Barrel lenth Vs. Boom

[RvanM]

How much does barrel lenth affect how loud the boom is? Example, I have a .22 riffle and a .22 pistol. When I fire the same round in both guns the pistol seems much louder. Does this effect hold true with cannons?

[GGaskill]

It probably is more or less true with all firearms.  The higher the exit velocity of the powder gasses, the louder the boom.  With cannons, however, shorter barrels tend to have larger bores (for the same scale, at least) and a larger bore requires a larger charge to produce the same amount of boom.

[RvanM]

What about mortars?  Would it seem like a mortar with a 2" bore is louder than a 2" bore napoleon with the same powder charge?

[GGaskill]

The deal with mortars and howitzers is they have a powder chamber that is substantially smaller than bore diameter, so a standard charge is going to expand even faster into the larger bore giving lower muzzle pressure.

You get a good boom from them when firing shot but not so good with blank loads.

[Cat Whisperer]

How much does barrel lenth affect how loud the boom is? Example, I have a .22 riffle and a .22 pistol. When I fire the same round in both guns the pistol seems much louder. Does this effect hold true with cannons?

The longer the tube the longer the burn.  A mortar with a 24" tube (beer can caliber) will do a dull 'thunk' - not unlike the sound on the video clips of the 60 and 81mm mortars.  BUT a mortar with a tube only as long as the beer can has quite a muzzle blast and sharp report!  The gasses are still expanding fast and support the shock wave that goes through you.

In the same respect, the longer tube requires less powder to launch thesame distance - it is more efficient in using the fuel it has to work with.

[RvanM]

So for a ground shaking boom from a signal cannon I would want a short barrel that could handle a large load, right? Please forgive my ignorance, I just have been around many cannons.

[GGaskill]

The bore needs to be small enough that there is resistance to the gasses escaping.  I have burnt 4 ounces of powder in an unloaded bowling ball mortar and got only a woosh while the same amount of  powder in the same barrel with a bowling ball gives a good boom.  The expanding gas needs to reach the muzzle under pressure, whether from a shot or inertia and confinement, to produce sound.  If you don't want to fire a shot, load up a small paper bag with some dry sand and ram that down over the powder.  Just make sure it doesn't weigh more than a proper shot would or you will be creating a dangerous situation.

Try to go to a cannon shoot and see what gun produces what sound.

[Cat Whisperer]

The bore needs to be small enough that there is resistance to the gasses escaping.  I have burnt 4 ounces of powder in an unloaded bowling ball mortar and got only a woosh while the same amount of  powder in the same barrel with a bowling ball gives a good boom.  The expanding gas needs to reach the muzzle under pressure, whether from a shot or inertia and confinement, to produce sound.  If you don't want to fire a shot, load up a small paper bag with some dry sand and ram that down over the powder.  Just make sure it doesn't weigh more than a proper shot would or you will be creating a dangerous situation.

Try to go to a cannon shoot and see what gun produces what sound.

Good advice.  Most signal cannons I've seen have 1" bores with 12 to 18" tubes.

[RvanM]

Any cannon shooting going on around Kansas City? I think I would enjoy looking at cannons and watching them fired.

[Cat Whisperer]

Any cannon shooting going on around Kansas City? I think I would enjoy looking at cannons and watching them fired.

I've only heard small arms fire when going through KC.



Serously, though, I'm sure that there are a few cannon folk in the area, it's just a matter of finding them.

[Double D]

Again I turn to the  Complete Cannoneer for the answer.  Use double the charge recommended for ball.  No wad of any kind.

A package of dry granular material can be loaded over the charge. Dry flour is commonly used and was shown in some 1988 pressure transducer test to not cause any significant breech pressure issues.  Other concerns were the type of fouling  and the possibility of flour dust explosions or the flour gets loaded first.  The complete Cannoneer mentions just such an incident happening and the primer set the flour to smoldering creating  a whole new set of problems in how to clear the gun.  The Complete cannoneer  recommends no wadding over charge.

[RvanM]

Ok Ok Double D, I can take a hint  :grin:  I'm going to order the complete cannoneer as soon as my South-Bend  catalog gets here. Sounds like this is the book that tells you how to operate your cannon and keep your body parts.