Question for aviation engineers

[mbear]

Recently I've seen a lot of calls for the USAF to restart F-22 production. One of the bigger arguments against it is apparently that the equipment used by the F-22 (processors, avionics, engines, etc.) are no longer in production.

However, when I look at the the next aircraft in production, the F-35, it seems that maybe those older out of production systems in the F-22 could be replaced by the F-35 equipment. For example the F135 engine is derived from the F119 used in the F-22.

Lockheed Martin has made it clear that they want to focus on the F-35, so restarting Raptor production isn't going to happen, but as a thought experiment, what would happen if new-build F-22s were equipped with F135 engines, F-35 avionics/computers, and EOTS/DAS? I mean to the airframe itself: Weight imbalances? New control schemes needed? Updates to software (obviously)?

I'm trying to wrap my head around the challenges of production.

[Maingunnery]

Well those are reliable components, however the adaptions that need to made to the F-22 airframe/software could cause some performance losses (stealth, efficiency, etc).
Also the end result will have to go through testing all over again.  xp

[Feenix74]

Caveat upfront, I am an airfield (civil) engineer not an aviation engineer by trade but I have worked in an aerospace project office, so have a general understanding their airworthiness processes but will happily be corrected by an aviation engineer.

F-35 effectively uses ruggedised, liquid-cooled Pentium processors, so the upgrade would be to 15 year old technology  :-\

The entire F-22B "Super" Raptor with the upgraded engines and avionics (possibly latest generation of stealth coatings) would need to be certified for airworthiness (same as what happened with the F/A-18E/F Super Hornet).

Probably the biggest challenges is that while all the tooling has been mothballed, the corporate knowledge on how to actually redesign/upgrade/assemble a Raptor has retired/resigned/been forgotten which means that it has to be re-discovered/re-learnt. So by the time you do that you may as well be building a new aircraft with the latest technology (and lessons learnt from F-35), the upgraded F-22B "Super" Raptor's relationship to the F-22 Raptor will probably resemble the relationship between the Super Hornet and the Classic Hornet.

[ANS Kamas P81]

You'd need to redesign the engine housings and the rear of the airframe at the very least - the F-135 is 43cm longer and 3-11cm smaller in diameter, as well as 100kg lighter.  The turbine system is also different, 1-stage high pressure and 2-stage low on the F135 and 1 & 1 on the F-119.  With the different shape requires different inlet dimensions and shaping to get subsonic airflow, plus it's very likely that the various fuel, coolant, sensor, and whatnot other connections are all going to be completely different as well.  That's just the engines...now, I imagine the avionics (being a digital glass cockpit) could be easier to swap out, though the only reason to do that is the EOTS system, which necessitates poking holes in the skin of the jet and wiring those up, and so on...

Honestly an F-22F could be done, but it really would be just like the difference between a Hornet and Super Hornet.  A lot of parts commonality (landing gear, most of the cockpit, maybe most of the wings and all the tail/elevators offhand, but you'd have some definite changes to the airframe - and the F-22's stealth requirement means balancing that out a lot more carefully than the Super Bug does.  It's not doable and it's frankly not a bad idea - good god, how many other aircraft have been rebuilt for modernization like that?  Looking at you, B-52...  It's just gonna be complex, especially because of the shape requirements for stealth capability.

Now, if you're gonna go that far, well, there's that Northrop/Grumman prototype still out there...anyone?  Anyone?  Bueller?