User blog comment:Generale wareagle/Mods for Ace Combat 5/@comment-1824272-20190730000017

No, this is not going to happen. It is really easy to mod Ace Combat 7 because of how the game was built; it runs on Unreal Engine and allows for the addition of external files to modify the game structure. Project Aces can turn this off at any time, but they haven't.

Ace Combat 5, on the other hand, is on a proprietary engine not used by any company outside of Bandai Namco to the best of our knowledge. It was custom-built for the PlayStation 2, and is packed tightly into a CD ISO. Programs exist that allow you to change textures and models in PS2 games, but this has not been done in any of the Ace Combat games, and more importantly, nothing like that allows adding new content. For example, at the time of me posting this comment, EVERY Ace Combat 7 mod just replaces a skin texture. No one has managed to insert a new model or any other new content that exists alongside the original content. The idea of doing this in Ace Combat 5 to add a brand-new fully-functional aircraft, AND forcing it to only be unlocked upon filling the Kill Rate for the ADF-01...

tl;dr No.