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Old 06-12-2019, 01:19 PM   #21
Join Date: Jul 2008
Default Re: Approaching TL9?

Originally Posted by TGLS View Post
I hate to break this to you, but the Chemical Rockets presented in GURPS Spaceships are almost implausibly efficient compared to chemical rockets we have today. Even assuming that Fuel Tanks have a negligible dry mass, the specific impulse ends up around 468.38 seconds, slightly more efficient than modern upper stages. Adding in an adjustment for fuel tank structure makes them even more efficient. On top of this, rocket engines designed to operate from launch aren't even close to this level of efficiency because of higher thrust demands and pressure differences.
Fuel tanks are clearly written to have zero dry mass in the rules, and I'm getting a value within easy rounding of 480 seconds (based on the one-tank performance).
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
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