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The KF-X merry-go-round

Discussions regarding an indigenous fifth generation fighter jet have been swirling around the halls of Korean government, military and industry ever since President Kim Dae-jung blabbed about it way back in 2001 at some Air Force cadet graduation ceremony.  13 years later, it’s still mostly talk.  Sure, we got a few scale mock-ups, drawings, etc.  We may have some “just for shits and giggles” nascent technical drawings someplace too.

According to DefenseNews, here is the latest:

The state-funded Agency for Defense Development (ADD) has long studied a twin-engine concept, either of the C103 design that looks somewhat like the F-35 or the C203 design following the European approach and using forward canards in a stealth-shaped airframe.

Both of the twin-engine platforms would be powered by two 18,000-pound engines, ADD officials said.

Korea Aerospace Industries, on the other hand, prefers a single-engine concept, dubbed C501, which is to be built based on the FA-50, a light attack aircraft version of the T-50 supersonic trainer jet co-produced by Lockheed Martin.

The C501, powered by a 29,000-pound engine, is designed to be fitted with a limited low-observable configuration and advanced avionics.

Ah, the C501 vs. the C103.  The choices that a medium sized country with a limited aerospace budget has when it comes to developing stealth.  C103 will be the hard way and very expensive, but tempting for those who want to have a jet that can be spoken in the same breath as China’s J-20, Russia’s T-50 or America’s F-35.  The C501 is the easier way and more realistic for a country that doesn’t have unlimited fighter development budgets.  It will, however, create what may be just a stealthy, but up engined, version of an FA-50, with limited stores for weapons or future upgrades.

  • redwhitedude

    Talk about indecision. Perhaps Korea doesn’t have the capability to go the next step beyond the FA-50? Maybe they’d be able to get some sort of deal over production of the F-35? I seriously doubt it.

  • Wedge1

    If they’re smart, they’ll make the world’s first widely adopted UCAV, since that’s the future sooner or later.

  • cjm

    Buy the damn Super Hornets, A-10s and Super Sea Harriers

  • wangkon936

    Normally I would agree, but I think the ROKs have these three jets in mind that they would like to counter:




    The Super Hornet is an excellent 4th generation jet. However, it is still 4th generation. The A-10 is also excellent. KAI should rescue a few from the boneyard and copy the hell out of it. Probably wouldn’t cost too much money either. However, methinks money that normally would be spent on copying and building an A-10 copy will go to developing and building a Korean attack helicopter. Why? Because there is a greater international market for exportable attack choppers vs. fixed wing ground attack jets.

    Currently, the Koreans don’t have a platform to support Super Sea Harriers. The Dokdo class LPH’s deck, as currently built, cannot support jet exhaust from vectored thrust nozzles.

  • jk641

    Actually, the C103 will be not too much more expensive than the C501.
    It is expected to cost 2 trillion won more to develop the twin-engine version.

    But Indonesia will pitch in 20% of the development cost.
    Indonesia, being an island nation, also prefers the twin-engine version.
    If Korea decides to go with the single-engine version, who knows, Indonesia may choose to drop out, leaving Korea to foot the entire development cost.
    So in that case the C501 would be just as expensive as the C103.

    The C103, while it will be more challenging to develop, will offer much more rewards than the C501.

  • Sumo294

    I have to disagree as well–but I am no expert. However–I believe the ROK needs to have some sort of first strike capability on the table. Having the ability to hit something twenty minutes before everything goes to hell might actually save Seoul.

  • wangkon936

    It saved Israel in the Six-Day War. How do you defeat a conbination of Egypt, Syria, Jordan and Iraq? You strike first.


  • wangkon936

    Adding a second engine is no small feat and it isn’t cheap. A plane needs a bigger and stronger airframe. The fuel tanks need to be much bigger. The landing gear needs to be more robust.

    Then there is the issue of the internal weapons bays. You need to be able to launch weapons and quickly close doors as soon as possible and all that needs to work perfectly while the plane is going at least Mach 1 or Mach 2 if you want to use optimal kinematics to maximize the effectiveness of your long-range air-to-air missiles.

    These are technical issues that, if one wants solved properly with working real world solutions, will cost money. Lots of money.

  • jk641


    Like I said, the twin-engine design will be more challenging, but it will be a heck of a lot more rewarding.

    The C501 is simply inadequate.
    It’s impossible to install an internal weapons bay.
    Also, its single vertical tail is not stealthy at all; ideally it should have two angled vertical stabilizers. But if you were to put twin vertical stabilizers on the C501, that would drive up costs.
    And I don’t think the C501 will be that cheap anyway.
    It may be based on the FA-50, but it’s a new bigger airframe with a bigger engine, and stealthy-looking as well.
    It will mean that they have to develop a whole new flight model, and it will have to go through extensive testing and tweaking.

    I think if they’re gonna spend billions and billions of dollars, they should just go with a twin-engine design while they’re at it.
    The C103 has the potential to become a real stealth fighter. (and stealth is an absolute must in the 21st century, esp. in Korea’s neighborhood.)
    Also, a twin-engine platform means that it will be easier to boost engine thrust in the future. Which will mean more speed, better performance, and a bigger weapons payload.

    Overall, the C103 is much more upgradeable and future-proof; it will be able to serve Korea’s Air Force for many decades to come.

  • wangkon936

    Well, now the ROK air force agrees with you.


    I will write a longer response to you later.

  • jk641

    Yes, the ROKAF clearly prefers the twin-engine version.
    So do the Indonesians, with whom ADD designed the C103.

  • wangkon936
  • redwhitedude

    This KF-X thing is turning out to be a tall order for Korea. It’s unfortunate that Korea doesn’t have companies that are comparable to Raytheon, General Dynamics and so forth.