The limiting factor

[LayeredOgre]

As an engineering student its so cool seeing the complexity in airguns, especially what is to me a doing more with less feeling. I’m not an expert in fluid dynamics, physics, ballistics, or anything like that but I see the difference in working pressures between airguns and powder burners as the most obvious cause for the disparity in terms of power and shot count, I mean we’re talking like 10x higher pressures with powder burners! So, why do we only see airguns with working pressures of 3600-4500psi? Is it a materials thing? Laws/regulations on air cylinders? Just that these pressures are what modern compressors can achieve? Or are current pressures already maxed out by Bernoulli’s Law? I feel like higher working pressures are an obvious or at least desireable next step in airgun tech- more power, more air to reg down for more shots.

Would love to hear from the experts out there!

 

[AirNGasman]

Yes, that's what it is.

But also the fact that airguns (on the whole) are extremely undependable. I'd speculate exponential increases in pressure would similarly decrease dependability, while similarly increase complexity(s), manufacturing challenges, and expense... EXPONENTIALLY.

FYI- the most dependable airguns are the simplest airguns.

"Simplicity is the hallmark of good design".

.

 

[JDR]

Yes, that's what it is.

But also the fact that airguns (on the whole) are extremely undependable. I'd speculate exponential increases in pressure would similarly decrease dependability, while similarly increase complexity(s), manufacturing challenges, and expense... EXPONENTIALLY.

FYI- the most dependable airguns are the simplest airguns.

"Simplicity is the hallmark of good design".

.

Safety concerns would increase greatly. Gotta think the dependability would also decrease on compressors with higher pressures.

 

[Scotchmo]

Not sure about “maxed out by Bernoulli’s Law”, but we do work under Boyle’s Law which is still just an approximation at the relatively low pressures that airguns use, where air behaves much like an ideal gas. But once we get much above 3000psi, air becomes less “ideal”. So we are close to “maxed out” with Boyle’s Law.

Are you contemplating use of 6000psi? 10,000psi? Air is way past being an ideal gas at those pressures. For an accurate assessment at those pressures, Van der Waals equation is used (or data from actual measurements). The pressure now rises fast without packing much more air. So there is much less energy available than predicted by Boyle’s Law. And you still have the requirement for proportionally thicker/stronger air tanks in the airgun. So a lot of extra weight, with very little benefit. Shot count will suffer greatly. You can use the higher pressures, but be aware of the drawbacks. 4500psi is kind of a standard currently, so I’d keep the pressure at 4500psi and use a bigger air tank and longer barrel.

Regardless of which way you go, there is still the fact that room temperature air is very dense, so it will not be able to accelerate as fast as the gases in a firearm, regardless of pressure.

 

[Treefrog]

I don't disagree with any of the above, but I firmly believe Murphy's Law plays a large part in all this as well.

Having seen a man manage to cram an 8mm Mauser cartridge into a 7mm Mauser rifle and then fire it, I can't help but think that human stupidity plays a part as well. (The stock shattered, but the action held. The bolt never opened again.)

Cheers,

J~

 

[Vana2]

Technical stuff is interesting. Having worked in an engineering environment my whole career playing "what if" in the pursuit of some ultimate goal was always fun but can easily get out of hand.

(Ever watched the BBQ lighting contests?

)

Yeah, you could go for higher pressures. Personally, if I need that kinda power I just use a powder-burner.

Most of my PCPs are 30ish fpe and I'm happy with that.

Cheers!

 

[boscoebrea]

You get passed a certain point and the danger becomes too great to overcome.Also you are talking two different power outputs.The end results are two different ways to achieve the same results within reason. It is a different ballgame. People shoot Air Guns because they choice to and become skillful at using what power the air gun has to achieve the results they want with that type of power plant.. So it is more a matter of Skill .Another thing is if more power is needed then it is easy enough to use a powder burner,Right?

 

[Stubbers]

There is a company working on higher pressures (480 bar / 7000 psi) called AEA.

They mentioned in a video that, they could not release the gun/compressor in the United States due to DOT regulatory reasons as they were still trying to get passed them, while in other jurisdictions they have gotten approval. Hope that helps answer your question some.

-Matt

 

[3Crows]

The compressors we have now struggle to get 4500 psi air and most dive shops and other places usually have no need for beyond 5000 psi. And there is this thing called a .22 Long Rifle cartridge and it's two big brothers .22 Winchester Magnum and .17 Hornady Magnum!. And any of them can wipe the floor with air rifles with the little .22LR making upwards of 150 fpe and with good accuracy. For me, air rifles already fill that very narrow niche that overlaps into the .22LR territory and beyond that, just hand me my .45-70 Government, the only government a man can trust .

If there was a reliable compressor for under $1500 that could produce 6000 psi air, all I could want or need, then sure, give me a lightweight rifle that can duplicate .22 Magnum performance or near enough, probably a .35 caliber. Sure, I might go for it. But not if FX makes it as it would always leak. Oh, and whatever it is, it must hold zero for real world knocks and bumps. The point being before going into 6000 psi rifles there are many areas of accuracy, durability and real world viability to address not to mention these air rifles are largely pigs. And I am body shamming them with no apology.

 

[Scotchmo]

If I own the 7000psi airgun, and the 7000psi compressor, I could fill it myself. So why is a DOT stamp needed?

Is DOT approval required to sell an airgun? Maybe the DOT approval is really a CYA requirement.

Doesn’t Huben sell a 6000psi airgun?

 

[Stubbers]

If I own the 7000psi airgun, and the 7000psi compressor, I could fill it myself. So why is a DOT stamp needed?

Is DOT approval required to sell an airgun? Maybe the DOT approval is really a CYA requirement.

Doesn’t Huben sell a 6000psi airgun?

Don't shoot the messenger, just forwarding the information from the video, however I cannot verify if 4,500 psi fill limits on DOT tanks is a DOT regulation or what.

Could have been a language barrier with something lost in translation for all I know!
I believe the huben K1 is max 5000 psi fill, but of course their tubes aren't held to DOT requirements.

But there is a 7,000 psi compressor on the market so, take with that what you will.

AEA Airguns 480 BAR/7000 PSI Air Compressor

Introducing the AEA PCP Air Compressor, engineered to deliver unmatched pressure capacity for your airgun needs. Certified for use up to an impressive 450 BAR (7500 PSI), this compressor is the best option for PCP airguns and sets a new standard in high-pressure air-filling equipment. Many guns...

www.hubenairguns.shop

CE certified, however I don't believe they have obtained DOT certifications yet. And it's 7,500 limit is software limited, but it can push 620 bar/9000 psi!

-Matt

 

[AirNGasman]

there is this thing called a .22 Long Rifle cartridge and it's two big brothers .22 Winchester Magnum and .17 Hornady Magnum!. And any of them can wipe the floor with air rifles

Great point, 3C. But the .17 WSM (Winchester Super Magnum) rimfire wipes the floor of the .22 WMR and .17 HMR.

Even in a pistol the WSM wipes the floor of all other rimfires in rifles. I get an honest 2750 FPS with 20 grain ammo, and honest 1" average five-shot groups at 100. It's also a 200 yard handgun.

 

[AirNGasman]

Ummmm... not to bust anyone's bubble, but the primary ADVANTAGE of airguns is their limited power. Just sayin'.

.

 

[AirNGasman]

So why is a DOT stamp needed?

Is DOT approval required to sell an airgun?

Hey Scott, keep that stuff to yourself; lest the deep state commies spying on us pass another 20,000 new gun control laws... this time targeting law-abiding airgunners. If that happens, only outlaws will own 7.000 PSI airguns and compressors; and a booming black market for them will develop...

Overnight.

.

 

[Stubbers]

Ummmm... not to bust anyone's bubble, but the primary ADVANTAGE of airguns is their limited power. Just sayin'.

.

Subjectively.

Power limit depends on jurisdiction and the individual, such as the UK and their 12 fpe limit. Commercially there are, as days go on, more and more readily available airguns that make gobs of power with promises of great performance shooting slugs.

Could be for some its their rate of energy decay ballistically (primarily with pellets) which makes them more friendly for certain environments.

For others the primary advantage is their softness in both recoil and muzzle report.

To each their own, as they say.

-Matt

 

[LayeredOgre]

Great ideas all! I’ve got way more Wikipedia articles to read over…

 

[AirNGasman]

For others the primary advantage is their softness in both recoil

Obviously not including Spoingers.

.

 

[Scotchmo]

Great ideas all! I’ve got way more Wikipedia articles to read over…

Here’s a couple more that might be pertinent:

Phase transition - Wikipedia

en.m.wikipedia.org

Supercritical fluid - Wikipedia

en.m.wikipedia.org

Once the gas behaves more like a liquid, there might be no benefit to going higher in pressure. That’s why CO2,guns have a practical limit in the 1000psi range. Higher pressures will just stress the pressure vessel without storing any more gas, or any more energy. That’s also why they do stress (hydro) tests with water rather than gas pressure tests. A hydro tests stresses the vessel without risking an explosion.

Air is a mixture of different gases (mostly nitrogen). I don’t know that much about air in the supercritical region. But I’d bet there is a limit on pressure before it behaves like a liquid.

 

[Stubbers]

Here’s a couple more that might be pertinent:

Phase transition - Wikipedia

en.m.wikipedia.org

Supercritical fluid - Wikipedia

en.m.wikipedia.org

Once the gas behaves more like a liquid, there might be no benefit to going higher in pressure. That’s why CO2,guns have a practical limit in the 1000psi range. Higher pressures will just stress the pressure vessel without storing any more gas, or any more energy. That’s also why they do stress (hydro) tests with water rather than gas pressure tests. A hydro tests stresses the vessel without risking an explosion.

Air is a mixture of different gases (mostly nitrogen). I don’t know that much about air in the supercritical region. But I’d bet there is a limit on pressure before it behaves like a liquid.

From https://www.researchgate.net/publication/326191398_Internal_Ballistics_of_PCP_Airguns

OP, if you wanna hurt your brain, give this article a read. Lol

 

[cavedweller]

As an engineering student its so cool seeing the complexity in airguns, especially what is to me a doing more with less feeling. I’m not an expert in fluid dynamics, physics, ballistics, or anything like that but I see the difference in working pressures between airguns and powder burners as the most obvious cause for the disparity in terms of power and shot count, I mean we’re talking like 10x higher pressures with powder burners! So, why do we only see airguns with working pressures of 3600-4500psi? Is it a materials thing? Laws/regulations on air cylinders? Just that these pressures are what modern compressors can achieve? Or are current pressures already maxed out by Bernoulli’s Law? I feel like higher working pressures are an obvious or at least desireable next step in airgun tech- more power, more air to reg down for more shots.

Would love to hear from the experts out there!

Law of diminishing returns - more air pressure more engineering, more expensive materials and more liability for the manufacturers and consumers. Then there’s more noise