07-06-2021, 08:57 PM | #1 |
Join Date: Jun 2019
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Can you Design a Beam Weapon by power output?
I have been a fan of GURPS for a while but I have been flummoxed by the following:
With great enjoyment, I have been using David Pulver's excellent article "Blaster and Laser Design" in Pyr 3-37 Tech and Toys II. But my difficulty has been extrapolating Power Requirements versus Energy Output. In Other Words, how many KWs does a beam weapon use per Kj of energy output? This should vary by beam type, but how can the number be found? Many Thanks... M. |
07-06-2021, 09:43 PM | #2 |
Join Date: Jun 2013
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Re: Can you Design a Beam Weapon by power output?
It’s a question of efficiency, and you’ll have to make your own decision there (I feel a decent progression is 30% at TL9, 50% at TL10, 70% at TL11, and functionally 100% at TL12). For something with 100% efficiency, (kJ output)*(RoF)=(kW input); lower efficiency calls for more energy input - 50% efficiency requires double the input (with my suggested progression, a 30 kJ, ROF 10 laser would require ~1000 kW at TL9, ~700 kW at TL10, ~500 kW at TL11, and ~300 kW at TL12; note I rounded most of these numbers to conform to the Size and Speed/Range Table).
As for energy per shot, a kWs is a kJ, but efficiency comes into play (above, energy required per shot is 100, 70, 50, and 30 kWs, respectively).
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07-06-2021, 09:44 PM | #3 |
Join Date: Aug 2007
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Re: Can you Design a Beam Weapon by power output?
[QUOTE=Malachite72;2387241
In Other Words, how many KWs does a beam weapon use per Kj of energy output? This should vary by beam type, but how can the number be found? [/QUOTE] I'm afraid the answer is "By looking in Gurps Vehicles Second Edition." (which was a 3e book). The beam weapon design section in Ve2 dealt with things in the requisite level of detail. I don't think any thing in 4e does.
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Fred Brackin |
07-06-2021, 10:40 PM | #4 | |
Join Date: Nov 2005
Location: Renton, WA
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Re: Can you Design a Beam Weapon by power output?
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This is a great answer, and if given the choice, I would choose to go this route vs. diving into vehicles. Simple, straightforward, and easy to figure out how big the backpack is going to be. :-) |
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07-07-2021, 04:25 AM | #5 | |
Join Date: Jun 2005
Location: Lawrence, KS
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Re: Can you Design a Beam Weapon by power output?
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If you want to use the speed/range table, why not say efficiency = energy in/energy out? Then 30 kJ/70 kWs = 43% efficiency at TL 10, and 30 kJ/50 kWs = 60% efficiency at TL 11.
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Bill Stoddard I don't think we're in Oz any more. |
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07-07-2021, 06:10 AM | #6 | |
Join Date: Jun 2013
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Re: Can you Design a Beam Weapon by power output?
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07-07-2021, 03:01 PM | #7 |
Join Date: Mar 2005
Location: The deep dark haunted woods
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Re: Can you Design a Beam Weapon by power output?
GURPS 3rd Edition Vehicles, pg 123-127 - detailed steps for designing a beam weapon by output in kj, from handheld to vehicular.
Just do that, then convert to 4th Edition. Easy-peasey.
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"When you talk about damage radius, even atomic weapons pale before that of an unfettered idiot in a position of power." - Sam Starfall from the webcomic Freefall |
07-07-2021, 04:51 PM | #8 | |
Join Date: Sep 2014
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Re: Can you Design a Beam Weapon by power output?
According to David Pulver, the energy to damage formula for generic lasers is dice = 2 * cube root of kJ. This also approximately matches beam outputs in, for example, Spaceships, so it appears to be correct. Then you just pick your efficiency and you can calculate the energy per shot, etc. A TL9 C cell holds 90 kJ, so you can work out the rest from there if you want.
David also had the following useful bit of preliminary Vehicle Design info: Quote:
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07-07-2021, 06:53 PM | #9 |
Join Date: Jun 2019
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Re: Can you Design a Beam Weapon by power output?
Thank you all! This is the type of feedback I was searching for.
My aim (no pun intended) is to be able to use Pulver's Beam Design article to construct spacecraft and installation cannon, and have them powered by larger power plants. I a mish-mash of design systems for spacecraft design, and weaponry can be powered by the spacecraft's power plant, or have an energy bank for independent power. That's why I wanted to know how much power (in Kj per second, i.e. Kilowatts) a shot would use, based on kilojoules of energy of the energy blast. I am looking to be compatible with Ultratech, etc. TY muchly, all! M. |
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