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IFX Indonesian Fighter Experiment (KF21/IFX program)

UAE unveiled stealth UAV as well but the design is completely opposite the Korean one looks like a bomber.

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Bomber or it can also be tanker, both are needed for future war. I hope Indonesian Aerospace also develop wingman stealth drones for KF21. I expect Indonesian Air Force will have 120 KF 21 fighter, it then needs at least 200 wingman Stealth drone. There should also be 35 Stealth UCAV bomber and around 15 Stealth tanker drone.

If KF21, N219 Amphibious, and MALE UCAV development are completed, I hope Indonesian Aerospace conduct 2 new development program, R80 turboprop program and Stealth wingman drone for IFX. They should start R80 program in 2025, this plane can also be used for AWACS, MPA, and Anti Submarine planes beside to serve civilian market (Airline).
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More pictures on Tandem Variant



KAI vice-president and head of international business department, JaeHong Jake Kim, said the aircraft would feature air-to-air missiles, air-to-ground munitions, and a Gatling-type 20mm machine gun.

There are also plans to combine AI, verbal communication, and teaming with unmanned vehicles.

“This kind of concept is not mature, but the concept should be two-seater piloted jet with four unmanned aircraft,” said Kim.

“The design can be easily turned into an export version. The beauty of this aircraft is that we have a one-seater and two-seater aircraft.”

What is the timeline for Indonesia. When will first deliveries happen? Will they be block 1 or 2.

Also, what are some of Indonesia's most important contributions to this aircraft?
What is the timeline for Indonesia. When will first deliveries happen? Will they be block 1 or 2.

Also, what are some of Indonesia's most important contributions to this aircraft?

The time line is the same with Korean. First deliveries dont know, better dont talk about deliveries yet, base on schedule fight test will be completed in February 2026 inshaAllah. Base on plan, block 2 development will be completed in 2028 inshaAllah.

About the most important contribution is the air inlet design. The design uses C103 design which is developed by ADD Korea and Indonesian (Indonesian Aerospace + Institute Teknologi Bandung). During first development phase 2011-2012 December, there is no Lockheed Martin and KAI Korea participation, their participation started in 2016.

Only Indonesian engineer who master this technology during first development phase

YF23 Air Inlet Design (Example)


I will show you credible source from credible person in the program who said it
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What is the timeline for Indonesia. When will first deliveries happen? Will they be block 1 or 2.

Also, what are some of Indonesia's most important contributions to this aircraft?

2016 News:

Dalam pembuatan prototipe pesawat tempur multiperan itu, menurut Kepala Badan Penelitian dan Pengembangan Kementerian Pertahanan Anne Kusmayati, PTDI akan membuat sayap, penguat di bagian bawah sayap, dan ekor.

Pengerjaan jet tempur KF-X/IF-X akan dipusatkan di Sacheon, Provinsi Gyeongsang Selatan, Korea Selatan –kota yang menjadi lokasi markas dan pabrik utama Korea Aerospace Industries.

Sebanyak 200 insinyur Indonesia secara bertahap berangkat ke Sacheon selama satu-dua tahun ini. Mula-mula mereka akan merancang desain pesawat. Para insinyur itu juga akan ikut mendesain seluruh komponen pesawat.

Dari total pekerja kedua negara yang terlibat pembuatan KF-X/IF-X, 30 persen lebih berasal dari Indonesia dan mayoritas sisanya dari Korea Selatan. Ini pula alasan pembuatan pesawat dipusatkan di Sacheon, bukan di Indonesia.

Proporsi 30 persen lebih insinyur Indonesia yang terlibat pengerjaan KF-X/IF-X itu sesungguhnya bertambah dari jumlah semula sebanyak 20 persen. Penambahan pekerja Indonesia itu terjadi seiring berjalannya waktu penggarapan.

“Itu menandakan insinyur Indonesia diperhitungkan Korea. Bahkan ada paket pekerjaan yang satu teknologinya hanya dimiliki orang Indonesia. Dia doktor dari ITB (Institut Teknologi Bandung), satu-satunya yang memiliki kemampuan inlight design. Jadi Korea tak memandang enteng Indonesia,” kata Anne.

Google Translate

In making the prototype of the multi-fighter aircraft, according to Head of the Ministry of Defense's Research and Development Agency Anne Kusmayati, PTDI will make wings, boosters at the bottom of the wing and tail.

Work on KF-X / IF-X fighter jets will be centered in Sacheon, South Gyeongsang Province, South Korea, the city which is the headquarters and main factory of Korea Aerospace Industries.

A total of 200 Indonesian engineers have gradually departed for Sacheon for one or two years. At first they will design the aircraft design. The engineers will also participate in designing all aircraft components.

Of the total workers of the two countries involved in the making of KF-X / IF-X, 30 percent are more from Indonesia and the majority of the rest are from South Korea. This is also the reason for making aircraft centered on Sacheon, not in Indonesia.

The proportion of more than 30 percent of Indonesian engineers involved in working on the KF-X / IF-X actually increased from the original amount of 20 percent. The addition of Indonesian workers occurred as time went by cultivation.

"It signifies that Indonesian engineers count on Korea. There is even a work package whose technology is only owned by Indonesians. He is a doctor from ITB (Bandung Institute of Technology), the only one who has inlight (read : inlet) design capabilities. So Korea does not take Indonesia lightly, "Anne said.

Source : CNN Indonesia


The reporter doesnt understand aerospace technology, he/she just hearing. It is Inlet design, not inlight design


Anne Kusmayanti is the Hijabi women sit in the front during CDR meeting 2019


More on what happen during first phase development

The design completed in 2012 December (Before KAI Korea and Lockheed Martin join the program since 2015)

2 Basic design of KFX/IFX C 100 and C 200 posted by credible South Korean Defense related blog, Naver in 2012.


Check the Air Inlet (Intake) with the real plane, no different. You dont see this Inlet in other 5 generation fighters like J31/TFX/ AMCA. It has combination of F22 and F35 intake

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Inlate/Intake design is very crucial since it is about the flow of air into propulsion.



Check J31






VS KF21 Inlet/Intake




Right and Left from the top



Most modern passenger and military aircraft are powered by gas turbine engines, which are also called jet engines. There are several different types of gas turbine engines, but all turbine engines have some parts in common. All turbine engines have an inlet to bring free stream air into the engine. The inlet sits upstream of the compressor and, while the inlet does no work on the flow, inlet performance has a strong influence on engine net thrust. As shown in the figures above, inlets come in a variety of shapes and sizes with the specifics usually dictated by the speed of the aircraft.


For aircraft that cannot go faster than the speed of sound, like large airliners, a simple, straight, short inlet works quite well. On a typical subsonic inlet, the surface of the inlet from outside to inside is a continuous smooth curve with some thickness from inside to outside. The most upstream portion of the inlet is called the highlight, or the inlet lip. A subsonic aircraft has an inlet with a relatively thick lip.


An inlet for a supersonic aircraft, on the other hand, has a relatively sharp lip. The inlet lip is sharpened to minimize the performance losses from shock waves that occur during supersonic flight. For a supersonic aircraft, the inlet must slow the flow down to subsonic speeds before the air reaches the compressor. Some supersonic inlets, like the one at the upper right, use a central cone to shock the flow down to subsonic speeds. Other inlets, like the one shown at the lower left, use flat hinged plates to generate the compression shocks, with the resulting inlet geometry having a rectangular cross section. This variable geometry inlet is used on the F-14 and F-15 fighter aircraft. More exotic inlet shapes are used on some aircraft for a variety of reasons. The inlets of the Mach 3+ SR-71 aircraft are specially designed to allow cruising flight at high speed. The inlets of the SR-71 actually produce thrust during flight.


Inlets for hypersonic aircraft present the ultimate design challenge. For ramjet-powered aircraft, the inlet must bring the high speed external flow down to subsonic conditions in the burner. High stagnation temperatures are present in this speed regime and variable geometry may not be an option for the inlet designer because of possible flow leaks through the hinges. For scramjet-powered aircraft, the heat environment is even worse because the flight Mach number is higher than that for a ramjet-powered aircraft. Scramjet inlets are highly integrated with the fuselage of the aircraft. On the X-43A, the inlet includes the entire lower surface of the aircraft forward of the cowl lip. Thick, hot boundary layers are usually present on the compression surfaces of hypersonic inlets. The flow exiting a scramjet inlet must remain supersonic.


An inlet must operate efficiently over the entire flight envelope of the aircraft. At very low aircraft speeds, or when just sitting on the runway, free stream air is pulled into the engine by the compressor. In England, inlets are called intakes, which is a more accurate description of their function at low aircraft speeds. At high speeds, a good inlet will allow the aircraft to maneuver to high angles of attack and sideslip without disrupting flow to the compressor. Because the inlet is so important to overall aircraft operation, it is usually designed and tested by the airframe company, not the engine manufacturer. But because inlet operation is so important to engine performance, all engine manufacturers also employ inlet aerodynamicists. The amount of disruption of the flow is characterized by a numerical inlet distortion index. Different airframers use different indices, but all of the indices are based on ratios of the local variation of pressure to the average pressure at the compressor face.

The ratio of the average total pressure at the compressor face to the free stream total pressure is called the total pressure recovery. Pressure recovery is another inlet performance index; the higher the value, the better the inlet. For hypersonic inlets the value of pressure recovery is very low and nearly constant because of shock losses, so hypersonic inlets are normally characterized by their kinetic energy efficiency. If the airflow demanded by the engine is much less than the airflow that can be captured by the inlet, then the difference in airflow is spilled around the inlet. The airflow mis-match can produce spillage drag on the aircraft.

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2016 news. Old news but some information here is quite important to share.




Korean Indonesian KFX/IFX Fighter Project​

Monday, 2 May 2016

The development project for the 4.5 generation advanced fighter named KFX/IFX run by South Korea and Indonesia has officially started in recent months. Indonesia, which bears 20% of the development funds, has also prepared infrastructure and human resources to support the success of Indonesia's largest military project. Then what has Indonesia prepared?

The first thing that has been prepared by the Indonesian government is to build facilities to support this project in the future. The ongoing facility is a special hangar for composing hangar facilities, titanium hangars, production hangars, and final assembly hangars for this fighter aircraft in Bandung, West Java. This special hangar is located in the area of PT Dirgantara Indonesia, it is almost complete.

In a special facility for the KFX / IFX project, it will later be used by the Indonesian side for the purposes of this project. Indonesia itself is rumored to have a part to make a number of important components of this advanced fighter. Among them are the components of the wing part, tail and wing strengthening components of this fighter.

In addition, it is also rumored that in this facility, one of the prototypes of IFX fighters will also be built which will be part of Indonesia. As we all know that in this KFX / IFX project, 6 fighter prototypes will be built that will undergo a series of flight tests. One of these 6 prototypes will belong to Indonesia. In addition to those 6 prototypes, there will be 2 other prototypes to be built that will not be tested but will undergo a series of aircraft structure tests. The KFX/IFX fighter prototype to be produced in Indonesia is the fifth prototype, and will be a fully conducted flight test aircraft in Indonesia.

Design KFX/IFX C-103 Conventional Wing Dual Engine

Not only preparing itself in terms of infrastructure, Indonesia has also begun to prepare human resources since a few years ago to support this modern fighter development project. The Indonesian government and PT Dirgantara Indonesia are reported to have prepared around 200 to 300 experts to be involved in this Indonesian military mega project. However, this large number of experts will come to South Korea gradually over the next 10 years. But there are also experts who will be involved for 10 years from the beginning.

Some of these experts from Indonesia themselves will be schooled first abroad, especially to Europe to sharpen their knowledge, before being directly involved in this project. The additional knowledge they have gained from European countries is expected to be an additional positive value for the development of Indonesian fighters in the future.

The number of Indonesian experts involved in the second phase called the Engineering and Manufaturing Development (EMD) phase was far more than the first phase (Technical Development Phase) which only numbered 52 people at that time. The first phase (Technical Development Phase) itself lasted for 18 months from 2011 to 2012. While the second phase (EMD) will last for 10 years involving 200-300 Indonesian experts.

Not only aerospace experts, the Indonesian military has also prepared several pilots from the Air Force as test pilots for this fighter aircraft later. It is rumored that currently 5 test pilots have been prepared for this KFX/IFX fighter later. The five pilots reportedly already have qualified and sufficient flying hours with the KT-1B Wongbee and T-50i Golden Eagle trainer aircraft.

Not only that, the five prospective KFX / IFX fighter test pilots have also been specially invited at S1 Aeronautical Engineering – Bandung Institute of Technology (ITB). This is done so that the five prospective test pilots are also equipped with adequate flight knowledge in addition to the ability to be fighter pilots.

This considerable preparation is expected to be a step to make the KFX/IFX fighter development project a success which in the future is expected to become the fulcrum of TNI defense equipment, especially for Indonesian fighters in the future. Although this fighter is not purely a fighter made in Indonesia, Indonesia hopes a lot for the success of this project.

But of course, all these preparations are not guaranteed that this project will run smoothly and smoothly. Of course, there will be many obstacles and obstacles that will still be faced, but at least all the preparations that have been carried out are a good first step. Whether or not this Indonesian military mega project is successful is not certain and only time will be able to

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Tested with AESA radar


(translated and edited by Maro.Kyo from the original KAI presentation slide)

Joko Widodo speech during KF21 roll out ceremony in April 2021. He said KF21/IFX will be Indonesian backbone fighter until 2040.

Actually KF21 program is started since SBY administration in 2009. SBY administration lead by Democrat Party who currently support Anies Baswedan as President. Together with PKS party, three of them are seen as opposition for Jokowi administration but very likely to support KFX/IFX program if Anies become President as the program as I said earlier is started under Democrat coalition ruler.

Indonesia also has law that forbid foreign defense equipment to be bought if local industry has already been able to produce it. The law is made in 2009 and until now it remains, it has nationalistic tendency.
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