KF-21 Block I - The Young Hawk Leaves the Nest

SP_Sabre · February 27, 2026, 6:59pm

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KF-21 Block I - The Young Hawk Leaves the Nest

Good day all!^^
I’ve written a couple of threads in the past, but this will be my first suggestion. Today, I introduce the KF-21 Block 1. With the conclusion of its flight tests and service entry planned as early as Spring 2026, I thought it well-timed to propose its addition to War Thunder. With its standard and armament deemed sufficient for introduction, I believe the KF-21 would be an excellent and unique top-tier addition. It’s important to note this variant of the KF-21 is only essentially complete, planned munitions are still undergoing integration or are under development.

Note:

This is merely a suggestion for an aircraft who may be represented in the future, the specific timing is irrelevant
Feel free to share any additional information you may have, as the KF-21 always has the chance of receiving additional changes before entering service
Feel free to inquire or correct me on anything that is incorrect or seems wrong

General Information

Originating from the Korean Fighter eXperimental (KF-X) development program, the KF-21 is a medium-weight “4.5” generation (+/++) designed to secure air superiority, perform long-range precision strikes and neutralize land and sea infiltration forces. Greatly responsible for the KF-X system’s development, Korea Aerospace Industries (Ltd.), or KAI (Ltd.), along with 16 domestic universities, 11 research institutes, and 553 partner companies participated in the KF-21’s creation.

The development of the KF-21 was envisioned to advance the industrial manufacturing capabilities of South Korea while preventing a power vacuum, as the Republic of Korea Air Force (ROKAF) intends to replace dated aircraft with an initial order of 120 aircraft, and a maximum of 250. Some KF-21s will be introduced as two-seat models for conversion training.

Fraught with delays and postponement as the feasibility and economic cost were debated, renewed interest in the KF-X program arose. A study published in 2008 and incidents with North Korea throughout 2010 concluded the KF-X program was a matter of national importance.

Designed to fulfill the requirements of structural strength and durability to withstand high maneuvering loads in transonic and subsonic ranges, the KF-21 secures excellent combat maneuverability through high lift-to-drag ratio in a wide flight envelope, enabling performance of various missions with high angle of attack characteristics. Smaller than the F/A-18E/F while using the F414-GE-400, the KF-21’s thrust -to-weight ratio is more comparable to the Eurofighter Typhoon. The KF-21’s wing loading is lower than the F-35 while maintaining similar thrust. To fulfill the requirements of a 4.5 generation (+/++) in a timely and cost-effective manner, KAI and the ADD opted for a Dual-path approach involving the indigenization of key components wherever possible and utilizing proven international expertise wherever necessary.

The KF-21 Block I

Despite the Dual-path approach, four major technologies required indigenous development, in some capacity, after failure to achieve approval for transfer from the United States: The IRST, the Radar, the Radio Frequency Jammer (RF Jammer), and the Electro-optical Targeting Pod (EOTGP). These critical components were required for the successful achievement of a functional modern fighter jet.

The KF-21’s IRST was developed based on Leonard’s Skyward. The Skyward-K was modified back-end and features South Korean software. Denoted as APY-016K, the active electronically scanned array (AESA) radar of the KF-21 was developed by the Agency for Defense Development (ADD) and Hanwha Systems.

The KF-21’s integrated electronic warfare (EW) suite, or KF-21 EW Suite, consists of a radar warning receiver (RWR), electronic countermeasures (ECM), and a chaff/flare dispenser (CMDS). With an ECM based on the ALQ-200K, the KF-21 EW suite can detect across the C~J-Band, and for E~J-Band against multiple threats. The KF-21’s Electro-optical Targeting Pod (EOTGP) is used in air- to-air missions and can detect enemy aircraft more effectively through IRST and sensor fusion.

In need of an interim engine, the General Electric F414 was selected on July 12, 2016, being approved for production under license after winning contention against the Eurojet EJ200. The HUD utilized by the KF-21 is developed by LIG Nex1, with ELTA’s JHMCS-II as the HMD and featuring Hands-on Throttle and Stick (HOTAS) controls with Direct Voice Input (DVI).

The development and maturation of these critical components coincided with successful testing of the KF-21’s Prototype Batch, allowing for the KF-X program to transition to the Initial Mass-Production phase. Between 2026 to 2028, a production volume of 40 units is expected for the completed KF-21 in the Block I standard.

Armament of KF-21 Block I

The KF-21 is due to expand dramatically with each successive block. The Block 1 is part of the “initial mass-production” phase, equipped for a very limited armament and focused on air-to-air engagements only. Munitions such as the MBDA Meteor and Diehl IRIS-T were expedited for integration thanks to export restrictions preventing Raytheon’s AIM-120s and AIM-9Xs from installation.

Note: The KF-21 was often planned to use Raytheon’s AIM-120s and AIM-9Xs, these are still likely to be integrated into KF-21s at a later date.

Air-to-Air Missiles

6x MBDA Meteor

4x Diehl IRIS-T

Internal Gun

1x General Dynamics Ordnance and Tactical Systems M61A2 20mm Gatling Gun w/ 480 rounds and 6000 RPM

Specifications and Internal

Crew: 1
Length: 16.9 m (55.4 ft)
Wingspan: 11.2 m (36.7 ft)
Height: 4.7 m (15.5 ft)
Wing area: 46.5 m2
Empty weight: 11,800 kg
Loaded weight: 17,200 kg
Maximum Takeoff Weight (MTOW): 25,600 kg
Powerplant: 2 × General Electric F414-GE-400K
- Dry thrust: 57.8 kN
- Thrust with afterburner: 97.9 kN
Maximum speed is Mach 1.81
- 1378 km/h at sea level
- 2200 km/h at altitude
Service ceiling: 16,768 m
Rate of climb: >305 m/s
Wing loading:
- Max. Payload: 7,700 kg
Thrust/weight:
- Maximum: 1.69
- Minimum: 0.79
Maximum g-load: +9g / -3g