Light gas guns

[Strykervet]

Who has any experience with these? Anyone interested in making one? I have the mathematics and physics, need an engineer that is well versed in materials, and a good machine shop.

I have the prototype drawing for the simple experiment, but my idea is to include feeding mechanisms and valves, all timed by a "smart chassis" or digital exoframe if you will. It will require a new way of looking at firearms.

Anyway, I think I can make this work. It is complicated, you have three feeding devices, a powder charge, and hydrogen gas, all of which have to be timed to a cycle of operation. Because of lack of reciprocal force, electronic mechanical systems will be required to operate the cycles.

While I have most of this figured out, my problems are in sealing and just how to manufacture the feeding mechanisms.

But if this works, it should be many times more powerful than the average rifle. I thought a good use for it up front would be as a kinetic kill weapon on a Stryker. Then it could be minimized to a shoulder fired system.

Thus changing firearms history.

Any constructive criticism is welcome, any ideas or comments as to how to overcome sealing problems with pressurized light gas, how to keep it noble (ie, no O2 mixing) etc.

This shouldn't viewed as a "never happen" or "pipe dream" thread. This is a legitimate endeavour that, were I better funded, would be at the range this weekend. They do work, but so far have only been used as test mules by NASA. They are using it for a different reason though. They want to test meteor velocities, I want to see what meteor velocity projectiles do to various targets.

Any engineers out there with suggestions? My primary problems are 1. sealing and 2. feeding (then sealing). These are mechanical problems. You'll understand what I mean when you see basic light gun prototypes.

 

[chhodge69]

very cool - I just read the wiki page on this and it sounds like the ultimate spud gun

http://en.wikipedia.org/wiki/Light_gas_gun

good luck!

 

[Jim Watson]

Just in the interest of staying in one piece for the next generation of development, I think I'd do my proof of concept work with a real inert gas like nitrogen or argon and take the hit on velocity from the higher m.w.

No reciprocal force? Newton still works here and if you drive a worthwhile projectile at meteoric velocity, there will be substantial reciprocal force; recoil or gas pressure. Electromechanical feed a la Vulcan gun might be easier to build, though.

 

[Kliegl]

You may have the "mathematics and physics" but you yourself need the engineering before you do anything. Equally importantly, you'll need the money. There's a reason revolutionary technology is made by giant companies these days; it's expensive to do.

Up front, the engineering problems I can think of using this technology as a personnel weapon is portability and more than one shot capacity.

May I recommend you pursue a rail gun instead?

 

[Sam Cade]

Light gas guns of this type arent really suitable as weapons of any kind and are a mature technology. If it was feasible to weaponize, it would have been done.
Its great for accelerating tiny payloads really fast but in the end you are limited by newton and how energetic your propellent is.

In order to generate the same amount on power as say a 5.56, you are going to have to deal with the same amount of recoil regardless of how the projectile gets up to speed.


...anything NASA describes as "temperamental" probably is.
http://ares.jsc.nasa.gov/Education/websites/craters/lgg.htm

 

[Sam Cade]

They do work, but so far have only been used as test mules by NASA.

A quick google will show that that isn't true. They are pretty common. Check the attached file for a common use.


Remember we are talking 1960s technology here. I did a Journal search and got hits on "light gas gun" going back to 1961.

...even the Australians build em.....

http://dspace.dsto.defence.gov.au/dspace/bitstream/1947/4048/1/DSTO-TR-1092 PR.pdf

The use of hydrogen as a driver gas was also
investigated and it was found that, for this configuration, performance increases were marginal and did not justify the increase in risk to operators.

Neat.

 

[Clifford]

Neat! I agree that if one could make a vehicle mounted and shoulder fired version of these weapons the military would surely show interest. A weapon like that would make a great anti-tank weapon.

I do have a question thou. What happens to the gases in the first stage of combustion (the gunpowder charge)? Where and at what pressure do they vent? I would imagine a shoulder fired arm would be very heavy if built to handle the pressures involved.

 

[brickeyee]

Light gas guns generate tremendous pressures in the driving gas.

Think of it as the ultimate sabot system.

A large piston is accelerated and used to compress a gas that is then used to drive the projectile.

There use is mostly confined to hyper velocity research (think satellite impact issues).

Scaling up to a large enough projectile to do damage runs the pressures above most materials.

Large naval guns dealt with material limits by using heat shrunk on shells around the breech end of the barrel, creating huge compression forces on the inner layers.

The barrel does not see any loading from the chamber pressure until the compressive loading is overcome.

Gas guns have very thick wall sections around the projectile drive portion to contain the pressure.

 

[tyeo098]

Maybe not for a combat rifle, but for a long range thing, it might be feasible.

you just need to contain the charge, piston, gas, and projectile in one shell, that gets loaded into the breach. (And you thought 30-06 was long...)

Might work with a .17cal projectile, smaller the better

 

[Sam Cade]

I do have a question thou. What happens to the gases in the first stage of combustion (the gunpowder charge)?

It would have to be bled off or else you have a bomb.

Looking at pictures of small LGGs installed at universities they all seem to have piping running away from that section.

 

[Sam Cade]

Maybe not for a combat rifle, but for a long range thing, it might be feasible.

Its pretty much just a Lab tool. DARPA spent untold millions trying to find a military use for the technology (space launch, weapons etc) before giving up on it.


An LGG is always going to be limited by the power of its chemical propellent.

 

[JustinJ]

Most bullet velocities are limited by the amount of pressure the gun can actually endure instead of by the amount of pressure that can be generated so a shoulder fired weapon of this type would be far too heavy. Not to mention, i don't think mosts soldiers would enjoy carrying around a tank of highly explosive hydrogen gas.

 

[Sam Cade]

Most bullet velocities are limited by the amount of pressure the gun can actually endure instead of by the amount of pressure that can be generated so a shoulder fired weapon of this type would be far too heavy.

Imagine a weaponized LGG of say, 5mm bore being powered by something like a 40mm bofors shell throwing a 2 lb piston at around 2500 feet a second.
Imagine what a graph of the recoil would look like. Weapon recoils rearward as the piston accelerates then WHAM!!! Its pulled forward as the piston impacts at the end of its run.... how fast was that piston going again?


Makes me wish I had access to The International Journal of Impact Engineering since they blast stuff with LGGs pretty regularly in its pages.

Not to mention, i don't think mosts soldiers would enjoy carrying around a tank of highly explosive hydrogen gas.

You don't need hydrogen, just a light gas.

 

[mortablunt]

I've read about them and I have considered getting them at a few points. Interestingly, the Czech Government actually recommends their use to citizens as a defense against crime .

 

[Sam Cade]

I've read about them and I have considered getting them at a few points. Interestingly, the Czech Government actually recommends their use to citizens as a defense against crime .

...I think you are confusing your gas guns here.

 

[mortablunt]

http://en.wikipedia.org/wiki/Gun_politics_in_the_Czech_Republic
http://en.wikipedia.org/wiki/Gas_pistol

That's what they're talking about.

 

[Sam Cade]

http://en.wikipedia.org/wiki/Gun_politics_in_the_Czech_Republic
http://en.wikipedia.org/wiki/Gas_pistol

That's what they're talking about.

..but the thread is about these:

http://www.physicsapp.com/nwc_lgg.jpg

 

[mortablunt]

Oops, sorry.

 

[Strykervet]

Okay, I know there are engineering difficulties. I don't need anyone to tell me how hard it is. I understand enough about engineering to get it rolling, and I understand I would need to make a small single shot one first. A test mule. Making it into a semi auto weapon would be nice, but I understand that would be expensive and difficult. I just had the idea for it, but I know that the reality would be a single shot if I were to be able to cobble one together.

I simply want to tackle the physics problem of it. If an accurate light gas gun projectile can be made that can be fired from the shoulder, that would be cool, period. A single shot rifle, if that were as far as it went, would still be cool. May be the ultimate varmint rifle. Now if that could be made, then of course it could be automated.

I just wondered if any tinkerers on here have tried it. The single shot test mule I mean. Maybe the potato gun crowd?

When I get enough shop equipment to try to make a test setup, perhaps I will. I was thinking maybe a heavy cylinder with some kind of breech block with a piston inside and a barrel blank threaded into the other end with a blow out valve in between. The projectile would be loaded into the barrel before threading it on, the charge installed, and then the cylinder purged and filled with light gas.

Of course it would need to be tested from a safe distance...

Helium CAN work, but it doesn't work as well as hydrogen, just like in airships. And for a similar reason.

Light gas guns are not limited by the chemical propellant... That is the whole point of using them.

Rail guns are much more expensive, less realistic as far as a shoulder fired one goes, and much more in depth in regards to the engineering feats. It is also a better project for one more electrically inclined, I am more mechanically inclined. There is a guy that has some stuff online that is pretty good with home made rail guns, coil guns, and the such, but they aren't for me.

 

[Sam Cade]

Light gas guns are not limited by the chemical propellant...

Sure they are. Its the only source of energy in the system.

 

[Kliegl]

I thought we put this one to bed. Sorry to be harsh man, but, unless you got MAD BANK it isn't happening. This isn't your daddy's shotgun, Private Cowboy. You claim to be mechanically inclined, but you show that you aren't mechanically educated enough to understand that the startup costs are way out of the range of a private tinkerer.

If you can't be dissuaded, please at least be careful. I doubt you'll be able to make a working prototype, but I don't doubt for a second that you could blow yourself up. You're one of those guys we call "with just enough knowledge to be dangerous."

 

[Maple_City_Woodsman]

http://en.wikipedia.org/wiki/Gun_pol...Czech_Republic
http://en.wikipedia.org/wiki/Gas_pistol

That's what they're talking about.

HAHA! My dad has one of those things, from the early 60's. It is a small .22 caliber revolver that will shoot starter pistol blanks, tear gas rounds, and perhaps some kind of rubber pellet if I recall correctly. The brass casing is very short, and the chambers are cut short to keep it from accepting any serious ammunition.

He purchased it as a young boy with his paper route money, to scare off aggressive dogs. It's both laughable and sad to think that European adults rely on tinker toys like that for serious self defense.

 

[Strykervet]

HAHA! My dad has one of those things, from the early 60's. It is a small .22 caliber revolver that will shoot starter pistol blanks, tear gas rounds, and perhaps some kind of rubber pellet if I recall correctly. The brass casing is very short, and the chambers are cut short to keep it from accepting any serious ammunition.

He purchased it as a young boy with his paper route money, to scare off aggressive dogs. It's both laughable and sad to think that European adults rely on tinker toys like that for serious self defense.

No, that's not it.

 

[Sam Cade]

If anyone is interested there is a regular "International Symposium on Ballistics" held in which the best minds in the field come together and present bleeding edge research for their peers.

It is always interesting, often surprising and sometimes a little scary.
http://www.ballistics.org/index.php


...cool stuff like this (see attachment)

 

[Strykervet]

I thought we put this one to bed. Sorry to be harsh man, but, unless you got MAD BANK it isn't happening. This isn't your daddy's shotgun, Private Cowboy. You claim to be mechanically inclined, but you show that you aren't mechanically educated enough to understand that the startup costs are way out of the range of a private tinkerer.

If you can't be dissuaded, please at least be careful. I doubt you'll be able to make a working prototype, but I don't doubt for a second that you could blow yourself up. You're one of those guys we call "with just enough knowledge to be dangerous."

I see you have nothing to add. Please go elsewhere.