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Panzerabwehrwerfer 600 and the high-low pressure system

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: jackssmirkingrevenge » Thu Aug 16, 2018 3:06 am

A relatively obscure artillery piece that came online in the dying days of the Third Reich was the 8 cm PAW 600:

Image

This weapon used the then novel Hoch-Niederdruck or "high-low pressure" system, where a conventional charge generated high pressures in the breech that was bled into the barrel through a series of ports until it generated enough pressure to shear the pin that was holding the projectile - just under 8000 psi - thereby firing it at considerable velocity, around 1700 feet per second.

Image

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Pneumatic launchers naturally have lower pressures so the high-low system is not really relevant to spudguns, but I think the shear pin mechanism is an interesting alternative to the burst disk, here is one way it could be configured:

Image

It has to be said that it's rather more complex than a burst disk, and indeed the ubiquitous 40mm grenade launcher cartridge that works on the same principle does exactly this, with a copper cup separating the high and low pressure chambers, bursting through the ports when sufficiently high pressure was generated. The shear pin is therefore perhaps not the most practical alternative, especially as it relies on an airtight projectile, but I thought the concept was worth mentioning.

It's effectively a variation of a detent that retains the projectile by friction until there is sufficient pressure to release it:

Image
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: wyz2285 » Fri Aug 17, 2018 12:02 pm

Na with 3D printing burst discs and such are easy to make. problem with these would be slightly higher ammo cost.
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: hectmarr » Fri Aug 17, 2018 5:19 pm

Curious design of weapon :shock:
I think that the disadvantage of using a pin is that it divides the double utility of a rupture disc, sealing and letting escape whatever, projectile or cold or hot air, when it breaks at the firing pressure. The pin only complies with letting the projectile escape, but does not seal. Although it is a valid option in this case.
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: Cthulhu » Fri Aug 17, 2018 6:05 pm

I like this idea, seems a lot less tedious than cutting burst disks. Perhaps by pairing it with the friction O-ring detent you could make a reliable system that doesn't expend an O-ring each shot.
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: mark.f » Mon Aug 27, 2018 9:57 am

I have been interested in the high-low design for what seems like ages now, for reasons which may or may not be relevant to this hobby.

It's what's responsible for being able to launch an almost 2" bore projectile with a conventional powder charge from a light, thin-walled piece of tubing that can "comfortably" be mounted under most rifles.

In other words, very, very relevant to launching things like golfballs or even tennis balls recreationally if you're not of the airhead or Hank Hill persuasion... :D
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: jackssmirkingrevenge » Mon Aug 27, 2018 6:46 pm

mark.f wrote:It's what's responsible for being able to launch an almost 2" bore projectile with a conventional powder charge from a light, thin-walled piece of tubing that can "comfortably" be mounted under most rifles.


Those damn Ruskies have apparently scaled it up a little further, quite a kick but still manageable from the shoulder:

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: mark.f » Tue Aug 28, 2018 9:38 am

The specificity of the application being to attack some swimmy bois is a little disconcerting, but I'm sure they have their reasons and the platform is a little more flexible than that.
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Re: Panzerabwehrwerfer 600 and the high-low pressure system

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Re: Panzerabwehrwerfer 600 and the high-low pressure system

Unread postAuthor: jackssmirkingrevenge » Tue Aug 28, 2018 2:24 pm

mark.f wrote:The specificity of the application being to attack some swimmy bois is a little disconcerting


oh internet :roll: :D

While there are some underwater guns in Western arsenals, it's Eastern Europeans in particular that seem to be unusually preoccupied with divers:

https://en.wikipedia.org/wiki/APS_underwater_rifle

https://en.wikipedia.org/wiki/SPP-1_underwater_pistol

https://en.wikipedia.org/wiki/ASM-DT_amphibious_rifle

https://en.wikipedia.org/wiki/ADS_amphibious_rifle

http://bulcomersks.com/index.php/53-amu ... und-rlv-ad

http://www.dogswar.ru/oryjeinaia-ekzoti ... let-s.html

Last I saw they fitted an APS to a Unmanned Vehicle...
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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