Full Thrust is an excellent set of starship combat rules — my personal favorite, in fact. Here are a set of modifications and statistics for playing Star Wars battles.
starships
Big Burn Fleet Actions
Big Burn is a set of free wargames rules for fleet actions in space.
Fires of Space Rules
Fires of Space is a space combat game with a WWII naval flavor. From the author’s introduction:
Here is my take on battles between big ships in space. This rules set has a deliberately 20th century naval warfare flavor, but with adaptations for space and far future technology. Included are the rules, tables, designer’s notes, a series of ships from various space navies, scenarios, a probability table for 20 sided dice, counters, and a 50 by 50 hex map. With the map are marked map sections showing showing the map’s center hex and deployment areas for tactical scenarios. Ideally, the game is played with two 50 by 50 hex maps: one for operational movement and the other for tactical engagements. In a pinch, a single map can double as both the operational and tactical map. Finally, I include a copy of the Excel workbook that I used to create the ships in the game.