Cannon Internal ballistics

T

TXAZ

New member
How much powder at what angle yields what range?

Ballistics is one of our HS Physics topics.
The external ballistics of a cannon ball are well modeled for HS students.

But I don’t find internal ballistics calculators for a simple cannon that can take a given powder, barrel length, bore and cannon ball weight to establish muzzle velocity.

Any help or pointers appreciated.
 
Thanks KKB. That helps.
Now all I need is a conversion for how much powder creates how much pressure.

Anyone have a source for something like “each grain of powder xxx creates Y psi in a volume of zzz”? Or other expansion ratio?
 
TXAZ said:
Now all I need is a conversion for how much powder creates how much pressure.

Anyone have a source for something like “each grain of powder xxx creates Y psi in a volume of zzz”? Or other expansion ratio?
Click to expand...
Isn't that built into the formula?
 
AB,
the formula talks about the 'length' of the powder charge. I"d like to start with a weight of a specific common powder and show a certain quantity by weight is going to generate a certain pressure in a certain time that then pneumatically(?) pushes the cannon ball out of the barrel.

I've seen some loads aren't necessarily in a disk shape with the same diameter as the barrel and specific thickness.
 
Since you say cannonball, that tells me you're talking about muzzle loading cannon, and the "specific common powder" used in muzzle loading cannon was, and is, "gunpowder", today referred to as "black powder".

I"d like to start with a weight of a specific common powder and show a certain quantity by weight is going to generate a certain pressure in a certain time that then pneumatically(?) pushes the cannon ball out of the barrel.
Click to expand...

A given weight of powder does not produce any pressure, it produces a given amount of gas when "burned". Containment of the gas, is what produces pressure. So one of the important factors that must be accounted for in any formula intending to show "X amt powder produces Y amount pressure" must include the VOLUME of the containment.

Light off a certain weight of powder in the small "pressure vessel" of a cartridge case and you get several thousand PSI pressure, enough to do the useful work of launching the bullet.

Light off the same amount of powder in a (sealed) 55 gallon drum and you get a much, much lower amount of pressure, due to the volume of the containment vessel vs. amount of gas produced.

Light that same amount of powder on the floor of a warehouse, where the building is the containment vessel, and you get about zilch for pressure. (unless you face is close to the burn you won't notice the pressure :rolleyes::eek:)
 
quite meaningless in the end.

doesnt explain the big boost that occured when the english started creating the wrought iron breech loaders used on the mary rose.

last i checked, the ENTIRE BARREL was part of the chamber just like a muzzle loading shotgun.
 
last i checked, the ENTIRE BARREL was part of the chamber just like a muzzle loading shotgun.
Click to expand...

Since the chamber and bore are cut from the same piece of metal, you can say that about all firearms, other than revolvers.

The increase in area the powder gas fills as the bullet moves down the barrel is covered by expansion ratio calculations. Which are the step beyond what the OP was asking about. If he continues his research, he'll run across them soon...
 
And if you are dealing with "old" enough data to worry about the Mary Rose then do you have "corned powder" or just mixed. And what size granules? And how consistent is the mix?
It was not uncommon for the first couple hundred years of gunpowder weapons to have powder mixed by the gun crews, part of the important skills. Which leads to LOTS of variation between powder lots from different formulae, quality of the charcoal/nitre/sulfur used and even the weather when mixed.
 
even into the civil war each barrel was technically going to need a different load to get the powder tester to hit the minimum number for the infantry load. Cannon no less different.

and if you calculate windage of the projectile into the formula, you get an even larger migraine from trying to calculate.

in reality the only things to worry about are :

did we go over the maximum powder charge for the projectile?
 
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