[비즈한국] It has been confirmed that the KF-21EX, an improved variant of the KF-21, can carry the 2,000-pound class ‘Bunker Buster’ GBU-31(v)3/B guided bomb in its internal weapons bay. This allows the KF-21EX to stealthily penetrate enemy lines and destroy underground targets protected by 2m-thick reinforced concrete, as well as critical equipment. This capability is currently possessed only by the U.S. F-35A among combat aircraft in active service, which is expected to further increase interest from international customers in the KF-21EX.
At the ‘Aerospace Weapon System Technology Development Conference’ held in Daejeon on July 28, Korea Aerospace Industries (KAI)047810 explained the functions and capabilities of the KF-21EX—an upgraded version of the KF-21, which is currently nearing the final stages of Block 1 development—under the theme of ‘KF-21 Performance Improvement Plan for the Deployment of Manned-Unmanned Teaming Combat Systems.’
The KF-21EX is a model that upgrades the 4.5-generation KF-21 into a 5.5-generation fighter. According to KAI, it can be classified as 5.5-generation by incorporating Manned-Unmanned Teaming (MUM-T) functions and Artificial Intelligence (AI)—features not currently applied to 5th-generation fighters—while maintaining low observability, the hallmark of 5th-generation fighters.
KAI announced the features of the KF-21EX in July last year, highlighting its low-observability performance and unmanned aerial vehicle operation capabilities. Specifically, Radar Absorbent Material (RAM), Radar Absorbent Structure (RAS), an internal weapons bay, and AI-assisted functions for combat mission execution were unveiled.
There are three major improvements to the KF-21EX revealed this year. The first is the inclusion of an air-launched decoy. An air-launched decoy is equipment dropped into the air to confuse enemy radar when the enemy targets the aircraft or launches a missile. The Digital RF Memory (DRFM) chip inside the decoy mimics the aircraft's radio signals, causing enemy missiles to track the decoy instead of the actual aircraft. A representative product is Leonardo’s BriteCloud, which the U.S. Air Force also purchased in December 2023.
The second is the expansion of fuel tanks. Since the KF-21EX cannot carry external fuel tanks or weapons to maintain its stealth capabilities, its flight range is limited. To improve this, the plan is to increase the fuel capacity by utilizing idle space inside the airframe, thereby expanding the radius of action by more than 10%. Since this method increases fuel capacity without altering the exterior of the airframe, development cost increases are also minimized.
The third is the loading capacity of the internal weapons bay. Previously, it was known that the KF-21EX possessed two internal weapons bays under the fuselage capable of carrying four MBDA Meteor air-to-air missiles. However, this latest announcement revealed that it can now carry 2,000-pound class guided bombs internally.
The 2,000-pound class guided bomb refers to the GBU-31(v)1/B or GBU-31(v)3/B. In particular, the GBU-31(v)3/B is equipped with a BLU-109 warhead for penetrating underground targets and is known as a ‘Bunker Buster.’ This bomb can penetrate 2m-thick reinforced concrete and explode inside, allowing it to strike enemy concrete hangars or tunnel facilities where equipment is hidden. In September 2024, the Israeli Air Force used such bombs to destroy an underground missile production facility in Masyaf, Syria.
The fact that the KF-21EX can internally carry two GBU-31 guided bombs means it has secured the same internal armament capability as the F-35A. This enables the KF-21EX to perform missions such as strategically striking deep underground facilities in enemy territory by utilizing its stealth performance, just like the F-35A.
Furthermore, as armament compatibility with the F-35A has been secured, the latest weapons being developed for the F-35A can be easily mounted on the KF-21EX. For instance, Kongsberg’s JSM (Joint Strike Missile) from Norway, Turkey’s SOM-J, and the 1,000-pound class modular missile currently being developed by LIG Nex1079550 are also expected to be integrated into the KF-21EX’s internal weapons bay. As such, the KF-21EX is expected to attract high interest from many international customers as a fighter that possesses both stealth and heavy armament capabilities.