KAI KF-X

The Korea Aerospace Industries KF-X is a South Korean program to develop an advanced multirole fighter for the Republic of Korea Air Force (ROKAF) and Indonesian Air Force (TNI-AU), spearheaded by South Korea with Indonesia as the primary partner. It is South Korea's second fighter development program following the FA-50.

The project was first announced by South Korean President Kim Dae-Jung at the graduation ceremony of the Air Force Academy in March 2001. South Korea and Indonesia had agreed to cooperate in the production of KF-X warplanes in Seoul on July 15, 2010. The initial operational requirements for the KF-X program as stated by the ADD (Agency for Defence Development) were to develop a single-seat, twin-engine jet with stealth capabilities beyond either the Dassault Rafale or Eurofighter Typhoon, but still less than the Lockheed Martin F-35 Lightning II. The overall focus of the program is producing a 4.5th generation fighter with higher capabilities than a KF-16 class fighter by 2020.

Design and development
According to the Weapon Systems Concept Development and Application Research Center of Konkuk University, the KF-X is intended to be superior than the KF-16, which would replace South Korea's aging F-4D/E Phantom II and F-5E/F Tiger II aircraft, with production numbers estimated to be over 250 aircraft. Compared to KF-16, the KF-X will have a 50% greater combat radius, 34% longer airframe lifespan, better avionics including a domestically produced AESA radar, and better electronic warfare, IRST, and datalink capabilities. Operational requirements also specify approx 50,000 pounds of thrust provided by one or preferably two engines, high-speed interception and supercruise capabilities, basic stealth technology, and multirole capabilities. There are currently two competing designs for the KFX, the  KFX-201 which has a tri-plane layout with canards and a more conventional, Single Engine F-35 style KFX-101 design.

South Korea will fund 60% of the aircraft's development, and expects foreign partners to provide the remaining 40% of the development funding. South Korea possesses 63% of the necessary technology to produce the KF-X, and is therefore seeking cooperation from Indonesian Aerospace, Turkish Aerospace Industries, Saab, Boeing, and Lockheed Martin to develop the KF-X. About 120 KF-Xs would be built initially and more than 130 aircraft would be produced additionally after the first-phase models reach operational capability. The cost of each KF-X aircraft is estimated to be roughly $50 million +.

In October 2009 a retired general in the South Korean Air Force was arrested for leaking classified documents to Swedish aviation and defence corporation Saab. The general was to have been given a bribe of several hundred thousand dollars for copies of a number of secret documents that he had photographed in the South Korean Defence University. Saab officials denied any involvement.

On 15 July 2010, the Indonesia government agreed to fund 20% of KF-X project cost in return of around 50 planes built for Indonesian Air Force after project completion. In September 2010, Indonesia sent a team of legal and aviation experts to South Korea to discuss copyright issues of the aircraft.

On 7 September 2010, Maj. Gen. Choi Cha-kyu, director general of the aircraft program bureau at the Korean Defense Acquisition Program Administration (DAPA) said that Turkey was interested in joining the program.

On 15 December 2010, a senior Turkish procurement official said that "What we need is a true and equal partnership for the development of a fighter. The problem is that South Korea is not likely to agree to an equal partnership".

In December 2010 the program shifted from a F-16 class fighter to a stealth aircraft in order to respond to North Korean pressure.

On 20 April 2011, South Korea's Defense Acquisition Programme Administration (DAPA) confirmed the signing of a definitive agreement between South Korea and Indonesia to jointly develop the Korean KF-X next-generation fighter aircraft.

On 2 August 2011, a joint research center was opened in Daejeon.

In a public meeting the Korean Institute for Defense Analysis revealed the development would cost more than 10 trillion won. Over the lifetime of the program the KF-X would cost more than twice as much as an imported aircraft. The institute openly questions whether the U.S. will be willing to help. Similary in 2007, the Korean Development Institute reported that the KF-X was not viable. Lee Daeyearl, KF-X program director at the Agency for Defense Development, said the fighter would cost 6 trillion won in development, 8 trillion in production, and 9 trillion for operation over 30 years.

The Agency for Defense Development has prepared two series of designs, one for an aircraft with aft horizontal stabilizers, and with a canard stabilizer. The aft-tail series has run through the iterations C101, C102 and, C103, all with two engines and a single seat. The C102 design was further broken down into three variants: C102E with one engine, C102I with internal weapons and C102T with two seats. Similarly, the canard series had the iterations C201, C202 (also with variants E, I and T) and the current C203 follow the same pattern. The agency proposes that either C103 or C203, whichever was chosen, would then advance through three design standards. Block 1 would be "reduced observable," which would be equivalent to the B-1B, Boeing F/A-18E/F Super Hornet and Eurofighter Typhoon. Block 1 would rely on fuselage and inlet shaping, edge alignment, radar-absorbing material, and semiconformal weapons carriage for reducing signature. Block 2 would carry internal weapons, have conformal antennas, and sensors would be "integrated". There would be minimal gaps and additional radarabsorbing coating on the canopy, and the structure of the aircraft. It would be as stealthy as the F-117. Block 3 would advance the aircraft to the level of the B-2, F-22 and F-35, but no details are given. All of this is a step beyond the previous concept. The aircraft is expected to be between the General Dynamics F-16 Fighting Falcon and the McDonnell Douglas F-15 Eagle in size. The C103 design with two engines of 18,000 lb. thrust each. According to a 2009 external review of the program, the empty mass of the KF-X should be 10.4 metric tons.

A decision on the selection of either design lines was expected to be made in 2013. However Indonesian Defense Ministry spokesman Pos Hutabarat announced a year and a half suspension of the project in 2013. This delay was said to be caused by uneasiness in the new South Korean government over the expense of the program.

On 23 May 2013, EADS stated that if South Korea selects its Eurofighter Typhoon as the winner of the K-X program, they will invest $2 billion into the KF-X program.

In July 2013, the Indonesian government announced it intends to continue development of the KF-X. Indonesian Aerospace is getting ready to undertake the second stage of the aircraft's development.

Starting in July 2013, KAI revealed plans for a much smaller single engine design that resembled a scaled down F-35.