3 Block Development Phase of KF-X
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.
KF-X Block 1
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 Block 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.
KF-X Block 2
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.
KF-X Block 3
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. At this stage of the program, any dates given would be wildly unreliable anyway.
The ROK Agency for Defense Development says that if full-scale development begins in October 2014, the 1st KF-X Block 1 prototype flight wouldn’t take place until September 2020. Based on the history of other programs, the new plane would be hard pressed to enter service before 2025. (DefenseIndustryDaily)
Block 1 for Indonesia, Block 2 & 3 for Korea
"At this point, there is almost no difference between KF-X and IF-X shapes," says the official.
Still, the South Korean and Indonesian examples are likely to be different. Previously, officials have said that a Block I configuration without stealth coatings and the ability to carry weapons internally will go to Indonesia. South Korea will have a Block II aircraft, with stealth coatings and weapons bays.
Seoul will also develop indigenous capabilities in key areas where it failed to obtain export licences from the US, an early stumbling block for the programme. These include the jet's active electronically scanned array (AESA), which will be developed with Israeli assistance, infrared search & track (IRST), electro-optical targeting, and the aircraft's electronic warfare suite.