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Old 09-21-2017, 01:37 PM   #11
hal
 
Join Date: Aug 2004
Location: Buffalo, New York
Default Re: Binary propellant and Standard TL 8 guns?

Quote:
Originally Posted by Fred Brackin View Post
The G-11 has nothing to go with binary liquid propellant and will not yield you any data relevant to the question.
Unfortunately, the G-11 stats are the only real world stats we have for caseless ammunition. As such, any of the Binary propellant rules are modifiers of the Caseless Ammunition rules elsewhere in GURPS ULTRATECH. As such, the G-11 is all I have to work with without it being "data pulled out of thin air" kind of things.

See next comment...

Quote:
Originally Posted by Fred Brackin View Post
You have the data for the bullets that would be used with liquid propellant. They're the same bullets used in cased ammo at equivalent velocities. Liquid propellant would just do away with the gunpowder and the cartridge that holds it.

If you think lwcamp's suggestions for propellant are much too dangerous for practical use that probably means the idea isn't practical.

After digging a bit in a book I didn't think would contain any real data on Caseless Ammunition, THE BLACKHILL MILITARY SMALL ARMS DATA BOOK published 1999, had this to say about the 4.73mm Round (page 275 if it helps anyone who also has a copy of the book!)

Bullet: 4.73 x 33 mm DM1 Caseless:

Bullet weight: 49 grains or 3.1 grams
Round weight: 186 grains or 12.05 grams
Muzzle velocity: 3051 feet per second or 930 meters per second (page 144 for the stats on the gun itself)

Propellant weight assuming round weight less bullet weight: 8.95 grams

Muzzle energy in joules would be 1373, or roughly 1012 foot/pounds per the spreadsheet that I'm working off.

Damage works out to be an average of 17.7 points per Doug's formula. Per his spreadsheet formula, that works out to 5d6, which matches the value given in GURPS CLASSIC MODERN GUNS at 5d6, and misses the newer volume of HIGH TECH's damage of 4d6+2. But, if 4d6 averages to 14 and +2 makes the average damage 16, then the difference between Doug's formula and the New 4e stats on the G11 (as compared against the older 3e version in GURPS MODERN GUNS), is about 1.7 points calculated versus the stuff that Hans says is official.

Since I don't know how Max range is calculated, and Doug's formula doesn't seem to show that value - I'm at a slight loss here. In order to bump up the damage by +1 using my spreadsheet, I have to increase velocity of the same bullet by roughly 4% (from 3051 to 3172 feet per second).

Mind you, this is all in an effort to try to create sci-fi guns that have some semblance based in realism. If the G11 round is anything to go by, then the ratio of bullet weight to propellant weight is roughly 2.89 to 1.

I'm going to have to dig up my other thread to continue discussing thoughts on caseless rounds and GURPS ULTRATECH...
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Old 09-21-2017, 03:03 PM   #12
Fred Brackin
 
Join Date: Aug 2007
Default Re: Binary propellant and Standard TL 8 guns?

Going back to 3e (specifically Ve2) Caseless ammo guns are 2x the cost of conventional guns but their ammo is half weight and volume (wps and vps). Liquid propellant guns are then treated like caseless guns but cost is 3s conventional.

So it looks to me that the stats of real world caseless guns are not special or specially related to liquid propellant. They're just both part of a simple modification scheme that could indeed be called "pulled out of thin air".

As the two caseless weapons HT has stats for are either a simple modification of a basic hunting rifle (the Saco) or a unique prototype (the G-11) that has no cased equivalent and no one has to my knowledge ever built a functional liquid propellant smallarm there just isn't much to base stats on.
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Old 09-21-2017, 03:08 PM   #13
johndallman
 
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Default Re: Binary propellant and Standard TL 8 guns?

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Originally Posted by hal View Post
Since I don't know how Max range is calculated, and Doug's formula doesn't seem to show that value - I'm at a slight loss here.
Max is the furthest distance the projectile can travel (presumably under 1G, near sea-level, and definitely with more elevation than gun sights normally provide for). It's usually very hard to hit anything near Max range on Acc grounds, but someone beyond Max range definitely can't be hit.
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Old 09-21-2017, 03:18 PM   #14
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: Binary propellant and Standard TL 8 guns?

Note that, had ultra-tech been written completely from scratch in 2007 rather than being based on earlier work, I suspect liquid propellant guns wouldn't even be in there; liquid propellant guns were a hot topic briefly in the early 90s, and thus made sense for inclusion in GURPS Vehicles, but appear to have subsided back into obscurity since then.

The big theoretical benefit of liquid propellant is that it lets have variable muzzle velocity relatively easily. This is a significant benefit for artillery (with fixed muzzle velocity, at close ranges you're forced to choose between low angle shots that may not clear near obstacles, or very high angle shots that have extreme travel time), but is not terribly useful for direct fire weapons.
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Old 09-21-2017, 05:00 PM   #15
hal
 
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Default Re: Binary propellant and Standard TL 8 guns?

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Originally Posted by Anthony View Post
Note that, had ultra-tech been written completely from scratch in 2007 rather than being based on earlier work, I suspect liquid propellant guns wouldn't even be in there; liquid propellant guns were a hot topic briefly in the early 90s, and thus made sense for inclusion in GURPS Vehicles, but appear to have subsided back into obscurity since then.

The big theoretical benefit of liquid propellant is that it lets have variable muzzle velocity relatively easily. This is a significant benefit for artillery (with fixed muzzle velocity, at close ranges you're forced to choose between low angle shots that may not clear near obstacles, or very high angle shots that have extreme travel time), but is not terribly useful for direct fire weapons.
Good point. Come to think of it, I've not bothered to do a one for one examination of the GURPS CLASSIC ULTRATECH versus GURPS ULTRATECH. Makes me wonder now (thanks for pointing it out) how much of the problems are legacy issues.
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Old 09-21-2017, 05:18 PM   #16
hal
 
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Location: Buffalo, New York
Default Re: Binary propellant and Standard TL 8 guns?

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Originally Posted by Fred Brackin View Post
Going back to 3e (specifically Ve2) Caseless ammo guns are 2x the cost of conventional guns but their ammo is half weight and volume (wps and vps). Liquid propellant guns are then treated like caseless guns but cost is 3s conventional.

So it looks to me that the stats of real world caseless guns are not special or specially related to liquid propellant. They're just both part of a simple modification scheme that could indeed be called "pulled out of thin air".

As the two caseless weapons HT has stats for are either a simple modification of a basic hunting rifle (the Saco) or a unique prototype (the G-11) that has no cased equivalent and no one has to my knowledge ever built a functional liquid propellant smallarm there just isn't much to base stats on.
Based on that observation, I'm largely going to ignore the liquid binary propellant concept for the cyberpunk campaign I'm running. What bothers me most about the ULTRATECh book is that there aren't rules for gun evolution going into TL 9 (if any).

I guess one kludge might be that just as guns built for black power can't use smokeless powder or risk bursting, the guns manufactured in TL 9 may be of better quality due to material science increases, and ammunition can take advantage of that fact by being strong, or perhaps the gunpowder manufactured with modern industrial processes have more surface area per granule and thus combusts more thoroughly than gunpowder of the 1990's for example. A simple "does same damage as High Tech guns, but adds +1 damage and increases range by 1.3 might fit the bill.

I hate "tinkering" with something if I don't know the underlying principles involved in the first pace, or have no clue at all what I'm doing. Doug's spreadsheet demonstrates the relationship between bullet weight, diameter, and velocity in such a way that I can play with the velocity numbers just to see how much velocity change is required to get a +1 damage bonus. At least with HIGH TECH guns, I've a chance to add new guns for a Near Future campaign set 30 years from now - something that GURPS ULTRATECH doesn't really allow me at present. :(
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Old 09-21-2017, 05:20 PM   #17
hal
 
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Location: Buffalo, New York
Default Re: Binary propellant and Standard TL 8 guns?

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Originally Posted by johndallman View Post
Max is the furthest distance the projectile can travel (presumably under 1G, near sea-level, and definitely with more elevation than gun sights normally provide for). It's usually very hard to hit anything near Max range on Acc grounds, but someone beyond Max range definitely can't be hit.
Maybe what I should do is get the actual max ranges listed for actual guns, and plot them as data points or create a spreadsheet that lists the ranges as well as the velocity of the round from CARTRIDGES OF THE WORLD. That in turn might give me a way to figure out the max damage range. (in a doubtful voice) That might work with 1/2 damage ranges as well, maybe. *cough*
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Old 09-21-2017, 05:21 PM   #18
hal
 
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Default Re: Binary propellant and Standard TL 8 guns?

Just taking a moment to say "Thanks guys" for your input. Much appreciated.

:)
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Old 09-21-2017, 05:21 PM   #19
Anthony
 
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Default Re: Binary propellant and Standard TL 8 guns?

One of the primary problems with theorizing about advanced guns is that they appear to be a non-priority for any actual military.
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Old 09-21-2017, 05:37 PM   #20
hal
 
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Default Re: Binary propellant and Standard TL 8 guns?

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One of the primary problems with theorizing about advanced guns is that they appear to be a non-priority for any actual military.
Part of the problem too is that if you stockpile ammunition for war time use, switching to a new system for ammunition causes logistics issues. Then there is the investment required to stockpile the new munitions. I can't help but wonder if that is one of the reasons that the G11 was scrapped, aside from the reunification of Germany and budget constraints etc.

Even now, there's talk about ammunition shortages with speculation that the US government is buying more pistol ammunition than it had in the past. But that's a market issue rather than anything else that I can see.

If I had a set of guidelines on propellants and bullet weights etc (such as can be found with GUNS GUNS GUNS by Greg Porter), I'd be a little happier. GURPS VEHICLES had rules for building guns, and GUNS GUNS GUNS even had rules for porting over designs for use with different game systems (like CP2020, MegaTraveller, GURPS, etc)

In the end, if SJGames doesn't build something I want, I'll have to build my own. I did it once before using AFTERMATH rules for building guns, using the M-16 as a baseline since they were in both AFTERMATH and GURPS, and working it that way - or I can simply do the same with ULTRATECH using some other material. I just hate pulling numbers out of thin air is all. ;)
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