How would this work with bomber formations? If one of the bombs from your drone did the final hit, and then the drone was killed before the expire time, does that count?
Players that fly Bombers the intended way would be penalized, as many times, the fighters attack when the bomber pilot is in the sight trying to do a real bomb run. It's easy to tell when they have no gunner and go auto-pilot to calibrate and drop.
If the timer is 10 seconds, 1 minute or 2 minutes, it won't matter all that much to the pork and auger crowd anyway, all they will do is just modify their behavior to stay alive just long enough to keep their damage done, then auger or bail.
Someone else suggested to make the player use perk points to buy the bombs.
How about, if the player loads bombs, they do not cost anything until they actually get dropped (No loosing perks if vultched or shot down en-route) Once the bombs are dropped, they cost perk points. If the player then gets home to land, all bombs that hit a target get 2x the amount of perks earned for what they cost (I.e. if bomb cost 2 perks, and bomb hit target, and player lands, player recieves 4 perks.) If the bomb missed target, but player lands, 1/2 perks earned back. If bomb hits and player dies, 1/2 perk earned back, if bomb missed and player dies, no perks.)