Civil War seacoast mortars, why such thick tubes?

[shred]

The latest round of mortar pics got me thinking again....

Why do the big Seacoast mortars (1861 Dictator, 10", et al) have such thick wall tubes?   Is there really that much pressure in one of those loaded to max?  Are they being good boys and keeping a caliber of thickness all the way to the muzzle?  Does the weight help them with recoil?  The Coehorns and smaller mortars obviously figured out they didn't need to lug that much metal around, albeit usually at shorter ranges. 

[Artilleryman]

I was part of this crew that worked a 13 inch seacoast mortar, and no the image was not taken during the Civil War.



This mortar weighs 17,000 lbs and with the bed over 10 tons.  We were firing a 200 lb shell using 5 lbs of powder to a range of 1 mile.  The recoil caused the mortar to move about 8-10 inches on the platform.  This was a relatively light charge.  So I would agree that the thickness of the barrel was due in part because of the pressures and in part because of the recoil.

[Cannon salute]

I was part of this crew that worked a 13 inch seacoast mortar, and no the image was not taken during the Civil War.



This mortar weighs 17,000 lbs and with the bed over 10 tons.  We were firing a 200 lb shell using 5 lbs of powder to a range of 1 mile.  The recoil caused the mortar to move about 8-10 inches on the platform.  This was a relatively light charge.  So I would agree that the thickness of the barrel was due in part because of the pressures and in part because of the recoil.

That second picture is awesome got anymore that capture the whole plume?

[Cat Whisperer]

The second one looks like Range 10 at Fort McCoy, WI. by the Paulson brothers.  I imaging there are quite a few pictures around from those shoots.

[Artilleryman]

Both were taken at McCoy.

[shred]

FWIW, I found an interesting book while poking around for more information on the subject.   It claims that until Rodman came up with cooling the bore during casting, it was impossible to make an effective solid-cast gun over 10" bore.  Anyone know how the big mortars were cast?


http://books.google.com/books?id=Un4DAAAAYAAJ&ots=VFtnCikVaH&dq=Notes%20On%20Seacoast%20Defense%3A%20Consisting%20Of%20Seacoast%20Fortification%2C%20The%20Fifteen-inch%20Gun%2C%20And%20Casemate%20Embrasures%20(1861)&pg=PP1#v=onepage&q&f=false

[Cat Whisperer]

Both were taken at McCoy.

I've seen TOW's and Dragons launched from that site.  Must have REALLY been impressive to crew/see the 13" shot there!!!!!

[GGaskill]

Remember the 13" mortars were made of brittle cast iron and they used a lot of powder for long range shots.

[Double D]

Bull barrel concept?  Heavier barrels don't heat up as fast and vibrate less when fired...just my SWAG.

[Frank46]

Well this is a question that begs to be answered. I'm guessing that these projectiles in modern day firing are dug up and cleaned before being fired again. If this is true how far do they penetrate into the ground. And I for one would not want to be on the shovel brigade having to dig them up. Frank

[Artilleryman]

The ones we were firing had time fuses and were set to explode a mile out just above ground level.   I was told that the ones that didn't explode buried 5-6 feet in the ground.  This was on a military artillery and bomb range.  You had to have special permission and take special precautions to retrieve them.  I didn't go down range.

[BoomLover]

  ...firing one of those big beauties would be plenty of excitement, so I would forgo going down range to dig an unexploded one up, too! Sounds like a job for "Superman"    ......BoomLover

[shred]

Presumably the max mortar charges were similar to those used in direct-fire guns of the time.  Do, say 10" guns of the period have roughly the same thickness of wall for the first few calibers as a 10" sea-coast mortar? 

[seacoastartillery]

 FWIW, I found an interesting book while poking around for more information on the subject.   It claims that until Rodman came up with cooling the bore during casting, it was impossible to make an effective solid-cast gun over 10" bore. Anyone know how the big mortars were cast?
 
 
 http://books.google.com/books?id=Un4DAAAAYAAJ&ots=VFtnCikVaH&dq=Notes%20On%20Seacoast%20Defense%3A%20Consisting%20Of%20Seacoast%20Fortification%2C%20The%20Fifteen-inch%20Gun%2C%20And%20Casemate%20Embrasures%20(1861)&pg=PP1#v=onepage&q&f=false   

 
      The heavy, 1861 13" Seacoast Mortar was made using the same "Water Core" Rodman process as many other seacoast guns.  I saw a photo of 14 or 15 of them on the foundry dock in South Boston once.  Wish I had saved that one.  Approx 1/2 of the heavy Parrott rifles were also made with this same process.  The one we have in Denver, Colo. at City Park is one of those cast per Rodman's process.  It has WATER CORE stamped on the face of the muzzle in capital letters as does our re-creation of that piece.
 
 
 

 Presumably the max mortar charges were similar to those used in direct-fire guns of the time.  Do, say 10" guns of the period have roughly the same thickness of wall for the first few calibers as a 10" sea-coast mortar? 

 
      That's an excellent question.  Offhand we could not answer that with certainty, so we looked it up in the Big Red Book, The Big Guns by Olmstead, Stark and Tucker.  We found that the 10.0" Mortar that you mentioned has a dia. of 27.5", bore of 10.0" and walls of 8.75".  Don't get all twitterpated, folks.  Remember that mortars have chambers and that the largest chamber dia. of 7.5" is LESS than this mortar's wall thk. of 8.75".  The big seacoast guns and howitzers do even better.  All of these have 10.0" bore dias.: Seacoast Howitzer, Pattern 1839, wall thk. of 11.5".  How about the Columbiad, Pattern 1844, wall thk. 10.5", or the New Columbiad of 1857, wall thk. of 10.5".  As you would expect, the 10" Rodman Gun, Pattern 1861 has a wall thickness greater than the bore dia., it's 11.0" as is the wall thickness of the XI Dahlgren Shell Gun.   Even this big Navy gun satisfies the 1:1:1 Rule if you consider the 7.0" chamber on the the 10" Navy Shell Gun of 86 cwt.  It's wall thk. is only 7.75.  Big guns=Thick Cast Iron.
 
 Tracy and Mike       Yes, we occasionally work on Saturdays.

[Double D]

I'm retired and find the use of the  "W" word offensive...oh wait, go ahead and use the "W" word, that is as long as you are paying your taxes and keeping my Sociable Security check funded! 

[shred]

      The heavy, 1861 13" Seacoast Mortar was made using the same "Water Core" Rodman process as many other seacoast guns.  I saw a photo of 14 or 15 of them on the foundry dock in South Boston once.  Wish I had saved that one.  Approx 1/2 of the heavy Parrott rifles were also made with this same process.  The one we have in Denver, Colo. at City Park is one of those cast per Rodman's process.  It has WATER CORE stamped on the face of the muzzle in capital letters as does our re-creation of that piece.
 

Presumably the max mortar charges were similar to those used in direct-fire guns of the time.  Do, say 10" guns of the period have roughly the same thickness of wall for the first few calibers as a 10" sea-coast mortar? 

  As you would expect, the 10" Rodman Gun, Pattern 1861 has a wall thickness greater than the bore dia., it's 11.0" as is the wall thickness of the XI Dahlgren Shell Gun.   Even this big Navy gun satisfies the 1:1:1 Rule if you consider the 7.0" chamber on the the 10" Navy Shell Gun of 86 cwt.  It's wall thk. is only 7.75.  Big guns=Thick Cast Iron.
 
 Tracy and Mike       Yes, we occasionally work on Saturdays.

Cool, thanks.  So it seems the big mortar tubes are not way out-of-line compared to sawing off a different type gun at the same length.  They just look different due to the lack of remaining barrel.

Btw, where are the guns in City Park?  I had time for a quick drive-by a couple weeks ago but didn't spy them and was unable to convince my fellow non-cannon-nut passengers it was worth a lengthy search.

[seacoastartillery]

     Shred,     Too bad you didn't get a chance to see the naval and seacoast ordnance in Denver.  It's a little difficult to find if you don't know where, in the park, to look.  First find I-70 and Colorado Blvd., go south approx 3 miles to E. 22nd Ave.  This is the East Entrance to the Denver Museum of Nature and Science.  Take a right here; note the Museum on the left and large parking lot. Just past the lot's last exit/entrance, take a left on the small lane which goes westward through the park.  You will see the 3 big cannon on the left in about 1/3 mile.  The 1861 13" Seacoast Mortar is nearest to the lane (15 feet), and the 100 Pdr. Parrott Seacoast and Navy rifle due south about 100 feet and the XI Inch Dahlgren Shell Gun lies about 100 feet SW.  I have tried to link a map, but it probably won't work.  Good luck!  BTW, do you live in Colorado?  Where?

Tracy and Mike

The cannon lie equally disposed about the faint circle denoting a flower bed just south of Duck Lake (a small pond).

http://maps.yahoo.com/#q=City+Park%2C+Denver&conf=1&start=1&lat=39.74722296564399&lon=-104.94468927383423&zoom=16&mvt=m&trf=0

[shred]

     Shred,     Too bad you didn't get a chance to see the naval and seacoast ordnance in Denver.  It's a little difficult to find if you don't know where, in the park, to look.  First find I-70 and Colorado Blvd., go south approx 3 miles to E. 22nd Ave.  This is the East Entrance to the Denver Museum of Nature and Science.  Take a right here; note the Museum on the left and large parking lot. Just past the lot's last exit/entrance, take a left on the small lane which goes westward through the park.  You will see the 3 big cannon on the left in about 1/3 mile.  The 1861 13" Seacoast Mortar is nearest to the lane (15 feet), and the 100 Pdr. Parrot Seacoast and Navy rifle due south about 100 feet and the XI Inch Dahlgren Shell Gun lies about 100 feet SW.  I have tried to link a map, but it probably won't work.  Good luck!  BTW, do you live in Colorado?  Where?

Tracy and Mike
http://maps.yahoo.com/#q=City+Park%2C+Denver&conf=1&start=1&lat=39.74722296564399&lon=-104.94468927383423&zoom=16&mvt=m&trf=0

Thanks,  I think I can find them next time from that description (the point on the map appears to be inside a lake, but I've been to the museum many times).  I grew up in Englewood, but moved away about 20 years ago.  I still come back every so often for visits and ski trips, which is what the last one was.  'Touring the Capitol and Mint' beat out 'searching City Park for ordnance' in the killing-time-before-going-to-the-airport decision. 
 

[Artilleryman]

Presumably the max mortar charges were similar to those used in direct-fire guns of the time.  Do, say 10" guns of the period have roughly the same thickness of wall for the first few calibers as a 10" sea-coast mortar?

The maximum powder charge for the 13 inch seacoast mortar is 20 lbs.  That launches a 200 lb shell 3 miles.  Targets at this range generally are towns or cities.

[Frank46]

Norm, thanks for clearing that up. I would not go down range either. Frank

[GLS]

Tried a little Google Earth to find the Denver Park and snapped these pics.  There still there.

[shred]

Presumably the max mortar charges were similar to those used in direct-fire guns of the time.  Do, say 10" guns of the period have roughly the same thickness of wall for the first few calibers as a 10" sea-coast mortar?

The maximum powder charge for the 13 inch seacoast mortar is 20 lbs.  That launches a 200 lb shell 3 miles.  Targets at this range generally are towns or cities.

Thanks, that jives ok with the theory that the max charges are about the same.  I don't know of any other 13" guns used (anything else shoot a 200 lb shell, and is it's max charge about 20 lb powder?) but in the 10" sizes, the sea-coast mortar max loads and the max loads for columbiads and howitzers are close enough (scaling for projectile weight & such) that the thickness-is-for-burst-strength theory holds up.

[The Jeff]

Presumably the max mortar charges were similar to those used in direct-fire guns of the time.  Do, say 10" guns of the period have roughly the same thickness of wall for the first few calibers as a 10" sea-coast mortar?

The maximum powder charge for the 13 inch seacoast mortar is 20 lbs.  That launches a 200 lb shell 3 miles.  Targets at this range generally are towns or cities.

Thanks, that jives ok with the theory that the max charges are about the same.  I don't know of any other 13" guns used (anything else shoot a 200 lb shell, and is it's max charge about 20 lb powder?) but in the 10" sizes, the sea-coast mortar max loads and the max loads for columbiads and howitzers are close enough (scaling for projectile weight & such) that the thickness-is-for-burst-strength theory holds up.

There were 13" Rodman and Dahlgren guns. According to a chart on Wikipedia, the Model 1864, 13 inch Rodman had a 30 pound charge. Apparently the 13 inch Dahlgren gun used 40 pounds of powder, but each tube burst after several rounds of solid shot.


Here's an interesting article about the 13 inch Rodman: http://markerhunter.wordpress.com/2012/02/05/13-inch-rodman-gun/

[seacoastartillery]

http://books.google.com/books?id=wSQAAAAAMAAJ&pg=PA124&lpg=PA124&dq=mare+island+cannon&source=web&ots=Z--gm4dMqJ&sig=ex5ZZ0juc9BoDF0lsKRQ2aZaRUE&hl=en&sa=X&oi=book_result&resnum=9&ct=result#v=onepage&q=mare%20island%20cannon&f=false

    The link above shows what happened to the 13" Dahlgren cannons and more than a few 15" Dahlgrens as well.  That, I believe, is the gang drill of ALL gang drills.  Just like splitting tree trunks!  Don't know about the 13" Rodman guns.  Mare Island Naval Ship Yard just handled the Navy's ordnance.  Jeff,  Thanks for posting that interesting link for the Markerhunter's article on the 13" Rodmans.

Tracy

[Artilleryman]

Interesting reading.  I found the statement that unfired guns were harder to split than guns that had been fired particularly interesting.  I wonder what the wages of the two men were that split the guns up.

[GGaskill]

... unfired guns were harder to split than guns that had been fired ...

Probably no microcracking.  My grandfather worked in the Chevron refinery in El Segundo in the early 1900's for about a dollar a day.  New Colt revolvers cost less than $10.  When I  first joined the work force (mid 60's), it still took a week's pay to buy a new Colt.  But the government collected more taxes because the quantity of dollars was higher.

[Victor3]

... unfired guns were harder to split than guns that had been fired ...

Probably no microcracking.  My grandfather worked in the Chevron refinery in El Segundo in the early 1900's for about a dollar a day.  New Colt revolvers cost less than $10.  When I  first joined the work force (mid 60's), it still took a week's pay to buy a new Colt.  But the government collected more taxes because the quantity of dollars was higher.

 Bet that was an interesting job, before EH&S came around. I've known two guys who died in that facility in the past 30 years. In the early 80s I interviewed there to be a maintenance mechanic @ $14/hr. Figured it would be great since I only lived three miles away. Then they told me some of what I'd have to do. Makes longshore work seem incredibly safe, even though most safety rules are regularly ignored at the LA/LB ports.

[Artilleryman]

I wonder what iron was worth so that they could pay two men for six weeks to break up one barrel?