Sadly, I suck / suck / suck at this game (even when I play with that look of determination like the pilot in the attract mode), but I want to get higher scores. It seems like (besides killing everything and not dying) maxing out your lock-ons before cutting loose gets you the big points. Is each additional lock-on target destroyed in a single salvo worth exactly double the previous target's value, or does it ramp up more than that at some point? I can never seem to catch what the fifth, sixth, etc. are worth.

Also, does a locked-on target "unlock" when your fighter passes it, or when it falls off the bottom of the screen, or sometime else?