A worthwhile predecessor to my present musings is the 1996 efforts by Kelly Starks & the gang at the Lunar Institute of Technology. As you’ll note the “updates” have lagged somewhat, but the Starship Design Study is well worth a look. They went into a lot of detail and their discussion of drive technology, life-support, the trade-off between prepacked supplies and CELSS, and similar minutiae is very handy, if dated slightly.
Fuel/Sail Class Starships …explains the basics.
Explorer Class Starships …details the “small” design (25,000,000 tons!)
Mission Plan & Manifest for Explorer Class …breakdown of payload and mission plan. Lots of mining of Lithium-6 at destination for journey home.
Bussard Fusor Discussion …for a long time my only reference on Bussard fusor performance available online. Now Askmar.com is the place to go to.
Of course such gigantism is unlikely to ever be very practical. Real crewed starships need something better than mere fusion to get up to decent speeds. I’d bet on Hawking radiation powered Black Hole Starships and/or Reverse Baryogenesis Total Annihilation drives. The ultimate IMO would be the Neutrino Ramjet – basically it uses macroscopic sphaleron fields to annihilate scooped mass, producing a pure collimated neutrino beam. Such a vehicle would be able to launch from planets without melting down continents and have essentially unlimited range. The stuff dreams are made of…