preloaded pneumatic cartridge

[jackssmirkingrevenge]

Wait, so if you pull back on it, how are you going to make a gun that will actually use them? Some sort of pneumatic piston that pushes them forward or something?

A spring loaded hammer, something like this:

[jor2daje]

just throwing a reply in here to say its looking great jsr and to make sure I get email notifications haha

[LovableAirGuns]

Very keen to see thus finshed, its looking good.

[jackssmirkingrevenge]

Just a niggling thought, converting a 7.62/308 cartridge to pneumatic using a 7mm OD tube insert:

[jhalek90]

you last videos look like a much more complex version of what i did over a year ago.

Take a female quick disconnect, and remove all the internals except for the rubber washer, and the bearings.... it will hold a 7/16'' steel ball air tight.

I have taken that design up to 350 psi... the only problem i had, was pulling the sleeve back at higher pressure. Your idea of using a hammer to move the sleeve is excellent. I now want to revisit my design.

Thanks!

[LeMaudit]

Did you got some inspiration from here ?

[jackssmirkingrevenge]

Did you got some inspiration from here ?

Totally

Doing some prototyping in the meantime, another pop at the hybrid cartridge and a decent fill rig.

[jackssmirkingrevenge]

Something which came out of this visit, I got to look at a Korean air cartridge rifle from the 1950s. They work on the same principle as the Saxby Palmer air carts, basically a hammer valve where the hammer smacks the bottom of the cartridge pushing it against the valve.

This is the English variation:





This is the one I saw yesterday, bigger internal volume and apparently in the 50 ft/lbs range...

[iknowmy3tables]

I really like the idea of a large hammer valve that also acts as the check valve for filling, however I've never seen any of us use a fill valve that wasn't a quick connect or a Schrader

[jackssmirkingrevenge]

I really like the idea of a large hammer valve that also acts as the check valve for filling, however I've never seen any of us use a fill valve that wasn't a quick connect or a Schrader

Looks like you missed this

[jackssmirkingrevenge]

Revisiting this idea in my head, looks to me that a variation of the Saxby Palmer with a balanced spool would make a lot of sense. There's still the o-ring friction but nothing like the force of keeping a poppet type valve closed, which would mean less force to open it, so the bolt spring might be weak enough to allow for shell ejection and therefore potentially semi/full auto fire...



edit: alternative configuration with greater internal volume:

[wyz2285]

You would have to reverse the fill plug on the last design.

[jackssmirkingrevenge]

Oh no it's one of these:



Wonderful things, if only I had discovered them earlier.

[jackssmirkingrevenge]

Some more idle musings, combining the locked projectile "valveless" design with a balanced spool. The problem with the latter is that even in small calibers, beyond a certain pressure it becomes far too difficult to actuate when made like this, however if you incorporate in a system where the friction is being balanced out in the opposite direction it should make it relatively easy to fire without too much effort.

valvelessbalabced.png (12.6 KiB) Viewed 5655 times

[jackssmirkingrevenge]

Something interesting on this subject, there is a company called Inovairtech making Magnum Air Cartridges made for larger bores (0.257"-0.40") with some impressive performance characteristics, exceeding 100 ft lbs of energy for most projectiles.

There is nothing particularly innovative about the cartridge mechanism, it's a balanced spool that is hollow, hammering the base of the spool exposes ports at the rear which allows the air to vent through the hollow spool into the barrel:

[youtube][/youtube]



This is virtually identical to the airsoft APS APM50 cartridges:



The difference is obviously the volume and the pressure, they can take up to 4500 psi.

Another clever feature is the head shaped like a quick connect fitting which allows for rapid filling without the need for a complex fill rig:



Overview of one of their single shot rifles:

[youtube][/youtube]