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Austro-Hungarian valveless pneumatic mortars of World War I

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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Austro-Hungarian valveless pneumatic mortars of World War I

Unread postAuthor: jackssmirkingrevenge » Mon Apr 09, 2012 1:11 pm

I had touched on the subject of these devices here, and posted some details of French launchers of the same era here.

The Austro-Hungarian empire was heavily involved with such mortars, they are detailed on this fine (German language) page.

Having had the opportunity to look at surviving examples of the 12 cm Luftminenwerfer M.16 and 20 cm Luftminenwerfer System Bartlmus preserved at the Heeresgeschichtliches Museum close up, I thought I would share some photos. Not my best effort, flash photography was not allowed.

Unfortunately I was unable to get any details of the clutch, but the function can be easily imagined as a quick-release mechanism which releases the projectile when pulled.

One thing I don't understand is how the projectiles are stabilised. Having seen the studs on the projectiles, my initial idea was that they engaged rifling in the barrel in a manner similar to the La Hitte system, but in actual fact the barrels are smoothbores, and the studs do not project beyond the major diameter of the projectiles.

Looking at a cross section, the CG and CP are about central, so it doesn't appear that it would be drag stabilised.

The most plausible answer to me is that the place where the projectile sits actually contains a short rifled section. Even thought it's only over half the length of the projectile, this could provide enough spin to stabilise the relatively short projectile in flight. The 20cm model had its breech open but a projectile was in place and I was unable to confirm this. Any other theories welcome :)

One other interesting thing is that the 12cm model has a spring loaded shutter at the muzzle. The springs look fairly weak so I imagine this was mostly to keep debris out when not in use, but it could also have had a limited suppressing effect.

I digress, herewith the pictures:
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Attachments
lmwpair.jpg
The display including the 12cm mortar in the foreground and 20cm mortar in the background
lmw12cmrear.jpg
12cm rear view
lmw12cmrear2.jpg
12cm rear view
lmw12cmshutter.jpg
12cm muzzle shutter
lmw12cmclutch.jpg
12cm clutch detail, the central pin is pulled to fire
lmw12cmbreechconnection.jpg
12cm breech connection detail
lmw12cmcylinderconnection.jpg
12cm cylinder connection
lmw12cmprojectiles.jpg
12cm projectiles
lmw20cmfrontannoyedgirlfriend.jpg
20cm mortar with attention seeking lady
lmw20cmrear.jpg
20cm rear view
lmw20cmbreech.jpg
20cm breech
lmw20cmbreechdetail.jpg
20cm breech detail
lmw20cmclutch.jpg
20cm clutch detail
lmw20cmbarrelpinion.jpg
20cm reloading rack and pinion. Elevation was fixed with range being varied by altering pressure.
lmw20cmprojectile.jpg
20cm projectile
lmw20cmsmoothborebarrel.jpg
20cm view up the barrel
lmw20cmplate.jpg
20cm manufacturer's plate
lmwcylinder1.jpg
cylinder detail
lmwcylinder2.jpg
cylinder detail
luftmin2_88.jpg
12cm in action
luftminenwerfer_25_07_2011_750.jpg
20cm in action
wefer6a_1_400.jpg
projectile cutaway diagram
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Unread postAuthor: wyz2285 » Mon Apr 09, 2012 1:21 pm

Wow, didn´t knew that pneumatics was popular in old time wars :lol:
Any hybrid out there?
Question: what´s the pressure they used? pretty high I guess.
How does the firing mechanism work?
Also the muzzle shutter is open before shot right? Or does the air/projectile force it to open when fired?(witch reminds me, did your shut off suppressor ever worked?)
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Unread postAuthor: Hotwired » Mon Apr 09, 2012 1:32 pm

It would be a hinged claw that held the flared end of the pin then opened when the firing knob was pulled back.

At a guess, imagine a clothes peg.

The jaws will not open if you block the opening levers from closing.

Remove the block and the jaws will open.


The screw part at the rear I imagine would be to loosen and tighten the grasp on the pin of the projectile. Possibly requires resetting after each shot.



As for the studs...

Could be we are not seeing the projectile as they were and the studs were to hold a material which would have helped sealing.

Alternatively the seal may have been generated by the force of the "clutch" pulling the projectile onto a sealing material within the mortar.

If it's to engage a rifled section its an incredibly short one since the studs don't seem to protrude past the diameter of the shell.
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Last edited by Hotwired on Mon Apr 09, 2012 1:44 pm, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Mon Apr 09, 2012 1:35 pm

wyz2285 wrote:Question: what´s the pressure they used? pretty high I guess.


Around 55 bar, not bad :)

How does the firing mechanism work?


see the basic attached diagram, the clutch holds the pin at the base of the projectile, at the moment of firing the clutch releases the pin and bang!

They also had a smaller mortar where the pin actually sheared when a specific pressure was reached.

Also the muzzle shutter is open before shot right? Or does the air/projectile force it to open when fired?


It seems the force of the shot opened it.

(witch reminds me, did your shut off suppressor ever worked?)


Not that well at high pressures, I think the concept is sound but I'm not willing to put in the work to perfect it.
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Unread postAuthor: wyz2285 » Mon Apr 09, 2012 1:40 pm

see the basic attached diagram, the clutch holds the pin at the base of the projectile, at the moment of firing the clutch releases the pin and bang!


So the Germans got a leak-free high pressure valveless(metal on metal seal) 100 years before you did :lol:
Wow 55bar was low, what was the range of these thing? I thought they were using more than 200 bar at least :roll:
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Unread postAuthor: jackssmirkingrevenge » Mon Apr 09, 2012 1:46 pm

wyz2285 wrote:So the Germans got a leak-free high pressure valveless(metal on metal seal) 100 years before you did :lol:


hehe not sure it was a metal on metal seal, and it seems that sealing problems were one of the issues of this type of weapon.

Wow 55bar was low, what was the range of these thing? I thought they were using more than 200 bar at least :roll:


1150 metres for the 20cm one, not bad eh.
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Unread postAuthor: warhead052 » Mon Apr 09, 2012 1:47 pm

Interesting. I may have to take notes now... How did the clutch work? Was it pretty much a jaw that was released when you wanted to fire?
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Unread postAuthor: wyz2285 » Mon Apr 09, 2012 1:55 pm

1150 metres for the 20cm one, not bad eh.
:shock: what?
Wow pneumatics have future :P That big fat metal projectile, with a relatively short barrel goes 1km...
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: jackssmirkingrevenge » Mon Apr 09, 2012 2:50 pm

warhead052 wrote:Interesting. I may have to take notes now... How did the clutch work? Was it pretty much a jaw that was released when you wanted to fire?


I imagine so, have a look at other quick release mechanisms:

Image

Essentially my ballistic knives use exactly the same principle - a projectile held in the barrel by a mechanical catch, and is released to fire.

Wow pneumatics have future That big fat metal projectile, with a relatively short barrel goes 1km...


Imagine if they used that 55 bar for a 56x hybrid, it would have gone much, much further ;)
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Unread postAuthor: wyz2285 » Mon Apr 09, 2012 3:07 pm

Or just use a common cannon :lol: for a hybrid that size they need pressured fuel as well, also a small leak would set the mix off.
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: warhead052 » Mon Apr 09, 2012 3:07 pm

I've seen those before, industrial quick release for cables right?
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Unread postAuthor: jackssmirkingrevenge » Mon Apr 09, 2012 3:13 pm

wyz2285 wrote:Or just use a common cannon :lol: for a hybrid that size they need pressured fuel as well, also a small leak would set the mix off.


Naturally, given the inconvenience... which is why these things have long since disappeared from the battlefield.

I'm fascinated most though by what I imagine to be the rifling system. Only having to rifle a tiny part of the breech would be infinitely easier than having to rifle an entire barrel...
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Unread postAuthor: wyz2285 » Mon Apr 09, 2012 4:29 pm

But fire arms were very available already in the early 20th century...
Well some FX airguns are only rifled in the end of the barrel, giving the pellet a initial space to accelerate, then in the end, give it the spin.~
[youtube]http://www.youtube.com/watch?v=xPF6dWAqfhY[/youtube]
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: Gun Freak » Mon Apr 09, 2012 4:52 pm

Thanks for sharing :D very fascinating indeed!
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Unread postAuthor: POLAND_SPUD » Mon Apr 09, 2012 5:55 pm

So the Germans got a leak-free high pressure valveless(metal on metal seal) 100 years before you did
lol isn't it ironic ? you think you invented something and then you find out that the thing had been created years ago


thx for sharing


12cm breech connection detail
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Hmm that's clever
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