Ground test and system evaluation of KF-21 fighter before first flight in July (photos : Kookbang)
The KF-21 Boramae fighter, which is being developed with domestic technology from design to production, is expected to serve as a new leap forward for the improvement of the Korean Air Force's power and the development of the defense industry. It started development in 2016 and achieved a splendid achievement by releasing a prototype in April last year through endless research and challenges. After that, systematic ground tests were continued, and next month, the thrilling first flight test of 'Prototype Unit 1' will be conducted.
On the 9th, June at the fuel test building of the Korea Aerospace Industries (KAI) in Sacheon-si, Gyeongsangnam-do, the fuel system test of the KF-21 prototype No. 4 was in progress. Engineers standing on the central part of the aircraft were calculating data by connecting or comparing the aerial refueling devices installed in the building with the aircraft. Numerous cables and connecting wires connected to the aircraft led to various measurement and test equipment, and complex numbers and graphs continued to pour on laptops and monitors of each equipment.
In such a process, engineers from the technical departments for each system who raised the test requirements and the agents who will perform the work in the actual field work together. Functional tests, performance tests, environmental tests, and life tests are performed starting with the smallest unit that constitutes an aircraft, and soundness is checked in consideration of the aircraft operating environment.
There are many types of tests that require 95% completion of the ground test before the flight test, but the perfect aircraft is born through each process that is repeated in detail. After the prototype was released last year, the time given until the flight test scheduled for next month is about a year and three months. Every minute and every second is precious to complete the ground test within the period.
Currently, the KF-21 ground test is being conducted with 6 flight prototypes and 2 rescue prototypes. Each prototype gives a common test and a specific test for each unit. This is because it is difficult to carry out various difficult tests within the deadline. Accordingly, in the nearby structural test building, the 3rd prototype was conducting a load correction test, and the 5th and 6th units were performing a functional check at another location.
Up to this day, the progress of the ground test is about 50% of the overall test plan (based on test conditions). However, about 95% of progress has been made in terms of test conditions for safe flight (SOF) that must be performed before the first flight. The remaining 5% is expected to be filled by a ground run test starting next week. In addition, if the runway test is completed as scheduled, Prototype No. 1 is expected to take off for the first time next month.
The runway test will be conducted in stages such as low speed, medium speed, and high speed. In particular, a test to check the speed at which the vertical tail effect, a type of tail, occurs, and a test to check whether the emergency braking cable installed at the end of the runway engages properly with the hook installed at the rear of the aircraft in consideration of emergency situations such as brake failure.
In the flight test, six prototypes participate sequentially. About 2,000 flights are scheduled, and the number may increase or decrease depending on circumstances. The field engineer explained that one flight would be filled with all kinds of tension and pressure. In the process of finding safety and stability, every test moment carries risks.
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