09-21-2017, 05:50 PM | #21 | |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Binary propellant and Standard TL 8 guns?
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09-21-2017, 06:35 PM | #22 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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Frankly? I think the best route to take with this is to apply the ETC rules to ANY conventional round as it appears to make the combustion of propellant more optimized. Otherwise, like the Binary, too "new" and probably not worth considering for anything save perhaps specialty weapons (such as a sniper rifle for example). Perhaps the best thing to do is simply use TL 8 guns in a TL9 campaign on the premise that some of the TL 7 guns are still in production and use today. |
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09-21-2017, 08:04 PM | #23 | |
Join Date: Aug 2007
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Re: Binary propellant and Standard TL 8 guns?
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You might want to alter a few things. The 10mm has Rcl 3 as a conversion artifact but 4e Rcl is a more severe drawback than the 3e stat. The 7.5 mm could be upgraded to an 8 and that would get rid of the "P- curse". Then your new 8mm actually would replace compact 9mm Parabellums and a holdout version would replace .380s. If you wonder what might push the military into caseless ammo I think it might be a new SAW weapon. Judging from HT stats caseless ammo actually is half the weight of the cased variety. Doubling your SAW gunner's ammo load might be the thing that's worth the trouble.
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Fred Brackin |
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09-21-2017, 08:25 PM | #24 |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
Hi Fred,
If I were to go the route you're suggesting, which isn't a bad thing to do overall... I suspect that I'd probably try out the GunsGunsGuns design sequence to see if they're even close to what would happen using real world data. I've already noted that when designing the bullet weights using their generic formulas for sphere, elongated sphere (pistol bullets) and the bullet rules for rifle bullets, they don't exactly match the real world information. Of course, real world physics being what it is, has different shapes for the bullets that don't exactly match the simplified scheme of things done by Greg Porter. However, he does suggest ratios of bullet lengths and propellant weights to bullet weights etc. I think he suggest and 8:1 ratio for bullets to propellants for caseless (and darned if that isn't close to the G11 stats by the way). If his formula works? We can pick bullet weights for the most part, velocities we wish to achieve, and determine whether or not the propellant energy in joules and receiver efficiency works or not. Then, it would be simple enough to use Doug's formula for damage. I've heard people dismiss Greg Porter's design system, so I don't know how well it would work. Something to do for tomorrow I guess. It will keep me out of mischief and maybe not say anything here in the forums for a couple of days. ;) |
09-21-2017, 08:46 PM | #25 | |
Join Date: Aug 2004
Location: Austin, TX
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Re: Binary propellant and Standard TL 8 guns?
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I checked the numbers versus US naval cannon, and the numbers look close enough - within 5-10% of the published maximum ranges. * You can add more cells, but recalculating through 300 columns already takes a while.
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Read my GURPS blog: http://noschoolgrognard.blogspot.com |
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09-21-2017, 09:13 PM | #26 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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Thank you for the offer, much appreciated! |
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09-22-2017, 07:10 AM | #27 | |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: Binary propellant and Standard TL 8 guns?
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As for 1/2D range - you'll have a similar problem, with the added issue that 1/2D range doesn't match any simple real life 'thing
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Rupert Boleyn "A pessimist is an optimist with a sense of history." |
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09-22-2017, 07:19 AM | #28 |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: Binary propellant and Standard TL 8 guns?
Indeed, especially as what really matters is selling the new weapon and ammo to the US military, and their last major requirement for a new infantry rifle, for the ACR trials, required such an improvement in hit chance that the only realistic way of meeting it with a small arm would be to use a belt-fed machinegun. Of course, since then they've been moving to weapons that are worse than the M16A2 at the long-range accuracy part of the requirement, and without bothering with full trial and tender processes, so it seems they've decided that the ACR requirements were in error (not that they've actually said this officially).
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Rupert Boleyn "A pessimist is an optimist with a sense of history." |
09-22-2017, 07:51 AM | #29 | |
Join Date: Aug 2004
Location: Buffalo, New York
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Re: Binary propellant and Standard TL 8 guns?
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The formula that Doug gave us earlier in his spreadsheet can be made to solve for 1/2 damage value along with Velocity, as the bullet mass remains the same. Knowing how fast a bullet's speed will decline to meet that half damage velocity might be the other piece of the puzzle. Using the old displacement formula for 1/2 AT^2 to determine how far the bullet travels from the muzzle of the gun until it reaches the velocity for half damage might be a close enough value to be viable. Maybe. I'd have to experiment with it to see how well it works. :) |
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09-22-2017, 09:57 AM | #30 |
Doctor of GURPS Ballistics
Join Date: Sep 2004
Location: Lakeville, MN
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Re: Binary propellant and Standard TL 8 guns?
The spreadsheet already has Max range and 1/2 D range in it, by the way.
If you're working with Ballistics Model July 30-2013, which is I think my newest one: The 1/2D and Max Ranges for a projectile are listed in cells D36 and D37, explicitly. The 1/2D range is based on an exponential decay using sectional density as the primary variable. It's not bad, though a full ballistics model would of course be better. It will tend to underestimate the 1/2D ranges of big, heavy projectiles that start subsonic and stay that way. For GURPS case, it probably won't matter. The Max Range is a fitting parameter whose provenance I simply do not recall. I'm sure I did a model regression on real projectiles max ranges with the parameters I calculated, but this was a long, long time ago. If you don't have the most recent version, ping me.
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