Korean stealth fighter is extremely unlikely
I am skeptical of a Korean stealth fighter.
The Koreans have yet to indigenously produce a fourth-generation fighter (e.g. F-16, J-10, or Su-30). It is highly unlikely the Koreans can skip the fourth generation and manufacture a fifth-generation stealth fighter.
Even the Japanese can't do it and they possess the transfer of licensed technology to produce a fourth-generation F-2 fighter (e.g. a large F-16).
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20-year delay between fourth and fifth generation fighters
20 years of aviation mastery are required after the manufacture of a fourth-generation fighter to produce a fifth-generation stealth fighter.
For example, the U.S. F-16 had "first flight" in 1974. The F-22 had its "first flight" in 1997. A period of 23 years was necessary before the United States developed the expertise to build a stealth fighter.
For China, the J-10 had its "first flight" in 1998. The J-20 had its "first flight" in 2011. China needed 13 years to transition from a fourth-generation to a fifth-generation fighter.
Korea has not yet produced a fourth-generation fighter. Furthermore, Korea is a tiny country with a small economy and narrow technological base. With inadequate funding and lack of a broad technological base (e.g. cannot launch satellites into orbit, cannot build nuclear submarines, cannot build indigenous Aegis system, etc.), there is no chance Korea will build an indigenous stealth fighter in the next thirty years.
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