Why KF-21 Is Considered 'Virtually' 5th Generation Abroad [Reading Science]

[Image source=Yonhap News]

[Asia Economy Reporter Kim Bong-su] "What generation is Korea's KF-21 Boramae exactly?"

This is one of the controversies raised domestically and internationally surrounding Korea's KF-21 fighter jet, which has entered mass production. Fighter jets are classified as 5th or 4th generation depending on whether they possess radar evasion capability (stealth function), but the Korean government and developers have shown ambiguous attitudes by calling it 4.5 generation.

The fuselage shape of the KF-21 has some stealth fighter characteristics. It is even said to resemble the F-22 Raptor, the world's strongest stealth fighter proudly developed by the United States. This means the aircraft shape is designed to minimize reflection of enemy radar waves. A representative example is the semi-recessed installation of four air-to-air missiles. However, it is not yet perfect. Korea Aerospace Industries (KAI) plans for the KF-21 Block 1 and Block 2 to have stealth performance (0.5㎡ radar cross-section, RCS) slightly superior to the latest models like the Eurofighter Typhoon and Rafale (RCS 1㎡). On the other hand, from Block 3 after 2028, they are considering upgrading to the level of the U.S. Air Force's F-22 (0.0001㎡) and F-35 (0.001㎡) by inserting internal weapon bays. Currently, the main fighter of the Korean Air Force, the 4th generation F-15K, has an RCS of 10㎡.

Overseas, some view the KF-21 as literally 4.5 generation, but many experts consider it a "practical" 5th generation fighter. They do not openly say so due to external pressures from the U.S. and China, but analyze it as a 5th generation fighter equipped with cutting-edge avionics (AESA radar, etc.) and stealth functions.

Meanwhile, a next-generation material technology included in the 25 excellent research achievements announced by the National Science and Technology Council (NST) last May stands out. NST selected and awarded the Ti3CN MXene electromagnetic wave absorbing material developed last year by Dr. Gu Jong-min's team at the Korea Institute of Science and Technology (KIST) as one of the "Top 10 Excellent Research Achievements."

This material is evaluated to significantly enhance the stealth performance of major weapons including the KF-21 simply by painting or coating, without additional technology development or performance improvement. It is a kind of "metamaterial" designed at the atomic level with properties not found in nature. It is synthesized as a two-dimensional flat structure with a thickness of nanometers (nm) and a size of micrometers (μm) using electrically conductive metal (titanium), carbon (C), and nitrogen (N), and processed through heat treatment to have excellent electromagnetic wave absorption ability. It is as thin as paper, even processed to a thickness 1/500,000 of a human hair.

Functional simulation of Ti3CN MXene material, an electromagnetic wave shielding and absorption material.

Therefore, it can be used in the form of coating or painting like ink or paint. By layering multiple times, thickness, transmittance, and surface resistance can be freely controlled. Especially, when this film is layered to a thickness of 55nm, it was able to block more than 99% of electromagnetic waves. This is superior to any electromagnetic wave shielding material reported so far.

Above all, its excellent electromagnetic wave absorption ability can prevent malfunction and ensure stable performance when applied to smartphones, wearable devices, autonomous vehicles, and urban air mobility, which are becoming high-power and highly integrated with the 4th industrial revolution. In particular, when applied to military equipment such as warships, fighter jets, and tanks, it can maximize stealth performance. Korea is known to introduce stealth functions not only to the KF-21 but also to next-generation tanks K-3 and next-generation destroyers KDDX. Depending on research and development, it may also provide low-observable capabilities to existing combat assets. There is also ongoing research on using it for fixed electromagnetic wave protection structures to respond to EMP (electromagnetic pulse) attacks caused by North Korea's nuclear delivery means in emergencies.

Dr. Gu explained in a phone interview with Asia Economy, "We are currently conducting follow-up research for rapid commercialization related to EMP and electromagnetic wave shielding capabilities," adding, "We are also cooperating with relevant authorities."