GURPS O'Neill Cylinder Design

[thrash]

Originally Posted by Tyneras

This touches on one of the tricky aspects of the O'Neill cylinder, it's tremendously low density. While most craft in GURPS Spaceships are roughly analogous to modern watercraft and aircraft, the O'Neill cylinder is more like a metal balloon, mostly air.

That sounds like a Gasbag system (SS7, pp. 9-10). Of course, such a thing would be useless in microgravity (or at SM +21), but it might give you a way to account for the difference.

Disappointingly, SS7 doesn't address what should be the immensely increased SM of a vessel using these systems.

Next, dirt to plant all those trees and grass on.

Aren't those Open systems, by definition? Then you could use the Ecological Life Support design switch (Pyr 3/49, p. 24) to calculate carrying capacity.

In fact, that whole article ("Generation Ships," by David Pulver) would probably be helpful.