[2025 New Year's Plan] A Thousand Test Flights... The Real KF-21 Is Coming
Reporter Ahn Du-won
2024-12-25 17:47:19
KAI 'Yangsang 1st' production site report
Wings, 80-layer carbon fiber pressurized
Assembly work begins with the central fuselage
Prototype overcomes 10 years of trial and error
Scheduled for delivery to the Air Force in September 2026
First press release of the assembly site of the 'KF-21' mass-produced 1st
2025 New Year Plan: K-Defense Industry Leaping Forward
KF-21 Boramae mass production unit 1.
The first combination of the central fuselage and main wing took place at the Korea Aerospace Industries (KAI) plant in Sacheon, Gyeongnam Province, on the 28th of last month.
This is the biggest hurdle in the production of cutting-edge domestic fighter jets. In the future, numerous avionics equipment will be installed on this foundation to complete it.
Maeil Kyungjae was the first domestic media outlet to cover the production process of the KF-21 Boramae mass production unit 1 at the KAI plant. The KF-21 Boramae is the result of the Korea Fighter (KFX) project, the largest arms import since Dangun.
It is a supersonic fighter jet that will replace the aging fighter jets (F-4 Phantom and F-5 Jeogho) of the Korean Air Force, and is a 4.5-generation fighter jet that is closely following the 5th-generation stealth fighter jet (F-35) manufactured by Lockheed Martin.
The investment budget alone exceeds 8 trillion won. If it is completed as scheduled in September 2026 and delivered to the Air Force, it will become a key force in airspace defense.
The advanced fighter jet manufacturing capability is the springboard for K-Defense's leap forward. It hints at K-Defense's potential for exporting advanced fighter jets to the global defense industry market worth 1 trillion dollars.
The first mass-produced KF-21 Boramae aircraft has taken shape thanks to the trial and error of numerous prototypes (airframes for test and evaluation) over the past 10 years and test flights that pushed human limits.

The first mass-produced Korean fighter jet KF-21, which is being assembled at Korea Aerospace Industries (KAI) in Sacheon, Gyeongnam, was erected on the 12th with the central fuselage and main wings attached, and hole drilling work is underway.
This is the first time that the first mass-produced aircraft for the Air Force, not the test and evaluation aircraft, has been revealed to the press (small photo below). After this work, the front, center, and rear fuselage will be attached to take the shape of a fighter jet, and then the engine and various avionics equipment will be installed to complete it. The large photo shows the assembled test and evaluation aircraft, and it has been included for the reader's understanding. KAI
When I visited the plant on the 12th, KAI was in the middle of a test flight of the KF-21 prototype with the soldiers of the Air Force 3rd Training Squadron adjacent to the Sacheon plant. The 1,000th test flight sortie (the number of flights) was completed without any accidents at the end of last month.
Noh Ji-man, head of the Korea Fighter Program at the Defense Acquisition Program Administration, said, “Test flights require pushing the aircraft to its limits, so we cannot let our guard down as unexpected situations may arise,” adding, “The final result of the 2,000 test flight sorties planned for next year will be the first mass-produced aircraft.” The fuselage of the first mass-produced KF-21 was standing on a workbench.
Lee Sang-hui, head of KAI’s aircraft production division, explained, “We had to lie down and work in an uncomfortable position if the fuselage was on the floor, so we put it upright.” He added, “The work of drilling holes for rivets and bolts is automated, but the speed and strength of the drill must be set extremely sensitively for accurate work.”
The wing attached to the fuselage was made by compressing 80 layers of carbon fiber. Two prototypes were placed together on the production line. Orange lines were hanging from the fuselage. These were the lines that connected the sensors that measured the pressure and vibration generated by the fuselage during the test flight.
"We made six prototypes, but their appearances are slightly different," said Director Lee. "The first mass-produced aircraft will be designed and manufactured through the test flight."
KAI '양산 1호기' 제작 현장 르포날개, 80겹 탄소섬유로 압착중앙 동체와 조립작업 돌입시제機 10년 시행착오 딛고2026년 9월 공군 인도 예정'KF-21' 양산 1호기 조립현장 언론 첫 공개
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