I'll just be happy with my 36 shots at 30fpe with the conventional valve spring, and call it a learning experience :)
Donny I had a quick look at my BT65 valve and I think the volume inside the valve is too small . That is unless you move the cobra tube to the outside and thread it into the spring retainer. This would mean much longer valve stem or a two piece that looks like a dumbbell . This could allow for a much bigger diameter tube and would help with shortening the dwell.
That could work, but I don't have the means to make that part :( Another solution may be to machine out the interior of the valve assembly to accept a larger poppet/valve seat/cobra tube? I know I've seen others doing really high power tunes on the BT valves did that. If the interior of the valve were opened up, then you could use a larger valve seat, poppet/valve pin. I'm thinking it would take some serious HS to crack that though. Just thinking out loud. Hopefully, you'll come up with something ;)
Donny-- unfortunately I have nothing more to add at this time. Hurricane Michael had been a distraction, my parents live in St Joe Beach and were displaced by the storm......thank you for continuing to share your efforts and findings. Hopefully I'll get back to testing sometime in upcoming months.
Sorry to hear that man! Hopefully, they'll get things back on track soon, and so will you :)
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Ok Donny heres the problem i see its a matter of flow restriction you have a small valve being pushed to its limmits so you have to dwell it long to make the power your getting this means using the cobra tech will yield very little to no use to your set up and likely will have negative effects. i would open up the power train to breath better before going forward(exhaust port. TP. BP etc.) When i seen the pics of the valve poppet I knew right away this was likely a no go. The only way to make it work would be to put a short stiff spring inside the Cobra chamber,
Boooo, not what I wanted to hear,lol! No, I figured as much already with my testing. I knew it was likely a no go when all I was achieving was the need to increase the HS. The Cobra isn't meant for this gun, unless at a lower power level maybe(or on a .177). If I had a lathe, I could fix that small poppet issue, but... Trust me when I say, everything is opened up as far as I can safely take it. It can do 60fpe with that short barrel in .22, so it is breathing quite well. I'll just be happy with my 36 shots at 30fpe with the conventional valve spring, and call it a learning experience :)
Donny I had a quick look at my BT65 valve and I think the volume inside the valve is too small . That is unless you move the cobra tube to the outside and thread it into the spring retainer. This would mean much longer valve stem or a two piece that looks like a dumbbell . This could allow for a much bigger diameter tube and would help with shortening the dwell.
That could work, but I don't have the means to make that part :( Another solution may be to machine out the interior of the valve assembly to accept a larger poppet/valve seat/cobra tube? I know I've seen others doing really high power tunes on the BT valves did that. If the interior of the valve were opened up, then you could use a larger valve seat, poppet/valve pin. I'm thinking it would take some serious HS to crack that though. Just thinking out loud. Hopefully, you'll come up with something ;)
Donny-- unfortunately I have nothing more to add at this time. Hurricane Michael had been a distraction, my parents live in St Joe Beach and were displaced by the storm......thank you for continuing to share your efforts and findings. Hopefully I'll get back to testing sometime in upcoming months.
Sorry to hear that man! Hopefully, they'll get things back on track soon, and so will you :)
Before you abandon your progress try a stiffer spring inside the thimble.
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Travis, the stiffer spring in the cobra tube would surely help. However, with the way the Flash cocks, I'm afraid it will make for a very stiff hammer spring setting for that gun. I think the valve is already closing too fast to make the 30fpe without significant hammer strike and no gain in shot count. It wouldn't be all that fun to shoot, given the straight pull bolt. The extra cocking effort wouldn't be worth the extra(if any) shots in this case to me. As I mentioned earlier, the "cobra effect" is definitely happening, but it would be far more beneficial at a power level of 25fpe or less in this particular gun.
My gun has .187 porting all the way through, and the PEEK valve seat is at .200. I don't have much more room to make it breath any better. I could open the seat up to .210, but that is about all I have left. I think I've just hit the wall for what I'm willing to accept with HS settings vs shot count gains. I'm getting an efficiency of around 1.4 with the conventional valve spring, so even if I got it up to 1.6, I'd only be gaining 4-5 shots. I could be wrong, but I feel like the law of diminishing returns has come and smacked me upside the head on this one,lol.
It seems the way the hammer/hammer spring set up is in this gun, combined with the valve design, is just working against me. Please correct me if I'm off course though! I wouldn't mind one bit being wrong on this one. Either way, I REALLY APPRECIATE your, and everyone else's input and advice on this!
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Travis, the stiffer spring in the cobra tube would surely help. However, with the way the Flash cocks, I'm afraid it will make for a very stiff hammer spring setting for that gun. I think the valve is already closing too fast to make the 30fpe without significant hammer strike and no gain in shot count. It wouldn't be all that fun to shoot, given the straight pull bolt. The extra cocking effort wouldn't be worth the extra(if any) shots in this case to me. As I mentioned earlier, the "cobra effect" is definitely happening, but it would be far more beneficial at a power level of 25fpe or less in this particular gun.
My gun has .187 porting all the way through, and the PEEK valve seat is at .200. I don't have much more room to make it breath any better. I could open the seat up to .210, but that is about all I have left. I think I've just hit the wall for what I'm willing to accept with HS settings vs shot count gains. I'm getting an efficiency of around 1.4 with the conventional valve spring, so even if I got it up to 1.6, I'd only be gaining 4-5 shots. I could be wrong, but I feel like the law of diminishing returns has come and smacked me upside the head on this one,lol.
It seems the way the hammer/hammer spring set up is in this gun, combined with the valve design, is just working against me. Please correct me if I'm off course though! I wouldn't mind one bit being wrong on this one. Either way, I REALLY APPRECIATE your, and everyone else's input and advice on this!
A heavier spring inside the thimble will have twice the effect as your original valve spring so if the spring inside the thimble is the same rate as your old valve spring you should have better dwell control without added cocking force
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Okay, I gave up on the cobra tech for my .22 Flash. I have a .177 that I couldn't seem to get the numbers I wanted on, so I gave it another go with the .177. I figured that it may have a better chance of helping on that lower power gun, and it did!! I knew it was working on the .22, but all gains were erased given the design of the gun and power level I was trying to get with the .22.
It is hard enough to get great efficiency when shooting a 10.5 grain pellet at 900fps regulated, and I needed all the help I could get. Of course, I did all the porting/valve seat etc. etc. Drum roll.... I went from 42 shots at 908fps to 56 shots at 903fps with the cobra valve spring :D :D :D I can shoot four 14 round magazines before having to refill now! This really made my day guys ;) All of the work and frustration I went through on the .22 paid off quite well with the lower powered .177. Thanks for the help!
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I think I am seeing an interesting phenomenon related to the cobra tech......maybe this was previously explained, but only now have I seen it for myself.
On my P15 I went back to as small diameter of a poppet (peek material) as possible. The P15 OEM valve throat measures .235 and has a tapered seat. It took several tries using my crude dremel "lathe." But I finally made as small of a poppet as would seal in the tapered seat. My poppet ended up merely .250 in diameter. The result is an extremely easy to open valve, considering the throat size.
This time I made a slightly longer cobra chamber, right at 1.5" overall length. The poppet is inserted approximately .25" from the bottom and a threaded plug that the jet screws into is .125" deep from the top. This leaves a 1.125" by .25" cobra chamber and places the jet far up into the plenum and away from the valve seat. It is currently jetted .035 IIRC...
It appears that I am not seeing as drastic of an increase in velocity when coming off regulator---almost no increase. It's almost as if the cobra chamber is "damping" the changing relationship between HST and pressure. Maybe not the best explanation but I'm definitely seeing something different here. It has appeared with a few different HST settings, with no change in reg set point.
So many variables to work with now.........makes my head hurt but in a good way LOL...
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Question is ... are you seeing better efficiency, quieter shot cycle ... loss of power at equal HST to non cobra ... etc ?
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Question is ... are you seeing better efficiency, quieter shot cycle ... loss of power at equal HST to non cobra ... etc ?
Definitely more quiet and snappy shot cycle, and better efficiency than without the cobra chamber.
In the very first test where all I changed was adding a cobra chamber to an existing poppet diameter/reg setpoint/HST combination it required significantly more HST to achieve similar velocity.
At this point I haven't shot the gun without a cobra chamber since at least a half dozen different combinations ago.
I was hoping to test a 40fpe or so tune using my extended plenum and cobra to see if it helps there. The best I could previously achieve, non-cobra, was something like 25 shots in the 41fpe range. But I was a single 2x19mm oring shy of being able to assemble my spare tube.
My desired goal is to be able to change tubes, complete from gauge to reg/plenum, similar to what the Hatsan guys do, make an HST adjustment, and have the ability to switch between a 80+ shot 30+fpe tune and a xx shot 40+fpe tune. A 40/40 tune would be ideal, but previous testing shows I'm pretty far off from there.
Once the 2x19 orings arrive I'll see if the cobra chamber will help me do better than 25 shots at 41fpe....
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Thinking this thread & subject has been buried long enough .... Shameless bump to get the info out there to a new audience.
I dont think people quite understand whats taking place in the thimble or understand how it helps. Might need to make a video or something.
YES - Some principle video/animation may help for sure because understanding in alien language is not easy .
Cracking/opening force at standard valve depend of area on which HPA is pressing/pushing. Reducing this area at SS balanced valve is make via creating zero/atmospheric pressure on part of it.
At cobra valve it is make probably via creating the same HPA pressing/pushing from opposite side ? - which way?
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Today I found the missing oring which allowed me to finish my spare P15 tube. This one is equipped with an extended plenum, which yields 25cc plenum of regulated air and 195cc of high pressure air, 220cc total. I made a 2" long .25" in diameter cobra chamber. The poppet extends approximately .25" into the cobra chamber. A threaded plug extends approximately 1/8" into the top, leaving an open chamber of approximately 1.625" I guessed at jetting and started with a .055 jet. My reasoning for the larger jet was the larger cobra chamber should have a greater affect on the poppet. The reg is set around 1900psi I believe.
After degassing and switching tubes I ran some tests to dial in HST for 850ish FPS.
Previously (non-cobra) the best I could do with the extended plenum and a >40fpe tune was 26 shots averaging 855fps with JSB Redesigned Monster 25gr. Granted I didn't spend much time, but I did try a few different reg/hst settings and the above numbers were representative of non-cobra results.
With the added cobra chamber there is a significant improvement. 45 shots averaging 856fps. This is without an SSG, so I'm sure there is a little more room for improvement.
Note ES is rather high, I have a Huma reg on order that will hopefully help in the ES department.
Here is a chart:
(http://i66.tinypic.com/4vmyyr.png)
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Today I found the missing oring which allowed me to finish my spare P15 tube. This one is equipped with an extended plenum, which yields 25cc plenum of regulated air and 195cc of high pressure air, 220cc total. I made a 2" long .25" in diameter cobra chamber. The poppet extends approximately .25" into the cobra chamber. A threaded plug extends approximately 1/8" into the top, leaving an open chamber of approximately 1.625" I guessed at jetting and started with a .055 jet. My reasoning for the larger jet was the larger cobra chamber should have a greater affect on the poppet. The reg is set around 1900psi I believe.
After degassing and switching tubes I ran some tests to dial in HST for 850ish FPS.
Previously (non-cobra) the best I could do with the extended plenum and a >40fpe tune was 26 shots averaging 855fps with JSB Redesigned Monster 25gr. Granted I didn't spend much time, but I did try a few different reg/hst settings and the above numbers were representative of non-cobra results.
With the added cobra chamber there is a significant improvement. 45 shots averaging 856fps. This is without an SSG, so I'm sure there is a little more room for improvement.
Note ES is rather high, I have a Huma reg on order that will hopefully help in the ES department.
Here is a chart:
(http://i66.tinypic.com/4vmyyr.png)
Huge improvement!
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Today I found the missing oring which allowed me to finish my spare P15 tube. This one is equipped with an extended plenum, which yields 25cc plenum of regulated air and 195cc of high pressure air, 220cc total. I made a 2" long .25" in diameter cobra chamber. The poppet extends approximately .25" into the cobra chamber. A threaded plug extends approximately 1/8" into the top, leaving an open chamber of approximately 1.625" I guessed at jetting and started with a .055 jet. My reasoning for the larger jet was the larger cobra chamber should have a greater affect on the poppet. The reg is set around 1900psi I believe.
After degassing and switching tubes I ran some tests to dial in HST for 850ish FPS.
Previously (non-cobra) the best I could do with the extended plenum and a >40fpe tune was 26 shots averaging 855fps with JSB Redesigned Monster 25gr. Granted I didn't spend much time, but I did try a few different reg/hst settings and the above numbers were representative of non-cobra results.
With the added cobra chamber there is a significant improvement. 45 shots averaging 856fps. This is without an SSG, so I'm sure there is a little more room for improvement.
Note ES is rather high, I have a Huma reg on order that will hopefully help in the ES department.
Here is a chart:
(http://i66.tinypic.com/4vmyyr.png)
WOW! That is an awesome improvement there, and I bet you're right about that ES. The Huma should help with that. Great job!!
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I tried adding the SSG back into the mix and I actually lost efficiency. I'm thinking with hammer free flight the cobra chamber needs a larger jet. with no hammer spring preload against the valve the cobra effect is so great that it is requiring excessive hammer strike to achieve the desired velocity and in turn this is causing excessive dwell before the valve slams shut. that's just a hypothesis...
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I tried adding the SSG back into the mix and I actually lost efficiency. I'm thinking with hammer free flight the cobra chamber needs a larger jet. with no hammer spring preload against the valve the cobra effect is so great that it is requiring excessive hammer strike to achieve the desired velocity and in turn this is causing excessive dwell before the valve slams shut. that's just a hypothesis...
I run mine with no ssg or tss its plenty efficient without any extra help that robs power BUT if i was in a competition wanting every extra es% I would run a ssg.
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I tried adding the SSG back into the mix and I actually lost efficiency. I'm thinking with hammer free flight the cobra chamber needs a larger jet. with no hammer spring preload against the valve the cobra effect is so great that it is requiring excessive hammer strike to achieve the desired velocity and in turn this is causing excessive dwell before the valve slams shut. that's just a hypothesis...
I run mine with no ssg or tss its plenty efficient without any extra help that robs power BUT if i was in a competition wanting every extra es% I would run a ssg.
No further comment ;D ;D ;D ... ;)
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I tried adding the SSG back into the mix and I actually lost efficiency. I'm thinking with hammer free flight the cobra chamber needs a larger jet. with no hammer spring preload against the valve the cobra effect is so great that it is requiring excessive hammer strike to achieve the desired velocity and in turn this is causing excessive dwell before the valve slams shut. that's just a hypothesis...
I run mine with no ssg or tss its plenty efficient without any extra help that robs power BUT if i was in a competition wanting every extra es% I would run a ssg.
No further comment ;D ;D ;D ... ;)
Thanks guys, again. That makes life easier. With a .25" OD poppet and no ssg cocking is buttery smooth even over 40 fpe.....
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Over on another thread I posted my intentions to test my .22 P15 unregulated with Cobra and without. Scott predicted the results would not be favorable, and surprise, he was correct.
Based on the expectation of unfavorable results I decided to quickly test at max preload and compare the cobra and non-cobra numbers. I only filled to 3k for each test. JSB Redesigned Monster 25gr pellets.
The unregulated, cobra string went like this: 899 to 997 on shot 7 then down to 870 on shot 25. 127fps ES, lol..
Then I removed the jet from the cobra chamber and also removed the oring from the poppet, effectively disabling the cobra chamber. Refilled to 3k and took a shot...
1033fps!!!!!! took another shot 1024fps!!! remember, the first shot of the cobra equipped string was only 899fps. The cobra chamber has major influence on the poppet.
I dialed hst down to around 900fps and shot a non-cobra, unregulated string. This string went 905 up to 995 on shot 6 and back down to 881 on shot 25. 25 shots averaging 937fps with an ES of 118, lol.
Scott predicted the Cobra chamber would result in greater ES than non-cobra and he was correct. Sometimes I have to see things with my own eyes, this was one of those times.....
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I was having same problem with my war Cobra valve and SS valve . I was able to make smaller transfer ports to bring the es down to 20 fps but I also had to use more preload to get the same power while running unregulated
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It's still More efficient than running stock valve unregulated once your able to get the es down
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It's still More efficient than running stock valve unregulated once your able to get the es down
Understood, I've been following your threads. I don't intend to pursue unregulated cobra testing any further at this time. It was more of a curiosity than anything else....
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Understood. It's crazy how much of an effect it has on the poppet . I guess I think of it as a air spring with more of an effect at higher pressure
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Understood. It's crazy how much of an effect it has on the poppet . I guess I think of it as a air spring with more of an effect at higher pressure
It works evenly across the board down to very low pressures I actually tried to get mine to burp and blow the valve open but it never did all the way down to 200 psi.
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Scott predicted the Cobra chamber would result in greater ES than non-cobra and he was correct. Sometimes I have to see things with my own eyes, this was one of those times.....
Whats that TAG line .... Experience is :P
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Scott predicted the Cobra chamber would result in greater ES than non-cobra and he was correct. Sometimes I have to see things with my own eyes, this was one of those times.....
Whats that TAG line .... Experience is :P
Thats only because the strings are twice as long LOL
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That's a good point Travis.
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Now that i've seen Cobra effect on a few different applications I have a couple of questions around volume of the Cobra chamber itself. Travis' thread on his latest project, the Python valve, discusses this topic a bit.
for 2 Cobra chambers using the same jet, a .056" for example... One just large enough to allow room for the light valve spring and enough travel to not bottom out during valve lift. The second would be say, 3x the volume. If I am interpreting things correctly, the smaller in volume the Cobra chamber, the harder the valve will be to open. The larger volume Cobra chamber will be easier to open due to more room to compress the charge in the Cobra chamber????
In closing the valve with Cobra affect-----is the Cobra effect greater with a larger volume Cobra Chamber as there is more air to expand???
Thanks in advance.
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Yes the smaller the cobra chamber the shorter the dwell so getting the power back to previous setting requires more hammer strike so the same goes with larger chamber= less hammer strike but less effect on dwell. Dwell is the time it takes to fully open and close the valve from start to finish and this can be divided into smaller sections. Start/peak/fall/finish.
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Yes the smaller the cobra chamber the shorter the dwell so getting the power back to previous setting requires more hammer strike so the same goes with larger chamber= less hammer strike but less effect on dwell. Dwell is the time it takes to fully open and close the valve from start to finish and this can be divided into smaller sections. Start/peak/fall/finish.
Been a LONG time sense offering up info on this subject .... reading the last post travis had made WOKE ME UP !
That said is INCORRECT .... and here the why for behind that statement.
Bigger the chambers volume, flowing threw a fixed hole size during the shot cycle ... LESS WILL BE the pressure drop within the chamber than a smaller chamber will see.
Smaller the chambers volume, FASTER the pressure differential will collapse on the same jetting size.
There is TUNING is how quickly or slowly the chamber is allowed to equalize / collapse during the shot cycle.
In the near 15 months sense the post above personally have made many more versions, gotten distracted with the balanced valves and finding myself revisiting "Cobra" tech in lower to mid power applications.
in the past 3-4 months have eclipsed the best of my best in efficiency having had 2 tunes go beyond 2.0 fpe/ci
The most recent and in need of some more validation is this tune in a Highly Modified JSAR Raptor mini .... https://www.gatewaytoairguns.org/GTA/index.php?topic=171248.msg155960614#msg155960614 (https://www.gatewaytoairguns.org/GTA/index.php?topic=171248.msg155960614#msg155960614)
Scott S
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Actually Scott it’s almost the exact opposite of your statement in my testing. The smaller chamber has more effect closing the valve due to less air volume inside the chamber so less air volume means quicker direction change of the poppet from opens to closing its like a air shock the larger the piston the slower and softer the rebound. Short stiff shocks or long soft shocks that’s what we’re talking about here, I am however interested in the data you have that supports your testing maybe I’ve missed something important. Always something new to learn.
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In this equation is how jetted / vented .... Not an exact science by a long shot !!
We can agree to disagree on the subject of chamber sizing, but can agree either way you go if you are paying attention to cause & effect some pretty impressive results can be achieved.
My latest & link above is a rather large chamber on quite small venting FWIW ???
Scott
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Huh, never using this valves tech I'll give my impression of it, as I certainly do not intend to steer anyone wrong feel free to correct me.
Pressure differential inside chamber is determined by initial pressure, volume and vent size or 'leak rate'.
Larger vent / leak = larger pressure differential
Smaller vent / leak = lower pressure differential (pressure in chamber remains closer to initial)
Smaller chamber = larger pressure differential
Larger chamber = lower pressure differential (pressure in chamber remains closer to initial)
You also have to consider the potential "pressure shock" the chamber sees upon initial strike of the hammer where the distance the poppet travels and the pressure rise it would cause in a closed chamber MAY exceed the leak rate inside the chamber, meaning you're compressing air even if ever so minutely for a fraction of a millisecond...(small enough chambers and vents will see this phenomenon IMO)
These valves have lots of room for arrangement, and what works best for a 20 fpe gun may not for a 200 fpe gun, or maybe it does, I wouldn't know but its good to ponder such questions...
Nearly most any airgun may see benefit with these types of valves, but where they truly shine is in air guns with high pressure drops in the plenum during the shot cycle, as this helps maintain a higher pressure behind the poppet as to reduce the chance for a second or third opening which is ever so more likely as you have higher pressure drops within a valve, or in cases where there's little force holding the valve closed to begin with (ie: low pressure operating guns, or extremely balanced valves, both being very prone to hammer bounce). Any benefits beyond that are outside of my current realm of understanding.
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In this equation is how jetted / vented .... Not an exact science by a long shot !!
We can agree to disagree on the subject of chamber sizing, but can agree either way you go if you are paying attention to cause & effect some pretty impressive results can be achieved.
My latest & link above is a rather large chamber on quite small venting FWIW ???
Scott
The venting will definitely have the greatest effect regardless of chamber size. I found that chamber size mattered very little because it could be tuned by the venting quite easily
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Travis,
Since you are active in this thread, several of us have been trying to find out the correct or-ring (size/material/hardness) used in the chamber in the JSAR SS2 valve. Scott said you would know. Can you please let us know? Thanks!
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Being this thread is likely to live for many years .... wish to elaborate a bit on the disagreements in chamber size and how this effects the tune.
These numbers will be that of a sample only so one can easily follow / understand whats going on ( As i see it )
So lets say our poppet sitting over the valves throat is .350" in diameter and the stem length hammer can strike sticks out .125" .. so the max lift obtained is no greater than .125"
And for sake of simple design the o-ring for chamber in contained within the poppet head and the tube Cobra tube attached to intake end of valve such as 1st picture.
IF the chambers volume is kept small and the vent hole small ..... As poppet is lifted off the seat the air space within the chamber creates COMPRESSION and higher the poppet is pushed within chamber GREATER will be the opening resistance. It acts very progressive in that harder you strike the valve driving it towards more lift, more it resists ! Valve will indeed exhibit a short dwell tendency. Because the vent is small, the contained air is slow to bleed off and this compression rise is exaggerated.
* If the venting was made larger while using a small chamber volume it would result in less effort required to open and keep the valve open while ALSO having the lower volume tube more quickly equalize / collapse to the surrounding pressure drop within the valve/plenum.
Next example is we have the chamber LARGER with a small vent .... As poppet is lifted off the seat there is LESS compression happening simply because the Stroke has remained the same, but chamber volume is greater so in simple terms a lower compression ratio. The valves resistance to lift becomes far less progressive and Does Not increase in opening resistance as sharply as a smaller volume does.
Being vented small it contains nearly the same pressure within tube from where it started before the shot cycle & the retained pressure has increased the ability to push the poppet closed.
* IF the venting is made larger while using the larger chamber volume the opening forces would still be low and the closing effect would be of a tad longer dwell.
These two examples really in my experience shape the picture of how the system works. They are in application if looked at in extremes of each example ... Majorly different in the way valve will operate requiring pretty drastic changes it hammer mass, spring energy to get EITHER to make the same power. Or in a tuners sense, each extreme or middle ground becomes what one uses based upon the guns hammer weight, spring in use, caliber and power, tuning flexibility wanted.
JMO,
Scott S
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The question remains - when will a Cobra valve for a mid-power .22 be available for those of us that do not have access to machine shop tools?
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The question remains - when will a Cobra valve for a mid-power .22 be available for those of us that do not have access to machine shop tools?
Likely not .... The man behind the tech and getting them and other valve designs made for the masses has stepped away from such endeavors as i see it.
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I'm willing to be a Cobra conversion could be had as a component of a FULL TUNE service, from a certain tuner located in the NW...
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Thanks for all your contributions into the cobra valves and their evolution Scott. Your observations line up well with my theories and thoughts.
I'd love to see a version ran with just the tolerance between chamber and poppet being its only 'vent', which with some ingenuity could be expanded in a way that is adjustable, thus eliminating a need for a seal. Say an inner poppet stem that opens a 'disc' at the opposing end of the poppet that either increases or reduces the tolerance between poppet and chamber. Which would make it externally adjustable with the only need to remove hammer to access adjustment opposed to requiring degas/valve removal.
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I'm willing to be a Cobra conversion could be had as a component of a FULL TUNE service, from a certain tuner located in the NW...
Lol ... It has happened ;)
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here are a few Cobra transplants.....All have very light hammers and pretty good efficiency numbers. I gravitate towards Scott's theories around ultralight hammers, and barely-there OD peek poppets....I add my own twist of reducing stem diameter vs. increasing throat diameter where possible, working towards one of Bob Sterne's targets of valve throat area = valve exhaust area + 10%.
QB78/Gauntlet
(https://i.imgur.com/5W93UL7.jpg)
(https://i.imgur.com/rdbCsX1.jpg)
Edgun R3
(https://i.imgur.com/et1Zx2I.jpg)
P15
(https://i.imgur.com/Q6hWHDV.jpg)
(https://i.imgur.com/I2p0U8i.jpg)
Bulldog
(https://i.imgur.com/xbcLS3Y.jpg)
(https://i.imgur.com/B23Xwxo.jpg)
(https://i.imgur.com/LCFlgfm.jpg)
Note the lack of adjustable jetting in the Bulldog..... that was my most recent conversion. I won't use jets going forward, no need to adjust once set up properly. Start small, go larger until desired effect achieved---once you have a nice snappy shot cycle you are very close. Start running strings and calculating efficency....
Note as Matt described Cobra valves shining in regulated applications with extreme pressure drop, these are all in regulated guns with roughly .5-.75cc plenum.....
Also note, no machine shop required.... They are not pretty, but they are fully functional and could be easily replicated using my crude, or someone else's advanced fabrication methods....