[grumbler]

Nomor, I hear whatcher sayin', but I think the show makes it clear that oxygen regeneration wasn't in fighters:
1. Lannier and the other ranger trainee launched "with just an hour's supply of oxygen."
2. Montoya noting to Delenn that Lennier's oxygen would now be depleted even if he went into suspension to extend it.
3. Knight One noting to Sinclair that when he went off the screens in the Battle of the Line he had only 16 hours of oxygen left.

"Life Support" probably included CO2 scrubbers and fans, plus heating, water, etc. In fact, this is pretty much what the Space Shuttle has right now.