Let me refraise the question...

[brettt777]

What determines whether an aircraft shows up as flyable or AI, and can it be adjusted/altered, i.e., can I make a flyabe aircraft an AI plane?

[Hagar]

The default 'AI Only drones' like the B24D_LIBERATOR are defined as Aircraft Type 2 in the AIR file. You can change this to type 0 to make them selectable from the Free Flight menu. They won't have panels but you can fix that later.  Edit the AIR file with AirEd here. http://www.simviation.com/fsutilities_gen2.htm
Don't expect them to look or perform like proper flyable aircraft.

Any installed aircraft can be used as AI. You can add 3rd party aircraft to the QC database with the CFS Quick Combat Editor by Jaesen Jones. http://www.simviation.com/cfs2utilities1.htm

[H]

Contrarily, you can also leave the "title=" blank in the aircraft.cfg if you don't want the aircraft to show up in the selection list without changing anything in the aircraft's .air file. AI aircraft often handle different when used as 'flyable' thus a preference for added .air file editing.

8-)