Hiiiiiii Mr. RX!
Looking at your preferences you probably can fit into just about any plot here, actually - most of them are focused on military forces, of course, but we do have some civilian ones in the mix as well. Let's see...
Military plots I'd recommend:
-Task Force Inquisition, hosted by
@paladinrpg and
@Ethereal . This plot's just kicking off still, but it's all about working as a large glorious army, in the air/space as well as on the ground!
-The YSS Eucharis, hosted by
@Wes ! This is I think the oldest plot on the site, but a lot of people there are really fun! It's pretty much the perfect benchmark for what Yamatai Star Empire plots are about, with a ship and her crew exploring, fighting, diplomacy-ing, and sciencing their way through just about everything!
Civilian plots I'd recommend:
-Sector Searchers by
@Alex Hart is a fairly small plot about Alex Tasuki searching for a childhood friend - and also looking for a bit of his own history.
-Something on the planet of 188604, owned by Uso's Star Organization and run by
@Jack Pine and
@Zack might be interesting- though, I haven't paid very much attention to their forum recently unfortunately, so I can't really give any specific details at this time ^^;