Paixhans' Monster Mortar

[Terry C.]

While searching out mortar photos (for possible future projects) I came across the subject of the "Mortier Monstre" invented by Henri-Joseph Paixhans.

Paixhans is also credited with invention of the shell gun in 1823.


I know about Mallet's Mortar from our discussions here, and Tracy and Mike's excellent scale reproduction.

Like Mallet's Mortar, the Monster Mortar had a 36" diameter bore. The shells weighed 500kg.

Unlike Mallet's Mortar which was not finished in time to be used in the Crimean War, the Monster Mortar was "used to terrible effect in the Siege of Antwerp in 1832."

This would mean that the Monster Mortar predates Mallet's mortar by at least two decades.

This drawing is the only image I've found of the Monster Mortar on the web:


click here for full sized image


Does anyone have more information on this huge mortar (and hopefully a more detailed image)?

Paixhans' Monster Mortar on Wikipedia

[seacoastartillery]

Terry,

     I did a little research on this big mortar tonight and I found that it was a 24" mortar which threw a 1,015 lb. shell and was indeed used at the seige of Antwerp, Belgium by the French.  The results were not stellar though.  As sometimes happens with Wikipedia info., it's just plain wrong.  I kept wondering, how could the shell for the Mallet's Mortar weigh 2,500 lbs. and the one for Paixhan's Monster Mortar weigh only about a 1,000 lbs?  It can only be the bore size.  After all the two 20" Rodman guns which still exist in NY and in NJ each throw 1,080 lb. cored shot which has a much much thicker wall than Paixhans'  24" mortar bomb.  You can read all this for yourself at the following link to Ure's Dictionary of Arts, Manufactures and Mines, published in 1867.


                                               http://books.google.com/books?id=IgQMAAAAYAAJ&pg=RA1-PA209&lpg=RA1-PA209&dq=paixhans+mortars+seige+of+antwerp&source=web&ots=cr0H2EcOEO&sig=b61mKDHWmzGYsCGczLYibVJ4pOU#PRA1-PA209,M1

I did about 25 searches; this is the only one that gave some useful info.

Good luck with it!

Tracy   

[Terry C.]

As sometimes happens with Wikipedia info., it's just plain wrong.

Yep.

Reading the article again, Wiki lumps the Mallet and the Paixhans together, but only gives the bore of the Mallet as 36". So it could have been my misinterpretation of the article. It was late.

Even so, this was a BIG mortar.


I found another link this morning that gives more details and actually some dimensions. According to The Mechanics' Magazine, Museum, Register, Journal, and Gazette, the tube was 4'11" inches long, 39½" in diameter, 24½" diameter in the bore, and weighed 14,700 pounds.

The bore was shallow at 27", only a little over one caliber.

The chamber, which is a 9" x 19" cylinder (as best I can read it) with a hemispherical bottom, held a maximum charge of 30 pounds.

See pages 374 & 375

[seacoastartillery]

     Terry,    You really found a gem there with the Mechanics Magazine.  We believe you could build a real nice scale mortar with that good dimensional information.  Was Paixhans' mortar participating in a civil war, or was Antwerp located in a different country back in 1832?  How could Belgian officers be standing around, when you are bombarding Antwerp?? 

Regards,

Mike and Tracy

[Terry C.]

That historical information is beyond my realm of knowledge. The article does say that the mortar was tested "in the presence of a number of French and Belgian officers."

Perhaps the illustration represents the trials and not the siege itself.

Also interesting is that there were problems with the first batch of shells rupturing when they exited the muzzle, because they were cast too thin. That could definitely have a negative impact on the gun crew's morale!


The dimensions given would be sufficient to build a tube to scale. Something that is not shown in the detail drawing is the lateral distance between the dolphins. Just from my impression of the original illustration, I would put them about 30° to either side of TDC. Their size and location can only be estimated from the overall proportions.

[Terry C.]

With straight sides, a flat bottom, and no trunnion, this would not be a difficult tube to machine.

The dimensioned drawing in the article is not perfectly to scale, but it's very close. Close enough to work out the approximate size and position of the four welded-on dolphins to an acceptable degree. Unless a more detailed drawing is found, 'close' is as good as it can get.

Scaled to golfball caliber, it's also not very big. Should be a good project for smaller lathes.

These are the dimensions I got by converting the bore to golfball caliber and scaling the rest of the mortar proportionately:




The only change that I would make, were I to build this, would be to use a 5/8" drill for the chamber. The difference between .625" and .633" diameter is negligible, and I already have a 5/8" drill ground to cut a hemispherical chamber bottom.

[seacoastartillery]

These are the dimensions I got by converting the bore to golfball caliber and scaling the rest of the mortar proportionately:




     Terry,   We are happy that you brought this method to everyone's attention.  This is a very effective, but simple, way to keep things pretty much in scale.  This is our method for making anything, and, although we are slaves to detail, you can also make simple designs this way too.  A very clear drawing like yours will help to keep your thoughts and build error free.
Looking forward to seeing the siege of Antwerp in miniature when it's completed.

Regards,

Tracy and Mike

[Terry C.]

I did some quick calculations and the chamber should hold about 89½ grains of powder as drawn, about 87 grains if drilled .625" instead.

I need to get out the powder, the scoops, and the scale to verify the numbers.

[Cat Whisperer]

Don't forget to account for the size of the drilled hole being slightly larger than the size of the bit.