KAI KF-21 (KF-X)
22nd February 2022KAI KF-21 (KF-X) shambo.pfaff@i Tue, 02/22/2022 - 21:12
The Korea Aerospace Industries (KAI) KF-21 Boramae (Northern Goshawk) is a multi-role 4.5 generation fighter. The aircraft is powered by two General Electric (GE) F414-400K turbofan engines. The KF-21 was formerly designated as KF-X until April 2021. The Republic of Korea Air Force (ROKAF) plans to order at least 120 aircraft through 2032 at a projected program cost of more than $15 billion. Indonesia joined the program in 2010 and had planned to order 50 aircraft. The country's long-term participation in the program has since become remote as a result of budgetary pressures and more urgent operational requirements.
Prelude & Early Ambitions
In the early 1990s, South Korea sought to develop a robust domestic aerospace industry. Under the Peace Bridge II program, Lockheed Martin agreed to open a production line for F-16s in Korea. Hundreds of South Korean engineers were trained in the United States in preparation for domestic F-16 production and Lockheed Martin committed to a series of offset agreements including the development of a new Advanced Jet Trainer (AJT) designated as the KTX-2 which would become the T-50. In response to the Asian Financial Crisis of 1997, the Korean government directed the creation of KAI in October 1999 from the three largest aerospace chaebols (Korean conglomerates): Daewoo Heavy Machinery, Hyundai and Samsung Techwin (formerly Samsung Aerospace).
As KAI gained experienced with the KTX-2 program, the Kim Dae-jung Administration began to study proposals to develop an indigenous fighter. In August 2001, Defense Minister Kim Dong-shin announced the government would begin development of an indigenous fighter in 2003 which would enter service in 2015. In 2002, the Republic of Korea Air Force (ROKAF) wrote the initial Required Operational Characteristics (ROC) for a medium weight fighter which would be slightly superior to the F-16. The original requirements did not call for low observability (LO) or internal carriage of weapons. During the 197th meeting of the Korean Joint Chiefs in November 2002, initial KF-X ROCs were approved. A medium performance indigenous fighter would be developed to complement the higher-end F-15K which had been selected as the F-X in April 2002. The F-X program began in November 1997 and originally sought to procure 120 fighters by 2020 but was ultimately divided into three distinct phases for 40 (2002), 21 (including one attrition replacement, 2008) and 60 (revised down to 40, 2014) aircraft respectively.
Development work for the medium performance indigenous fighter would be led by the Agency for Defense Development (ADD) which coordinates nationwide defense R&D activities and reports directly to the Ministry of National Defense (formerly the Defense Acquisition Procurement Agency or DAPA until 2014). By 2007, South Korea was looking at developing a 5th generation, LO fighter. The world s first 5th generation fighter, the F-22, had reached initial operational capability (IOC) just two years prior following more than 20 years of development. Ambitious plans to expand domestic industry and discord amongst Korea s defense policy community greatly contributed towards the program s initial delays. Furthermore, differences in defense policy between subsequent administrations greatly affected the progress and funding of the KF-X program.
Feasibility Studies & Evolution of Requirements
Between 2002 and 2014, the government commissioned multiple feasibility studies on KF-X from the Korea Institute of Defense Analysis (KIDA), Korea Development Institute (KDI), Konkuk University and the Korean Institute of Science and Technology Evaluation Assessment (KISTEP). In 2012, the ADD also hired IHS Janes and Strategic Defense Intelligence to examine the KF-X s exportability.
In December 2007, the Korea Development Institute (KDI), an economic policy think tank staffed largely by government employees, found that the program would cost 10 trillion ($10.6 billion in adjusted 2020 dollars) and result in only 3 trillion ($3.2 billion in adjusted 2020 dollars) in economic benefits. KDI s ROCs assumed KF-X would be LO with internal carriage for four air-to-air missiles (AAMs) and performance characteristics in between the F-16 and F-15. In October of that year, four companies had submitted bids for KF-X (now nicknamed Boramae): Saab, Airbus (then EADS), Boeing and Lockheed Martin. Saab submitted two derivatives of its JAS 39 C/D fighter. The P305 was a single engine derivative while the P306 had twin engines, both stored weapons internally. EADS offered the Eurofighter Typhoon as the basis for a cooperative development program. Boeing and Lockheed Martin were operating under stringent U.S. export controls and kept a lower profile during the early stages of KF-X.
2009 marked a series of important milestones for the KF-X in terms of international participation and solidification of requirements. On March 9, 2009, South Korea and Indonesia and signed a Letter of Intent (LOI) for the joint development of KF-X. Indonesia committed to fund 20% of the KF-X development and purchase 50 IF-X (Indonesian derivative KF-X) aircraft. South Korea attempted to solicit Turkish participation in the program but Korea and Turkey were reportedly unable to reach an agreement regarding leadership of a co-development program.
KF-X program requirements
In 2009, the government commissioned Konkuk University s Weapons System Concept Development and Application Research Center to study the feasibility of the KF-X program. The study was led by Major General (ret.) Shin Bo Hyun who had previously led the original F-X evaluation team in 2002. Major Gen. Hyun s report found development and production of the KF-X was feasible if the KF-X was effectively downgraded to a 4.5 generation platform. The study concluded 5th generation capabilities were not necessary in a North Korea scenario. Stand-off weapons would allow non-LO aircraft to conduct strikes. The study proposed the following ROCs :
- Combat Radius: 1.5 times that of the F-16C/D Block 52 (approximately 500 miles or 800 km)
- Service Life: 1.34 times that of the F-16C/D (approximately 10,700 hours)
- Empty weight of 10.4 metric tons (22,928 lb.)
- Reduced radar cross section (RCS), but not true LO
- One to two engines
A 4.5 generation fighter would cost 6 trillion ($6.1 billion in adjusted 2020 dollars) to develop and approximately 50 billion to build ($51 million in adjusted 2020 dollars). A production run of 250 aircraft would be required to reach sufficient economies of scale. A total of 120 KF-Xs could be built to replace the legacy Boeing F-4 Phantom and Northrop F-5 fleets. An additional 130 could be built to eventually replace the ROKAF s F-16 fleet. The study concluded that South Korean industry possessed 63% of the required technologies for the program. Konkuk University s conclusions were well received and the program ultimately abandoned hopes to produce a fifth generation fighter at least in the short term (Block II and notional Block III).
Ties to F-X
The DAPA under the Myung-bak Lee Administration (Feb. 2008 to Feb. 2013) lowered F-X Phase III ROCs in an effort to make the bid more competitive and emphasize technology transfer for F-X at the cost of platform capability (particularly in terms of LO). The new ROCs enabled Boeing s F-15 Silent Eagle (F-15SE) and Airbus Eurofighter Typhoon to participate alongside Lockheed Martin s F-35. EADS (Airbus) offered to invest $2 billion in the KF-X program as part of its Eurofighter Typhoon bid. In August 2013, the DAPA selected the F-15SE as the only qualified bidder of the F-X Phase III as Lockheed s bid exceeded the specified price restrictions and the Eurofighter Typhoon was disqualified for a bidding irregularity. Later that month, a group of 15 former ROKAF Generals signed a petition against the F-15SE s selection. The Defense Project Promotion Committee chaired by Defense Minister Kim Kwan-jin overturned the initial DAPA decision in accordance with new ROCs from the Joint Chiefs favoring LO performance. On March 24, 2014, Seoul announced its intent to purchase 40 F-35As a reduction from 60 for budgetary purposes. On Sep.24, it announced it had completed negotiations with the U.S. government regarding price, offsets and technical details. As part of the 7.34 trillion ($6.5 billion in adjusted 2020 dollars) deal, Korea requested the transfer of 25 technologies to support the KF-X program.
KAI Down Select
In December 2014, the DAPA issued a request for proposals (RFP) for the KF-X program. Two teams participated throughout the competition: KAI-Lockheed Martin and Korean Air Lines (KAL)-Airbus-Boeing. The RFP requires a clean sheet design, but the KAL team reportedly wanted to use a modified F/A-18E/F with Airbus supplying components the U.S. manufacturer could not. However, Boeing ultimately withdrew before bidding which opened in February 2015. The Defense Acquisition Program Administration (DAPA) selected the KAI-Lockheed Martin team for the Korean Fighter Experimental (KF-X) program a month later. In November 2015, Indonesia agreed to fund 1.7 trillion ($1.54 billion in inflation adjusted 2020 dollars) or approximately 20% of the program s development costs. South Korea followed through by awarding the KF-X development contract to KAI in December.
The Finance Ministry approved 8.69 trillion budget ($7.65 billion in adjusted 2020 dollars) for KF-X s development over a period of 10 years and 6 months. Korean industry and Indonesia will fund 20% of the aircraft s development costs each with South Korean government financing the remaining 60%. The total program is expected to cost 18 trillion ($15.1 billion) for both development and production of 120 aircraft. Lockheed Martin will provide more than 300 man-years worth of engineering expertise in assisting Seoul in designing its KF-X. Lockheed Martin will also offer more than 500,000 pages of technical documentation derived from the F-16, F-22 and F-35.
With the objective of creating a reduced RCS but not LO design established, the ADD began exploring designs in 2012. The two primary candidates were a delta-wing canard design and a conventional tail and horizontal stabilizer layout which it considered to be European and U.S. style designs respectively. The C101 design followed the U.S. style wing-tail arrangement and progressed to the C-102, C-102E (single engine), C-102I (internal weapons bay), C-102T (twin-seat) and finally the C-103. The C-201 followed a similar progression with its own C-202, C-202E, C-202I, C-202T and C-203.
Separately, KAI initially wanted to develop its own KFX-E which had a single engine which it argued was cheaper than the more ambitious C-103 and C-203 designs put forward by the ADD. The company developed two versions of the KFX-E, one with a single vertical tail and one with canted twin tails. The KFX-E had an empty weight of 20,500 lb. (9.3 metric tons) and made use of technologies used on the FA-50 in flight control, landing gear, auxiliary power, electrical and environmental systems. During the 290th meeting of the Joint Chiefs in July 2014, the Joint Chiefs ruled that the KF-X must have two engines following an internal study as well as consultations with the DAPA, ADD and KIDA.
By the time Lockheed Martin won the separate F-X phase III in 2013, the ADD had moved to develop C-103 into the C-104 which featured conformal antennas and refined placement of internal systems. Full scale development began in late 2015. The design grew significantly from the original C-103 which had a 10.7-meter wingspan and 10.9 metric ton empty weight. The intake was enlarged on the C-105 design likely following the selection of the GE F414. The fuselage length and wingspan grew progressively throughout the design. The cockpit was moved forward in C-106 and the engines were spaced farther apart in C-107.