The two-seat KF-21 fighter prototype carries the flags of South Korea and Indonesia on its nose

A team led by Korea Aerospace Industries (KAI) developing the KF-21 "Boramae" fighter has flown the first two-seat prototype. The aircraft (serial number 004), took off from Sacheon at 11.19 am local time on February 20 and flew for 34 minutes, according to South Korea’s Defence Acquisition Program Administration (DAPA), which manages the project.

The KF-21's undercarriage remained extended throughout the flight, during which the operation of basic aircraft systems and controls was verified. The two-seater had a single test pilot aboard, and was accompanied by a T-50 chase aircraft and another carrying a photographic team.

The addition of a fourth aircraft to the test fleet will allow an acceleration of the flight test campaign: although 004 will initially test the two-seat configuration it will later be used for trials of the KF-21’s avionics and active electronically scanned antenna radar. The first single-seat prototype flew on July 19 last year and was joined by a second in November. The third of the initial single-seat developmental aircraft undertook its maiden flight in January, the month in which the KF-21 first achieved supersonic flight.

DAPA expects the fifth (single-seat) and sixth (two-seat) prototypes to fly in the first half of 2023. The fleet involved in the trials campaign is scheduled to complete around 2,000 flights by February 2026. The three single-seaters had flown 110 times between them at the time of 004’s first flight.

Launched in 2015, the $6.8 billion KF-21 program is intended to provide a replacement for the Republic of Korea Air Force’s F-4E Phantom-II and F-5E/F Tiger-II fleets, and also for service with Indonesia, which is a 20 percent partner in the project. The projected production run is 160 fighters. Serial production is due to start in 2026, with an aim of having 40 aircraft in service by 2028, with subsequent aircraft being produced at a rate of 20 per year.

No breakdown of single-seat/two-seat versions has been announced, but for now, the two-seater’s primary role will be type conversion. However, DAPA has referred to electronic warfare and other operational missions in the future that would be more suited to a two-seat platform.