Hi Steve,
if you are looking for the stock AI planes made flyable, here's one of the first tweaks made to operate their bomb doors animation:
http://simviation.com/1/browse-Aircraft-83-65
fourth entry from the top.
Originally the bomb door animation for the stock AI B-24, B-25, TBF, G4M2 Betty was tied to the CFS2
spoiler key,
forward slash /. From then on, the vast majority of WWII addon bomber models, any nationality, followed suit and their bomb doors opened/closed with the spoiler key.
All of the CFS2 stock models overhauled by The B24Guy stuck to the same standard, including later updates designed by our good Allen.
As Bearcat241 wrote, in recent times, other keys were used for the bombdoors when the spoiler was tied to some other animation, like dropping a ball turret or animating waist gunners. The Concorde nose key is a good example.
As a rule of thumb, the most diffused key for bomb door animation is, again, the spoiler key. Therefore, if nothing is mentioned in the designer's readme, try it first to see if it works. If the original designer did not provide a key assignment or even forgot to animate the bomb doors, there's little that can be done, unless some airplane expert modeller here disassembles the mdl file and works with either FSDS or Gmax to add the animation.
In case of the stock AI planes, only activating the spoilers in each *.mdl file did the trick, the animation was already in place.
KH 