A Game-Changer For Future Indian Space Missions

The Indian Space Research Organisation (ISRO) has achieved a major milestone in its Semi-Cryogenic Engine Development Program with the successful hot test of the Engine Power Head Test Article (PHTA) on March 28, 2025, at the ISRO Propulsion Complex, Mahendragiri.

ISRO is achieving progress in the design & development of a Semi-cryogenic engine or Liquid Oxygen / Kerosene engine with a high thrust of 2000 kNthat will power the Semi-Cryogenic booster stage of the LVM3 launch vehicle. The first major breakthrough in the Semi-cryogenic engine development program was achieved on March 28, 2025, when the first successful hot test of Engine Power Head Test Article (PHTA),was carried out at ISRO Propulsion Complex, Mahendragiri, Tamil Nadu.

The Liquid Propulsion Systems Centre (LPSC) of ISRO is developing the Semi cryogenic propulsion Engine and Stage. The stage (SC120) powered by the 2000kN semi-cryogenic engine (SE2000) will replace the present core liquid stage (L110) of LVM3 for payload enhancement and power the booster stages of future launch vehicles. Non toxic and non hazardous propellants (Liquid Oxygen and Kerosene) are employed in Semi cryogenic propulsion and this will deliver higher performance compared to existing L110 stage. Induction of Semi cryogenic propulsion system along with uprated cryogenic stage in the LVM3 vehicle enhances its payload capability from 4 tonne to 5 tonne in GTO.

Cutting-Edge Technology In Engine Development

Major subsystems of SE-2000 engine include thrust chamber, pre-burner, turbo pump system, control components and start up system. The SE2000 engine works with a complex oxidizer rich staged combustion cycle with high chamber pressure of 180 bar (with propellant feed system delivering pressures up to 600 bar) & specific impulse of 335s. The complex engine hardware uses special materials to withstand the high temperature and oxidiser rich combustion. The hardware along with the space grade kerosene are realised in partnership with Indian industry. The development of this engine in these high thrust levels is highly challenging and this technology is available with only very few nations.

The realisation of a test facility to qualify the engine and stage is equally complex and challenging. The complex Semi-Cryogenic Integrated Engine Test facility (SIET) was established at ISRO Propulsion Research Complex (IPRC), Mahendragiri for testing the engine and stage and was dedicated to the nation by PM Modi, on February 27, 2024.

This facility caters to storage and servicing of large volume of propellants and service fluids at high pressures. The capability of the test stand is validated through several flow and ignition trials. The test stand which involves many sophisticated control components are managed from a Test Control Centre that is also developed indigenously. This facility with a state-of-art PLC-based control system and data acquisition system is capable of testing semi-cryogenic engines up to 2600 kN thrust.

Prior to the conduct of integrated engine level hot tests, it is planned to carry out performance evaluation tests of the intermediate configuration, designated as Power Head Test Article (PHTA),that comprises all the engine systems except the thrust chamber. The hot test that was carried out today, is the first of a series of tests planned to validate the design of the propellant feed system, including the low-pressure and high-pressure turbo-pumps, the pre-burner, start system and control components. All subsystems for the test were realized and had undergone rigorous qualification test prior to integration to Power Head Test Article.

The Ignition sequence for PHTA was derived from a series of hot tests in single element level. In order to ensure the smooth ignition process during the PHTA test, another test article, Pre-burner Ignition Test Article (PITA), was realized, which consists of the pre-burner along with its feed systems, start-systems, and related control components. A series of tests were successfully completed using the PITA and the optimum start sequence for power head test article was derived.

Today’s test demonstrated the smooth ignition and boost strap mode operation of engine over a test duration of 2.5 seconds. The objective of the test was to validate the integrated performance of the critical subsystems such as the pre-burner, turbo pumps, start system and control components by carrying out a hot-firing for a short-duration of 2.5 seconds. The test proceeded as predicted and all the engine parameters were as expected.

With this breakthrough, ISRO is further planning a series of tests on the PHTA to further validate and fine tune the performance before the realization of the fully integrated engine.

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