09-21-2017, 01:37 PM | #11 | ||
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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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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09-21-2017, 03:03 PM | #12 |
Join Date: Aug 2007
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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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Fred Brackin |
09-21-2017, 03:08 PM | #13 |
Night Watchman
Join Date: Oct 2010
Location: Cambridge, UK
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Re: Binary propellant and Standard TL 8 guns?
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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The Path of Cunning. Indexes: DFRPG Characters, Advantage of the Week, Disadvantage of the Week, Skill of the Week, Techniques. |
09-21-2017, 03:18 PM | #14 |
Join Date: Feb 2005
Location: Berkeley, CA
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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. |
09-21-2017, 05:00 PM | #15 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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09-21-2017, 05:18 PM | #16 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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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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09-21-2017, 05:20 PM | #17 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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09-21-2017, 05:21 PM | #18 |
Join Date: Aug 2004
Location: Buffalo, New York
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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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09-21-2017, 05:37 PM | #20 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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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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