Coastal Ron: "X" low-g testbed and minimum viable station (2019)

Design summary

Minimum Viable Rotating Space Station. Small = sooner (mass = cost). It may lack elevators, with Mars g (0.37 g) as the lower limit. Test Mars g in LEO, and test lunar g on the Moon itself (3 days away). V1 is likely a 4-arm station with docking at the centre of rotation Coastal Ron, 2019-03-24; Coastal Ron, 2019-03-25.
"X" configuration. Four arms (an X) stabilize docked mass: ISS-module-sized docked mass is negligible, and only long (≥20 m) protruding items risk instability Coastal Ron, 2019-03-25; Coastal Ron, 2019-03-25.
Low-g "X" testbed described in the "Artificial Gravity Testbeds" thread (external post); Coastal Ron, 2019-05-04. It is cited again when arguing against spinning Starships Coastal Ron, 2023-01-07.
Goals first: can humans spend years at Mars g? Coastal Ron, 2019-03-26

Twark_Main: 3 arms suffice for intermediate-axis stability (−25% for an MVP) Twark_Main, 2023-06-09. Paul451: 3 longer arms reach the same g at lower rpm Paul451, 2023-06-10.

Coastal Ron, 2019-03-24 (reply #1383, 3 likes): MVP definition. Post.
Coastal Ron, 2019-03-25 (reply #1389): X station stability. Post.
Coastal Ron, 2019-03-25 (reply #1391): ≥20 m items. Post.
Coastal Ron, 2019-03-25 (reply #1401, 3 likes): 4-arm V1. Post.
Coastal Ron, 2019-03-26 (reply #1403): Goals first. Post.
Coastal Ron, 2019-05-04 (reply #1590, 3 likes): Splinter threads created. Post.
Coastal Ron, 2023-01-07 (reply #2799): X testbed cited. Post.
Twark_Main, 2023-06-09 (reply #3813): Three arms suffice. Post.
Paul451, 2023-06-10 (reply #3825): Three longer arms. Post.