The bimonthly website of National Interest in the United States recently published an article titled "KF-21 fighter jets may be the real rule changers" by Alex Hollins. The article excerpt is as follows: South Korea's advanced KF-21 Falcon fighter jet is about to enter mass production. The KF-21 Falcon is a unique fighter jet that incorporates design elements from multiple fifth generation (or stealth) fighter jets, while still carrying ammunition externally like the old-fashioned fourth generation fighter jet. The Falcon may not be classified as a stealth fighter because its external components will greatly reduce its stealth, but its overall radar reflection design will still delay the detection of it by enemy ground to air radar arrays to some extent. For some aviation enthusiasts, these radar reflection characteristics may be familiar, as the fighter jet is indeed somewhat similar to the US stealth fighter F-22 Raptor. The manufacturer of the F-22, Lockheed Martin of the United States, has collaborated with Korean Aerospace Industries to provide technical support in the development process of the KF-21. The original intention of this move was to develop and deploy South Korea's so-called 4.5 generation fighter jet, which has a radar cross-section comparable to the F/A-18 Super Hornet or the European Typhoon fighter jet. South Korean media reported that the radar reflection cross-section of the fighter jet is 0.1 to 1 square meter, and compared it to Russia's Su-57, but only when there is no external ammunition or fuel. However, the design of the aircraft has taken into account the possibility of installing built-in weapons in the future, which will have a significant impact on its overall radar reflection, truly blurring the boundary between the design of fourth and fifth generation aircraft. This fighter jet is powered by two General Electric F414-GE-400K afterburner turbofan engines - the same power system as some other fighter jets (such as the Super Hornet and some iteration models of the JAS-39 Gripen) - giving it enough power to reach speeds of 1.8 Mach. It has 10 external mounting points, including 6 traditional mounting points under the wings and 4 semi buried mounting points at the bottom of the fuselage, making its appearance more discreet. These semi buried hanging points will eventually be replaced by built-in weapon compartments. It is expected that the KF-21 will also carry various advanced avionics equipment, including modern active electronic scanning array radar, infrared search and tracking equipment (which can detect and lock the aircraft solely through thermal signals), electronic optical sights, and so on. The flight testing of the KF-21 is expected to continue until 2028, when the first batch of KF-21s put into use is expected to begin carrying out missions to gain air superiority. (Lai Xin She)