How to make my hollow 13 inch mortar shootable?

[Double D]

It's a liner George, it goes inside of something else!

[entsminger]

Wow, am I impressed! Where did you guys go to school? The Harvard School or Ordnance? I'm gonna have to take some of this stuff and have my engineer friend explain it to me. I'm not sure if you two ( Double D and Gasskill) came to any agreement as I don't understand yet what was said but just for my feeble brains sake, in real simple terms did you all come to any conclusions or agreement on what thickness barrel/breech I would need to make this mortar safe. Just pretend it is a stand alone piece of pipe that I intend to shoot either solid or hollow aluminum 13 inch cannon balls from. What would that require in wall thickness? I am most appreciative of you guys helping me out here!!!!!!!!!

  Scott

[Double D]

I think we were talking apples and oranges.  

Let me put it this way.  Bowling ball mortars are frequently made from nothing more than welding gas cylinders that have muzzle walls in the area  1/2 inch or less.

[GGaskill]

Although I am not satisfied with the state of this discussion (almost used the word argument  ), I am going to let it ride until a decision is made regarding how much powder is going to be used as the charge.  So Scott, make a decision on how much powder you are willing to burn for each shot.  Remember, powder costs from $12 to $20 dollars a pound.  

School:  UCLA, but dropped out to staff Lyndon Johnson's little exercise in southeast Asia and never returned.

[entsminger]

Boy I wish I could answer you on how much powder I would use? Not having had a mortar to shoot I guess I would use what ever amount of powder it would take to safely throw a 13 inch solid  or possibly hollow aluminum 13 inch ball the typical distance folks are shooting their cannon at mortar shooting contests and events.  What that amont of powder is I have no idea at this point in my learning process of cannon shooting. Being a man with little money to play with I would error on the cheap side? The only 13 incher I've ever heard of being shot is Paulson Brothers but I believe they are using iron or equivilant weight zinc balls? You guys are great for indulging me with such learned answers. I just hope to be able to understand them soon. If I ever figure out how to post pictures I'll post my propane, scrap steel pictures for all to see my crazy project.

  Scott

  Scott

[GGaskill]

A real one launched a 220 lb shell 4300 yards using 20 lbs of powder.  Where can you shoot yours?  What is the maximum range there?  You need to see the shot land to be able to recover it.

6 oz of powder will throw a 16 lb bowling ball 500 yards.  I am told a pound will launch one out of sight.  I think I would make yours hold a pound, because more than that will require a more massive tube.

[GGaskill]

I went to my steel supplier today and while there, I perused his collection of cutoffs of large diameter steel tubing.  While it is probably impractical to ship a piece from So. Calif. to WashDC, I did determine that 13" inside diameter tubing is produced in several wall thicknesses.  So keep looking for steel suppliers and visit their yards to look for the ideal piece of metal.

Also keep in mind that this stuff is usually not perfectly round.

[entsminger]

You guys have been great answering all my questions but in all the discussion of this thread I still haven't got a clue to the cost of a piece of seamless pipe capable of shooting a 13 inch aluminum ball or how thick the pipe should be and what to really look for?  Can I please talk to one of you or someone who knows  by phone instead of all this e-mail tag? My number is 703 528 1548 and I live in Virginia so if you like I can call you if I can get your phone number. My e-mail address is sdakss@aol.com  I'm usually home in the evenings.

 Scott Springston

[Double D]

Scott,

Next week October 7th and 8th out at Fort Shenandoah near Winchester VA. The North-South Skimish Association will hold it's fall skirmish.  The 7th the mortars shoot at about 2PM. Go out and talk to the people out there. See what they say.


The walls of seamless tube portion of your barrel need only be  3/8 inch thick.  This is a liner and goes inside of something else.

The breech section of your barrel needs to be three times the diameter of the powder chamber.

But I'm with George on this, you have to decide what size powder chamber you want before any other figures can be determined.

[Cat Whisperer]

I think next week is October 7/8 (F/S).

I recommend two things to consider when choosing caliber - one is availability of ammo and the other is where you have to shoot.

That translates to range - do you want to launch these things a few hundered yards (that makes life easy) or a couple of miles.  BOTH are possible - one takes a little powder the other 10's of pounds of powder.

Consider transportation - that is, to the firing site.  (I've limited myself to what I can lift - which is getting less and less each year.)

[GGaskill]

I have suggested a couple of times that you go out and find some steel vendors and see what they have and how much it costs.  New costs at least twice surplus.  A half inch wall 13" ID by 24" long tube will weigh about 140 lbs; the breech piece (15" diameter by 15.5" long) will weigh about 760 lbs (before machining; 2/3 of that will end up as chips.)  Figure 50 cents a pound for surplus, maybe $1.50 per pound for new stuff.  Do the math.  Other estimates may vary.

If you keep your eyes open, you may stumble over a piece that will do the job for free, but what's your time worth waiting for that to happen?

[entsminger]

Ok, what was just said helps a little. I'll start looking for steel shops. As for how far I want to shoot it? Well what ever distance these folks are shooting at mortar shoot competitions? I've only watched, never been in one. I'm guessing it's only a couple hundred yards at best? One reason I want to do this is that I love the big mortars and I don't know of  many people ever shooting anything as big as a 13 inch mortar at mortar competitions.  Of course maybe they have and I just haven't heard of them? Anyway, I know mine would not be authentic in that it might be hollow but if it was solid it would be too dang heavy to take to any competitions unless I brought it by tractor trailer and crane which I don't have. I'm guessing mine might end up weighing around 2 or 3 thousand pounds or more. I can deal with that. I still would really like to talk to one of you in person. Maybe then I could better explain what I'm trying to do ?

  Scott

[Double D]

let me repeat my self...

Next week October 7th and 8th out at Fort Shenandoah near Winchester VA. The North-South Skimish Association will hold it's fall skirmish. The 7th the mortars shoot at about 2PM. Go out and talk to the people out there. See what they say.

[Cat Whisperer]

Perspective & reality check.

Petersburg earlier this afternoon.


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One of these (Darlene) stands right at 5'-0" high.
One of these is real, the other a replica.
One of these is the love of my life, the other just fun to shoot.
One of these is more dangerous than the other - perhaps a toss up.

[entsminger]

Are you serious about the Petersberg 13 inch mortar being a replica?? I know they just had the carriage replaced but I always assumed the barrel was authentic?
  Well I just got an e-mail from a cannon maker where I posed my question of either me or them making my hollow cannon shootable with a thick steel liner and he said emphatically not to do it citing a bunch of over my head ordnance lingo/math fit for a rocket scientist. Very discouraging. Still looking into the possibility of doing it any way for now.

  Scott

[Cat Whisperer]

I was just quoting the sign inside the building that said 'replica'.  There is a website (one of those in the sticky's) that lists the # of 13" seacoast mortars made, number remaining (known) and I think the locations.

The tube did look much older than the rest of the ironwork, but then, it was a casting and not CRS.