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KAI KF-21 Boramae

KAI · Fighter / Attack · South Korea · Digital Age (2010–present)

KAI KF-21 Boramae — Fighter / Attack
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The KAI KF-21 Boramae ('Hawk' in Korean) is South Korea's first domestically developed twin-engine supersonic fighter, designed by Korea Aerospace Industries with a $7.5 billion programme budget and technology partnership with Indonesia. The programme launched in January 2016 after South Korea concluded that continued reliance on imported F-35As and ageing F-4E/F-5E airframes left an unacceptable performance gap in the mid-tier fighter bracket. KAI rolled out the first prototype on 9 April 2021, and the KF-21 made its maiden flight on 19 July 2022 — the first supersonic flight of an indigenously designed Korean fighter.

Two General Electric F414-GE-400K turbofans, each producing 22,000 lbf with afterburner, power the KF-21 to a maximum speed of Mach 1.81 and a service ceiling of 52,000 ft. Maximum take-off weight is 56,400 lb with 17,637 lb of external payload across ten hardpoints. Range reaches 1,800 miles in a clean configuration. The airframe employs an infrared search-and-track sensor (IRST), AESA radar, and semi-conformal external weapons carriage in Blocks I and II — partial stealth through careful shaping and radar-absorbing materials on the fuselage spine and leading edges. Block III, planned for the 2030s, introduces internal weapons bays for full low-observable performance comparable to a fifth-generation fighter.

The Republic of Korea Air Force plans to acquire 120 aircraft: 40 Block I (air-to-air focus), 40 Block II (air-to-ground integration), and 40 Block III (full stealth). Unit cost is approximately $65 million, cheaper than the Eurofighter Typhoon and Dassault Rafale while matching them in empty-weight class. Indonesia is a 20% cost-sharing partner and is entitled to 48 aircraft, though Jakarta's funding contributions have faced parliamentary delays since 2021.

The KF-21 carries the Meteor beyond-visual-range missile, IRIS-T short-range air-to-air missile, and is planned to integrate the JSOW glide bomb and a locally-developed long-range air-to-surface missile. Its AESA radar — jointly developed by Hanwha Systems and the Agency for Defence Development — uses approximately 1,000 transmit-receive modules. The programme represents the anchor of South Korea's Atmanirbhar-equivalent defence-industrial strategy: KF-21 components are produced by Hanwha Aerospace, LIG Nex1, and Korea Air Lines Technical Operations, spreading aerospace manufacturing skill across 700 domestic suppliers.

For Kids — a shorter, friendlier version

The KAI KF-21 Boramae is South Korea's new supersonic fighter jet. The name Boramae means young hawk in Korean. South Korea built it because it wanted its own modern fighter. The KF-21 made its first flight in July 2022.

The KF-21 has two powerful engines. It can fly faster than a rifle bullet at top speed. It carries a radar in its nose that tracks many aircraft at once. Missiles hang under the wings ready to fire.

Indonesia helped pay for the project in exchange for technology and some finished jets. South Korea plans to build at least 120 KF-21s for its Air Force. Most of the parts and electronics are made inside South Korea.

The KF-21 is a big step for the country. Decades ago, South Korea bought all its jets from other nations. Now it builds its own world-class fighter at home.

Fun Facts

  • Boramae means young hawk or fierce hawk in Korean.
  • The KF-21 made its first flight in July 2022.
  • Indonesia is a partner in the project, helping fund development costs.
  • South Korea plans to build at least 120 KF-21s for its Air Force.
  • The jet uses radar and electronics developed almost entirely inside South Korea.
  • South Korea is one of only a few countries outside Europe and America to build its own supersonic fighter.

Kids’ Questions

Why is building your own fighter jet so difficult?

A modern fighter jet has hundreds of thousands of parts made to incredibly tight tolerances. The engines, radar, flight computer, and weapons systems all have to work perfectly together, often at speeds and temperatures that push materials to their limits. It takes thousands of engineers, years of testing, and enormous investment. Most countries buy jets from America, Europe, or Russia rather than attempt it themselves. South Korea's success with the KF-21 puts it in a very small and impressive group.

What does a fighter jet's radar do?

The radar in the nose of a fighter jet sends out radio waves that bounce back when they hit another aircraft. By measuring how long the echo takes to return, the pilot's computer calculates where the other aircraft is, how fast it is moving, and in which direction. A modern radar can track many aircraft at once, even ones trying to hide at low altitude. The KF-21's radar was developed in South Korea and can detect aircraft from far away, giving the pilot more time to react.

Variants

KF-21 Block I
Initial 40-aircraft ROKAF batch with AESA radar and IRST, optimised for beyond-visual-range air-to-air combat. Semi-conformal external weapons only. First deliveries from 2026.
KF-21 Block II
Second 40-aircraft batch adding full air-to-ground precision weapons integration: JSOW, guided bombs, and a targeting pod. Deliveries scheduled for late 2020s.
KF-21 Block III / KF-21EX
Full-stealth variant with internal weapons bays, upgraded engine variants, and potential manned-unmanned teaming. Planned for the early 2030s; key specifications remain in development.
KF-21N (Navy)
Carrier-capable derivative under early-stage study for a potential future Korean light carrier. No development contract awarded as of 2026.

Notable Operators

Republic of Korea Air Force
Primary customer; 120 aircraft planned across Blocks I–III to replace ageing F-4E Phantom IIs and F-5E Tiger IIs from the late 1970s fleet.
Indonesian Air Force (planned)
Co-development partner entitled to 48 aircraft. Indonesia contributed 20% of development costs (~$1.5 billion) in exchange for technology transfer and production work-share.

Frequently Asked Questions

Is the KF-21 a fifth-generation fighter?

The KF-21 Block I and II are classified as 4.5-generation fighters — they use fifth-generation sensor fusion and an AESA radar but lack internal weapons bays. Block III, planned for the 2030s, is intended to be a full fifth-generation design with stealth weapons carriage. KAI and the South Korean government have referred to the overall programme as 'fourth-and-a-half to fifth generation.'

How does the KF-21 compare to the <a href="/v/f-35-lightning-ii.html">F-35</a>?

The F-35A has internal weapons bays, full all-aspect low-observable stealth, and a sensor-fusion architecture the KF-21 Block I does not match. The F-35 costs around $90–100 million per aircraft versus $65 million for the KF-21. South Korea operates both types: F-35As for deep-penetration stealth missions, KF-21s for air superiority and ground attack in contested but not fully denied airspace. The KF-21 Block III may close much of the stealth gap by the 2030s.

What is Indonesia's role in the KF-21 programme?

Indonesia signed the co-development agreement in 2016, committing to pay 20% of the development cost (~$1.5 billion) over 10 years in exchange for 48 aircraft, technology transfer, and domestic production work-share. By 2022, Indonesia had only paid around $215 million, triggering negotiations over revised payment schedules. South Korea has continued development regardless; the original technology transfer terms remain in place.

When will the KF-21 enter full service?

Initial fielding with the first ROKAF squadron is targeted for 2026–2028 with Block I aircraft. Block II (air-to-ground) is scheduled for the late 2020s. Full inventory of 120 aircraft is planned by the early 2030s. The first prototype made its maiden flight in July 2022, and a 2,200-hour flight test programme was underway by 2024.

What weapons does the KF-21 carry?

Block I and II aircraft carry the Meteor beyond-visual-range missile, IRIS-T short-range air-to-air missile, and are being wired for the JSOW-C glide bomb and a Korean-developed long-range air-to-surface missile. Armament options also include 1× 20 mm M61A1 internal cannon and multiple laser-guided bomb configurations. Block III will add internal bay carriage for reduced radar signature on strike profiles.

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See Also