Within the scope of the ‘Turbojet Engine Development Project Contract’ signed with the Defence Industry Agency on February 22, 2012, Kale Arge had to develop all necessary technology and critical subsystems on its own since there was a severe lack of skilled human resources in Türkiye (both in terms of academic staff and workforce), technological infrastructure, and the ecosystem in the field of gas turbine engines at that time and started to work on three different turbojet engine development projects (KTJ-1750, KTJ-3700, and ARAT Engine) with varying thrust levels for both domestic and international customers in 2021, with its own resources using the know-how from the KTJ-3200.

The KTJ-3200 Turbojet Engine, which was indigenously developed by Kale Arge, including all engine controls and accessories, was subjected to comprehensive tests in the Altitude Test System at Kale Arge Tuzla Development & Test Center and was made ready for acceptance tests in mid-2021. The engines were successfully delivered under the Development Contract following the completion of their acceptance process, and the Turbojet Engines Procurement and Integration Project Protocol was signed on August 18, 2021.

Thanks to the expertise and high Technology Readiness Level it has acquired throughout the Turbojet Engines Development Project over 9 years, the company is now able to commission and complete new engine projects in a shorter timeframe and very quickly. For example, the KTJ-1750 Turbojet Engine Project, which started development with the company's own resources in March 2021, went from the design phase to the captive test phase in just 15 months. During the unveiling ceremony of the ÇAKIR Cruise Missile Family held on March 31, 2022, it was shared with the public that the KTJ-1750 TJ Engine was chosen to power the ÇAKIR Missiles, and a contract was signed between ROKETSAN and Kale Arge on the National Turbojet Engine Development.

Prototype production of the KTJ-1750 TJ Engine, which was developed by utilizing KTJ-3200 experience, was completed in the first half of 2022, and ground tests started at the Altitude Test System at Kale Arge Tuzla Development and Test Center in June 2022. The KTJ-1750 TJ Engine reached 50,000rpm during the tests in September. The ongoing qualification tests of the engine are expected to be completed in the last quarter of 2022. The KTJ-1750 Turbojet Engine had recently completed the first firing test with the ÇAKIR Cruise Missile developed by ROKETSAN. According to the information shared by the Defence Industry Agency on May 11, the ÇAKIR Cruise Missile (without live warhead and seeker, only INS/GPS guidance), launched from an AKINCI UAV at an altitude of 7,000 meters, successfully hit the target coordinate in the Black Sea at a speed of Mach 0.9. ÇAKIR, the first cruise missile launched from an Armed Unmanned Aerial Vehicle, weighs 245kg and has a range of 150km+. Thanks to the ITAR-Free KTJ-1750 Turbojet Engine, the ÇAKIR Cruise Missile can be sold to potential customers abroad without any export restrictions.

The KTJ-1750, a product of domestic and national engineering, draws attention with its compact design, lightweight, and low fuel consumption thanks to its very high compression ratio and thermodynamic efficiency provided by the axial compressor design. Designed for the ÇAKIR Cruise Missile Family, the KTJ-1750, which can offer superior performance at high altitudes, can produce 1,750N thrust at sea level.

KTJ Series Turbojet Engine Family and Technical Features

KTJ-3200: Kale Arge's first engine, the KTJ-3200, was developed for SOM (SAGE) and ATMACA (ROKETSAN) Cruise Missiles. The KTJ-3200 Turbojet Engine, consisting of a 4-stage axial compressor, annular combustion chamber, and a single-stage turbine, with a thrust power of 3,200N (Newton), is 63cm in length, approximately 30cm in diameter, and weighs 50kg. The Compressor stages of the ITAR-Free engine are made of Aluminum, and the Combustion Chamber and Turbine are made of special alloys and Nickel Superalloys. Since the compressor uses monolithic (one-piece) rotors, the engine has low fuel consumption and high thermal efficiency.

The KTJ-3200 has been developed and optimized over many years and has similar capabilities to its competitors in terms of performance and thrust capacity though it has a longer service life (both in terms of aerodynamic components, for example, a far more advanced turbine material is used in the engine, so the turbine service life is significantly prolonged, and the indigenously designed and produced bearings have a longer service life than their counterparts) and substantially lower fuel consumption values.

The KTJ-3200, which stands out with its low fuel consumption and ability to be launched at different altitude/speed conditions, has been designed to operate at an altitude of 5,000m and Mach 0.95 in accordance with the operational flight envelope of SOM ALCM and ATMACA Anti-Ship Cruise Missiles. However, the KTJ-3200 has a much wider starting envelope than equivalent engines. This makes it possible to run the engine even at extremely low speeds. The Altitude Test System at the Kale Arge Tuzla Development and Test Center has played a key role in the development and testing process of the KTJ-3200 engine, which features a pyrotechnic igniter and a windmilling capability. The KTJ-3200 Turbojet Engine was developed by Kale Arge with only domestic resources and no reliance on foreign sources since all components are designed and manufactured in Türkiye, making them not subject to export restrictions. The qualification process of hundreds of ordered KTJ-3200 Engines has been successfully completed, and serial production has begun.

KTJ-3200 has been a great opportunity for the Kale Arge engineering team to gain experience in managing a holistic engine development project from start to finish, including design, testing, production, and assembly activities. The capabilities acquired during the KTJ-3200 Project have provided Kale Arge with sufficient flexibility to carry out cruise missile programs of different thrusts and ranges.

KTJ-1750: The KTJ-1750 TJ Engine, designed and developed based on the KTJ-3200 technology, has a 4-stage Axial Compressor design like the KTJ-3200. Capable of producing 1,750N of thrust at sea level and operating at speeds up to Mach 0.95, the KTJ-1750 has a diameter of 202mm and a weight of 25kg. With a Specific Fuel Consumption Value of 0.12KG/H/N (SLS, at Max RPM), and a thrust/weight ratio of >11, the total length of the KTJ-1750 is 464mm.

In general, single-stage centrifugal compressors are used in this type of small turbojet engine. However, since the compression ratio is low due to the single-stage configuration, these engines have higher fuel consumption because of low thermal efficiency. It is stated that there is no other engine of this size and class in the world with a 4-stage Axial Compressor design. The KTJ-1750 is unique in this sense in the world.

KTJ-3700: The KTJ-3700, which will power the KARA ATMACA Surface-To-Surface Cruise Missile being developed by ROKETSAN, is another turbojet engine project initiated by Kale Arge with its own resources. The KTJ-3700, which weighs 50kg, is aimed to have an operating altitude of 10,000 meters and a flight speed of Mach 0.95.

Although it has similar weight and dimensions, the KTJ-3700 produces 500N more thrust than the KTJ-3200 and offers better Specific Fuel Consumption, thanks to its improved aerodynamic design. Thanks to its lower fuel consumption, it provides a longer range to the missiles/platforms. As with the other two engines, the closed-circuit fuel lubrication technique is used in the KTJ-3700. However, Kale Arge also worked on closed-loop oil-lubricated versions of the engines.

Ground tests of the prototype KTJ-3700 Engine will be carried out at the Altitude Test System located at the Kale Arge Tuzla Development and Test Center campus. For this purpose, the running/test altitude conditions of the Altitude Test System, designed to simulate flights at 0-5km and speeds up to 0.95M, will be increased to 10,000 meters for the testing of both KTJ-3700 and ARAT Turbojet Engines. In this way, the weather conditions 10,000 meters above the ground will be simulated, and testing will be performed to see how the engine responds to those circumstances. It is aimed to start ground tests with the KTJ-3700 before the end of 2022 and use the KTJ-3700 in the first firing test of the KARA ATMACA Surface-to-Surface Cruise Missile in 2023.