[Low-Tech] Chinese Guns

[Icelander]

Originally Posted by The_Ryujin

I ran the numbers for the Long Range Cannon based on the lead shot weighing 1.19kg and was fired at your estimate of 152m/s with a diameter of 58.4mm and a density of 11.34g/cc. This gives me 17.4 dice with my formula. I ran it again with Doug's and got 15.5. If I ignore density for my formula I get 15.4 dice.

That's quite a lot, considering that my estimate of 500 fps was derived from at what velocity Doug Cole's Ballistics sheet gave a projectile of that size Dmg 7d-1.

Granted, 1.19 kg for the lead ball is slightly heavier than I had modelled, as I tried lead ball from 2-lb to 2.5 lbs. (0.9 1kg to 1.13 kg). Remember, the WPS of 3 lbs. includes the propellant and that propellant is at minimum 8 oz. or 0.23 kg, according to sources on the Long-Range-Awe-Inspiring Gun.

But this is not enough of a discrepancy to explain such a wide range in the calculated damage. I'm using a version of Doug's file from February 24th, 2011.

This is how my assumptions look:

Chamber Pressure --	1090 	psi
Barrel bore -------- 	59	mm
Case Length --------	30	mm
Chamber Bore ------	60	mm
Barrel length -------	610	mm
Bullet Mass ---------	17500	grains
Aspect Ratio --------	1	L/Bore
Burn length --------	300	mm
Projectile Caliber ---	58	mm
Total Accelerated Mass	17500	grains

Velocity ---	137,1	m/sec
 -----------	450	feet/sec
Kinetic Energy	10657,7	Joules

Note that Chamber Pressure and Burn Length are not necessarily historically right, but it doesn't matter, as they are only set up to produce the right velocity. One might be higher and the other lower, as long as velocity comes out the same.

With this size ball, I get Dmg 7d-1 at velocity 450 fps. If I go down to a smaller ball of 2-lb, I need velocity 500 fps for the same damage.

Originally Posted by The_Ryujin

In order to get the books number of 7d-1 or 6.85 dice the gun could only fire at 71m/s!

That seems too high a damage for such low velocity.

Originally Posted by The_Ryujin

Given that the numbers I'm getting is roughly twice as high, I wonder if Bill accidentally halved the Long Range Cannon and left the Crouching Tiger one at full damage.

I'd think that the Crouching Tiger Gun is more likely to be wrong, as the Long-Range-Awe-Inspiring Gun actually has plausible enough stats at 450 fps, very similar to a Swivel-Gun.