A KF-21 ‘Boramae’ or ‘Hawk’ prototype recently completed a 30-minute test flight. Design suggests limited stealth capabilities, but new jet could still impact regional power balance, Macau-based observer says

South Korea is working on a new warplane as it seeks to catch up with China and Russia, but military observers believe its new KF-21 fighter jet is far from comparable to advanced fifth-generation fighters like China’s Chengdu J-20.

However, if mass-deployed, the KF-21 could still alter the regional air force power balance, and also has potential to become a strong competitor in the global market, a Macau-based analyst said.

This came as the prototype of a KF-21 “Boramae” or “Hawk” completed a 30-minute test flight last Tuesday from the southern city of Sacheon.

South Korea hopes the home-grown four-plus generation warplane will serve as a cheaper alternative to the imported US Lockheed Martin F-35 Lightning II, and also aims to promote it on the international arms market.

Its developer, Korea Aerospace Industries, even announced an upgrade plan to eventually modify the jet into a stealth fighter.

Only the United States, China and Russia currently have combat-ready fifth generation fighters – the US F-22 and F-35, China’s J-20 and the Russian Su-57 – that combine stealth, super manoeuvrability, supersonic cruise and advanced avionics.

A key characteristic of all fifth-generation fighters is their optimised surface design and storage of weapons in internal bays to reduce radar reflection and maintain stealth.

However, although the KF-21’s aerodynamic design adopted much of the features of a stealth fighter, the test flight indicated that it carried four model missiles on external hard points, suggesting very limited stealth capabilities.

The KF-21’s American-made F414-GE-400K engines are also a clear shortcoming, as their power would not be able to match fifth-generation fighters’ requirements for supercruise and manoeuvrability.

Nonetheless, with advanced avionics such as active electronically scanned array (AESA) radar, electro-optical targeting pod, an infrared search and track system, and capable armaments including air-to-air and air-to-surface missiles, the KF-21 is well-qualified to be a modern fourth- or four-plus-generation fighter.

“The KF-21 is not even a competitor to the Chinese FC-31 [fighter jet], let alone the J-20,” Macau-based military commentator Antony Wong Tong said. “But it can be a good opponent to the later J-10 variants.”

The Chengdu J-10 is a Chinese-made fourth-generation multi-role combat aircraft introduced in 2005, with hundreds now in service. As a single-engine jet, the J-10 is relatively narrower and lighter than the KF-21, and its latest variants, the J-10B and J-10C, are also equipped with advanced avionics like AESA radar, electro-optic target sensor and infrared seeker, and they too carry powerful weapons.

The Shenyang FC-31 is China’s second fifth-generation fighter, which had its first test flight in 2012 and is still under development. Both the KF-21 and FC-31 are medium twinjet fighters, with similar size and specifications, and even some resemblance in their silhouettes. The Korean jet is designed for a top speed of Mach 1.8, same as the FC-31.

Their weapon payloads are 7.7 tons and 8 tons, with combat ranges of 1,450km (900 miles) and 1,200km, respectively.

If it performs well, the KF-21 might pose some threat to China, given the US-South Korea military alliance, Wong added.

Wong predicts a direct rivalry between the KF-21 and FC-31 in the international market, adding that positioned in the same market niche are also the US F-16 series, Russia’s Su-57 and the Turkish TF-X.

Indonesia is already on board for the development of the KF-21, having pledged 20 per cent of the US$6.7 billion total project costs.

The first batch of KF-21 is expected to be finalised and enter mass production in 2026, with at least 40 to be delivered by 2028 and up to 120 by 2032. It will be the first fighter jet to meet the demands of the South Korean Air Force to replace its outdated F-5E/F and F-16C/D warplanes.