Cylinders for copper-crusher pressure tests


#1

Some more stuff from my almost-forgotten cigar boxes. Just hope this is considered ammunition-related by the administrators.

This is a box of copper cylinders for a copper crusher device. These were used to test the pressures of ammunition. In a previous post, I sent the link to a pdf document where the procedure was briefly explained.

home.comcast.net/~ehorton/The%20 … 20NATO.pdf

Here’s also a calibrating table that came inside the box. It is dated 1945. If one measures the cylinder’s lenght after firing, and checks the table, the pressure is given.

The pasted label translation reads:

ARTILLERY
PRECISION WORKSHOP AND ELECTRO-TECHNICAL CENTER
100 copper cylinders 7 x 5 mm for manometers small model (5 mm piston)
TABLE NUMBER 2.004

Wrapped and pasted around the other three sides of the wooden box there’s a copy of the pressures table, number 2004.

There are 4 or five copies of the table inside the box, wrapping the paper tubes containing the copper cylinders. This should be for cushioning and avoiding them to dent.


Cheers,

Schneider.


#2

Thank you for bringing this up. It reminded me of the one which I have. This was one of the last items which I got from Col. Jarrett before he went on to search out celestial technology.

He said that these were used with the German 80cm DORA cannon and that each time they fired the gun they used a special pressure device in the cartridge case to test the pressure.

He died before I got the paper work which he said was at Aberdeen PG and I have never been able to locate it since.

Maybe someone else has information.

The cylinders are in remarkable condition for being made in 1943.


#3

Your’s here were certainly not for the 800mm Dora since the cylinder diameter was for the small gauges.
German pressure gauges called “Gasdruckmesseier” came in a range of different sizes and were marked accordingly by length of the
cylinder and the diameter of the contained cylinders. These gauges were put into the propellant case or chamber and were fired with the projectile.
After that they were picked up, disassembled, the cylinder extracted and measured.
The smallest gauge was a bit less than 20mm if I recall right. We also found these in Hillersleben.

Here the 28/5:

And here the 52/8 (the Dora used certainly a larger one). The cylinder in this one was missing as was the hexagonal rubber adapter but here the
"transmission piece" (rivet shaped) was loose enough to be extracted - in the smaller one above it was stuck:

These are still in use today but have no copper cylinder anymore. The pressure is applied to a piezo element contained inside these gauges and
depending on the generated currency the pressure can be detected.


#4

The UK used these gauges as well. However they were placed in the cartridge case as close to the bottom as possible and then the charge replaced on top of them. The intention was that the gauge would remain inside the case after the gun was fired, if you were unlucky it followed the projectile out of the barrel and was usually lost. If this did happen then the test shot had to be repeated. If the gun was using bagged charges then the gauge cylinder was placed just inside the rear of the chamber.

gravelbelly


#5

Dave, I actually meant that but it seems I missed to pass it.


#6

[quote=“EOD”]Your’s here were certainly not for the 800mm Dora since the cylinder diameter was for the small gauges.
German pressure gauges called “Gasdruckmesseier” came in a range of different sizes and were marked accordingly by length of the
cylinder and the diameter of the contained cylinders. These gauges were put into the propellant case or chamber and were fired with the projectile.
After that they were picked up, disassembled, the cylinder extracted and measured.
The smallest gauge was a bit less than 20mm if I recall right. We also found these in Hillersleben.

Here the 28/5:

And here the 52/8 (the Dora used certainly a larger one). The cylinder in this one was missing as was the hexagonal rubber adapter but here the
"transmission piece" (rivet shaped) was loose enough to be extracted - in the smaller one above it was stuck:

These are still in use today but have no copper cylinder anymore. The pressure is applied to a piezo element contained inside these gauges and
depending on the generated currency the pressure can be detected.[/quote]

Thanks I got that also. Do you have a reference for the cylinder sizes ?


#7

I do not but if I crecall right the German Army Museum in Dresden has a manual on those.


#8

Are they open to questions ?


#9

EOD,

Am I following you right in that these gauges were fired out of the barrel and exited behind the projectile with the powder gases? Would think that would make for one heck of an “Easter Egg Hunt” to recover them!

Dave


#10

I guess not - as most museums they avoid to deal with details.


#11

[quote=“DaveE”]EOD,

Am I following you right in that these gauges were fired out of the barrel and exited behind the projectile with the powder gases? Would think that would make for one heck of an “Easter Egg Hunt” to recover them!

Dave[/quote]

Dave,

See my post above.

gravelbelly


#12

The powder charge pushes the projectile forward and the case and anything heavy in the base to the rear. The case is trying along with the gun to get away from the explosion - recoil . As I understand this the device is dropped in the bottom of the case before the powder bag is inserted. In some cases the vacuum produced could pull the thing out after the initial explosion or in some guns compressed air is forced through the bore to clear it if there is no evacuator mounted .


#13

Gravelbelly,

Sorry, I missed your post amongst the multiple photo sets!

Dr. Schmitt,

Thank you for the further description of the application. If I had to guess what the event was like for the gauge device, I would envision one of those ping-pong ball lottery machines with a very random swirling action. Where it was when the rush of propellant mass mostly leaves the barrel behind the exiting projectile likely being critical, I can see the hit or miss success of recovery. Very fascinating thread and items shown and very interesting for me to learn that this process was used!

I’ve often wondered what modern technology is offering on getting a glimpse of the interior ballistics of a gun (big or small). Anyone seen anything on this?

Dave


#14

[quote=“DaveE”]Gravelbelly,

Sorry, I missed your post amongst the multiple photo sets!

Dr. Schmitt,

Thank you for the further description of the application. If I had to guess what the event was like for the gauge device, I would envision one of those ping-pong ball lottery machines with a very random swirling action. Where it was when the rush of propellant mass mostly leaves the barrel behind the exiting projectile likely being critical, I can see the hit or miss success of recovery. Very fascinating thread and items shown and very interesting for me to learn that this process was used!

I’ve often wondered what modern technology is offering on getting a glimpse of the interior ballistics of a gun (big or small). Anyone seen anything on this?

Dave[/quote]

There are many exhaustive studies about this subject. Could be more than you even want in a google search.


#15

[quote=“DaveE”]EOD,

Am I following you right in that these gauges were fired out of the barrel and exited behind the projectile with the powder gases? Would think that would make for one heck of an “Easter Egg Hunt” to recover them!

Dave[/quote]

As Dave (Gravelbelly) wrote above already these gauges stayed inside the barrel in the best case.
I can not prove it but as I heard they were having raked sand in front of the firing positions what made it easier to find those once they escaped the barrel.


#16

[quote=“EOD”] These gauges were put into the propellant case or chamber and were fired with the projectile.
[/quote]

EOD, forgive me if this is a silly question, but… if a copper cylinder is put inside one of these closed containers and the container is put inside an artillery cartridge and the cartridge is fired… whose dimension of the copper cylinder is crushed? Top, bottom, the sides, or all of them?

In the copper-crusher gauges it’s easy: pressure is applied to the bottom of the cylinder so it crushes longitudinally.

Cheers,

Schneider.


#17

Schneider, no silly question at all. The pressure is applied along the longitudal axis as in those measuring devices built onto the test barrels.

The main body of the gauge here has a hole in it’s base, there the pressure-transmission cylinder is located (on image no 4 it is shown). Below this transmission cylinder the copper cylinder is located and held in place by the rubber piece and the screw on lid. All parts are high precision products with polished surfaces. The whole gauge body has a copper sleeve to protect chamber and barrel.


#18

As I found just now the company producing these “Hugo Wollmershäusser & Gurth Maschinen- und Apparatebau” was dismantled on 15 June 1946 and shipped to Russia.