Then why the hell do you keep talking about cruise missiles when this is a thread about the North Koreans developing a fighter? I assumed you were in some way tying it to fighter development, because otherwise this is extremely off-topic.Yes and why do you say that? Did I anywhere assert it to be the case? No.
You are framing it as such when I stated what is know about what they achieved and it certainly was not focused on jet engines for cruise missiles as you and other choose to grasp straws about that while ignoring other elements besides jet engines such as ability to produce passive electronically scanned array radars such as 30N6E and 48N6 equivalent surface to air missile along recently testing new surface to air missile reminiscent of 9M96E2 with addition of large solid fuel booster thus they have decent radar and anti-air missile technology.
If I'm ignoring something, it's because it's either not relevant, in the case of the SAMs, or I've already conceded it in the case of the PESA radar. See, this is my point: why on earth is their ability to develop a surface to air missile relevant to their ability to develop a fighter? It's not.
I'm focusing on the F-5 precisely because you pointed out that the J85 is in use - it is in use on a fighter that's not competitive in air to air and is on the way out. As for the J-6 and Q-5, well, I'll admit to being a little hasty in declaring the Q-5 out of service, but the J-6 definitely is (pg.15), and this brings me back to my original point: just because the engine is being used does not mean it's a viable fighter engine. The Q-5 is old, a dedicated ground attacker, being shoved out of service as fast as the Chinese can afford to do so, and was produced at a time when China couldn't do any better than modify the MiG-19. None of this points to it being useful for a current fighter project.Why are you focusing on F-5 when you were talking about viability of RD-9? Because I pointed out that J85 is still in use while being still in use just as is when Chinese produced RD-9 designated WP-6 with JJ-6 and Q-5 still in service as decommission process is gradual.
That is my point when you complained about RD-9 not being viable while its still being used just like J85.
As for F-5 when you mention about it not being competitive fighter, do you mean in original configuration made by its manufacturer or localized upgrades since Brazil arranged extensive upgrades of F-5s that those can use Derby BVRAAM and they outlived Mirage 2000.
And I mean both - Brazil's F-5s are rocking a small pulse-doppler radar set and frankly would get eaten alive by any sort remotely modern fighter. They've outlasted Brazil's Mirage 2000 fleet not on any sort of technical merits, but because the Mirage 2000s were hand-me-downs from the French Air Force (And thus old) and the maintenance contract with Dassault was about to run out.
You have zero evidence that that 2.3-fold increase carries over the -21 model. And even if it did that doesn't change all the rest of the advantages the twin J85 setup has over a single RD-9.RD-9 is 25% heavier than two J85-GE-21 combined.
Two J85-GE-21 combined produce 6 percent more thrust without afterburner and RD-9 consumes 6 percent more.
RD-9 when using afterburners consumes (1.66 lb/h·lbf) per kN.
J85-GE-5 on T-38 Talon for example consumes (0.57 lb/h·lbf) per kN and (1.34 lb/h·lbf) per kN using afterburners.
Apply that 2.3 fold increase to J85-GE-21 used on F-5E Tiger II and that would be (2.23 lb/h·lbf) per kN when using afterburners.
J85-GE-21 would be consuming 34% more per kN with afterburners while generating 20% more afterburner thrust than RD-9.