Unrealistic early visions of an F-35 class stealth aircraft developed on the cheap produced some attention-getting models, but they appear to have given way to the idea of a fighter with slightly better kinematic performance than an F-16C/D Block 50, along with more advanced electronics that include a made-in-Korea AESA radar, the ability to carry a range of new South Korean weapons under development, and a better radar signature. The Jakarta Globe adds that the plane is eventually slated to get the designation F-33.
The project goes ahead, the 1st step will involve picking a foreign development partner, and the next step will involve choosing between 1 of 2 competing designs. The C103 design’s conventional fighter layout would look somewhat like the F-35, while the C203 design follows the European approach and uses forward canards in a stealth-shaped airframe. It’s likely that the choice of their foreign development partner will determine the design choice pursued.
Either aircraft would be a twin-engine fighter weighing around 10.4 tonnes, with stealth shaping. In order to keep ambitions within the bounds of realism, KFX Bock 1 fighters would only have to meet the radar cross-section of the F/A-18E/F Super Hornet or Eurofighter Typhoon. Sources have used figures of 0.1 – 1.0 square meters.
Note that even this specification amounts to developing a plane similar to or more advanced than the JAS-39E/F Gripen, from a lower technological base, with less international help on key components, all for less development money than a more experienced firm needed to spend. South Korea’s own KIDA takes a similar view, questioning the country’s technical readiness for something this complicated, and noting an overall cost per aircraft that’s twice as much as similar imported fighters.
KFX Block 2 would add internal weapon bays. Present plans call for Block 1 would be compatible with the bays, and hence upgradeable to Block 2 status, but Block 1 planes wouldn’t begin with internal bays. The fighter’s size and twin-engine design offer added space compared to a plan like the Gripen, but this feature will still be a notable design challenge. Additional tolerance and coating improvements are envisioned to reduce stealth to the level of an F-117: about 0.025 square meters.
KFX Block 3 would aim for further stealth improvements to the level of the B-2 bomber or F-35.
No timeline has been discussed for Block 2 and Block 3 improvements, and at this stage of the program, any dates given would be wildly unreliable anyway.