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09-15-2021, 10:08 PM   #51
GURPS Fox

Join Date: Jun 2020
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by Fred Brackin UT says "probably not". The 3D6 Laser Pistol weighs only 1 lb sans power cell. The 6D6 Laser Rifle is 8lbs (it's D cell is in a power pack). That's 8x weight for 2x damage. The 3D6 Gauss Machine Pistol weighs 2.4 lbs without ammo or power cells (2 Bs). The 6D+2 Gauss Rifle weighs 6.6 lbs in the same condition. Not a cubed relationship. You might get different results from Spaceships but Spaceships is very gamist in its' scaling.
From what I've been told, this is the back-engineered EM Gun equation for 4e:

EM gun weight = muzzle energy in KJ × 0.735 if RoF=1, if RoF is >1, then use KJ ×(1+(ROF/20)²) and if RoF <1, then use KJ × √(1/the number of seconds between firings).

So, a 10,000kJ EM gun firing once a second would mean 10,000 x 0.735 which means 7350lbs (roughly).

09-15-2021, 10:15 PM   #52
Fred Brackin

Join Date: Aug 2007
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by GURPS Fox From what I've been told, this is the back-engineered EM Gun equation for 4e: E.
Back engineered from _what_?
__________________
Fred Brackin

09-15-2021, 10:30 PM   #53
GURPS Fox

Join Date: Jun 2020
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by Fred Brackin Back engineered from _what_?
From what the guy that I worked with said, Ultra-Tech although the equation doesn't 100% work with the stated stats.

09-15-2021, 11:42 PM   #54
Rupert

Join Date: Aug 2004
Location: Wellington, NZ
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by Fred Brackin Spaceships' Projectile base damage is linear with caliber and doubles every 4 SM or 100x mass. I don't think that's the relationship GURPS Fox was aniticipating and isn't the same one the Energy Weapons use. I generally don't use Spacships as a primary source for tech facts. That's not what it was designed for.
I agree. It can be used to gain some insights, but should be used for this cautiously and after other sources have been found to be lacking.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."

09-16-2021, 10:02 AM   #55
Fred Brackin

Join Date: Aug 2007
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by GURPS Fox From what the guy that I worked with said, Ultra-Tech although the equation doesn't 100% work with the stated stats.
UT seems a unlikely source. It doesn't work with outputs in kj. Even Ve2 didn't.
__________________
Fred Brackin

09-16-2021, 05:01 PM   #56
GURPS Fox

Join Date: Jun 2020
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by Fred Brackin UT seems a unlikely source. It doesn't work with outputs in kj. Even Ve2 didn't.
Then again, 3G3 does, surprisingly enough, and that is very in line with 3e's weapons in terms of weight.

 09-16-2021, 06:19 PM #57 Anthony   Join Date: Feb 2005 Location: Berkeley, CA Re: Guns! Guns! Guns! and GURPS VE2 does tell you the energy cost per shot for EM weapons, though it has some glitches. __________________ My GURPS site and Blog.
09-16-2021, 08:01 PM   #58
GURPS Fox

Join Date: Jun 2020
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by Anthony VE2 does tell you the energy cost per shot for EM weapons, though it has some glitches.
Yeah, but the real problem is that, for my purposes (which uses high-density ammunition), that makes it insane to keep firing. The original 5k kW discharge rate is, insane when you've got a projectile that is, roughly, 13.5 kg, let alone one that is firing 40 rounds a second.

09-16-2021, 09:21 PM   #59
Rupert

Join Date: Aug 2004
Location: Wellington, NZ
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by GURPS Fox Yeah, but the real problem is that, for my purposes (which uses high-density ammunition), that makes it insane to keep firing. The original 5k kW discharge rate is, insane when you've got a projectile that is, roughly, 13.5 kg, let alone one that is firing 40 rounds a second.
Well if you're firing 13.5 Kg projectiles at 40/s, if they're going at any reasonable velocity you're going to have a massive energy consumption, and that's all there is to it. If the muzzle velocity is 1000 m/s (for example) that's 270 MW at 100% efficiency. Whether it comes from chemical propellants, electromagnetic drivers, or electrically generated plasma doesn't matter, it has to come from somewhere, and that's a lot of energy.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."

09-16-2021, 10:22 PM   #60
GURPS Fox

Join Date: Jun 2020
Re: Guns! Guns! Guns! and GURPS

Quote:
 Originally Posted by Rupert Well if you're firing 13.5 Kg projectiles at 40/s, if they're going at any reasonable velocity you're going to have a massive energy consumption, and that's all there is to it. If the muzzle velocity is 1000 m/s (for example) that's 270 MW at 100% efficiency. Whether it comes from chemical propellants, electromagnetic drivers, or electrically generated plasma doesn't matter, it has to come from somewhere, and that's a lot of energy.
Well, the guns are railguns (of the Gatling kind) flinging rounds at 5km/s, but the biggest problem is that using the standard electric consumption rate, you just reinforce the 'all guns in the future will be DEWs' trope, which is something I want to avoid.

The smaller weapons tend to be using far smaller (and thus lighter) rounds at 1.25 to 3km/s, depending on the weapon. To power a 32mm coilgun that flings something on the order of 10kg rounds at 3km/s, that would take a lot of electricity, requiring reactors that are impossible to fit within a vehicle even with using alternative fuels and ultratech forcefield modifier rules.

EDIT: the most powerful weapon can send metric ton projectiles at 10km/s and is able to reach 20 megameters.

Last edited by GURPS Fox; 09-16-2021 at 11:59 PM.