Originally Posted by
George K Lee
There are certainly a number of suitable engines, and with luck, military requirements will not require too many modifications (= cost and risk). I would just hope that the REP would include an early demonstrator with a pair of new engines in an installation that traces directly to production.
Current plans (which are very much still in flux) are to replace all 8 engines on a single "pathfinder" airframe that will also do a lot of flight testing to ensure the flight envelope (and more importantly, the weapons release envelope) is not affected by the new engines and engine installation. Swapping out only a single pair of engines will not enable the level of testing that is needed.