Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos - Graybeard Outdoors
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post #1 of 94 (permalink) Old 01-19-2009, 12:11 AM Thread Starter
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Default Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

This will be Mike and Tracy's first mortar build, so we are asking for a little help from those of you who have built mortars before. This mortar will not be duplicated by us. One is going to be enough, we believe. The object of this build is to launch a heavy, solid concrete projectile weighing approx. 180 lbs. from a mortar set at 60 deg. elevation to a distance of at least 100 yards accurately and SAFELY, and perhaps have a 300 yard maximum range. We think that 1 lb. of 1 Fg BP should get us to 100 yards and maybe 2 lbs. should be adequate for 300, so our chamber size should hold 2 lbs. until range experiments prove otherwise. An initial design sketch is almost done and we will post it in a day or two and you experienced builders can rip it to shreds. We expect at least two or three rounds of revisions before an effective and SAFE design can be decided upon. The photo below shows a 5 Gallon water jug flanked by a 4" cannonball and a 15" Beach Ball for scale.

If you are interested, a brief bio on Col. Paixhans and the testing and battle use of the Monster Mortar is also included below.

Regards,

Tracy and Mike






Henri-Joseph Paixhans, 1783-1854 was a French artillery officer and ordnance inventor. He graduated from the distinguished technical university, Ecole Polytechnique and fought in the Napoleonic Wars.

In 1823, he invented the first shell guns, which came to be called Paixhans guns (or "canon obusiers" in the French Navy). Paixhans guns became the first naval guns to combine explosive shells and a flat trajectory, thereby triggering the demise of wooden ships, and the iron hull revolution in boat building. Paixhans also invented a "Mortier monstre" ("Monster Mortar"), using 500 kg bombs, which was used to terrible effect in the Siege of Antwerp in 1832.

"Paixhans had so far satisfied naval men of the power of shell guns as to obtain their admission on shipboard; but by unduly developing the explosive element, he had sacrificed accuracy and range.... The difference between the system of Paixhans and my own was simply that Paixhans guns were strictly shell guns, and were not designed for shot, nor for great penetration or accuracy at long ranges. They were, therefore, auxiliary to, or associates of, the shot-guns. This made a mixed armament, was objectionable as such, and never was adopted to any extent in France... My idea was, to have a gun that should generally throw shells far and accurately, with the capacity to fire solid shot when needed. Also to compose the whole battery entirely of such guns."
—Admiral John A. Dahlgren.[1]

The United States Navy adopted the Paixhans Shell Gun design, and equipped several ships with 8-inch guns of 63 and 55 cwt. in 1845, and later a 10-inch shell gun of 86 cwt. Paixhans guns were used on the Constitution know as "Old Ironsides," a wooden-hulled, three-masted frigate of the United States Navy.... (4 Paixhans guns) in 1842, under the command of Foxhall A. Parker, Sr., and were also present onboard the Mississippi (1841), (10 Paixhans guns), and the USS Susquehanna (1847), a sidewheel steamer which was the first ship of the United States Navy to be named for a river and carried (6 Paixhans guns) during Commodore Perry's mission to open Japan in 1853.

Legacy
Ironclad warships
Wooden boats became so vulnerable that the only possible response could come with the introduction of the iron-hulled Warship.

The first of them was the French La Gloire, soon followed by the HMS Warrior (1860).

HMS Warrior was the world's first ocean-going iron-hulled armored battleship.
.

The Celebrated Mortar.— It having been announced that an experiment would be made on the 24-inch (English) mortar on the heath of Braeschaet, a number of generals and officers of all arms proceeded to that village. The previous experiments made at Liege had not succeeded, either from some defect in the shell, or in the mode of firing. It had been tried with the usual wooden sabot, as well as with a wad of twisted straw ; but, with one or two exceptions, the projectile burst at the moment of quitting the piece. This was attributed to a want of thickness in the shell, particularly of the culot or part coming in contact with the charge, which, from the great diameter of the cavity, had not sufficient thickness to resist the shock of the powder and concussion of the air. Fresh shells were subsequently directed to be cast.

The first eight or ten experiments were made with the dead shell filled with its proper weight in sand, and fired with various charges, from six to twelve pounds, gradually increasing. No accident occurred. The artillery officers being satisfied with these trials, the shell was loaded to a third, and so on to its full charge, upwards of a barrel and a quarter. One shell alone burst out of six, at the mouth of the piece; the remainder fell near the target, and exploded with a fierce detonation, tearing up many cubic feet of earth, and scattering splinters to the distance of 450 yards. The shells were hoisted to a level with the mouth of the cylinder by means of a chevalet supporting a swivel bar, on the one end of which were suspended two chains with hooks to catch the rings of the shell, and on the other a weight nearly equalling that of the projectile ; it was easily raised by this means, and then lowered without any jar into the chamber. A straw-twisted wad was employed as a sabot. The operation of loading required an average of 37 minutes to 50. The vent was fitted with a spring detonator, and the man who fired stood behind a traverse and pulled the spring with a long cord.

The experiment having succeeded, it was resolved to bring the mortar into Antwerp, and preparations were made to place it in battery on the covered way of the bastion of the city, between the re-entering place of arms of Montebello and the Malines gate. Eight horses were required to draw the carriage on which it was placed, and eight others to draw the carriage containing the bed. The weight of the empty shells being nearly 1,000 lbs. it is easy to calculate the number of these projectiles that could be moved in any ordinary ammunition wagon. The weight of the bed, which is of timber, is not given in the scale, but it may be taken as at somewhat more than the mortar itself, making altogether about 30,000lbs.; add to this 110 shells for 100 rounds at 1,000 lbs. each, and 110 barrels of 90 lbs. each, and it gives the enormous dead weight of 70 tons, exclusive of gins, triangle, chevalet, carriage, and sundries. The name of Monster-mortar seems to have been well selected, for it is scarcely possible to conceive a more ugly or unwieldy implement. With the exception of the mortar at Moscow, which has thirty-six inches in diameter at the mouth of the cylinder, and was, if ever used, employed for projecting masses of granite, the monster- mortar exceeds any other weapon of the kind hitherto known. The original conception is due to Colonel Paixhans ; it was executed under the direction of Baron Evain, and cast at the Belgian royal foundery at Liege.

Firing.—At midnight, the twenty-four-inch mortar was loaded with twelve and a half pounds of powder, and the first discharge took place. The huge projectile, of which the internal charge was fifty-four pounds of powder and combustibles, was watched with anxiety as it made its parabola, and a look-out person stationed on the tower of St. Andre reported that it had fallen and exploded near the great powder magazine at the gorge of bastion Fernando. The success of the experiment was thus demonstrated. At the second shot, which took place nearly an hour later, the shell burst on issuing from the mouth of the mortar, not by explosion from the fuze, hut from the weakness of the projectile itself. Great care was therefore ordered to be taken in selecting others, of which the culots were thicker.

The dimensions are as follows:

Calibre massive, 23.62 in.
Thickness, exclusive of culot .. 2 in ,,
Weight of empty shell 9l6 lbs. ,,
Powder contained in shell .... 99 lbs. „
Weight of Shell, full charge ..1015 lbs. „
Weight of mortar (metal) 14,700 lbs. „
Weight of bed (wood) 16,000 lbs. „
Powder in Chamber (full) 30 lbs. ..

The French weight has been preserved purposely for the sake of greater accuracy.



Smokin my pipe on the mountings, sniffin the mornin cool,
I walks in my old brown gaiters along o my old brown mule,
With seventy gunners beind me, an never a beggar forgets
Its only the pick of the Army that handles the dear little pets - Tss! Tss!

From the poem Screw-Guns by Rudyard Kipling
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post #2 of 94 (permalink) Old 01-19-2009, 12:36 AM
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

I think I know the answer to my question but will ask it anyway. How did you arrive at 1 pound for a powder charge.

By the way What was the range the mortar fire at Antwerp
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post #3 of 94 (permalink) Old 01-19-2009, 01:31 AM Thread Starter
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

Well, I better answer the second one first and the answer of that will lead to the one for the first. According to all accounts I have read the range of the Citadel at Antwerp was 1,000 yards from the Monster Mortar. I only found one declaration of the charge used and it was 12.5 lbs. So, in my head I got 1 lb., but after calc. I get .8 lb., so we would start at .5 lb. and work up to whatever we actually need. To get the weight of the reduced scale charge, first get the cube of the scale. Example: The cube of a 1/6 scale is 6x6x6= 216. Or, in our case we have a 2/5 scale and to get get the cube of the scale you need a whole number, so 5/2=2.5 and 2.5 cubed is 2.5x2.5x2.5=15.625 Then you divide the original weight of the powder by the scale cubed number. So, 12.5/15.625=.80 lb.

Anyway, we always start low and work up to an accurate load and we resist going for maximum range, especially with something this big. For those of you who understand how a 40mm grenade launcher cartridge works, you also understand why we can have 1/2" wall thickness on this mortar and still be safe when it fires. Small chamber and BIG BORE makes it possible. Sometimes referred to as the HI/LO Pressure principle. Thanks DD, great questions.

Regards,

Mike and Tracy

Smokin my pipe on the mountings, sniffin the mornin cool,
I walks in my old brown gaiters along o my old brown mule,
With seventy gunners beind me, an never a beggar forgets
Its only the pick of the Army that handles the dear little pets - Tss! Tss!

From the poem Screw-Guns by Rudyard Kipling
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post #4 of 94 (permalink) Old 01-19-2009, 04:02 AM
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

You know, when guys get together to launch high-flying model rockets they have to get a clearance from the FAA.

I think you might need an OK from the USGS to shoot this thing - So they don't get any false readings on their seismographs.

;D

Edit - Just curious M&T... Is this mortar going to look like the original? What prompted you guys to make something like this?

"It is a capital mistake to theorize before one has data. Insensibly, one begins to twist facts to suit theories, instead of theories to suit facts."

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post #5 of 94 (permalink) Old 01-19-2009, 07:38 AM
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

Safe - eh?

You could always proof test with a 1/2 pound of bullseye.
You might have to dig it out of the ground, but if it survived it would be OK.


Tim K www.GBOCANNONS.COM
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post #6 of 94 (permalink) Old 01-19-2009, 07:51 AM
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Interesting project. I guess if I were doing it, I'd use a 45 degree elevation so I'd have the benefit of many old range tables for various weights of shell and powder. At 180 lbs. you are nearly at the 213 lb. weight of a 13-inch mortar shell fired from the US M1861 13-in. seacoast mortar.

We fired a 9.5-inch mortar using undersize shells of proper weight, with U-haul moving blanket sabot/wads. I think an approx. 88 lb. "shell" went nearly 150 yards with 12 oz. black powder (1F?). Anyway, we showed five rounds and the various powder charges in our video "shooting the Spanish mortar." We always do 45 degrees so we can reference old range tables.

[yt=425,350]nVj-3Rzsu8M[/yt]
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post #7 of 94 (permalink) Old 01-19-2009, 10:52 AM
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

Quote:
Originally Posted by seacoastartillery
For those of you who understand how a 40mm grenade launcher cartridge works, you also understand why we can have 1/2" wall thickness on this mortar and still be safe when it fires. Small chamber and BIG BORE makes it possible. Sometimes referred to as the HI/LO Pressure principle. Thanks DD, great questions.

Regards,

Mike and Tracy
Rapid pressure curve drop.
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post #8 of 94 (permalink) Old 01-19-2009, 11:09 AM
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

One early gun to use the high/low principle was the Simms-Dudley "dynamite gun." There were actually two separate barrels, the lower one was strictly the expansion chamber for the propellant gases from a black-powder blank cartridge. A small orifice allowed the gas to bleed into the "real" 2.5-inch smoothbore barrel on top, which was something like 15 feet long, a lot for a rather small-caliber field gun.
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post #9 of 94 (permalink) Old 01-19-2009, 11:55 AM
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

I'm learning something here. The formula for scaling charges, I have never heard that one before...or have I? Now that I think about it you covered this before in an earlier discussion on one of your other guns. I think it is a math thing but I the not quite grasping the full effect of this. Is this a scaled volume.

Will PMM have a powder chamber? If so will the powder chamber measurements scaled 1/6 have the same volume as you scaled charges or will you have to adjust the chamber to fit the charge?

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post #10 of 94 (permalink) Old 01-19-2009, 12:34 PM Thread Starter
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Default Re: Building the Paixhans Monster Mortar & Water Cooler Jug w/Concrete Projos

Victor3, I suppose we could give the USGS a courtesy call. 25 years ago we used to shoot the 1/2 scale 8" 1797 mortar in northern Colorado within 2 or 3 miles of a Titan II missle silo cluster and we always wondered if we would ever see an Air Force extra cab pickup with the two M-16s in the "easy rider rifle rack" come whizzing down the dirt road to our location. Never happened, although we saw them on those roads all the time.

Mike and I have always been fascinated by the big mortars and the ultimate to us has always been Mallet's Mortar of 1857, but a 1/3 scale recreation of that would be extra heavy and very complicated. Dominick and The Paulson brothers have already done the 13" 1861 Seacoast Mortar thoroughly, so, "What's left to do?" The big Russian, "Great Mortar of Moscow" is really a stone-throwing howitzer so it is out, so that leaves Col. Paixhans 24" Monster Mortar. Yes, there are a few others that are worthy as well, but we have to keep things simple. Simplicity is another reason for choosing Paixhans' mortar. It was basically a cylinder of cast iron with a chamber, vent and bore machined into it. Yes, it will look like the original, as an outer, welded-steel-skin will surround the functional core.

Tim, Now, now, now........I suppose you want to see some pyrotechnics, eh? Hate to disappoint a good guy such as yourself, but BLACK POWDER ONLY rules are in affect with ALL muzzle-stuffers including this one. If you come out to Broomfield on business in April, maybe you can light the fuse on this beast for it's Black Powder Proof.

Cannonmn, Thanks for re-posting that video, John, Mike and I both like that one a lot. What a beautiful mortar that is!! We will consider the 45 deg. angle, but having not seen any reference to a firing angle for this mortar, we think it might have been steeper to effect a more crushing blow, because the yardage was so short, at only 1,000 yards. And, as you certainly know, to get powder magazine or casemate arch penetration you need lots of height in your trajectory for extra speed of impact. We will not be using any "wads", but are considering a couple 3/4" thick disks of Baltic Birch plywood and a 1/4" thick disk of boiler plate bolted on to the projectile's base to protect the concrete from the central powder blast.

Those Dynamite Guns were really weird looking, but I've read that you DID NOT want to be the object of their bombardment, especially of those 15 inchers on the Vesuvius! concerning the bleed-off of black powder gasses, I wonder how long that would work without vigorous cleaning of the parts in that assembly?

Dominick, Right on! That's exactly what we are talking about. All BP mortars use that principle to launch relatively heavy projectiles with moderate powder charges without causing damage to the relatively thin wall surrounding the projectile.

Double D, You can use this formula for scaling the weight of any object as long as every dimension is reduced by the same percentage. It can be used for forms like artillery tubes or powder charges, round balls or steel I-Beams. Yes, it is a scaled volume which directly effects weight. We probably mentioned this before, but I can't remember which thread it was on. Yes, the PPM, (Paixhans Monster Mortar) will have a powder chamber and it's measurements will be scaled down to hold two pounds and not thirty. The charge that we expect will push the projectile to 100 yards is only .8 lb., but the chamber will be designed to hold 2 lbs so that we can get 250 to 300 yards out of this mortar. The scale for this mortar is 2/5, although 1/6 is what we use to reduce those huge seacoast guns down to a manageable size and weight.

Regards, Tracy and Mike




Smokin my pipe on the mountings, sniffin the mornin cool,
I walks in my old brown gaiters along o my old brown mule,
With seventy gunners beind me, an never a beggar forgets
Its only the pick of the Army that handles the dear little pets - Tss! Tss!

From the poem Screw-Guns by Rudyard Kipling
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