That's what McDonnell ... the original F-15A/B was replaced by the F-15C/D in 1979 with its superior maneuverability, power, range, weapons, and avionics. The F-15E Strike Eagle then entered ...

The aircraft would go on to serve as a trainer, a testbed for the F-15E strike eagle, a technology demonstrator, and even a NASA research aircraft for several programs at the same time as the F16XL.