DEFENCE South Korea stealth fighter
South Korea bets big with its KF-21
The KF-21 fighter will grow into the backbone of the Republic of Korea Air Force and a pragmatic development approach could secure its export future, reports ATUL CHANDRA.
Unveiling of the first prototype of the homemade KF-21 Boramae supersonic fighter, formerly known as KF-X, at Korea Aerospace Industries (KAI) manufacturing facility in Sacheon, South Gyeongsang province.
South Korea’s indigenously developed KF-21 ‘Boramae’ (Hawk) fighter jet is an ambitious undertaking for the nation’s defence industry which has made dramatic strides in the last two decades. South Korea is one of less than a handful of nations pursuing the expensive development of an indigenous 4.5+ generation fighter aircraft and the only one with a close and significant partnership with the US military and defence industry.
The rollout of the first KF-21 prototype in April by Korea Aerospace Industries (KAI) was a major milestone for the 8.8tn won ($7.8bn) programme and marked the start of the monumental path towards testing, evaluation and production of South Korea’s first indigenously developed fighter aircraft.
South Korea has taken an export-driven approach to the KF-21 programme which includes industrial cooperation, as evidenced by the partnership with Indonesia to share 20% of R&D costs at approximately 1.6tn won ($1.3bn) between 2015 – 2028 to develop the 4.5 gen fighter type. Jakarta could procure as many as 50 of the type, which is to feature several Indonesiaspecific modifications and currently designated as Indonesia Fighter e-Xperimental (IF-X). The initial phases of the partnership moved ahead in fits and starts and eventually resulted in Indonesian teams being withdrawn from the project in March 2020 due to non-payment of dues and the Covid-19 pandemic. However, both nations have resumed their cooperation on the project with Indonesian technical staff to have returned to KAI’s Sacheon development site in Gyeongnam in August.
Korea’s close partnership with the US will be a key factor in unlocking future defence export sales for the programme, following a similar path as Israel has done. KAI has gained significant export contracts for its KT-1 turboprop basic trainer, along with the T-50 Advanced Jet Trainer (AJT), TA-50 Lead in Fighter Trainer (LIFT) and FA-50 light combat aircraft. However, getting new customers to sign up for the KF-21 will be a whole new ball game for KAI which estimates the type’s export potential at 600-700 aircraft.
Korea Aerospace Industries’ KF-21 production plant
“The KF-21 could be an export market success for countries that don’t want, or can’t get, an F-35, and aren’t eager to become dependent on US or Russian fighters,” said Richard Aboulafia, FRAeS, Vice President, Analysis at Teal Group Corporation. “KAI needs to keep the F-35 in their minds, but also all the other competitors. I’d say a unit recurring flyaway cost of less than $60m is key, along with operating costs in the $20,000 per hour or less range.” Competition in the global fighter market is brutal with the US, Russia and France leaving little room for new entrants. Pricing the KF-21 attractively and offering a robust upgrade roadmap could help KAI prise open a lucrative export market.
Other nations developing indigenous fighter aircraft in a similar category include China, Turkey, India and Japan. China’s twin-engine Chengdu Aerospace Corporation J-20 which is touted as a fifth-generation fighter is entering service in larger numbers while the Shenyang Aircraft Corporation FC-31, a new Chinese 4.5 generation single-engine fighter is still in development. Both Chinese types are unlikely to have serious export prospects.
Turkey’s Turkish fighter experimental (TF-X) and India’s Advanced Medium Combat Aircraft (AMCA) are also 4.5 gen twin-engine fighter programmes, though India is also pursuing a carrier-borne variant. “The original sin of the AMCA is that it’s dependent on a government-owned entity, HAL. The TF-X original sin is the Turkish government pretending that it doesn’t need to worry about key subsystems. In short, the KF-21 has much brighter export prospects than AMCA or TF-X,” Aboulafia said. Japan, another close US ally is pursuing its F-X sixth-generation twin-engine fighter programme.
Racing to meet timelines
Known prior to the rollout as the Korean FighterExperimental (KF-X), the aircraft is a dramatic leap for KAI which cut its teeth on licence production of F-5 and KF-16 fighter jets in the eighties and nineties, respectively. This was followed by development of the T-50 supersonic jet trainer in partnership with Lockheed Martin in the 2000s. KAI later selected Lockheed Martin to partner it on the KF-21 programme to deliver a total of 120 aircraft to the Republic of Korea Air Force (ROKAF) across single and twin-seat variants.
Korea Aerospace Industries’ HQ
Korea’s Defence Acquisition Program Administration (DAPA) selected KAI as the prime contractor for the programme in March 2015 and development started in January 2016. The programme faced setbacks with US refusal in 2015 to part with key technologies related to the active electronically scanned array (AESA) radar and other sensors planned for KF-X at that time. KAI completed the Preliminary Design Review (PDR) and Critical Design Review (CDR) in June 2018 and September 2019 respectively. The KF-21’s maiden flight is slated for 2022 and flight testing with six prototypes is slated for completion by June 2026. All 120 series production aircraft are planned for delivery by 2032 across Block I and Block II versions.
The KF-21 will be able to attain speeds of Mach 1.8 and will not have an internal weapons bay, instead carrying its four MBDA Meteor long-range beyond visual range air-to-air missiles (BVRAAM) in semi-recessed fuselage stations. KAI states aircraft range at 2,900km and a maximum payload of 7.7 tonnes across weapons, sensors and drop tanks can be carried on ten hard points.
Despite Korea having taken a pragmatic approach in terms of aircraft configuration and a balance of indigenous and foreign content with the KF-21, the 10.5-year developmental timeline can be termed as ambitious for an ab-initio fighter design in this class. “It’s a very ambitious timetable. What’s particularly ambitious is their effort to develop an in-country capability to build key component systems and technologies. This represents the biggest risk to the programme’s schedule and budget,” Aboulafia said.
The Korean JoongAng Daily reporting in June that the prototype aircraft had been largely dismantled in what appeared to be an unusual occurrence, considering that ground tests were to have begun by then. In a clarification issued the same month, DAPA denyed the extent of dissasembly, though it did acknowledge that the engine had been removed. KF-21 prototypes will undergo more than 2,000 ground and flight tests as part of the developmental programme. More than 3,000 hours of transonic wind tunnel testing has already been completed by KAI over the last five years at Calspan’s 8ft x 8ft continuous flow variable density transonic wind tunnel, located in Buffalo, New York.
A growing defence industrial base
The KF-21 programme is a showcase of the growth in Korea’s defence industry, which is now making its mark in export markets for land, naval and air systems. An estimated 800 Korean companies are already part of the KF-21 programme, generating 120,000 jobs across Tier 1 and Tier 2 vendors. A localisation rate of 65% is planned for series production aircraft, as compared to 59% for the T-50. Korean firms will use their experience from the KF-16, T-50 and FA-50 to develop an indigenous Mission Computer and access to indigenous avionics and sensors will provide an independent path for future upgrades.
Hanwha Systems has been developing the KF21’s AESA radar since 2016 with DAPA revealing a prototype in August 2020. Hanwha Systems will also provide the electro-optical targeting pod (EO TGP), infrared search and track (IRST) system and 20in x 8in low-reflection, resistive touch screen multifunction primary cockpit display, amongst several other systems. LIG Nex1 is developing the Electronic Warfare (EW) suite and working on a state-of-the-art embedded training system. It will also supply the storage management computer, flight data recorder, flight control computer, head-up display, ARC-232A U/VHF-AM radio and radar altimeter.
Rooted in Reality
Imported equipment and systems will comprise approximately 1/3rd of the KF-21, giving Western manufacturers a stake in its export success. General Electric’s (GE) F414-400K engine is the chosen power plant and Hanwha Aerospace will produce the engine in South Korea under license.
The President of South Korea, Moon Jae-in, at the launch of the KF-21 at KAI’s facility in Sacheon. KA
The engine cost alone is 15% of the KF-21’s unit price. GE delivered the first engine to KAI in May 2020 and is to supply 240 production engines for 120 aircraft (along with spare engines) under a May 2016 contract. GE is to complete delivery of 15 engines (including three spare engines) for the six prototype aircraft this year. GE engines already power ROK F-15Ks (F110), indigenously developed KUH-1 Surion helicopters (T700) and T-50, FA-50, TA-50 (F404). The ROKAF’s legacy F-4D/E Phantom II and F-5E/F Tiger II are powered by GE J79 and J85 engines respectively.
Amongst other Western suppliers is Collins Aerospace which is supplying several systems and working with KAES Hanwha to design, develop and produce the KF-21’s Main Electric Power Generation System which will also include Collins’ more electric variable speed constant frequency (VSCF) generator, being used for the first time on a fighter class aircraft.
Collins will also supply engine start systems and the KF-21’s complete environmental control system.
US firm PTI is supplying the KF-21’s aerial refueling receptacle (ARR) Alvis used during aerial refuelling to engage the flying boom from a tanker aircraft. The first unit was delivered in April and is installed on the first prototype. PTI leveraged its existing Boeing F-15 ARR design with modifications to cater for the new installation interfaces and operational loads of the KF-21.
Defending the Realm
The KF-21 will deliver a significant upgrade in combat capability to the ROKAF, which wants the new fighter to operate in close cooperation with its F-15Ks, F-35As, as well as USAF air assets. “With ROKAF warfighting doctrine based on combined ROK-US operations, the integration of communications security systems and combined tactical data communications systems was necessary. Weapons commonality with ROKAF and USAF types was necessary as, during combat operations, the two air arms would share ammunition,” Brig Gen (Ret.) Jung Kwang Sun, Director General for KF-X Programme Group at DAPA said in an article published in April by the Korea Institute for Defence Analysis.
A model of the KF-21. Alvis Cyrille Jiyong Jang (Alvis Jean)
Meteor BVRAAMs and Diehl Defence IRIS-T (infrared imaging system – tail/thrust vector controlled) close combat missiles make up the KF-21’s missile armament. MBDA will support KAI with integration of the Meteor system into the KF-21’s sensor suite, including the indigenously developed advanced radar system and other sensor components. Integration of Meteor onto KF-21 builds on the work already completed on Typhoon, Rafale and Gripen and under way on F-35. “The challenge in integration is to maximise the ability for the ROKAF to use the KF-21 and its Meteor missiles to their greatest advantage. To achieve this, MBDA is working with KAI to ensure that the advanced sensor fusion supplied by KF-21’s systems can prime and support Meteor during a wide array of operational scenarios. This work is key to providing the RoKAF with a decisive advantage,” an MBDA spokesperson told AEROSPACE in an email response.
MBDA is also exploring the use of innovative digital modelling techniques that will minimise the need for physical trials, reducing time and cost. “Utilising approaches proven on previous integrations, the aim of modelling is to provide the key certification evidence with validation through limited but specific live trials,” the spokesperson said. MBDA is also looking to enhance the realism and complexity of training scenarios while minimising the cost of live training by supporting development of the aircraft training systems that allow KF-21 operators to better understand operations with Meteor.
The KF-21 will feature a state-of-the-art Embedded Combat Aircraft Training System (E-CATS), similar to that available on the F-35. LIG Nex1 is responsible for the development of the embedded training (ET) unit on the KF-21 and received the final software package for E-CATS from the Royal Netherlands Aerospace Centre (NLR) and Airbus Defence and Space Netherlands in June, completing a 3.5 year development period. The recently delivered final software package also includes a simulation module that simulates tactical data link (TDL) messages used to exchange command and control information between pilots in the formation and the control and reporting centres (CRC).
The KF-21’s embedded training application allows cost-efficient and realistic air combat training using full-up live-constructive scenarios. E-CATS provides live mission training for fighter pilots against simulated adversaries (constructive threats), which are displayed on the cockpit displays and behave with realistic performance characteristics. Pilots will be able to train either individually or in multi-ship formations. Royal NLR and Airbus Defence and Space Netherlands first demonstrated E-CATS on an operational F-16 MLU fighter of the Royal Netherlands Air Force (RNLAF) in 2004 and were contracted by Lockheed Martin in early 2009 to develop the F-35’s embedded training solution, which was delivered in 2012.
Future Ready
The KF-21 programme, while complex and tight on timelines, showcases the coming of age of the South Korean defence industry which has leveraged its defence partnerships with Western partners to good effect in developing a strong defence industrial base. Korea’s aerospace industry today exports turboprop trainers, jet trainers and light fighters and is developing new helicopters and uncrewed aircraft. The KF-21 could emerge as the most exportable of the 4.5 gen fighters currently in development and emerge as the ace in the nation’s military aviation product portfolio.