On March 25, a rollout ceremony for the first mass-produced KF-21 "Boramae" was held at Korea Aerospace Industries (KAI) in Sacheon, South Gyeongsang Province. It is the first Korean fighter jet built with a substantial amount of domestic technology. With full-scale mass production now underway, the first aircraft is scheduled to be delivered to the Air Force as early as September this year.
The Defense Acquisition Program Administration (DAPA) will invest approximately 10 trillion won ($7.3 billion) to deliver 40 early-version aircraft (twin-seat and single-seat) to the Air Force by 2028. The Air Force aims to subsequently acquire 80 additional Block-II successor aircraft with enhanced air-to-ground capabilities, deploying a total of 120 units in active service by 2032.
However, the engine mounted on the KF-21 is the "F414-GE-400K" manufactured by General Electric (GE) of the United States, produced by Hanwha Aerospace (012450.KS) under a technology transfer arrangement. Because the KF-21's "heart," its engine, is borrowed from the United States, it effectively acts as a shackle.
The engine is subject to the International Traffic in Arms Regulations (ITAR) administered by the U.S. State Department. ITAR contains third-country transfer control provisions, meaning that if even a single core U.S. component is included, approval from the U.S. administration is required. As a result, Korea must obtain an Export License (EL) whenever exporting the KF-21.
If engine problems arise, the reality is that Korea has no choice but to rely entirely on GE for support. This is why technological independence through domestic aircraft engine development is needed. While the localization rate of the initial KF-21 model reaches about 65%, the engine localization rate stands at only 39%.
The engine mounted on the KF-21 is GE's F414-400K. This engine is a modified version of the "F414-400K" installed on the U.S. F/A-18 "Super Hornet," adapted to fit the KF-21. The situation is similar for the FA-50 light attack aircraft, developed before the KF-21, which is equipped with GE's F404-102 engine.
Because ownership of the core aircraft engine technology rests with GE, there are limits to raising the localization rate. Is engine localization for Korean fighter jets therefore impossible? In response, the government is making active national-level investments in the aircraft engine sector.
DAPA has launched development of a fully localized advanced aircraft engine to replace the KF-21's currently license-produced engine, which has a localization rate of about 40%. The agency has decided to invest 3.35 trillion won ($2.4 billion) with the goal of completing development by 2039.
On January 21 last year, DAPA held the 25-1 Advanced Technology Project Management Committee meeting and approved the "Basic Plan for Advanced Aircraft Engine Development," which includes the target performance, project execution method and schedule for engines needed for next-generation air weapon systems, including development of a 16,000 lbf-class (turbofan) advanced aircraft engine.
If the domestic advanced aircraft engine is successfully developed, it will have superior performance to the GE engine (14,770 lbf class) installed in the KF-21, Korea's domestic supersonic fighter. The 16,000 lbf (pound-force) class has thrust capable of pushing up a 16,000-pound weight.
The aircraft engine currently under development by DAPA is a 5,500 lbf-class engine that has been in development since 2020. That is about half the thrust of the FA-50 (11,000 lbf), which is classified as a light attack aircraft. If this engine is successfully developed, it will be mounted on unmanned wingmen within manned-unmanned teaming systems composed of manned and unmanned aircraft operating in formation.
The low-observable (stealth) unmanned wingman, which reduces the probability of detection, incorporates stealth technology that makes radar detection difficult and will perform missions such as reconnaissance and attack. Korean Air is currently developing a prototype (an aircraft for test flights) of the low-observable unmanned wingman, which will be equipped with the domestic 5,500 lbf-class engine.
According to military authorities, the "First Firing" test of the 5,500 lbf-class aircraft engine is scheduled for May. This test will verify operations such as startup, acceleration, deceleration and shutdown. It is the first procedure in ground testing conducted before the engine is mounted on an aircraft.
DAPA's goal is to successfully develop this engine and subsequently develop a supersonic fighter engine based on it. According to the Korea Research Institute for Defense Technology Planning and Advancement, if research to improve the performance of the 5,500 lbf class is supported, development of a 10,000 lbf-class engine will also be possible.
Full-scale development of a 10,000 lbf-class engine for unmanned aerial vehicles will also begin this year. The 10,000 lbf class is an engine aimed at long-endurance flight rather than high-speed, high-maneuver operations. Military authorities have been conducting research on turbine aerodynamic-cooling design and technology evaluation of core components of the 10,000 lbf-class turbofan engine.
Above all, development of the 10,000 lbf-class engine can be expanded up to a 25,000 lbf-class engine. Therefore, if a 15,000 lbf-class engine is successfully developed in the late 2030s, development of a 40,000 lbf-class engine will also become possible. The maximum thrust of the F414-400K engine mounted on the KF-21 is 22,000 lbf.
Only six countries can currently design and manufacture aircraft engines for fighter jets: the United States, the United Kingdom, France, Russia, China and Ukraine. The market is divided among three companies: GE and Pratt & Whitney (P&W) of the United States, and Rolls-Royce of the United Kingdom. GE holds a global market share of 58%.
The "industrial spillover power of aircraft engines" is another reason technological independence in aircraft engines is needed. The F101-GE-102 engine developed by GE in the 1970s is used in the U.S. strategic bomber B-1B Lancer. It was also derived into the F110 engine mounted on the F-15 fighter and further evolved into the F118 engine.
Going a step further, military engines also evolve into engines for commercial aircraft. The CFM56 engine is a commercial aircraft engine derived from the F101. Developed by CFM International, a joint venture between GE and France's Safran, the turbofan jet engine has been mounted on aircraft such as the B737 and A320, as well as on military transport aircraft.
The CFM56 engine was further derived into the more fuel-efficient LEAP engine. The LEAP engine has been mounted on the latest aircraft such as the B737-8 and A320neo. It has also been installed on the C919 commercial aircraft developed by China. Technological independence in aircraft engines serves as the foundation for developing various advanced engines.
