SpudFiles

Rheinmetall's Fly-K mortar operates on the same spigot mortar principle as much earlier weapons like the PIAThowever it marries the idea with the captive piston principle to provide a relatively quiet shot:



With some imagination I think the idea has potential for spudgun applications, something like this:

Also means more weight to carry if the projectile is taking the gas trap with it.

Depends how quiet you want to be.

Certainly a dam sight quieter than my last musings on hybrid launching which was literally launching an open chamber: http://www.spudfiles.com/forums/hybrid- ... t6559.html

Hotwired wrote:Also means more weight to carry if the projectile is taking the gas trap with it.

Depends how quiet you want to be.

It could be a good project for those with wide open areas to launch over, I certainly don't have the space I would envisage a parachute and camera...

Hotwired wrote:Certainly a damn sight quieter than my last musings on hybrid launching which was literally launching an open chamber

Had you actually built that?

Nope.

But going on differences between a closed chamber and having a hollow chamber directing blast back at you. I'd still stand by it being a lot quieter

Hotwired wrote:But going on differences between a closed chamber and having a hollow chamber directing blast back at you. I'd still stand by it being a lot quieter

Indeed.

The Armbrust also uses the captive piston concept, however this time with two pistons travelling in opposite directions, one firing the projectile while the other fires a plastic countermass of the same weight.

Another interesting "real world" example of the principle, the "Bigot" designed to be fired from a 0.45" pistol:

Came across this prototype, looks like the principle is still being examined for hand-held weaponry:



source video

https://www.ploughshareinnovations.com/ ... mmunition/

edit: more here: https://ndiastorage.blob.core.usgovclou ... t19185.pdf







https://accurate-mag.com/case-telescopi ... l-systems/

I like the system, I did not know it.
I have a kind of "grenade launcher" that works with a rupture disc, but it is not exactly like the drawing. The projectile is simply housed in the firing barrel. It is an ancient weapon that I built, that I adapted for this purpose. The "cartridge" that houses the o'ring and the rupture disk has no ammunition, and I only use the gases generated at 8X, to propel the self-built projectile, which is hollow. I increased the amount of air, because you need more air to decently throw the projectile. It is a plastic container, about 15 ml, with three fins and a hard aluminum tip. It weighs about 10 grams. I have tried to increase the weight by adding a little lead to the nose, but it seems to be a lot for the little base, and sometimes it inflates it. Besides, the roar is deafening and the ammo is damaged when it hits any target. I have left it at 10 grams and I shoot it against a thick fabric where it does not get damaged. One of the most fun weapons to shoot. I'll add some photos this afternoon.

This is. I know it is not the same because the weapon has a firing barrel, but it has something to do with it, I think.

Haha very nice

I increased the amount of air, because you need more air to decently throw the projectile.

That is usually the issue with this type of setup, a lot of dead volume and small surface for the pressure to act on vis a vis the projectile diameter. Still, it looks like it would be fun!

Air at atmospheric pressure within the barrel and projectile appears to act like an elastic. The gases of the combustion chamber compress this air and only then the ammunition survives, and the shot is observed smoother. The air inside the projectile where the force of the compressed air is exerted is about 3.8 cm2. The projectile fits very tightly inside the barrel, so that almost no air can escape.
I have tried placing the projectile 10mm from the rupture disk, and the projectile takes a sharp hit, and appears to fly less. I am burning 10 cm3 of butane and the amount of air in the mixture is about 200 cm3.

Something relevant to the original post, an animation I had made of the Russian 2B25 "silent" mortar that works on a principle similar to the Fly-K

Nice launching system!! The Diesel hammer came to mind. I imagine that it would be impossible due to the weight of the ammunition necessary to achieve the compression necessary to achieve self-ignition of an air-fuel mixture. My inspiring system!

Fun stuff... when I try to design along these lines I end up returning to crossbows though.

That's basically what they are, catapults where the power comes from something other than torsion.