I need help with Joint Assault.

I have been playing Ace Combat: Joint Assault since around christmas and I have unlocked most of the aircraft, but I have no idea how to unlock most of the experimental aircraft. I already have the XFA-24A Apalis and YR-99 Forneous but I need help and hints to unlock the rest which are YR-302 Fregata, XR-45 Cariburn, XFA-27, X-02 Wyvern, ADF-01 Falken, Fenrir and GAF-1 Varcolac. I thought it would be relative easy since I got Apalis and Forneous after the first playthrough on Normal difficulty, but it seems like I was wrong.