The AIDC F-CK-1 Ching-Kuo (), commonly known as the Indigenous Defense Fighter (IDF), is a multirole combat aircraft named after Chiang Ching-kuo, the late President of the Republic of China (Taiwan). The aircraft made its first flight in 1989. It entered service with the Republic of China Air Force (ROCAF) in 1992. All 130 production aircraft were manufactured by 1999.
Taiwan initiated the IDF program when the United States refused to sell them F-20 Tigershark and F-16 Fighting Falcon jet fighters following diplomatic pressure from China. Taiwan therefore decided to develop an advanced indigenous jet fighter. The Aerospace Industrial Development Corporation (AIDC), based in Taichung, Taiwan, designed and built the IDF jet fighter.
Development
Background
The preliminary search for a replacement for the ROCAF's F-5s and F-104s began in the late 1970s with the XF-6 indigenous fighter project, later renamed Ying Yang. After the United States established formal relations with the People's Republic of China and ended the Mutual Defense Treaty with Taiwan, President Chiang Ching-Kuo decided to expand the indigenous defense industry and on 28 August 1980 ordered Aerospace Industrial Development Corporation (AIDC) to design an indigenous interceptor. Originally, the ROCAF listed the priority of the XF-6 behind the XA-3 Lei Ming single-seat attack aircraft, due to the believed high risks of the XF-6 project.
The signing of the 1982 US–China joint statement limited US arms sales to Taiwan. The US refused to sell the General Dynamics F-16 Fighting Falcon and the Northrop F-20 Tigershark (which had been developed largely to meet Taiwanese national defense needs) thereby ensuring the continuation of the indigenous defense fighter (IDF) project. Although US President Ronald Reagan reluctantly accepted his advisers' suggestion of building relations with China to counter the USSR, Reagan decided to balance the 1982 US–PRC joint statement with the "Six Assurances" to Taiwan. This opened the door for US technology transfer and assistance to Taiwan's defense industry, including the IDF project.
Design phase
AIDC officially began the IDF development project in May 1982 following the ROCAF's inability to purchase new fighters from the US as a result of Chinese diplomatic pressure. AIDC was then led by Hsi-Chun Mike Hua, who the Taipei Times described as "the father of the Indigenous Defense Fighter" on his death in 2017. Hua contributed to the project, which was named An-Hsiang (安翔, Safe Flight) and in 1983 was divided into four sections:
Ying-Yang (鷹揚): "Soaring Eagle". Development of the airframe, with some cooperation from General Dynamics. Yun-Han (雲漢): "Cloud Man". Development of the aircraft powerplant and propulsion, in cooperation with Garrett (now Honeywell). Tien-Lei (天雷): "Heavenly Thunder". Development of the avionics systems, with some cooperation from Smiths Industries, and some components purchased directly from Lear Astronics (today a subsidiary of BAE Systems), Litton (today a subsidiary of Northrop Grumman) and Martin-Baker. Tien-Chien (天劍): "Sky Sword". Development of air-to-air missiles.
Chief of the General Staff General Hau Pei-tsun noted in his daily diary of 5 January 1983 that AIDC was moved under the administration of the defence ministry's Chungshan Institute of Science and Technology (CSIST). He believed that only CSIST could bring together the resources and personnel required for the IDF project.
Engines
Exports of advanced engines such as the General Electric F404 or the Pratt & Whitney F100 were not available to Taiwan. Both the General Electric J85 and General Electric J79 were considered unsuitable in their performance, and most European and American engine companies declined to cooperate with the project. Joint investment with Garrett became the only practical solution.
In 1978, following the success of the TFE731 engine, US engine company Garrett announced joint research of the TFE1042 afterburner with the Swedish company Volvo Flygmotor. The TFE731 Model 1042 was touted as a low bypass ratio "military derivative" of the proven commercial TFE731 engine, and that it would provide "efficient, reliable, cost-effective propulsion for the next generation of light strike and advanced trainer aircraft", with a thrust of 4260 lbf (18.9 kN) dry and 6790 lbf (30.2 kN) with afterburner. After the initial negotiation, the investment was divided between Garrett, Volvo, AIDC, and the Italian company Piaggio. The development would consist of the non-afterburning TFE1042-6 for light attack aircraft and advanced trainers, and the TFE1042-7 for the AMX or the F-5 upgrade. AIDC also suggested upgrading the TFE1042-7 to thrust in a twin-engine installation, in order to compete with the GE F404. However, the JAS 39 Gripen project decided to continue with a single F404, and Piaggio asked to participate at a later date due to financial concerns.
International Turbine Engine Corporation (ITEC) was formed as a joint venture of Garrett and AIDC, and completely redesigned the TFE1042-7 into the TFE1042-70 – for example, the bypass ratio was changed from 0.84 to 0.4 – and investment had increased from US$180 million to about US$320 million. However, to avoid pressures from China, the US government asked all American companies cooperating with the Taiwan on the IDF project to remain low-key. Therefore, the perception that "the TFE1042 is merely the civilian engine TFE731 with an afterburner" was never completely dispelled.
In 1985, the preliminary review of the IDF's design revealed performance requirement shortfalls, and it was determined that an upgrade of engine thrust by 10% was the simplest solution. Due to US export-license restrictions, ITEC artificially limited the engine's thrust (utilizing FADEC) below a certain altitude (this restriction was not removed until 1990). Although the upgrade essentially used the TFE1088-11 configuration, to reduce political interference ITEC renamed the lower-thrust version as the TFE1042-X70 and retained the TFE1042-70 designation for the full-thrust version.
In 1988, ITEC decided to invest in the thrust TFE1088-12, which was similarly re-designated as the TFE1042-70A for political reasons. Preliminary studies had shown that the IDF could supercruise with the new engine. At the same time, General Electric Aviation decided to enter the market with the J101/SF, a smaller version of the F404. However, after the IDF order was cut in half due to budget concerns, the TFE1088-12 engine upgrade plan ended as well.
Aerodynamics
The cooperation between AIDC and General Dynamics (GD) was divided into four phases: GD analyzed the ROCAF's aircraft performance and force requirements. Taiwan assessed GD's reports and chose between AIDC's original design and GD's new design. AIDC sent personnel to GD for the preliminary design phase. GD sent personnel to Taiwan to complete the project.
GD's assistance was restricted by US arms export control, which limited the company's work to consultation on the initial design with no further development, production, or marketing.IDF 20th year roll out recollection. Retrieved Sept 14, 2009.
Many different airframe design concepts were explored (e.g. the 2D Thrust-Vectoring nozzle of XX-201, the double delta wings/twin tailed 401). After the General Electric J79 was officially abandoned as the potential engine solution in 1983, three configurations emerged from AIDC.
Configuration A was similar to the F-5E. Configuration B was similar to the Eurofighter Typhoon and Saab Gripen. Configuration C was similar to the F-15.
At the same time, GD worked on the G configuration in parallel. Eventually the G-4 was selected, but with many features of the C-2 integrated. During this time, the project was named the "Light Weight Defense Fighter". In 1985, the configuration conceptual design had evolved into the SE-1 preliminary design. By the end of 1985, AIDC decided to skip the prototype stage and go into full-scale development (FSD) directly, in order to reduce time and save money. The project was again renamed as the Indigenous Defense Fighter (IDF). Four FSD aircraft were made, with three single-seaters and one double-seater.
Avionics
The IDF is equipped with a GD-53 Golden Dragon multi-mode monopulse pulse-Doppler radar, which is based on the General Electric AN/APG-67 X band radar developed for the F-20 while sharing some components and technologies of the AN/APG-66 radar of the F-16A, and using a larger antenna than the F-20. This adaptation resulted in the look-down and shoot-down capability of GD-53 being greatly enhanced and reaching that of the AN/APG-66. The radar can simultaneously track 10 targets and engage 2 of these 10 with TC-2 active-radar beyond-visual-range air-to-air missiles (BVRAAMs).
The design is inherently unstable in pitch, so the IDF incorporated a modern triple-redundant full authority fly-by-wire control system. The avionics suite was based on modular architecture with dual redundant MIL-STD-1553B digital databuses. The Honeywell H423 inertial navigation system, the TWS-95 RHAWS, and a Bendix-King head-up display were selected. Some capabilities may have been delayed or dropped in order to meet the performance requirement, since the engine limitation had resulted in the necessity of strict weight control.
Missiles
The Tien Chien (Sky Sword) project conducted at the Chungshan Institute of Science and Technology (CSIST) was slightly more independent, as the air-to-air missiles were developed for all ROCAF fighter aircraft. The Sky Sword I (TC-1) is a short range infrared-seeking missile with an external configuration similar to that of the AIM-9 Sidewinder, while the Sky Sword II (TC-2) is an active radar homing beyond-visual-range missile.
The first test firing of the TC-1 was performed by an F-5E in April 1986, with the Beech target drone successfully destroyed. Initial production of the TC-1 began in 1989, and it entered service in 1991. Both the AIM-9 and the TC-1 have been seen in use on operational IDFs.
CSIST is believed to have cooperated with Motorola and Raytheon on the TC-2's active seeker, which is believed to be based on a design the companies proposed for the AIM-120. 40 pre-production TC-2 missiles were produced before 1995, and were the only BVR AAMs that the ROCAF had in its inventory during the 1995–96 Taiwan Strait Missile Crisis. Over 200 production TC-2s were originally planned.
Upgrades In April 1997, AIDC awarded Litton's Applied Technology division a production contract and options totalling $116.2 million for improved radar warning receivers (IRWR) to be installed aboard.
The first stage of upgrades to the fleet was originally planned to be completed by 2013, and was planned to include improved avionics, radar, electronics, weapons capabilities and lifespan extensions. In May 2014, the ROCAF released photos of the fighters with enhanced Wan Chien long-range missile capabilities. The upgrade program was completed in 2018.
Operational history
Variants
Planned nuclear strike aircraft
CSIST planned to modify at least one of the IDF aircraft to enable it to deliver a nuclear weapon to a range of 1,000 km (621 mi). As a nuclear weapon would be carried in place of the IDF's centerline fuel drop tank, this would add weight while reducing fuel and nominal range. To compensate, CSIST planned engine modifications for greater fuel efficiency while sacrificing acceleration and engagement capability.
Taiwan's nuclear weapons program was shut down in early 1988, months before the first IDF prototype was delivered.
Prototypes