Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 09-16-2016, 12:56 PM   #11
johndallman
Night Watchman
 
Join Date: Oct 2010
Location: Cambridge, UK
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by Icelander View Post
At TL4, breech-loaders like the Swivel-Gun can be reloaded much faster than muzzleloaders, but cannot withstand as much pressure and presumably lose some of the potential energy from the propellant through the breech.

At least, the low, low damage for the swivel guns in Fantasy and LT seems to suggest this.

Does anyone have an idea as to how much energy is lost through a breechloading design at TL4, compared to a muzzleloading one?

That is, with a gun of the same caliber, weight of shot and weight of powder, how much less Dmg and Range should one get?
If you try to load a TL4 breech-loader with the same weight of powder as a muzzle-loader, you'll probably burst it. You need to use less powder, to make it even reasonably safe to use. I'd halve range and damage.

However, a small gun like a swivel is quite easy to muzzle-load compared to a gun on a carriage. The point of the swivel mount is that it does not recoil: the mount and the structure of the ship that it is mounted on take the shock without movement beyond brief flexing. To reload it, you can just swing it on the mount so that the muzzle is accessible, and sponge, load and ram it by hand. One man can operate it, and the only real role for a larger gun crew is a second man to pass him implements and ammunition, which will speed up the RoF a bit.

For your original questions, I'd use your steel supplies for the mounted muskets, and make the 1- and 3-pounders in bronze. The advantage of iron over bronze was its cheapness, once adequate furnaces were developed, but that doesn't apply in your circumstances. Steel artillery didn't become significant until good steel became cheap at the end of TL5.

To make better swivel guns, use good quality control, and invent a better boring machine, to make their bores more truly cylindrical. That seems like a job for your TL4+1 designer.

To make rifled muskets effective, invent the Minié ball, and apply good quality control. Again, a good job for a higher-TL man.
johndallman is online now   Reply With Quote
Old 09-16-2016, 02:18 PM   #12
Polydamas
 
Join Date: Jan 2006
Location: Central Europe
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by Whyte View Post
Thanks!

Quote:
Originally Posted by Icelander View Post
Does anyone have an idea as to how much energy is lost through a breechloading design at TL4, compared to a muzzleloading one?
No, but I am sure that one of the sixteenth-century manuals discusses it. Its probably even more a matter of rules of thumb than early gunnery in general (the first step was often "make sure that your gun has been bored straight and double check all its dimensions"), but they liked explaining how to calculate the appropriate load of powder.

Those books on the Armada may also discuss it. We have the reports of how much powder and shot the survivors had when they returned, and one of the things which leapt out is that many of them had fired their small pieces empty but only shot their big guns one or twice a day.

Edit: The big advantage of a breech-loader was that you could load the spare chambers in advance. That was a big deal in the days of hand-loading from a ladel while within pistol-shot of a lot of scared angry people. Guns which were too big for a swivel were rarely breach-loaders because of the problems containing the gas with high-tech mechanisms like a hammering a wedge between a frame and the breech.
__________________
"It is easier to banish a habit of thought than a piece of knowledge." H. Beam Piper

This forum got less aggravating when I started using the ignore feature

Last edited by Polydamas; 09-16-2016 at 02:53 PM.
Polydamas is offline   Reply With Quote
Old 09-16-2016, 03:36 PM   #13
johndallman
Night Watchman
 
Join Date: Oct 2010
Location: Cambridge, UK
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by Icelander View Post
There exists some REF 0.4-0.5 smokepowder, but the variety that the PCs use is REF 0.8, comparable in power to early smokeless powder.
Use the low-powered stuff for canister rounds. You'll only be firing those at very close range, so the reduced power is less of a problem.
johndallman is online now   Reply With Quote
Old 09-16-2016, 03:54 PM   #14
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by johndallman View Post
Use the low-powered stuff for canister rounds. You'll only be firing those at very close range, so the reduced power is less of a problem.
Unfortunately, the Dmg of canister is proportional to the Dmg of ball ammo, so using reduced power loads means reduced Dmg.

Which is contraindicated. Canister isn't worth much if it can't stop the armoured shock infantry that usually attacks in the first rank of the enemy.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 09-17-2016, 07:02 AM   #15
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by johndallman View Post
If you try to load a TL4 breech-loader with the same weight of powder as a muzzle-loader, you'll probably burst it. You need to use less powder, to make it even reasonably safe to use. I'd halve range and damage.
Ok, but are you using half a powder charge or are you using more than that and losing some of the power because the breech-loader bleeds energy through the breech?

The degree of inefficiency matters to my designers, because of the cost of the smokepowder. On the other hand, this is a fantasy setting with contacts to other lands, and the PCs did recently meet some giff who come from a place where ordinary black powder works. So they'll be able to see normal gun designs and decide whether to retain them for their advantages or discard them because inefficiency which is irrelevant where powder costs $10-$40 per pound can be crippling where it costs $700 to $7,000 per pound.

Quote:
Originally Posted by johndallman View Post
However, a small gun like a swivel is quite easy to muzzle-load compared to a gun on a carriage. The point of the swivel mount is that it does not recoil: the mount and the structure of the ship that it is mounted on take the shock without movement beyond brief flexing. To reload it, you can just swing it on the mount so that the muzzle is accessible, and sponge, load and ram it by hand. One man can operate it, and the only real role for a larger gun crew is a second man to pass him implements and ammunition, which will speed up the RoF a bit.
That's true, but wouldn't a breech-loader be even quicker to load?

Quote:
Originally Posted by johndallman View Post
For your original questions, I'd use your steel supplies for the mounted muskets, and make the 1- and 3-pounders in bronze. The advantage of iron over bronze was its cheapness, once adequate furnaces were developed, but that doesn't apply in your circumstances. Steel artillery didn't become significant until good steel became cheap at the end of TL5.
What benefit does the steel give us for the mounted muskets, over bronze?

There is a nearly inexhaustable demand for good steel for making springs for shipboard mechanical artillery and for crossbows. Swords, pikeheads, bayonets and armour-piercing lozenges or spikes for arrows and bolts also need steel. I suppose armour plates, helmets and bracers could use either bronze or steel, but the mercenaries that the PCs are mostly hiring from would consider bronze inferior to good steel, even if the stats were the same.

Quote:
Originally Posted by johndallman View Post
To make better swivel guns, use good quality control, and invent a better boring machine, to make their bores more truly cylindrical. That seems like a job for your TL4+1 designer.
Those who are TL4+1 in the setting are generally just TL4+1 in one or two skills and they tend to view themselves as master craftsmen. They have no showed much interest in making tools that allow less skilled craftsmen to duplicate their work.

What was used at historical TL4 to bore out the barrels and what would you imagine could be a better, TL4+1 method of doing it?

Good quality control will be implemented, largely because Administration and Merchant skills in the 20s must be good for ensuring that the supplies you get are those you really wanted and needed. Also, the Measurement spell can replace a lot of technology they do not have yet. A senior apprentice can cast it without FP cost, limited only by the time he can work at an acceptable level of mental focus and his work ethic, so eight hours for the best of them.

Quote:
Originally Posted by johndallman View Post
To make rifled muskets effective, invent the Minié ball, and apply good quality control. Again, a good job for a higher-TL man.
This didn't emerge for an incredible number of years in real history, despite obvious advantages. I think I'll avoid having anyone discover it until or unless PCs with Engineer skills decide to spend points on Gadgeteering and spent time on Inventing.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 09-17-2016, 07:38 AM   #16
johndallman
Night Watchman
 
Join Date: Oct 2010
Location: Cambridge, UK
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by Icelander View Post
Unfortunately, the Dmg of canister is proportional to the Dmg of ball ammo, so using reduced power loads means reduced Dmg.
OK, but you can use more of the low-powered stuff. Inverse proportion of REF would be a place to start for the charge ratios.
Quote:
Originally Posted by Icelander View Post
Ok, but are you using half a powder charge or are you using more than that and losing some of the power because the breech-loader bleeds energy through the breech?
Probably a little more than half, because of the bleed, but if you're developing enough pressure that the bleed is getting serious as the gun distorts, you ought to be using less powder.
Quote:
That's true, but wouldn't a breech-loader be even quicker to load?
Pretty similar, in that size. You need to take out the wedges, lift out the chamber - and it's pretty hot - drop in the other one, and re-wedge. And you drive those wedges hard, because if they come lose, you get injured. You need someone else to reload the other chamber.
Quote:
What benefit does the steel give us for the mounted muskets, over bronze?
Mostly less weight. With so much demand for steel for other purposes, probably not worth it.
Quote:
What was used at historical TL4 to bore out the barrels and what would you imagine could be a better, TL4+1 method of doing it?
Vertical boring machines, usually water-wheel powered, I believe. Getting truer bores would require a more rigid machine, probably metal-framed rather than timber, and a better clamping mechanism for the gun being bored.
johndallman is online now   Reply With Quote
Old 09-17-2016, 11:15 AM   #17
Polydamas
 
Join Date: Jan 2006
Location: Central Europe
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by johndallman View Post
Vertical boring machines, usually water-wheel powered, I believe. Getting truer bores would require a more rigid machine, probably metal-framed rather than timber, and a better clamping mechanism for the gun being bored.
However, before they could insert the borer, they had to remove the core around which the barrel had been cast or forged. If the core had shifted, and the walls of the tube were thick at one side and thin on the other ... well, that is why gunners prayed to St. Barbara and carefully inspected each new piece before trying it.
__________________
"It is easier to banish a habit of thought than a piece of knowledge." H. Beam Piper

This forum got less aggravating when I started using the ignore feature

Last edited by Polydamas; 09-17-2016 at 11:19 AM.
Polydamas is offline   Reply With Quote
Old 09-17-2016, 05:35 PM   #18
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by johndallman View Post
Vertical boring machines, usually water-wheel powered, I believe. Getting truer bores would require a more rigid machine, probably metal-framed rather than timber, and a better clamping mechanism for the gun being bored.
Quote:
Originally Posted by Polydamas View Post
However, before they could insert the borer, they had to remove the core around which the barrel had been cast or forged. If the core had shifted, and the walls of the tube were thick at one side and thin on the other ... well, that is why gunners prayed to St. Barbara and carefully inspected each new piece before trying it.
This is for bronze or steel barrels?

Making the machine out of metal should be doable, as I expect they'll be okay with spending several times more on each barrel than was done historically.

Hmmm... magic provides several options for improving the process. The core around which they cast could be made from something magical which disappears after a while or, alternatively, magic could be used to destroy the core.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 09-17-2016, 05:58 PM   #19
johndallman
Night Watchman
 
Join Date: Oct 2010
Location: Cambridge, UK
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by Icelander View Post
This is for bronze or steel barrels?
Bronze or cast iron. The casting and boring technology is actually quite similar for both materials.
johndallman is online now   Reply With Quote
Old 09-17-2016, 06:00 PM   #20
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Swivel Guns (TL4-TL5)

Quote:
Originally Posted by johndallman View Post
Bronze or cast iron. The casting and boring technology is actually quite similar for both materials.
Would having the core be made of iron work?*

Of course, if you're going to make cores with Shape Metal spells, you might as well make the barrels that way.

*The iron created with Wall of Iron is normal, average quality iron for most purposes, but will disappear if Dispel Magic is used.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Reply

Tags
artillery, cannon, fantasy, high-tech, low-tech

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 02:46 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.