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Pneumatic gun with power regulator vs no power regulator

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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DotzRemperas

New Member
Jul 30, 2020
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Lets just say two same length pneumatic gun with same air presure, the one gun with regulator and the other do not have... Now does is not affect a little bit of the power that will push the piston/shaft of the gun if you set the regulator to open vs the gun with no regulator at all? because for me i think pneumatic gun with no regulator will fire much more stronger than the one with power regulator inside even if you set that regulator to open because once you fired, the air in the other chamber of the tank will pass first through that small hole before it can join the other air of the other chamber which is the air who pushes the piston, in this quick process i don't think that the full force of the air in that second chamber can quickly pass trough that small hole to join the other air to pushed that piston/shaft... What do you think guys?
 
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popgun pete

Well-Known Member
Jul 30, 2008
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It does make a difference, but not a big one, as air flows from the tank into the inner barrel through the lower slot in the inner barrel which is mainly filled by the sear lever and another hole on top of the barrel which itself is not that large. Plus the sear lever occupies the barrel, so there are flow restrictions even in non-regulator block guns. The plastic grip handle interior also covers much of the rear of the inner barrel.
inner barrels.jpg

Releasing valve guns don't have a sear lever sitting inside the inner barrel, so they have better airflow properties.
 
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DotzRemperas

New Member
Jul 30, 2020
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It does make a difference, but not a big one, as air flows from the tank into the inner barrel through the lower slot in the inner barrel which is mainly filled by the sear lever and another hole on top of the barrel which itself is not that large. Plus the sear lever occupies the barrel, so there are flow restrictions even in non-regulator block guns. The plastic grip handle interior also covers much of the rear of the inner barrel.
View attachment 56442

ahh i see,, so you say there is no huge deference also in the hole of the power regulator and the holes in the inner barrel which the air will flow to push that piston? if they are little bit equal holes(the regulator holes and barrel holes) then i agree there will be no big difference ..... Thanks for this answer popgun pete (y)
 
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popgun pete

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Jul 30, 2008
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In the days when pneumatic spearguns all had metal pistons and shock absorber bodies the guns could be made more powerful by improving airflow inside the gun, but I think plastic pistons and shock absorbers put an end to that as they are susceptible to cracking. With the lower mass plastic piston’s introduction the muzzle relief holes were made much larger as the muzzle body suffered lower impacts than with the metal pistons. If the muzzle relief holes were made too big then the metal connecting webs to the muzzle tip may have failed in the past with metal pistons crashing into them. I had older guns start to unscrew the muzzle nose as the pistons hammered them, fortunately you could see the gap and retightened them before the end was blown out of the muzzle. Hence today pneumatic guns are designed to be somewhat self-limiting due to those weaker pistons.
 

Zahar

Well-Known Member
Jun 3, 2014
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Physics decided everything for Us long ago! The speed of the harpoon is 33m per second! Speed of sound = Velocity of air movement = 330 meters per second! A hole even half the section of the barrel does not affect the piston speed if there is no excess oil in the barrel of the rifle! Learn Physics Friends! All valve guns are based on this!
 

Diving Gecko

shooter & shooter
Jun 24, 2008
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Physics decided everything for Us long ago! The speed of the harpoon is 33m per second! Speed of sound = Velocity of air movement = 330 meters per second! A hole even half the section of the barrel does not affect the piston speed if there is no excess oil in the barrel of the rifle! Learn Physics Friends! All valve guns are based on this!

Please quote exactly where you got this from or elaborate somehow.
I have been looking for an answer to this exact question for a very long time and your answer does not align with the anecdotal evidence from the many people who pull out the power regulator and swear they see quite a bit of improvement.

I have long wanted to find a fluid dynamicist and pick his/her brain on this matter as to them, it's probably a fairly easy question to answer but I have yet to bump into one.

Now, if the question is whether you would want a gun with or without PR (Power Regulator) I would say it depends on your hunting grounds and technique. If you are shooting a big gun in blue water, then no need for a PR and I would personally pull it out. But the last few weeks I have shot a friend's Predathor 100 on the reef and even with the PR bulkhead doing a bit of throttling it's still powerful enough for the fish I can run into here. But having the PR is such a nice feature and the kind that you may not think you need before you have it.
E.g. two days ago, I shot seven fish on the reef, four of them was on full power as they didn't come super close but one of them came right up to me and even though there was water behind the fish, I shot it on low power to have the easy reloading when I surfaced. I also shot two red Googleeye fish in some deep caves. These fish are fairly small but very tasty so I sometimes take them if nothing bigger is around. But they like to stand right next to the wall but with the low power feature I had no problem shooting them up close and still not risk bending the shaft or getting it stuck. With a rubber gun, unless I had air left to unhook one rubber, I wouldn't have shot those two fish.
So, in short, for a reef gun, I would say go with the power regulator:)
 
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Zahar

Well-Known Member
Jun 3, 2014
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Please quote exactly where you got this from or elaborate somehow.
I have been looking for an answer to this exact question for a very long time and your answer does not really align with the anecdotal evidence from the many people who pull out the power regulator and swear they see quite a bit of improvement.


Practically I got the conclusions from my valve gun * Pike perch *! Theoretical arguments - from the difference between the speeds of sound and the harpoon and the presence of the inertial mass of the harpoon + water + piston!
деталировка 017.jpg
tn_gallery_3608_545_140966.jpg
 

popgun pete

Well-Known Member
Jul 30, 2008
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Differences may be more apparent at lower start pressures as basically it depends on how long the gas takes to refill the back end of the gun. Low power shots start the piston moving at the gun's cocked pressure and the pressure falls away until it reaches a lower value than the gun's start pressure. Full power shots start at the gun's cocked pressure and the piston moves until it stops at the gun's start pressure. Pneumatic guns that have a series of revolving holes to vary gun power have a very small hole to produce a large power reduction.
 

Diving Gecko

shooter & shooter
Jun 24, 2008
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Physics decided everything for Us long ago! [...]
A hole even half the section of the barrel does not affect the piston speed if there is no excess oil in the barrel of the rifle! [...]

This is exactly the rule of thumb I was hoping an engineer in fluid dynamics would be able to give me. I would have explained/shown the layout of a classic Italian airgun and asked something like:
"How much speed/energy would the piston loose with different sizes of air transfer holes (power regulator)?"
Maybe I would ask for losses at air transfer bore areas of 25%, 50%, 75% of the piston size or if he/she ran it through a simulation software it could probably output many more values fairly easily.
In lieu of this, I have been waiting to get back home and find the time to test this. The plan was to 3D-print a handful of bulkheads with different sizes of bores and then shoot penetration tests and possibly measure the speed, too of each iteration. But it's quite a lot of work as the gun would need to be taken apart for each change of bulkhead.

Now, the bore size is 7mm in traditional Italian airguns (bushing design, not Scubapro/Salvimar gasket version*) which in cross area is just 29% of the piston size and as I mentioned many other spearos say that when they pull their power regulator blocks out, they see an improvement. This suggests that a bore of 29% is still limiting the airflow quite a bit. But how much energy loss we are talking, I don't know.

*As for the Salvimar guns (old Scubapro design) they use a plate with a gasket that seals four oblong holes. If I had to guess, I would say the total cross area would be larger than on the 7mm bushings but I will measure it the next time, I take a Predathor apart.
 
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popgun pete

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Jul 30, 2008
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Please quote exactly where you got this from or elaborate somehow.
I have been looking for an answer to this exact question for a very long time and your answer does not really align with the anecdotal evidence from the many people who pull out the power regulator and swear they see quite a bit of improvement.



Practically I got the conclusions from my valve gun * Pike perch *! Theoretical arguments - from the difference between the speeds of sound and the harpoon and the presence of the inertial mass of the harpoon + water + piston! View attachment 56443 View attachment 56444
This one?
PIKE PERCH GUN.jpg
 

popgun pete

Well-Known Member
Jul 30, 2008
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Some years ago I read an article discussing flow restrictions in pneumatic guns. It indicated that flow restriction via hole diameters was less critical with gas than it was with water, such as in hydropneumatic guns where the spear is propelled out of the gun by a moving column of water. It was on a Russian site, but I cannot remember which one. To obtain power reductions by throttling you only need look at the revolving throttle in the Neptune pneumatic gun from Tula to see how small the holes have to be to produce appreciable reductions of power in the shots. The photo below shows the plastic throttle, it has four positions, safe (no hole) and three holes of varying sizes, but here we can only see two of them. The third hole will probably be a pin hole.
VARIABLE THROTTLE.jpg

regulator R.jpg
 
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popgun pete

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Jul 30, 2008
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The table for the gun shows the effect of the power reducer in the lower rhs.
Neptune table.jpg
 
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