8 inch & 10 inch Parrott rifles

[jacobmuller]

Originally Posted by Pursuivant

I'm not even going to try to guess as to the 10-inch 300 lb. Parrot Rifle's ballistics. Based on kinetic energy at the muzzle damage should be 426d cr per DHC's formula.

IMHO & YMMV
In my experience, endless hours of precision mathematics, when converted to GURPS granularity, are a disturbingly close match.
Case in point: all those stats &tc and you get 426d6... Spaceships 28cm gun 6dx7 dDam, ie 420d6.
It's a completely different thing? The damage in Spaceships is multiplied by the relative velocity, in miles per second 🤔 Bah, humbug, use the handy ballpark figures - they are a disturbingly good match (wonder why? They're a distillation of all that maths into a playable format at GURPS level of granularity - priceless cut gems, ready to mount).
IMHO & YMMV

[Rupert]

Originally Posted by jacobmuller

IMHO & YMMV
In my experience, endless hours of precision mathematics, when converted to GURPS granularity, are a disturbingly close match.
Case in point: all those stats &tc and you get 426d6... Spaceships 28cm gun 6dx7 dDam, ie 420d6.
It's a completely different thing? The damage in Spaceships is multiplied by the relative velocity, in miles per second 🤔 Bah, humbug, use the handy ballpark figures - they are a disturbingly good match (wonder why? They're a distillation of all that maths into a playable format at GURPS level of granularity - priceless cut gems, ready to mount).
IMHO & YMMV

Given that the 28cm gun is firing a warhead of about a 1/4 tons (500 pounds) and you're assuming the base damage, so an impact velocity of a mile per second (5280 ft/s), while even the 10" Parrott is only firing a ~300 pound shell at about ~1600 ft/s, something has gone badly wrong somewhere as the 28cm gun has approaching twenty times the kinetic energy of the Parrott.

[Fred Brackin]

Originally Posted by Rupert

Given that the 28cm gun is firing a warhead of about a 1/4 tons (500 pounds) and you're assuming the base damage, so an impact velocity of a mile per second (5280 ft/s), while even the 10" Parrott is only firing a ~300 pound shell at about ~1600 ft/s, something has gone badly wrong somewhere as the 28cm gun has approaching twenty times the kinetic energy of the Parrott.

To produce those smooth mathematical progressions it specializes in Spaceships is glossing over some important breakpoints. At 1 mile per second only pentrators made od DU still act like solid objects. Other compositions undergo structural failure and should probaly be treated as Frangiible or soemthign similar.

At 2 miles per second nothing penetrates like a solid and at 3 miles per second or higher everything explodes like a meteor.

This is very likely too complicated for a simple system like Spaceships to be simulationist about and indeed pretty much no other system does it either.

[Pursuivant]

Originally Posted by ericthered

Why are you using a long barrel? I'd though most TL5 artillery was considered short.

Some of the really big late 19th c. siege guns had barrel lengths which approached or exceeded those of later 20th c. artillery guns. They just appear shorter because the barrels had to be thicker due to lower TL/poorer quality metallurgy.

You might be right, however, since I didn't look up the exact barrel lengths for ACW era siege guns when I was doing my GURPS 3E Vehicles gun calculations.

[Pursuivant]

Originally Posted by johndallman

It was a lot faster than that for naval guns. Age of Napoleon for 3e has RoFs of 1/20 to 1/33 for cannon, and 1/55 for a 13" mortar.

Thanks for the data points. I knew they were lurking somewhere in the GURPS 3E library.

That said, most late 18th/early 19th c. naval guns topped out at 24 to 32 lbs. - meaning a maximum 32 lb. round ball as ammo plus powder charge, tamponade, etc. That's sufficiently "light" that it could be handled and loaded by one man, which makes sense given than most naval guns were designed to be operated and fired in incredibly cramped quarters.

The guns under discussion are monsters developed in the 1850s, which were the direct precursors of modern artillery. Some of them still used old style 24, 32, etc. pound round shot, others used bullet shaped shot.

[Rupert]

Originally Posted by Fred Brackin

To produce those smooth mathematical progressions it specializes in Spaceships is glossing over some important breakpoints. At 1 mile per second only pentrators made od DU still act like solid objects.

Tungsten carbide penetrators do too. Most others still act like solids, they just act like solids that aren't strong enough to stay in one piece and shatter or splash.

[Rupert]

Originally Posted by Pursuivant

Thanks for the data points. I knew they were lurking somewhere in the GURPS 3E library.

That said, most late 18th/early 19th c. naval guns topped out at 24 to 32 lbs. - meaning a maximum 32 lb. round ball as ammo plus powder charge, tamponade, etc. That's sufficiently "light" that it could be handled and loaded by one man, which makes sense given than most naval guns were designed to be operated and fired in incredibly cramped quarters.

The guns under discussion are monsters developed in the 1850s, which were the direct precursors of modern artillery. Some of them still used old style 24, 32, etc. pound round shot, others used bullet shaped shot.

The British were using 42-pounders for some of that period (though they didn't have as many as they wanted, so many ships that were intended to be fitted with them had to settle for 32-pounders), and 64-pounder carronades.

Such guns were manned by a team, not just one loader, and the limitation wasn't so much the weight of the shot (until the shot weight gets over 50-60 pounds, then it becomes a problem too), but the weight and handiness of the gun.