GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Engineering- Research & Development => Topic started by: shorty on February 03, 2016, 05:43:06 PM
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Last year it was power and this year it appears to be efficiency. With that being said I am going to try and go overboard. Now I am sure my thoughts and theories will be wrong (and some may agree) but, that's not going to stop me from figuring it out and sharing with GTA.
My hope is to work it out with the best of the best to get shot strings and power to the highest levels we never thought could be possible for the every day Joe. There's alot of excitement over the SSG which is going to change (if not already) our shot count for 2016 (I am still with the short stiff spring but Ill get over that during this exercise) :D
I have always wanted to regulate my marauder and I have always wanted to use the entire pressure range of the gun to get the most shots from a charge. Unfortunately we have had discussions that said regulation uses more air than self regulating ( I don't think so - at this point ) along with many other variables.
So,
I almost have an engineering plan and a budget to buy a regulator. I have started a spreadsheet to help along the way. Now please don't beat me up too bad on the spreadsheet as it is work in progress with assumptions (and I do not have a degree in fluid dynamic or physics).
The engineering plan is to try and:
Step 1: get the wife to allow me to buy a regulator. ;)
Step 2: Perform a factorial DOE on TP size, lift and spring force (SSG or short stiff spring) at the lowest pressure possible for 25 fpe (14.3 grain) (.22 cal) "goal is at or over 1.8 efficiency".
Step 3: Make a zillion assumptions
Step 4:install regulator (at assumed pressure) and appropriate plenum size.
Lastly, hope everything works out like it did in theory and run a string that no one has ever seen before ( hopefully not be embarrassed).
Well,
That's the plan and this is the start of the challenge. I would ( and I am sure ) the rest that follow and or contribute to this post want the same thing as me. A whole lot of shots with just one charge.
We need this for 2016. We need this for GTA. There's nothing better than knowing GTA is the airgun forum of the world and this is the place to be for cutting new airgun technology and we are part of it. This is the site to go to. We are the best.
What you thought last year was good for shot count is going to be blown away this year.
Tim
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You have chosen a great power level and caliber for this experiment.... It's not too much or too little, the velocity range (just under 900 fps) is practical and tend to be accurate, and 14.3 gr. pellets in .22 cal are plentiful and cheap (and that will be a consideration, because you will go through a LOT of them).... My only suggestion is don't focus on too low a pressure, because although it increases the volume ahead of the regulator, the lower pressure is less efficient in driving the pellet.... The higher the pressure, the shorter the dwell can be, while the lower the pressure the more dwell you need to reach your FPE.... and shorter dwell means more efficiency.... It will be a balancing act, like anything else.... Good Luck !!!
Bob
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Thanks Bob. I can sure use some help on this one from you :D.
My hopes are to understand the dwell at lower pressures. Most of us tune at 2000 psi and greater. I for one never tried tuning at 1300 psi and lower. Alot of spring changes for hammer and valve along with hammer weight/throat/poppet/TP will be interesting. I hope it doesn't have to go that far.
In the spreadsheet,
The predicted FPE is an assumption (along with other things). At this time I can not figure out the pressure difference across an orifice (TP).
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Well if you figure out the DeltaP, let us know.... Lloyd, Bill, Scott and I haven't been able to do it.... http://www.gatewaytoairguns.org/GTA/index.php?topic=102604.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=102604.0)
Bob
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Don't get too wrapped around the axle with the spreadsheet. It has taken me several years to get where I am with mine as it has Lloyd and we aren't done. It is a good tool but it is time consuming and will detract from your collection of hard data. The reality is that Lloyd has the most accurate version IMO and Bob has mastered it's use. The data that you publish here will be run through these calculators just too help refine the calculator. The exchange of information through this forum can result in great advancements in understanding internal ballistics of the PCP in various configurations. What we need is hard, real world data.
Bill G
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Ofcourse I am sick this weekend and pretty much lazy. The regulator should be on order soon, I have a working SSG equipped with a 6lb spring, I skipped all the boring engineering plan and ran some strings to see what pressure regulator range I will be needing.
Yes I am impressed with absolutely ZERO burping or hammer bounce even down to 800 psi. My short stiff spring can not do that. Thank you Bob.
I am looking at this regulator:
http://www.huma-air.com/Benjamin-Marauder-pressure-regulator-with-pressure-gauge-connection (http://www.huma-air.com/Benjamin-Marauder-pressure-regulator-with-pressure-gauge-connection)
Current valve,TP, and barrel porting.
Hogged out valve at .5"
Dual dimension poppet spring (>15lbs per inch) - .048 wire
Exit TP .2"
TP .168"
Barrel .168"
Stock 6 lb spring on SSG
Charge gun to 1500 and ended just below 1000 I would say it was 950 to be sure.
Shot/FPS / Psi / Efficiency
1 777 1500
2 789
3 799
4 800
5 807
6 804
7 809
8 811
9 823
10 834 1400 2.28
11 828
12 842
13 840
14 843
15 838
16 840
17 842
18 842
19 844
20 849 1250 1.65
21 841
22 864
23 847
24 845
25 845
26 863
27 850
28 832
29 852
30 841 1100 1.68
31 839
32 831
33 829
34 824
35 819
36 820
37 809
38 812
39 807
40 801 950 1.57
Looking at the string it appears that between 1200psi and 1250 is the highest power with an efficiency of around 1.66.
So,
Looks like with the correct plenum and a regulator set at 1200 to 1250 psi should yield 108 shots at 23-24 FPE using 14.3 grain with a full charge of 3000psi.
What has got me confused is trying to figure out the estimated shot count. If I use the 1.66 efficiency number and run it from 3000 psi to 1200 psi the potential is 108 shots.
But,
If I work off of volume at 1200 psi, it's approximately 13cuin/fpe at around 16.5psi. If the volume of air can be compressed in half at the same pressure, then shot count should exceed 108 if being charged at 3000psi.
If this is correct the shot count would be at or extremely close to 150 shots. And if you then punch those numbers into an efficiency it would come out to around 2.3 to 2.4.
I can use some help in understanding the predicted shot count based on the theories above. My numbers do not make sense because I have never seen anything like it to compare to. I must be missing something.
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You are using the air at 1200 psi to produce the power you need.... It does not matter what the pressure is in the reservoir.... The amount of air available in the tank is the pressure drop times the volume of the reservoir.... You start at 215 cc (13 CI).... then subtract the volume of the regulator and plenum.... If the regulator is 1.5" long, that is 21.7 cc, and if you use a plenum that is 1/2 cc per FPE, that's another 12 cc, so you will lose about 35 cc, so down to 180 cc (11 CI).... The pressure drop is (3000-1200) = 1800 psi / 14.5 = 124 bar.... so the total amount of air you have available is (11 x 124) = 1364 CI.... If your efficiency is 1.66 FPE/CI, that should produce (1364 x 1.66) = 2264 FPE.... At 23 FPE per shot, that works out to (2264/23) = 98 shots....
HTHs....
Bob
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Regulator has been ordered.....
Took a while but it sure did help. Just confuses me going back and forth from atmosphere pressure.
It's nice having a spreadsheet and doing the math upfront. It sure does take the guess work out of tuning.
With that being said, I ran some numbers with the reg set at 1400 psi.That should get me a 2.24 efficiency at 20 fpe and 136 shots on regulation. That's alot of shots if it holds true :D
Now I can't make my mind up to reg pressure setting. The whole madness is starting all over again.
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If you choose 1400 psi, when you go off reg. (ie below the setpoint), the velocity will increase.... If you are OK with that, you can get higher efficiency by using higher pressures.... You of course loose "headroom" as now you only have 1600 psi of air to play with instead of 1800.... If all you want is super efficiency, and don't care about shot count, set the reg. to 2000 psi....
Bob
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The best efficiency I have been able to get at 31fpe (jsb 18.1s) is 1.542 efficiency. This is a straight up tune on a disco with a regulator set at 1600. The efficiency was better at 1600 than at 1400 psi. That is a 140 shots string with a 22ci bottle.
the person I built the gun for not too long ago ran a string at 27 fpe and got 180 shots that pushed up the efficiency to 1.688. I wonder if we lowered the power to 24 if I will reach the 1.8 efficiency.
Then the last thing, would a SSG increase that efficiency by a lot. I wish I still had that gun on hand. :)
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Well,
Maybe I should have followed the plan set out in post 1. It's starting to look like there is NOT plenty of options here using a regulator and being super efficient with a heck load of shots on a full charge with a .22 platform.
The regulator is forcing me into a "fixed" decision of fps,power, and shot count over a fill charge. I am typically used to a HS change from 25 fpe to 50 fpe for backyard plinking to a hog killer.
It is what it is I guess. I am going to have to understand that my longest shot I am going to take is gonna be a max of 50 yards and there's no hogs in the backyard.
Here's why I say what Iam saying:
Current valve,TP, and barrel porting.
Hogged out valve at .5"
Dual dimension poppet spring (>15lbs per inch) - .048 wire
Exit TP .2"
TP .168"
Barrel .168"
10 lb spring on SSG
Charge gun to 1750 and ended just 1050psi.
Shot/FPS / Psi / Efficiency
1 926 1750
2 936
3 935
4 939
5 936
6 937
7 938
8 940
9 940
10 933 1600 2.05
11 934
12 909
13 929
14 927
15 918
16 924
17 910
18 906
19 899
20 898 1425 1.68
21 896
22 891
23 887
24 885
25 883
26 878
27 868
28 865
29 860
30 857 1050 0.72
Theoretically
If I where to set the reg at 1600 and shoot from 3000psi to 1600psi I would get 93 shots on regulation for a max of 27fpe using 14.3's and possibly 30fpe with 18.13's.
With that being said,
It looks like I have a choice to make. A normal powered .22 backyard plinker at 20fpe with over 140 shots per "full" charge or 27fpe/30fpe on a full charge for 93 shots.
I was hope-ing when I first started this post that I was going to be a little different than typical regulated .22 marauder. Maybe hit some shot counts and power levels that we have not observed yet.
I am not sure if it's looking like what I expected.
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If you tune for the higher FPE, and then reduce your hammer spring preload (or increase the gap on the SSG), you can retune with just that simple adjustment for less FPE and increased shot count.... The only thing you must be aware of, is that when the pressure drops below the regulator setpoint, your velocity will INCREASE.... The reason is that when detuned, and on the regulator, you are shooting on the upslope of the shot string you would have unregulated....
Bob
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I ran a close to as possible tune using the dual wire spring (short stiff spring) instead of the SSG. Nothing else changed. I started believing that the SSG was going to limit the full capabilities of tuning at different power levels when using the regulator.
Current valve,TP, and barrel porting.
Hogged out valve at .5"
Dual dimension poppet spring (>15lbs per inch) - .048 wire
Exit TP .2"
TP .168"
Barrel .168"
Dual wire spring (short stiff spring).
Charge gun to 1600 and ended just 1100psi.
Shot/FPS / Psi / Efficiency
1 782 1600
2 797
3 800
4 806
5 816
6 819
7 815
8 815
9 821
10 817 1500 2.29
11 832
12 840
13 832
14 841
15 843
16 843
17 856
18 847
19 841
20 847 1400 2.49
21 857
22 855
23 866
24 865
25 877
26 871
27 868
28 871
29 881
30 877 1250 1.75
31 880
32 874
33 867
34 870
35 872
36 862
37 865
38 860
39 856
40 851 1100 1.75
Efficiencies are higher with a higher power. I am going to stick with the dual wire spring. I have a feeling the extra weight of the SSG was adding just an extra small amount of dwell.
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A small table for comparison
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Statistics are like a bikini.... what they reveal is enticing, but what they conceal is vital.... I see you comparing three different power levels.... However, if you set your mind to it, you can prove just about anything.... Good luck with your build, I'm sure that if you approach it with an open mind, you will learn a lot....
Bob
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I hope I do learn something here. Too me, if the math adds up it should work and I did go into this with an open mind. That's why I gave the SSG an opportunity. I have some humility.
I am also doing the math upfront so that I can understand how many shots I "should achieve" at a given regulator setting. Also, what I should be able to achieve in power and shot counts with just a hammer spring adjustment.
It's not over yet as the regulator is not here. I just hope that this reg set up and homework upfront does just as good as our master regulator tuners are doing if not better.
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Been thinking about your comments all day and night.
Bob, I am not understanding what your indicating with the numbers. It would appear as if you see something in the data that I am missing. I re-ran the numbers and matched up the 6lb SSG vs dual wire spring to matching pressures in a graph.
The goal of me installing this regulator is to maximize the shot count over a full charge and pushing the efficiency to the max over a capable fpe range of the porting.
If you see something that I am missing, please help and point it out. :D
If your opinion is that Iam steering the data or fudging something, please point that out too. "I assure I am not". :o
If there is an error in the data, I would really like to get it squared away before I set the pressure on the regulator and install it. ;)
My next set of strings I plan on doing will be for FPE range around a specific pressure. I want to know what fpe ranges can be used while being on regulation and then calculate the expected shot count at those given power levels.
The more I look at the last 3 strings the more I am getting excited about installing the regulator. It sure would be great if the data supports the real build. So, if you think I am missing something please point it out.
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Been thinking about your comments all day and night.
Bob, I am not understanding what your indicating with the numbers. It would appear as if you see something in the data that I am missing. I re-ran the numbers and matched up the 6lb SSG vs dual wire spring to matching pressures in a graph.
I could be wrong, but I think he is eluding to the fact that the "reason" the SSP has a higher efficiency (in your chart) than the SSG (with 10lb spring) is due to the FPE being lower with the SSP.
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The chart shows the comparison of the 6lb SSG vs dual wire spring NOT the 10lb SSG.
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The chart shows the comparison of the 6lb SSG vs dual wire spring NOT the 10lb SSG.
sorry, didn't mean chart, I meant the table
(http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=103892.0;attach=150423;image)
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I like the way you presented that data, it's too bad you didn't complete the string with the dual wire spring down to the same end point as you did with the 6# SSG setup.... It would be interesting to see the 10# SSG setup plotted on the same graph as well.... I think the thing you will learn the most by doing that is what to use for your setpoint with the existing porting to achieve your goal of 25 FPE with the 14.3 gr. pellets, which is ~890 fps.... The 6# SSG setup is too far below that velocity, although you may be able to get there with more preload on the spring.... The 10# SSG setup may well be too much, you might need something in between to hit the sweet spot.... It takes some experimenting to find the best combination (of spring and preload) for an SSG, just like you probably didn't figure out your dual wire spring on the first attempt....
Tuning for the "knee" of the curve at 890 fps when regulated means you want to find the pressure / preload combination that puts you fairly close to the top of the curve when unregulated.... If you are on the downslope of the unregulated curve at any given pressure, then at that pressure you will be on the plateau if you regulate to that pressure.... meaning you will have to reduce the hammer strike to get to the knee.... On the other hand, if you on the upslope of the unregulated curve, and select that pressure, you will be on the downslope if you regulate there, causing a rise in velocity once you go off regulator.... This of course only applies if you have a very large plenum.... If the plenum is small, you will have to increase your setpoint to get back to where you were unregulated, to compensate for the pressure drop on firing....
Based on the data you have so far, my guess is that you want to regulate at about 1400 psi.... If you plot enough velocity curves, using the pressure on the horizontal axis like you did, you will get something like this (although this was plotted vs. shot number)....
(http://i378.photobucket.com/albums/oo221/rsterne/Hayabusa%20PCP/Hayabusa308BigValve_zps41105bd5.jpg) (http://s378.photobucket.com/user/rsterne/media/Hayabusa%20PCP/Hayabusa308BigValve_zps41105bd5.jpg.html)
Notice how you could place a straight edge across the curves from upper left to lower right, tangent to them?.... That line represents the maximum velocity compared to the pressure.... Here is another representation of that (look at the upper graph)....
(http://i378.photobucket.com/albums/oo221/rsterne/PCP%20Internal%20Ballistics/Preload%20and%20Tunes_zpsyiy8fu4s.jpg) (http://s378.photobucket.com/user/rsterne/media/PCP%20Internal%20Ballistics/Preload%20and%20Tunes_zpsyiy8fu4s.jpg.html)
You will note that the knee of each curve moves to lower velocity as you reduce the pressure, and you can again place a straight edge from upper right to lower left, across those knees.... What you want to find for your gun, is where does that straight line cross 890 fps, which is your target velocity (in the graph above, the 2200 psi curve comes the closest).... That will tell you the pressure you need.... Since you will probably be using a plenum of about 1/2 cc per FPE (ie 12-13 cc plenum in your case), you will have to increase the setpoint about 10% to get the 25 FPE you want and be on the knee of the curve....
HTHs....
Bob
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;)
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plenum in the valve calculates out just of 25cc being .5" inch diameter and 1" inch long. With the regulator I should be sitting at just over 30cc.
Seriously, thanks for taking the time to run some of the numbers. For me it takes a lot of time and effort. What you do to verify the work makes it better. ;D
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A plenum 0.5" diam. x 1.0" long is only 0.196 CI = 3.2 cc, which IMO is way too small.... That sounds like just the valve volume?.... If so, I would add almost 1" of length of full ID tube to that for your plenum.... An MRod tube has an internal area of 0.88 sq.in, so one inch of length is 14cc.... If you use a piece of tubing for a spacer to hold the regulator, you have to subtract the wall thickness of the spacer.... If your spacer is only 7/8" ID, that is only 10 cc.... Don't use too thin a wall for the spacer, or this can happen....
(http://i378.photobucket.com/albums/oo221/rsterne/Important/Tube1_zpsivm9fkay.jpg) (http://s378.photobucket.com/user/rsterne/media/Important/Tube1_zpsivm9fkay.jpg.html)
I assume you are removing the gauge block, as that restricts the flow into the valve, and just takes up space in the plenum?....
Bob
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Whoops, way wrong math there on the plenum.
I used diameter instead of radius. The regulator is one of those huma regs with gauge port built in so that it can breathe through the existing gauge port.
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If that is the case, you may not have much of a choice on increasing the plenum beyond what is built into the regulator.... If you slide it forward with a spacer, the rear O-ring cannot seal to the tube between the gauge hole and the valve.... Scott (Motorhead) may know what the plenum volume is....
Bob
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Yeah... Regulator came in.
It took some time getting the old gauge port out but all appears to be fine now. Huma reg with gauge port has been installed and set at 1500 psi. Charged the gun to 2000 psi and took 10 shots at 853 fps.
Gonna have to wait till tomorrow to run some strings.
Don't even feel like going to work tomorrow so I can play :D
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Ran the very first string with the regulator installed today. Not too bad for the very first time but here it is.
3000psi to 1500psi all shots on regulation
Average 864 fps with 14.3
Min 850fps Max 878
93 shots
3.19%ES
Efficiency 1.84
ES is terrible but I have a feeling my HS adjuster is wiggling around and moving ever so slightly. Iam going to have to tighten it up somehow or lock it down.
A couple interesting things though.
1) I tried maxing out the power with the regulator installed with 21.14 grain pellets. I only could hit 832 fps. That stinks.
2) I measured the plenum from the regulator at around .447" ID and .787" deep along with the valve around 1" deep and .5" ID for a combined plenum of 5.24cc's. Unless there is alot of room between the valve and regulator " I don't think there is" that stinks too.
3) The efficiency of 1.84 at 24 fpe is exactly the same as the table I generated last year for 24 fpe tune using the Dual Wire Spring Pretty cool.
4) I ran out of pellets already.... That stinks.
5) I hope everything settles down and ES gets below 2%.
Not too bad for the first time regulator tune. I find the plenum sizing the most interesting though. 5.24 cc plenum at 24 fpe is less the 1/4 cc per fpe and still a 1.84 efficiency. I don't know what you call it but refill of the plenum between shots was unnoticeable. Shot to shot was less than 5 seconds, just normal chrony shoot testing.
I need to do some more shooting and tuning for now to really try and tune it in. I am going to try and make a new HS adjuster with some kind of indicator on it to show power levels. I love how all you have to do is turn a 1/2 turn down and get 20 fpe and the turn 3/4 turn the other way for 30 fpe. Easiest power adjuster I ever dealt with while keeping the ES stable.
Accuracy ? Only at 10 yards today but 1 holes with those wallyworld chp's
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The plenum indeed sounds too small for the power level you desire.... I would suggest you plot a curve of the velocity vs. the preload to find out what the velocity is on the plateau (ie the maximum), and where the knee is and the beginning of the downslope.... That is the only way to really understand what your gun is capable of, and where to tune it....
Bob
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Plenum does sound too small to me as well but the goal was for 25 fpe and as many shots possible at an efficiency of 1.8 or greater. Looking at the chart using the dual wire spring from 1500psi down to 1110 indicates an additional 31 shots with the original 215cc tank.
Just a guess, it looks like there may be an additional 20 or more shots off regulation indicating the gun is tuned right at the top or just behind the knee. I have to get more pellets to prove it though.
That would put the 22 marauder with stock air tube at around 113 shots from a full charge at 24 to 25 fpe. Haven't seen that before or atleast I have not found a post similar to that yet.
You definitely got me thinking about plenum size and efficiency now. Being at 1/4cc per FPE also sounds interesting too since we had a discussion of 1cc vs 1/2cc a while back.
I got that estimated 1/4 cc plenum from calculating 1500 psi at 24fpe using the volume of the valve,ports, and barrel length plus the volume of air used per shot from the original shot string "off"regulation. I was figuring that I might be able to calculate an optimal plenum size while predicting the shot count at a given power level.
Interesting enough though, the predicted fpe (your guys "delta p") always seemed to max out to 27 or 28 fpe. I thought it was just a bogus calculation but it's kind of holding true with my max power levels.
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It only takes 1 or 2 shots at each preload setting to determine the plateau, knee, and downslope.... You can determine the entire curve on much less than one fill....
Bob
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The knee,
1/4 turn HS adjustments using 14.3 grain chp's. I know you write about tuning to the knee. Sometimes it's hard for me to grasp things so what does it mean besides max power at 28fpe using 14.3's and a little over 30 fpe with 21.14's?
I used a weird different method. I hate fishing in the same pond as everyone else.
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Other than the slight "notch" in the curve at 1.5 turns HS setting, which makes it a bit hard to decipher, the "plateau" is evident at 1.75 turns and above, at ~935 fps.... no amount of added preload will produce a significant increase in velocity, but it will burn up air in a hurry.... Once below 1 turn, (below 880 fps) you are on the "downslope" of the curve, and the efficiency will increase dramatically the lower you go in velocity.... In between (at 1.25-1.5 turns) is the "knee" of the curve, where the velocity starts to decrease, and simultaneously the efficiency increases.... Somewhere on that part of the curve will be your best balance between power and efficiency.... If you compare 1.25 turns with, say 2.5 turns, you will notice only a 3% percent difference in velocity (912 vs 939), but it could easily use twice the air per shot at 2.5 turns....
If you tune on the downslope, in a regulated PCP, when the tank pressure drops below the setpoint, the velocity will initially INCREASE.... and the further you are down that slope, the more noticeable that will be.... However, your efficiency will be great, because you are using tiny sips of air at a pressure higher than you need to get that velocity with that gun.... It's like shooting an unregulated PCP tuned to peak at 2000 psi at 2500 psi.... quiet and efficient.... If you tune on the plateau, you are wasting air, pure and simple.... the gun will be loud, and you need to reduce the preload.... and when you drop below the setpoint the velocity tanks immediately....
On the knee of the curve, where the velocity just starts to drop below the plateau velocity, it's like shooting an unregulated PCP very close to the peak of the velocity curve.... If you use the lower part of the knee (at 1.25 turns on your graph), it is like shooting an unregulated PCP that peaks at 1300 psi at just over that, say 1400.... Since you are on the high pressure side of the peak velocity, the gun will be quite efficient.... When the tank pressure drops below the setpoint of the regulator, the velocity will increase slightly (just as it would in an unregulated PCP) as the velocity peaks and then start to slowly decline.... This can extend the shot string at least 10% below the setpoint before you notice any real drop in velocity.... This adds quite a few shots to the usable string.... THAT is where I like to tune my regulated PCPs, and where you will find good tuners like Motorhead want to operate as well.... You also tend to get the lowest ES, because you are operating at, and just either side of, the peak velocity.... ie right in the "sweet spot" for a PCP.... Using this tune, and a 1400 psi setpoint, you should be able to shoot down to 1200 psi before refilling and not even notice the velocity change....
Now that you have determined this curve, you can use it to decide if you need to change the setpoint.... If you want a velocity around 880-910 fps, leave it alone.... If you want more power, you need to raise the setpoint.... If, on the other hand, you want to tune for, say, 800 fps, you can reduce the setpoint.... Any time you change the setpoint.... or even make a large change in pellet weight (eg. 14-21 gr.), you need to determine the position of the new "knee", because it will change.... Higher pressures (or heavier pellets) will move the knee to greater hammer spring preloads.... and vice versa....
HTHs....
Bob
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So in a nut shell,
Predictions I made using my spread sheet was very similar to looking at the knee and the way you tune a regulated gun. Except that, when setting up a regulated "in tube regulator" your not getting what you get "it is what it is". Your actually predicting what you should get if you choose to regulate and you have the capabilities to achieve a goal or desired effect.
Big difference in my eyes for any tuner. Which I am not and never will be because I am difficult.
Well atleast the way I see it. I am so darn happy things worked out.
So did I do good or what on the very first time doing a regulated conversion? Your opinion really does mean something to me.
Thanks Bob.
So I did a good job for the first time out or what? Give me a pat would ya.
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So if I understand things correctly, with the 14.3 gr. at 1 turn out, you got that string in post # 27, as 860ish fps?..... That then corresponds to just at the start of the downslope on the above chart?.... If so, then that is just about where you want to be.... great job !!!
Bob
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Shorty,
It would be pretty good bet your ES figures being wider than you were hoping is PELLET related.
Crosman pellets vary enough in head & skirt size / weight that even shot in a well tuned know low ES rifle with do the same thing.
At that weight @ ... some JSB RS 13.4 or Exact 15.9's shot with no other changes to rifle would be more telling to ES fluctuation your seeing and not knowing the origins to why.
JMO,
Scott
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Thanks Bob. It sure does mean alot.
Scott,
Thanks for the info on the CHP's from wallyworld. They are pretty inconsistent with weight. I have been waiting for you to post and give some insight to my expedition since you are known as one of the best regulator tuners on GTA with the marauder.
I think the biggest problem is with my HS adjuster. It's extremely loose and moves very easily. Gonna try and fix that this weekend with a brass adjuster with gauge marks for power levels.
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Yup, wiggly parts, dragging springs on guides, hammer & tube drag inconsistencies Show there UGLY head making an otherwise great tune look worse than it actually is.
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Shorty,
A couple of questions if you would be so kind.
Is the side of the Marauder rifle version of the Huma reg tapped for the standard Marauder pressure gage?
And are you using the pressure gage?
Are you happy with the plenum volume that the reg provides?
Thank you!
Just a side note about adjusting the Huma reg, and you might have already come up with your own solution. I have found the Huma reg to be very accurate and repeatable when adjusting the pressure up or down. At first I was taking the reg in and out of the gun to make the adjustments. Draining all the air is bad enough, but removing the reg is not easy. I ended up just flattening the end of an aluminum rod to make a super long screw driver to reach down inside the tube and and make the adjustment. Works like a charm, BUT, make sure you draw two index marks with a Sharpie on the end of the reg so that you can see how much you have turned it by looking down inside with a flash light. Otherwise you'll loose your adjustment and won't know what you have. Those tiny adjustments won't be noticeable on the Marauder gage.
Excellent work, BTW!
Lloyd-ss
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Sure thing LLoyd,
The regulator is tapped for the standard pressure gauge.
I am using a 4ksi pressure aftermarket pressure gauge (stock one crapped out a long time ago).
Not so happy with the plenum (right now).
I am not too sure of what's going on with the shot to shot consistency.
I think there is something more about the plenum sizing in regards not only to power but more importantly (too me right now) shot to shot consistency. All the reading I have done on everyone Else's reg set ups are typically always below 3% big plenums. Been thinking a lot about how the regulator works " in my head" and everything in my mind is pointing to inconsistent lift during the droop on the regulator ( I think it's called droop ). Don't think it is a dwell issue at this time due to the efficiency numbers.
I know it's not the engine (spring and hammer) being inconsistent because every time I come off regulation, the consistency comes back. The only thing that makes sense to me is that the inconsistent droop from the regulator caused by the Static COF (or when the pellet starts moving at different rates due to what ever ).
I just don't know what the problem is right now, although Npunk42 is running the same Huma regulator in his 22 and is observing the same inconsistencies. His reg is set at 2000psi, mine at 1500psi. My porting is .168" and his is stock. He is running an SSG and I am running my dual wire spring. Still, with all the difference in the porting, reg setting and power plant only leaves the plenum or just a plain ole crappy reg. I don't think it's the regulator. It better not be for $130 bucks.
The regulator appears to be consistent when firing and looking at the gauge. Hard to tell if it's perfect but appears to drop and go back to it's original position every time.
I do notice a tone change when a high fps or low fps is fired though. More so on the low fps sound. Don't know what it means yet.
I know it may sound stupid to some, but I am going to try a hammer stop again against the valve body to control lift more precision or atleast give more control to it.
Anyway,
Thanks for commenting in the post and I too agree that adjusting the regulator was straight forward and accurate. I have not played with the repeatability yet.
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Looking forward to the updates . Good luck convincing the wife .Thanks for sharing your data
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The idea of a hammer stop in a regulated gun makes some sense.... FX are using one in the Impact.... Unregulated PCPs, not so much.... unless you want a Korean Cliff shot string....
Bob
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Shorty,
I have 2 Humas in the .750 O.D. that fit the P-Rod and Discovery and both are very consistent.
Here is the "best" string that I got from a P-Rod, with the reg set at about 1740psi, a 10.8cc plenum, and a 57cc main reservoir. Fill pressure was about 3100-3200.
25 shots CPs in the tin 14.5 gn
752
743
751
747
747
746
744
746
753
747
747
745
749
745
753
743
750
747
750
751
747
743
743
745
747
25 shots, extreme spread of 9 fps (1.2%)
It took a lot of work on the hammer and spring and spring guide and getting everything just right. I was not using an SSG. And again, this was my most consistent string, but the others were pretty good with an occasional flyer that I would attribute to the pellets.
The Huma regs are very straightforward on the inside (I couldn't stop myself, I HAD to look and see ;D ). The movement of the piston in the reg is only a few thou, so there isn't much happening in there. If the inconsistency is indeed the Huma, maybe it is a speck of trash or something in there, but I would be surprised. The main outlet of the adjustable base looks to be only about .020" dia, and its entrance is protected by a small set screw so that the air has to filter in through the threads. I was VERY impressed with the workmanship of the Huma.
Another thought might be to drain the air and then set it several 100 pounds heavier and check the consistency. Then Drain it again and try it several 100 pounds lighter than your original setting. It might help it settle in. You say that the gun gets consistent after it comes off the reg, so maybe try that low pressure setting and see what happens. Maybe your set-up just behaves better at low pressure.
And, as a very last resort, and only if you love doing this sort of thing......you can always take it apart and check it for that tiny speck of something. Don't clean the lube off of the internal parts though and do it in a very clean area. Also, note the height of the adjuster sticking out of the body so that you won't get it back together and not know how far to screw in the adjuster. :-[
Lloyd-ss
(http://i226.photobucket.com/albums/dd79/loyd500/Huma%20Reg/HumaReg_zpsudtq2pvb.jpg) (http://s226.photobucket.com/user/loyd500/media/Huma%20Reg/HumaReg_zpsudtq2pvb.jpg.html)
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Thanks for the information and ideas. Just like always, if it was that easy everyone would be doing it. Great string on that Prod.
You better believe I wanted to pull that regulator apart and see how it ticks. Maybe soon.
Anywho, the hammer stop did not work. I turned one down out of PVC on the lathe and even though it fit and functioned ;D it did not work as expected. No go on that one.
I then removed the hammer stop and got out a 1/8" concrete bit and drilled a couple holes in the face of the hammer to allow any compressed air from the hammer face to valve face escape a little better.
I"ll have to wait until tomorrow to test out the hammer holes. The lighting in my garage gives me more errors than fps readings plus I can hear my wife yelling from the bedroom to stop shooting in the garage.
I'll get there sooner or later.
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...................................
plus I can hear my wife yelling from the bedroom to stop shooting in the garage.
.........
Ha, ha, I think we all know that one. I always warn my wife ahead of time. Then afterwards, I get, "Didn't even wake the cat," or, "Whatever that last one was, you probably shouldn't shoot it this late at night anymore."
Do you have florescents in your garage? They will make a chrony "see things", LOL.
Good luck on the mods.
Lloyd
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Just got home from work, said hello to the family, and fed the dogs. Charged the gun to 2000 psi and ran a string off using these BS new pellets from crossman called piranha (wallyworld was out of chp's). Same pellets I used for the 24 fpe tune at 3.19% ES. These pellets group terrible compared to the chp's (anything besides one hole at 10 yards is no longer acceptable) >:(
Hammer holes appear to be working. No loss of efficiency "or increase" but a definite DECREASE in ES. Looks like that entrapped air when the hammer comes home affects the free flight of the hammer of the short stiff spring when running negative preload. :D
I have only run one string so far but it made me happier. I got to tell Npunk42 to give it a try. Well, maybe, let me run a couple more strings to ring it out to say if it really is an improvement.
Efficiency still over 1.8 and ES under 3%. I am really shooting for that less than 2 % mark and I have a feeling when some new pellets come in from PA we are going to see it.
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Good deal! Headed in the right direction!
Lloyd
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Any Updates??
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No more updates on the gun. Haven't did anything else with it besides shoot paper and peach robbers.
End result with 3000psi charge and reg set at 1550:
21.14 grain, 60 to 65 shots on regulation (30 FPE).
14.66 grain , 90 to 93 shots on regulation with an additional 20 to 30 off reg to 1000 to 1100psi (25FPE).
14.66 grain , 110 shots on regulation (20 FPE).
I don't know what to do with it anymore. Tuning now from 20 fpe to 30 fpe is just a hammer spring adjustment. It's a little strange now because I used to change tunes, pull the gun apart, do this, do that and now I rarely shoot it.
Finally got time to punch paper at 50 yards over the weekend and was able to shot quarter sized groups. Didn't have to worry about any vertical stringing.
I am kind of glad it's done but, it's pretty boring now. It just does what it supposed to now. Fill with air, aim, hit target. Over and over and over again. The biggest thing I like about it is that I rarely charge the gun anymore and for some reason, there's always air in there to blast a few off.