By Jeff Sung/Seoul
South Korea’s ambitious plans to develop an indigenous fighter continue apace, with the stage set for production of a prototype to begin by 2021.
“The KF-X development is running smoothly on time, and the critical design reviews of the aircraft and radar systems are key milestones to produce the prototype of the KF-X jet,” says Korea Aerospace Industries (KAI), the prime contractor for the 4.5-generation fighter aircraft project.
At the time of writing, the Defense Acquisition Program Administration (DAPA) was set to achieve the critical design review of the KF-X aircraft in September, following the review of the homegrown active electronically scanned array (AESA) system in May.
The $7.2 billion KF-X development is led by the Agency for Defense Development (ADD) and KAI in partnership with Indonesia. The aim is to produce a fighter on par with the most advanced variants of the Lockheed Martin F-16 by 2026, with a first flight planned for 2022.
Korea Aerospace Industries
At least 120 examples are expected to replace the Republic of Korea Air Force’s (ROKAF) fleet of ageing McDonnell Douglas F-4D/E Phantom IIs and Northrop F-5E/F Tiger IIs. Indonesia appears likely obtain 48 examples of the IF-X variant, with an initial order of 16, and 32 to follow depending on finances. This is somewhat below the 80 examples spoken of in previous years.
The preliminary design of the KF-X was finished in June 2018, after wind tunnel tests and computational fluid dynamic analysis. Production of the aircraft’s bulkhead started in February 2019. Lockheed Martin has also played a role in its development, as part of offsets related to Seoul’s acquisition of 40 F-35As.
Photographs revealed of the preliminary design – codenamed C-109 – show the aircraft armed with European missiles, mainly owing to export restrictions on weapons from the USA.
Four MBDA Meteor long-range air-to-air missiles can be seen under the fuselage, with two IRIS-T short-range guided air-to-air missiles mounted on the jet’s wingtips.
DAPA originally preferred arming the KF-X with US weapons systems including Raytheon-built AMI-120 and AIM-9 Sidewinder missiles, but the US goverment has yet to approve export licenses for these systems.
For air-to-ground operations, the jet is expected to be fitted with the MBDA Taurus missile with a range of 300 miles (500km). These German missile systems could be replaced by locally-built long-range air-to-ground missiles after LIG Nex1, a local manufacturer of precision guided missiles, was chosen in January as preferred bidder for exploratory development of the long-range air-to-ground missile for the KF-X. This missile will be developed by the late 2020s, with deployment possible in the mid-2030s.
In a first for South Korea, the KF-X is employing incremental arms development procedures, with the jet to be developed in two configurations, an initial Block I configuration and a subsequent and Block II configuration.
The aircraft will be powered by two GE Aviation F414 engines, which also power the Boeing F/A-18 E/F Super Hornet and Saab Gripen E aircraft.
“The F414-GE-400-powered KF-X will deliver significantly greater mission capability, extended combat radius and longer lifespan compared to current aircraft,” GE Aviation says. “The prototype engine is set to be rolled out in the first half of 2020.”
Much attention has been given to the development of a homegrown AESA radar system, which industry officials and experts see as key to the success of KF-X programme. Owing to US export restrictions, it will be developed locally by Hanwha Systems.
On 30 May, the DAPA announced the critical design review of the indigenous AESA radar had been completed, and the first production prototype is set to be unveiled in the second half of 2020.
Hanhwa will produce the prototype with technical assistance from Israel’s Elta Systems. Under a contract with the ADD, Elta is responsible for verifying airborne tests evaluating the Korean AESA system.
In April, airborne tests of the KF-X’s AESA hardware systems, including the transmit-receive antenna and the power supply unit, took place in South Africa with the attendance of KF-X developers from the ADD, Hanwha and KAI.
“The KF-X mock-up radar was tested on board a leased 737-500 airplane, and the tests were successful,” said Lee Seung-keun, an ADD researcher involving the KF-X AESA development during an airworthiness seminar in April. “The radar is to be further tested in Korea with the follow-up [flight tests] focused on software for multi-missions.”
The radar is scheduled to be tested aboard an actual KF-X prototype aircraft in 2023 with the aim of completing all aspects of development by 2026.
The KF-X AESA is based on gallium nitride technology and aims for performance similar to the Northrop Grumman APG-83 Scalable Agile Beam Radar (SABR) that equips the F-16V, the ADD says. The radar will have slightly more than 1,000 transmit-receive antenna modules, with a beam-steering angle of 60 to 70 degrees.
Nonetheless, concerns and questions remain about the indigenous AESA development effort, including its integration. One issue is that the ADD has multiple contracts with both local and foreign defence manufacturers related to developing the radar.
Locally, it is working with both Hanwha and LIG Nex1. Hanwha is in charge of developing the AESA hardware, but LIG Nex1 is leading the equally crucial software development.
LIG Nex1 has long experience with AESA. It partnered with ADD between 2006 on 2013 on applied AESA research, and is also involved in phase I development of building an AESA antenna and other equipment for air-to-air missiles, as well as radar systems for air-to-ground systems.
For the KF-X radar, it is developing radar processing devices and software systems for air-to-air, air-to-ground, and air-to-sea modes – a process that started in 2017 and that will run to 2021.
Sweden’s Saab is assisting LIG Nex1 with AESA software. Under a contract with the ADD, the Swedish aerospace firm is helping to evaluate the radar’s algorithm.
On the hardware side, Hanwha is working with Leonardo, which had previously pitched its Vixen radar for the KF-X radar requirement. This co-operation falls under the auspices of a 2017 memorandum of understanding, whereby the companies have agreed to collaborate on AESA, as well as other airborne systems.
“Hanwha and Leonardo have been in talks on the development and upgrade of airborne radar systems for South Korean combat aircraft, such as the FA-50 and the KF-X,” a Hanwha source says.
However, the complexity of AESA development contracts could lead to glitches at the integration stage, local experts say.
“When you develop a radar, software is developed to fit in the hardware architecture,” says Chang Hyung-keun, a professor at Korea Aerospace University in Goyang, Gyeonggi Province. “In that sense, it’s absurd that two different companies are involved in software and hardware, respectively.”
“Even if the hardware development succeeds, developing AESA software and integrating it into the hardware is a totally different story,” says a retired air force brigadier general who serves as a member of DAPA’s KF-X advisory group. “There are risks down the road, although I hope the radar project will be successful in the end.”
COST CONCERNS IN JAKARTA
Another challenge for the KF-X programme is Seoul’s relationship with its only partner in the $7.2 billion programme, Jakarta. In addition to the vast technical issues facing the project, there is great uncertainty around how costs will be shared.
Despite early enthusiasm for the project, Indonesia has backtracked from its original commitment to fund about $1.4 billion – or 20% – of development costs. Citing domestic budgetary constraints, the government is seeking to renegotiate the terms of its participation.
Instead of cash, Jakarta would prefer to make payment in kind – including providing Airbus Defence & Space CN235 tactical transports produced under licence by Indonesian Aerospace, also known as PTDI, in Bandung. Whether or not South Korea will accept Indonesia’s suggestion is far from clear. Wiranto, Indonesia’s minister of security affairs, made country's intention to seek a barter deal public in July.
“We are adjusting (our involvement in the KFX/IFX project), so, for instance, in coming stages we don't have to pay in cash but in other (forms of exchange)," the minister told Indonesia’s Antara news agency.
He stressed that the Indonesian government doesn’t want to compromise the country's strong defence ties with South Korea, or diminish any technical gains from the programme. Still, he is adamant that Jakarta’s funding ratio needs to come down.
Indonesia has paid about $180 million of the 1.4 billion it committed to the KF-X/IF-X, and had a funding shortfall of $250 million as of July.
“The negotiation between the two governments are ongoing, and we hope the Indonesian funding issue will be resolved in a wise manner,” DAPA spokesman Park Jung-eun said, declining to elaborate.
KAI hopes the financial issue will not affect the aircraft's development schedule.
“We hope the governments of South Korea and Indonesia will solve the burden-sharing issue soon,” says KAI. “Nonetheless the funding issue is not expected to have a serious impact on the overall fighter development roadmap.”