So F-22 is a gen 6 fighter now? Started as a gen 4. I belive its time to let someone else than Lockheed Martin decide how we define fighter generations...
The first definition i saw in mid 90:s, and the one im following is:
(for jets)
Gen 1. Subsonic with all analog systems and unguided weapons (MiG-15, F-86)
Gen 2. Supersonic, guided weapons but still analog systems. ( F-4 Phantom, Mig 21)
Gen 3. As gen 2 but with computers, still conventional control system. F/A-18 A-D, JA-37)
Gen 4. Digital systems, fly-by-wire and relaxed stability (EF 2000, Rafale, JAS-39, F-22)
Gen 5. CUAV?
The problem with using stealth to define generation is that there is no clear definition of what "stealth" is. Planes like Rafale, JAS-39 use a lot of stealth technology compare to earlier fighters. And also if a stealth plane can be detected with new radar tecnology, is it still stealth?
(and yes, late versions of a plane did in some cases get features from a later generation, AAM on F-86 for ex)