In my last post about space combat in my Rogue Trader game (http://wh40krpg.blogspot.co.uk/2013/06/testing-proposed-narrative-space-combat.html for anyone interested) I talked a bit about using a narrative system for space combat; in my session earlier today however I found that the players moved through the plot I had envisioned fairly quickly and onto a space combat scene which I had not entirely scripted out.
In a moment of inspiration I decided to use the mook rules from Fate Accelerated, given any ships with an advantage in the combat +2 to their attack/defence rolls and giving any ships with a disadvantage a -2 to their attack/defence rolls; each normal sized ship was given three stress boxes with smaller ones being given a single stress box and larger ships being given five. We then just played the attack out as a fairly standard combat with the players rolling for their own and allied ships with myself rolling for the enemy ships.
The system seemed to work fairly well and we got through two space combats in a fairly small space of time, no-one was sat around bored and we paused every now and again to check on the overall tactics of the players and highlight important moments in the combat. We also had a few good compels where one of the ships was allowed to keep fighting in an almost crippled state in return for being boarded and another ship was allowed to remain undestroyed but was forced to withdraw from the fighting.
This seemed to work great and I highly recommend using the mook rules from Accelerated if you ever have a need to improv an encounter in a Fate game.