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Author Topic: SS valve annd Huma Reg  (Read 236 times)

bnowlin

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SS valve annd Huma Reg
« on: October 18, 2017, 05:26:52 PM »
Regul.ated 25 mrod with ss valve fill to 3200 and reg at 1600  What am I doing wrong and where did the 900s come from

Created: 10/18/17 02:01 PM
Description: JSB 25.00 1600 3200 fill
Notes 1: JSB 25.00 Pellet 25.40 0
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 25.40
Temp: 80 °F
BP: 30.15 inHg
Altitude: 0.00
#          FPS  FT-LBS      PF
61    827      38.58    21.01 
60    833      39.14    21.16 
59    835      39.33    21.21 
58    845      40.28    21.46 
57    844      40.18    21.44 
56    842      39.99    21.39 
55    840      39.80    21.34 
54    839      39.71    21.31 
53    836      39.42    21.23 
52    841      39.90    21.36 
51    841      39.90    21.36 
50    833      39.14    21.16 
49    818      37.74    20.78 
48    831      38.95    21.11 
47    826      38.49    20.98   
46    833      39.14    21.16 
45    836      39.42    21.23 
44    828      38.67    21.03 
43    832      39.05    21.13 
42    825      38.39    20.95   
41    818      37.74    20.78 
40    830      38.86    21.08   
39    832      39.05    21.13 
38    835      39.33    21.21 
37    832      39.05    21.13 
36    833      39.14    21.16 
35    830      38.86    21.08 
34    836      39.42    21.23 
33    819      37.84    20.80 
32    831      38.95    21.11 
31    828      38.67    21.03 
30    837      39.52    21.26 
29    830      38.86    21.08 
28    832      39.05    21.13 
27    837      39.52    21.26 
26    828      38.67    21.03 
25    820      37.93    20.83 
24    818      37.74    20.78 
23    832      39.05    21.13 
22    903      46.00    22.94   
21    903      46.00    22.94 
20    827      38.58    21.01 
19    912      46.92    23.16 
18    843      40.09    21.41 
17    905      46.20    22.99 
16    900      45.69    22.86 
15    823      38.21    20.90 
14    823      38.21    20.90 
13    819      37.84    20.80 
12    824      38.30    20.93 
11    814      37.38    20.68 
10    823      38.21    20.90 
9    898      45.49    22.81 
8    891      44.78    22.63 
7    823      38.21    20.90 
6    820      37.93    20.83 
5    818      37.74    20.78 
4    819      37.84    20.80 
3    820      37.93    20.83 
2    824      38.30    20.93 
1    819      37.84    20.80 
Average: 837.6 FPS
SD: 24.5 FPS
Min: 814 FPS
Max: 912 FPS
Spread: 98 FPS
Shot/sec: 0.1
True MV: 838 FPS
Group Size (in): 0.00



rsterne

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Re: SS valve annd Huma Reg
« Reply #1 on: October 18, 2017, 09:58:27 PM »
No idea where the 900s came from, but my bet is a change in hammer strike for some reason.... If you throw out those, the velocity is around the 820-830 range until about shot 50, and then you have a bump up for a few shots before the final decline.... This is typical of a slightly lighter than desired hammer strike for the setpoint pressure.... A bit more hammer strike should put you close to 850 fps above the setpoint....

Depending on your port sizes, I don't think 40 FPE is too far off the mark for a 1600 psi setpoint.... Using .219" porting in my 2560 (24" barrel) I am at 52 FPE at 1900 psi with a 65 cc plenum.... with my own modded Disco valve using 25 gr. pellets.... Most of that is the higher pressure, the rest is the larger ports (I assume you are using the 0.19" SS valve ports?).... What is the diameter of your smallest port, and the plenum volume?....

Bob
  • Coalmont, BC

bnowlin

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Re: SS valve annd Huma Reg
« Reply #2 on: October 19, 2017, 04:01:17 AM »
Thanks Bob.
The ports are whatever Travis used when he tuned and put the valve in.  The first string was worse than that so I went up a turn and for a few minutes I thought I had it.  The Huma I had was creeping up when I stopped for a couple of minutes so I put a new one in and that is the string I sent you.  Have to go to VA today but will check for spring bind and hammer strike and get back with you.
Bob

Motorhead

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Re: SS valve annd Huma Reg
« Reply #3 on: October 19, 2017, 08:31:56 AM »
My guess those few shots were too close to chrony and it was an error ...
  • Old Hangtown ... California
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Scott

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Re: SS valve annd Huma Reg
« Reply #4 on: October 19, 2017, 12:22:09 PM »
^ quite likely, Scott....

Bob
  • Coalmont, BC

bnowlin

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Re: SS valve annd Huma Reg
« Reply #5 on: October 19, 2017, 12:28:22 PM »
My guess those few shots were too close to chrony and it was an error ...
  to start my experiments, how far should I be Scott/Bob I hope it was that and not the spring catching at some point one time and not the other.  It has my valve and his innards so we'll see  the tube is as slick and smooth as he could get I think.
« Last Edit: October 19, 2017, 12:30:43 PM by bnowlin »

Motorhead

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Re: SS valve annd Huma Reg
« Reply #6 on: October 19, 2017, 08:54:27 PM »
When after accurate data make sure lighting is uniform & of the correct wave length ... Outside sun and screens OR inside under LED's with no cross light from shop lights etc ...
Muzzle to 1st screen no less than a foot or so with 2-3 feet being ideal.
« Last Edit: October 19, 2017, 09:00:21 PM by Motorhead »
  • Old Hangtown ... California
"Home of Motorheads Air Gun Tuning Service"
    ***** Airguns need love too !! *****
http://airgunguild.com/index.php/topic,38.0.html    
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bnowlin

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Re: SS valve annd Huma Reg
« Reply #7 on: October 20, 2017, 04:37:04 AM »
When after accurate data make sure lighting is uniform & of the correct wave length ... Outside sun and screens OR inside under LED's with no cross light from shop lights etc ...
Muzzle to 1st screen no less than a foot or so with 2-3 feet being ideal.
Thanks Scott
This is the new precision Ballistics  that Travis suggested.  I will try it today with IR Just to see if it makes a difference and move it further back.
Bob

bnowlin

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Re: SS valve annd Huma Reg
« Reply #8 on: October 21, 2017, 12:12:02 PM »
The are the post that I made this morning, turns out my Huma regulator was leaking which explain the high numbers at random.  Re placed the regulator and filled to 3200 and regg. at 1700.  on the second set is one turn in on the spring and that is about all I can get.  I tried a few more shots with turning the spring in a little more and only raised psi just a few points more do I increase the regulator to get 900 or what I think the hammer is hitting the valve.  and I know my rifle gauge is about 225 off on the low side. Got the sets backwards set one is on the bottom.  BTW this is the Gen 1 Mrod with early SS valve and .630 by 23.5 inch polygon barrel.
Bobn

Set TWO
Created: 10/21/17 11:29 AM
Description: JSB 25.00
Notes 1: JSB 25.00 Pellet 25.40
Notes 2: 1/2 turn in
Distance to Chrono(FT): 2.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 25.40
Temp: 80 °F
BP: 29.99 inHg
Altitude: 0.00
#          FPS  FT-LBS      PF
32    872      42.89    22.15 
31    871      42.79    22.12 
30    875      43.19    22.23 
29    875      43.19    22.23 
28    875      43.19    22.23 
27    877      43.39    22.28 
26    874      43.09    22.20 
25    873      42.99    22.17 
24    876      43.29    22.25 
23    874      43.09    22.20 
22    874      43.09    22.20 
21    873      42.99    22.17 
20    875      43.19    22.23 
19    871      42.79    22.12 
18    874      43.09    22.20 
17    873      42.99    22.17 
16    873      42.99    22.17 
15    875      43.19    22.23 
14    877      43.39    22.28 
13    877      43.39    22.28 
12    876      43.29    22.25 
11    878      43.48    22.30 
10    875      43.19    22.23 
9    872      42.89    22.15 
8    876      43.29    22.25 
7    877      43.39    22.28 
6    875      43.19    22.23 
5    875      43.19    22.23 
4    873      42.99    22.17 
3    875      43.19    22.23 
2    876      43.29    22.25 
1    879      43.58    22.33 
Average: 874.7 FPS
SD: 1.9 FPS
Min: 871 FPS
Max: 879 FPS
Spread: 8 FPS
Shot/sec: 0.1
True MV: 875 FPS
Group Size (in): 0.00

Set ONE
Created: 10/21/17 11:10 AM
Description: JSB 25.00
Notes 1: JSB 25.00 Pellet 25.40
Notes 2: 3200 fill  1700 off
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 25.40
Temp: 79 °F
BP: 29.99 inHg
Altitude: 0.00
#          FPS  FT-LBS      PF
37    863      42.01    21.92 
36    866      42.30    22.00   
35    866      42.30    22.00   
34    866      42.30    22.00   
33    867      42.40    22.02 
32    867      42.40    22.02 
31    867      42.40    22.02 
30    869      42.60    22.07   
29    869      42.60    22.07 
28    867      42.40    22.02 
27    871      42.79    22.12 
26    866      42.30    22.00   
25    869      42.60    22.07 
24    867      42.40    22.02 
23    866      42.30    22.00   
22    867      42.40    22.02 
21    866      42.30    22.00 
20    867      42.40    22.02 
19    866      42.30    22.00 
18    866      42.30    22.00 
17    869      42.60    22.07 
16    871      42.79    22.12 
15    866      42.30    22.00 
14    868      42.50    22.05 
13    868      42.50    22.05 
12    869      42.60    22.07 
11    867      42.40    22.02 
10    866      42.30    22.00 
9    868      42.50    22.05 
8    870      42.70    22.10 
7    869      42.60    22.07 
6    867      42.40    22.02 
5    870      42.70    22.10 
4    866      42.30    22.00 
3    867      42.40    22.02 
2    868      42.50    22.05 
1    868      42.50    22.05 
Average: 867.4 FPS
SD: 1.7 FPS
Min: 863 FPS
Max: 871 FPS
Spread: 8 FPS
Shot/sec: 0.1
True MV: 868 FPS
Group Size (in): 0.00


« Last Edit: October 21, 2017, 12:22:47 PM by bnowlin »

rsterne

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Re: SS valve annd Huma Reg
« Reply #9 on: October 21, 2017, 01:12:24 PM »
That sure fixed the consistency problem....  8)

Before I start shooting strings, I find out what the preload adjuster does to the velocity at my setpoint pressure.... Then you know what your maximum is, and where your sweet spot in velocity is likely to be (about 3-5% lower).... You only need to shoot 1 or 2 shots at each preload setting, and then graph them like this....



You could literally draw the velocity curve on that graph with only 16 shots or less, so one fill of air.... I used a bit more, because I wanted to take 5-10 shots at each velocity so I could measure the pressure drop more accurately to plot the efficiency.... but that's not necessary for preliminary testing to find the knee of the curve (4-5 turns out on that graph).... That graph tells you instantly that there is NO point in having more preload than 4 turns out, you gain no velocity and just waste air.... I ran that gun at 4.5 turns out for the best balance between power and shot count.... Running less preload, where you are down on the downslope, is very efficient, but the velocity will bump up if you allow the pressure to drop below the setpoint....

If your plateau velocity is below what you want, you have only two choices.... You can increase the setpoint pressure, or make the ports bigger.... Basically you need to force more air into the barrel, through one method or the other.... If, on the other hand, your target velocity puts you on the downslope, you may want to drop the setpoint pressure a bit.... This testing, IMO, is vital when setting up a regulated PCP to let you know if you have the right setpoint, before you spend the time, air, and pellets to fine tune it.... In an unregulated PCP, it will also tell you what your maximum FPE level is, and roughly where to start adjusting your preload to get the bell curve you want....

Bob
  • Coalmont, BC

bnowlin

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Re: SS valve annd Huma Reg
« Reply #10 on: October 21, 2017, 01:43:38 PM »
Ok this was the gun that Travis used to start the SS testing and he has the ports open I'm sure.  I wish they made an internal regulator that had an outside adjustment.  I could use my external regulator but that make the whole tube full of air.
BTW have you heard from him in a while.  I can't seem to get him oh well.  I will try it your way and see what I come up with.  Do I need maybe a stronger spring so the starting point on the adjuster spring will be further back and just be hitting the poppet and not the valve.
Bob

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Re: SS valve annd Huma Reg
« Reply #11 on: October 21, 2017, 03:03:15 PM »
If you can't reach a flat plateau before you get to maximum preload, you don't have enough hammer spring.... another advantage of doing this test first, to confirm you have enough spring to reach maximum velocity at your pressure....

Bob
  • Coalmont, BC

bnowlin

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Re: SS valve annd Huma Reg
« Reply #12 on: October 21, 2017, 05:06:48 PM »
Thanks Bob for your help, I will try that.  Appreciate ya,
Bobn