GURPS Spaceships Power Plants

Diomedes · 03-01-2008, 03:20 PM

Was playing around with GURPS Spaceships, and decided to work out the power levels of various ship sizes, based on weapon use.

a SM+5 Major Weapons Battery uses one power point to power one 10MJ beam weapon. It can fire this weapon once per 20 seconds, and I'm assuming that the designers are using capacitors to store energy from the power plant so they can use the entire amount of the power point over that period.

10 MJ/20sec gives you 500kW – but only if the weapon is (somehow) 100% efficient. In reality, there's going to be heat loss, so the power required is that 500kW divided by the efficiency.

Scaling to the various size classes gives:

Code:

Size Class     40% efficiency    33% efficiency    20% Efficiency 10% efficiency
SM+5              1.25MW             1.5MW             2.5MW            5MW
SM+6              3.75MW               5MW             7.5MW           15MW
SM+7              12.5MW              15MW              25MW           50MW
SM+8              37.5MW              50MW              75MW          150MW
SM+9              125MW              150MW             250MW          500MW
SM+10             375MW              500MW             750MW          1.5GW
SM+11             1.25GW             1.5GW             2.5GW            5GW
SM+12             3.75GW               5GW             7.5GW           15GW
SM+13             12.5GW              15GW              25GW           50GW
SM+14             37.5GW              50GW              75GW          150GW
SM+15             125GW              150GW             125GW          500GW

I ran the numbers for several efficiencies to find one that "worked" best, but using more than one column in a single game would result in mismatches.
An Improved beam weapon is simply one that is twice as energy-efficient, allowing two shots of a given power for each 20 second increment.

Under the 33% rules, a SM+7 Fusion Reactor would be rated for 100MW, a massive SM+14 Antimatter Reactor would be 600GW, and (extrapolating to the low end) a 10-pound Fuel Cell for a SM0 sized would give 5kW.

03-01-2008, 03:20 PM	#1
Diomedes Join Date: Mar 2008 Location: Dallas, TX	GURPS Spaceships Power Plants Was playing around with GURPS Spaceships, and decided to work out the power levels of various ship sizes, based on weapon use. a SM+5 Major Weapons Battery uses one power point to power one 10MJ beam weapon. It can fire this weapon once per 20 seconds, and I'm assuming that the designers are using capacitors to store energy from the power plant so they can use the entire amount of the power point over that period. 10 MJ/20sec gives you 500kW – but only if the weapon is (somehow) 100% efficient. In reality, there's going to be heat loss, so the power required is that 500kW divided by the efficiency. Scaling to the various size classes gives: Code: Size Class 40% efficiency 33% efficiency 20% Efficiency 10% efficiency SM+5 1.25MW 1.5MW 2.5MW 5MW SM+6 3.75MW 5MW 7.5MW 15MW SM+7 12.5MW 15MW 25MW 50MW SM+8 37.5MW 50MW 75MW 150MW SM+9 125MW 150MW 250MW 500MW SM+10 375MW 500MW 750MW 1.5GW SM+11 1.25GW 1.5GW 2.5GW 5GW SM+12 3.75GW 5GW 7.5GW 15GW SM+13 12.5GW 15GW 25GW 50GW SM+14 37.5GW 50GW 75GW 150GW SM+15 125GW 150GW 125GW 500GW I ran the numbers for several efficiencies to find one that "worked" best, but using more than one column in a single game would result in mismatches. An Improved beam weapon is simply one that is twice as energy-efficient, allowing two shots of a given power for each 20 second increment. Under the 33% rules, a SM+7 Fusion Reactor would be rated for 100MW, a massive SM+14 Antimatter Reactor would be 600GW, and (extrapolating to the low end) a 10-pound Fuel Cell for a SM0 sized would give 5kW.

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