Well that's a tough one. since you want simple. other than
BFG the only one that comes to mind is mongooses Babylon 5 system "a call to arms" . it is basically the same system they use for their WWII victory at sea system as well.
Unfortunately unlike
B5 wars, which is the best Newtonian based scific space skirmish system
IMHO(but also very complex by comparison), that has been converted into star trek, star wars, battlestar galactica, wing commander, stargate, macros/robotech, battlefleet gothic etc..
the "a call to arms" system is only for Babylon 5.
You can get the control sheet and such for it here
http://www.ibisfightclub.tk/
the
B5 wars stuff can be found here if you want to look into it.
http://b5warsvault.wikidot.com/