Metal Strength Obfuscation

[Cat Whisperer]

BUT it will give you plenty of velocity for not much powder!

[Dross Drunk]

The combination of bore diameter and length you propose will be more of a howitzer than a mortar.  Mortar bores are typically only two calibers (bore diameters) long.


 I think I might have misspoke, what I meant to say is that I plan on having a fixed mount like some mortars with the trunnions all the way to the rear,and mounted on more of a skid than with any style with wheels.

 The cannon itself I had thought of building would be more like a signal cannon, or line throwing cannon ,and the dimensions will be as I mentioned earlier, but with this information added, I plan on using one dimension from bore to breech, terminating in a concave,rather than having a powder chamber, and of the approx. 10" of length the bore depth will most likely be about 7 1/2", leaving 2 1/2 of solid material at its base, of which I will be most likely using up 1/2" of that thickness for machining and trunnion mounting.

 I am adding a couple of different pictures of others I have found that are similar to what I have in mind.



 
 It could by accident end up being a hybrid combination of both,but I will search endlessly to find an authentic to replicate before I draw one up...

[dan610324]

your second picture is what we in Sweden call an trap gun, used by hunters .
an thin line was attached to the gun, when the animal walked into that line the barrel tipped over and the percussion cap hit the stand and fired the gun in direction to the animal .

[Dross Drunk]

The second cannon

 Is actually called a Lyle Gun, Lyle guns were designed to throw projectiles weighing up to 15 pounds, carrying heavier rope over 1000 feet.and often times were used for boats in distress

 It's funny you would mention using them for hunting though because  this gun was actually made by Edmund S. Hunt, of Weymouth, Massachusetts..

 this is also a picture of a Lyle gun ,a little heavier but close to the design I'm thinking of making

 

[Dross Drunk]

Another Confusion


 I am going to try and add 2 pictures the normal way,but for some reason my ftp pages  are acting up,so I am trying one of my mail hosts.... so please excuse, any out of format pics until I can resolve this issue..

 My new question has to do with directional force with blank loads, pertaining to the 2 designs I have fashioned here.

 I understand in the pic with the powder chamber that I can keep the overall dimension down and leave out that first 1/4" reduction at the breach end,by just starting out with a smaller diameter piece, and still achieve the 1 caliber rule.

 but in the pic without the powder chamber I have maintained a 1 1/2" bore all the way to the end,

 So my question is this. isn't the design without the powder chamber just as safe if not safer than the one with ?

 True a reduced powder chamber could limit the powder charge to the chambers pocket size,but even with a smooth narrowing wont that result in  that instant of  transition from powder chamber to bore in  an increased radial pressure due to this instant widening, as this explosion does want to be 360 degrees, and will choose the path of least resistance to try and achieve this.

  The second question is, wouldn't the one without a powder chamber be satisfactory?, as the metals thickness still follows the 1 caliber rule in the breech area, and with  the intent of this design to only shoot blanks with maybe a small leather wad, is't it better that all roads lead straight out with no diviation ?

 any comments would be greatly appreciated

[Dross Drunk]

Sorry about that

 I will have to attach them like a newbie until I get my ftp sorted out...sorry.......

[GGaskill]

The increase in bore size at the mouth of the chamber will actually cause the pressure to go down at that point because of the larger volume in an equal length.

But the pressure goes down the whole length of the bore for the same reason (the volume is increasing.)  That is why barrels are thinner towards the muzzle.

[Dross Drunk]

 So then would it be suitable to use the design in the second pic, if say the measurements  were say 4 1/2" diameter at breech end with a 1 1/2" bore all the way down, and then just reduce the material, perhaps by an 8th of an inch on the 2 steps leaving it still either 4 inches or 4 1/4' at the bore end...

 Once again I want to mention that I intend this first mortar/cannon project to fire only blanks,and I would most likely use a powder chambered style design on any I had intended for projectiles.

 I guess everything evolves for the better to some degree,I remember when I first started firing big shells in fireworks we would load sometimes 4-5 oz of powder in a paper bag and just drop in the bottom of an iron tube,and lower a big 8 or 10inch shell fuse down on top of it,and that was that.

 Now most shells have their lift charge attached at the base of the shell in a cup greatly reduced from the shells diameter, just like a powder chamber.......

[GGaskill]

I would say you could run a straight taper from the front of the powder charge to the muzzle with a 2.5" diameter at the muzzle.  The pressure falls off faster than the volume increases due to heat loss.