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Old 09-01-2021, 05:24 PM   #11
Anthony
 
Join Date: Feb 2005
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Default Re: Guns! Guns! Guns! and GURPS

The normal use of ETC is "we'll ignite the propellant with a spark instead of a primer". This gives you more control over the behavior of the propellant, and lets you use propellants that you can't use with a primer, but does not otherwise make the propellant more powerful, which is what controls max velocity.

Now, it's possible to just directly use the spark to heat the propellant, which lets you go beyond the normal limits of the propellant, but doing so requires huge amounts of electrical power and has low efficiency, so unless you have super-batteries but don't have functional mass drivers there's no real incentive to do that.
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Old 09-01-2021, 05:49 PM   #12
GURPS Fox
 
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Default Re: Guns! Guns! Guns! and GURPS

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Originally Posted by Rupert View Post
Current Russian and German tank guns manage ~1800 m/s, and the Russians have a 150mm gun that supposedly manages just under 2000 m/s.
Please note I was remembering off the top of my head. Had to revisit some videos and articles to get the upper limit of current powder propellants.
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VE2's ETC rounds with 50% more energy from bullets of less mass would therefore be producing muzzle velocities in excess of 3000 m/s, well within the velocity range you give.
Yet I want to keep the heavy rounds, largely due to how armor in the setting is played.
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Originally Posted by Anthony View Post
The normal use of ETC is "we'll ignite the propellant with a spark instead of a primer". This gives you more control over the behavior of the propellant, and lets you use propellants that you can't use with a primer, but does not otherwise make the propellant more powerful, which is what controls max velocity.
From what I understand, ETC propellants become plasma (which, reminds me of the fact that Battletech autocannon are likely ETC guns given their naval autocannon being 'orion in a bottle' description) after ignition...
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Old 09-01-2021, 06:46 PM   #13
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Default Re: Guns! Guns! Guns! and GURPS

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Originally Posted by GURPS Fox View Post
From what I understand, ETC propellants become plasma
No more than any other propellant at the same energies, other than small amounts associated with the spark. Any large amount of plasma formation is going to destroy the barrel quite rapidly.
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Old 09-01-2021, 06:50 PM   #14
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Default Re: Guns! Guns! Guns! and GURPS

This will be an interesting exercise.

Also, the stats for TL slugthrowers using ETC isn't enough? I'm running a TL8+9^ campaign where a few prototype weapons for this special operators group have TL9 ETC weapons. The damage is horrible (in a good way). I feel like these could pull off Aliens weapons perfectly (IMHO). :-D

I have my math in a spreadsheet I could pop up on Google Sheets (the ETC damage math) if you're interested.
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Old 09-01-2021, 07:36 PM   #15
GURPS Fox
 
Join Date: Jun 2020
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This will be an interesting exercise.

Also, the stats for TL slugthrowers using ETC isn't enough? I'm running a TL8+9^ campaign where a few prototype weapons for this special operators group have TL9 ETC weapons. The damage is horrible (in a good way). I feel like these could pull off Aliens weapons perfectly (IMHO). :-D

I have my math in a spreadsheet I could pop up on Google Sheets (the ETC damage math) if you're interested.
Greatly appreciated. :) It would help me immensely... right after I reverse engineer how to get the 1/2D and max range of the ballistics model spreadsheet that I was pointed to...

The slight problem with that is that the setting is solidly in TL12 in 3e or early TL12 in 4e, so it might cause some ruckus in the numbers.
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Old 09-01-2021, 07:45 PM   #16
Fred Brackin
 
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Originally Posted by GURPS Fox View Post
In gameplay terms, the armor is an ablative laminate with a 1+ hardening (or, in gameplay terms, all armor divisors are halved, rounded to the nearest whole number, i.e. (2)s become standard, (3)s become (2)s, and (5)s become (3)s).
Those are the standard rules for the Hardened Advantage. They'll knock HEAT down from (10) to (5) or take a WWII bazooka down from 4Dx2(10) to 4Dx2(5). That is the difference between penetrating 4 inches of RHA and only 2 inches but the best man-portable anti-tank rocket in HT does 6Dx9 (10). That's a base of 27 inches of RHA and vehicle-based launchers do more than that.

Very few games besides Gurps undertand the power of HEAT and Battletech wasn't one of them. If I was trying to do Battletach in Gurps I'd just go ahead and give their ablative armor 4 levels of Hardened (and I'd be very coy about the technobabble that allowed for that).
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Old 09-01-2021, 08:33 PM   #17
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Those are the standard rules for the Hardened Advantage. They'll knock HEAT down from (10) to (5) or take a WWII bazooka down from 4Dx2(10) to 4Dx2(5). That is the difference between penetrating 4 inches of RHA and only 2 inches but the best man-portable anti-tank rocket in HT does 6Dx9 (10). That's a base of 27 inches of RHA and vehicle-based launchers do more than that.

Very few games besides Gurps undertand the power of HEAT and Battletech wasn't one of them. If I was trying to do Battletach in Gurps I'd just go ahead and give their ablative armor 4 levels of Hardened (and I'd be very coy about the technobabble that allowed for that).
Funny thing about that, Battletech Endosteel has been proven right back in 2016 with metal foam composites. Sure it's V0.1, but it makes BT materials go from 'something that is impossible' to 'somewhat plausible' oddly enough. Hell, during the tests they pitted the composite against a .50cal BMG AP round and it did worse than the ball round...

It's the same thing with Battletech power cells, they were considered -at one point in time- impossible but were later proven right via solid-state batteries.
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Old 09-01-2021, 09:04 PM   #18
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Default Re: Guns! Guns! Guns! and GURPS

GURPS does address HEAT countermeasure technology. And they do tend to be ablative. Usually a bit more violently ablative than your basic 'ablative armor because that makes it a convenient hitpoint system' models on though.
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Old 09-01-2021, 09:29 PM   #19
GURPS Fox
 
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GURPS does address HEAT countermeasure technology. And they do tend to be ablative. Usually a bit more violently ablative than your basic 'ablative armor because that makes it a convenient hitpoint system' models on though.
Well, my setting has the equivalent of Battletech's LAMS with Skill 60 gunners via the automated gunner program, the equivalent of Babylon 5's E-WEB (which disperses non-exotic/neutronic DEWs and work a bit on kinetics, acts like EmRA armor), in addition to the armor.

Also, I started going into GURPS because I can't get my spaceships to be workable. Either they have too little armament for their size (and are severely weberfoam) or they have too much armament...
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Old 09-01-2021, 09:36 PM   #20
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Default Re: Guns! Guns! Guns! and GURPS

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Originally Posted by GURPS Fox View Post
The setting had a period of time where everyone was having their soldiers run around with HMGs as their assault rifles because nothing else could reliably penetrate the armor of various power armor systems (be either armored combat exoskeletons or what would be considered the 'genuine article' by many). By the time of the setting's 'present', everyone is running around with an ablative armor scheme that requires a certain amount of energy to ablate ala Battletech armor.
As an aside, if your opposite number's pistol (a backup weapon) can reliably punch through your armour, that generally means it's time to not bother with armour and use the saved weight to be more mobile and/or otherwise better equipped because the armour isn't doing anything much for you.
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