I put a small tail engine in a concept multirole MPA in the militairy forum. For take-off performance/ engine redundancy during heavy take-offs. More optimized main engines for long range/slower speeds.
I could be far more efficient and flexible then 4 engined aircraft like P3C & Nimrod and still be smaller & cheaper..
http://i191.photobucket.com/albums/z...g?t=1311463937
http://i191.photobucket.com/albums/z...g?t=1311464000