What is this? Vicksburg Tour --- "Vent Holes"

1stMS-Arty

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The last time I was at the USS Cairo Museum I took some pictures of one of the exhibits inside...which isn't very easy to do since you can't use a flash...but I believe the brass items at the bottom of the picture are external firing mechanisms for cannon....

C01.jpg
 

redbob

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If you ever saw the movie Master and Commander, when the British crew has boarded the French ship (which in the book was an American Frigate); one of the crew puts his hand over the cap on the cap fire system to prevent the French from firing the gun and gets his hand hit by the hammer when the Frenchman pulls the lanyard.
 

redbob

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I read some of the Aubrey/Maturin books, but not that one. Was it the Essex, or did the author rename it?
I can't remember, but when it came out one of the actors said that they had changed the nationalities in the script because they didn't believe that it would go over very well in the United States if they left it as written.
 
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DixieRifles

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I also have real concern when I see holes drilled in the breech "business" end of a cannon. If these 3 holes were drilled through to the bore, then that would really weaken the cannon. I would still be a little nervous having 3 extra holes bored through only half of the wall thickness of the breech.
As an engineer, I have to look at the stress analysis of this "modification". The cannon is classified as a Thick-walled Pressure Cylinder, meaning it is a pressurized cylinder that has a wall thickness that has a large ratio of Wall thickness to Cylinder Outer Diameter. The stresses that build up on a pressure vessel will be different for the different wall thicknesses.
I worked on aircraft Landing Gears and I didn't understand these struts(basically a hydraulic actuator) as a cylinder. It wasn't until I observed a test that used polarized light and a plastic coating that allowed you to actually see the stress patterns. Under pressure, the cylinder walls expands like a balloon. And these were steel cylinders that have a 1/4 inch, high-strength(Rc=52) wall.

I found this stress analysis of a thick walled cylinder that shows a Computer Model(FEM) of the stress patterns that would match what a cannon would be exposed to during firing.
Some of these stresses are for a closed cylinders---as the pressure expands, it causes the cylinder to grow longer. This would not apply to a Cannon that has an open breech. Also, the computer model looks at principal stresses which are stresses going in one direction.
FEA of Thick-walled Cylinder

Some images from that paper.
Notice in the Left image, the stresses are in the YELLOW range at almost half the wall thickness. If a hole is drilled into this stress zone, then this acts as a stress multiplier (aka stress concentration factor).
FEM Model.JPG
 

Mark F. Jenkins

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Do we have any theories as to what the holes were used for? I saw the trio of holes for the sighting mechanism on the other gun at the same location, but these seem larger and irregularly-placed... unless it was a one-off "scratchbuilt" sighting device of some sort?
 

Kurt G

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If you ever saw the movie Master and Commander, when the British crew has boarded the French ship (which in the book was an American Frigate); one of the crew puts his hand over the cap on the cap fire system to prevent the French from firing the gun and gets his hand hit by the hammer when the Frenchman pulls the lanyard.
I believe that was a flintlock ignition system . Great movie .
 

redbob

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I also have real concern when I see holes drilled in the breech "business" end of a cannon. If these 3 holes were drilled through to the bore, then that would really weaken the cannon. I would still be a little nervous having 3 extra holes bored through only half of the wall thickness of the breech.
As an engineer, I have to look at the stress analysis of this "modification". The cannon is classified as a Thick-walled Pressure Cylinder, meaning it is a pressurized cylinder that has a wall thickness that has a large ratio of Wall thickness to Cylinder Outer Diameter. The stresses that build up on a pressure vessel will be different for the different wall thicknesses.
I worked on aircraft Landing Gears and I didn't understand these struts(basically a hydraulic actuator) as a cylinder. It wasn't until I observed a test that used polarized light and a plastic coating that allowed you to actually see the stress patterns. Under pressure, the cylinder walls expands like a balloon. And these were steel cylinders that have a 1/4 inch, high-strength(Rc=52) wall.

I found this stress analysis of a thick walled cylinder that shows a Computer Model(FEM) of the stress patterns that would match what a cannon would be exposed to during firing.
Some of these stresses are for a closed cylinders---as the pressure expands, it causes the cylinder to grow longer. This would not apply to a Cannon that has an open breech. Also, the computer model looks at principal stresses which are stresses going in one direction.
FEA of Thick-walled Cylinder

Some images from that paper.
Notice in the Left image, the stresses are in the YELLOW range at almost half the wall thickness. If a hole is drilled into this stress zone, then this acts as a stress multiplier (aka stress concentration factor).
View attachment 332029
Do we have any theories as to what the holes were used for? I saw the trio of holes for the sighting mechanism on the other gun at the same location, but these seem larger and irregularly-placed... unless it was a one-off "scratchbuilt" sighting device of some sort?
The holes were between 1/2-3/4 inches deep and as far as I could tell they were threaded to the bottom. They didn't penetrate the firing chamber and I wish that I had looked at their location from the muzzle end to see if I could estimate how close to the firing chamber they were. So far, the sight base or a firing mechanism theories seem to be the odds on favorites for what they are. Hopefully someone will give us proof positive as none of my artillery books seem to have anything on them. Also, hold on tight to your copy of Hazlett, Olmstead and Parks' Big Guns as the only copy that I have found is listed for $899.00. :frown:
 

Mark F. Jenkins

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The holes were between 1/2-3/4 inches deep and as far as I could tell they were threaded to the bottom. They didn't penetrate the firing chamber and I wish that I had looked at their location from the muzzle end to see if I could estimate how close to the firing chamber they were. So far, the sight base or a firing mechanism theories seem to be the odds on favorites for what they are. Hopefully someone will give us proof positive as none of my artillery books seem to have anything on them. Also, hold on tight to your copy of Hazlett, Olmstead and Parks' Big Guns as the only copy that I have found is listed for $899.00. :frown:

Olmstead, Stark, and Tucker, actually. I think I paid something like $260 on ebay a few years back for mine.
 

Blunderbuss2

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Just watched a 10Lb Parrott being fired this way at the NSSA halloween match. The problem with these or friction primers is you are liable to pull the gun slightly off target. Which isnt a big deal duringactual combat where you are using explosive projectiles, but when you are shooting for accuracy during a competition it does.
The tug it takes a friction primer to fire is not coming close to moving a barrel weighing hundreds of lbs.. I fired my 3" ord. rifle many times and that problem never even occurred to me. 816 lb. tube & 1800 lbs. total weight. What I don't understand is the way you see virtually all of these people pulling the lanyard in front of them. Proper way is a straight arm & pull behind you. Must be slow learners, as it only took me being hit in the side of the head by that hook on the other end of the lanyard once to figure I was doing something wrong. Sure wouldn't want to be hit in the eye with it !
 

Noonanda

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The tug it takes a friction primer to fire is not coming close to moving a barrel weighing hundreds of lbs.. I fired my 3" ord. rifle many times and that problem never even occurred to me. 816 lb. tube & 1800 lbs. total weight. What I don't understand is the way you see virtually all of these people pulling the lanyard in front of them. Proper way is a straight arm & pull behind you. Must be slow learners, as it only took me being hit in the side of the head by that hook on the other end of the lanyard once to figure I was doing something wrong. Sure wouldn't want to be hit in the eye with it !
Ive watched a couple of the smaller mountain howitzers get pulled off of aim, and asked one of the crews firing a 10lb parrott why they didnt use them and they told me the same thing. When you are shooting for a score that can be measured in 1/10th of an inch, you want zero influences potentially throwing off your aim. We won the Halloween skirmish using a linstock to light the fuzes and it worked good. Even the 20Lb Parrott at nationals was using a linstock.
 

Ole Miss

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Ever since this thread was posted I knew I had seen another tube with similar holes. Kept searching and found the other cannon.
In @Rusk County Avengers thread of July 13, 2019, CW Stops on a work trip, Michael posted this picture of a M1841 12-pound Field Howitzer with another 3 hole configuration outside of the Visitor's Center at Wilson Creek Battlefield. Perhaps you could contact the rangers there for assistance?
Regards
David
1572625327678.png
 

Rusk County Avengers

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Ever since this thread was posted I knew I had seen another tube with similar holes. Kept searching and found the other cannon.
In @Rusk County Avengers thread of July 13, 2019, CW Stops on a work trip, Michael posted this picture of a M1841 12-pound Field Howitzer with another 3 hole configuration outside of the Visitor's Center at Wilson Creek Battlefield. Perhaps you could contact the rangers there for assistance?
Regards
David
View attachment 332194

I need to send the Curator there an email anyway, I'd be happy to inquire. I don't know whether they'll know or not, but the Curator seemed very knowledgeable on each tubes history. We had a laugh when he explained the Napoleon in front of the Visitor's Center was sent to them from a Revolutionary War battlefield park, (I can't remember which one), mounted on a Rev. War carriage advertised as a Rev. War gun in that fort or whatever.

Glad you pointed that out, it never occurred to me I seen it before, though I haven't been keeping up with the discussion too much.
 

Rusk County Avengers

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Also a note on M1841 Field Howitzers.

The holes very well could be naval in origin. I know of at least one ship in the war I've been struggling to research, the blockade runner Velocity that was captured and outfitted as USS Velocity at Sabine Pass and was armed with two M1841 Field Howitzers on presumably naval carriages, (I remember them being described as old fashioned ones), before it was captured by the Confederates and christened CSS Velocity.

The USN had so many "new" ships and not enough guns to go around. Is it possible these three holed guns were ones given to the Navy to make up for the small numbers? After all the M1841 was viewed as obsolete by many in both armies, (though I'm personally real fond of them), and in the Union with so many new guns being manufactured, I think its possible in light of all this to say these M1841's were tubes given to the USN to arm their many "converted" gunboats and converted to naval cap-locks. Just a possibility.
 
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Rusk County Avengers

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I also have real concern when I see holes drilled in the breech "business" end of a cannon. If these 3 holes were drilled through to the bore, then that would really weaken the cannon. I would still be a little nervous having 3 extra holes bored through only half of the wall thickness of the breech.
As an engineer, I have to look at the stress analysis of this "modification". The cannon is classified as a Thick-walled Pressure Cylinder, meaning it is a pressurized cylinder that has a wall thickness that has a large ratio of Wall thickness to Cylinder Outer Diameter. The stresses that build up on a pressure vessel will be different for the different wall thicknesses.
I worked on aircraft Landing Gears and I didn't understand these struts(basically a hydraulic actuator) as a cylinder. It wasn't until I observed a test that used polarized light and a plastic coating that allowed you to actually see the stress patterns. Under pressure, the cylinder walls expands like a balloon. And these were steel cylinders that have a 1/4 inch, high-strength(Rc=52) wall.

I found this stress analysis of a thick walled cylinder that shows a Computer Model(FEM) of the stress patterns that would match what a cannon would be exposed to during firing.
Some of these stresses are for a closed cylinders---as the pressure expands, it causes the cylinder to grow longer. This would not apply to a Cannon that has an open breech. Also, the computer model looks at principal stresses which are stresses going in one direction.
FEA of Thick-walled Cylinder

Some images from that paper.
Notice in the Left image, the stresses are in the YELLOW range at almost half the wall thickness. If a hole is drilled into this stress zone, then this acts as a stress multiplier (aka stress concentration factor).
View attachment 332029

Great analysis, but one note. M1841's, and indeed howitzers in general, had significantly smaller chambers at the breech than the bore.
 

CivilWarTalk

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The holes were between 1/2-3/4 inches deep and as far as I could tell they were threaded to the bottom. They didn't penetrate the firing chamber and I wish that I had looked at their location from the muzzle end to see if I could estimate how close to the firing chamber they were. So far, the sight base or a firing mechanism theories seem to be the odds on favorites for what they are. Hopefully someone will give us proof positive as none of my artillery books seem to have anything on them. Also, hold on tight to your copy of Hazlett, Olmstead and Parks' Big Guns as the only copy that I have found is listed for $899.00. :frown:
Holy cow! Really? Um, Mom, I need that safe, sooner, rather than later....
 

redbob

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I have reached out to the lady that wrote the book that I was using during the gathering and hopefully she can give us some insight on the Great Three Holer Mystery. :cannon:
After five fun filled days of dealing with this conundrum, the answer came from the nice lady that literally wrote the book on artillery at Vicksburg and the answer is: THE THREE HOLES DRILLED AND TAPPED INTO THE BARRELS OF THE BRONZE FIELDPIECES IS(a drumroll please) FOR THE BASE OF A FIRING MECHANISM. If you had the correct answer, please contact me and your spectacular prizes will be on their way forthwith. And with this headscratcher out of the way, I'm going to take a handful of Tylenol and go to bed... :help:
 
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ucvrelics

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After five fun filled days of dealing with this conundrum, the answer came from the nice lady that literally wrote the book on artillery at Vicksburg and the answer is: THE THREE HOLES DRILLED AND TAPPED INTO THE BARRELS OF THE BRONZE FIELDPIECES IS(a drumroll please) FOR THE BASE OF A FIRING MECHANISM. If you had the correct answer, please contact me and your spectacular prizes will be on their way forthwith. And with this headscratcher out of the way, I'm going to take a handful of Tylenol and go to bed... :help:
Ok now for the hard part, what did it look like???
 
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