ISRO's engines : Designs , Components & Prototypes.
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ISRO achieves major breakthrough in Semi cryogenic Engine development
March 28, 2025
SCE 200 Engine
ISRO is achieving progress in the design &development of a Semi cryogenic engine or Liquid Oxygen / Kerosene engine with a high thrust of 2000 kN that will power the Semi cryogenic booster stage of the LVM3 launch vehicle. The first major breakthrough in the Semi cryogenic engine development programme 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 2000 kN semi-cryogenic engine (SCE 200) 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 ton to 5 ton in GTO.
Major subsystems of SCE 200 engine include thrust chamber, pre-burner, turbo pump system, control components and start up system. The SCE 200 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 oxidizer rich combustion. The hardware along with the space grade kerosene are realized 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.
Semi-cryogenic Integrated Engine Test facility, IPRC, Mahendragiri
The realization 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 the Honorable Prime Minister, Shri Narendra 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.
Power Head Test Article (PHTA)
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.
Pre-burner Ignition Test Article (PITA)
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.
PHTA Hot Test
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 finetune the performance before the realization of the fully integrated engine.
ISRO achieves major breakthrough in Semicryogenic Engine development
ISRO successfully completes 1000hrs Life Test of Stationary Plasma Thruster for Spacecraft Electric Propulsion System
March 28, 2025
On March 27, 2025, ISRO successfully completed the life test of 1000hrs on the 300mN Stationary Plasma Thruster, that is developed for induction into the Electric Propulsion System of satellites. The Electric Propulsion System is proposed to replace the chemical propulsion system in future satellites of ISRO and pave the way for communication satellites which use only electric propulsion systems for orbit raising and station keeping.
The induction of these thrusters will result in extensive mass savings thereby enabling the enhancement of transponder capacity in communication satellites. These thrusters use Xenon as the propellant. The Specific Impulse of the Electric Propulsion System, which is a major performance indicator of a space propulsion system, is at least 6 times that of the conventional propulsion system. The life test was carried out under the full power level of 5.4kW in a chamber that simulates the vacuum conditions of space, and the erosion of the electrode liners was periodically monitored.
The erosion data measured during the life test is essential for predicting the subsequent erosion and hence the life of the thruster. This will be an important input for the satellite orbit management. This test is a major milestone to demonstrate the reliability and robustness of the thrusters before induction into the satellites. The Electric propulsion System is proposed to be inducted and validated in the upcoming Technology Demonstration Satellite (TDS-01) of ISRO and will be used for orbit raising to the Geostationary orbit.
300mN SPT developed by ISRO
Thruster undergoing life test
ISRO successfully completes 1000hrs Life Test of Stationary Plasma Thruster for Spacecraft Electric Propulsion System
ISRO Successfully qualifies fourth stage engine of PSLV with Satellite Nozzle Divergent
April 18, 2025
The liquid engines being flown in the fourth stage of PSLV (PS4) use nozzle divergent made up of imported Columbium (C103) material. An alternate material, Stellite (KC20WN), was proposed for the nozzle divergent realization to achieve Atmanirbharatha along with associated cost savings. Stellite is a cobalt based alloy with additions of Chromium, Nickel, Tungsten and Iron. It is a material which retains good strength at high temperatures up to 11500C and hence becomes a suitable material for high temperature applications. As part of the qualification programme, 3 hot tests were already completed on two hardware in the first phase. On April 08, 2025, the final test of the qualification programme was successfully completed through a hot test for a long duration of 665 seconds at the test facility in ISRO Propulsion Complex, Mahendragiri. The use of this alloy has resulted in cost savings to the extent of 90%.
April 18, 2025
The liquid engines being flown in the fourth stage of PSLV (PS4) use nozzle divergent made up of imported Columbium (C103) material. An alternate material, Stellite (KC20WN), was proposed for the nozzle divergent realization to achieve Atmanirbharatha along with associated cost savings. Stellite is a cobalt based alloy with additions of Chromium, Nickel, Tungsten and Iron. It is a material which retains good strength at high temperatures up to 11500C and hence becomes a suitable material for high temperature applications. As part of the qualification programme, 3 hot tests were already completed on two hardware in the first phase. On April 08, 2025, the final test of the qualification programme was successfully completed through a hot test for a long duration of 665 seconds at the test facility in ISRO Propulsion Complex, Mahendragiri. The use of this alloy has resulted in cost savings to the extent of 90%.
ISRO successfully conducted the 3rd ignition and hot-fire test of the SE2000 (formerly, SCE-200) PHTA on Apr 24!!
First hot-fire test (July 2023)
Second hot-fire (March 2025)
Third hot-fire (last Thursday)
ISRO successfully conducted a short duration hot test of Semi cryogenic Engine
April 26, 2025
A short duration hot test of the Semicryogenic Engine was successfully conducted at the test facility in ISRO Propulsion Complex (IPRC), Mahendragiri on April 24, 2025. This ignition test is the second milestone after the successful first hot test on March 28 ,2025, that was a major breakthrough in the testing of the Semicryogenic engine test programme.
In this test, the Engine Power Head Test Article, encompassing all engine systems except the thrust chamber, was subjected to a hot test for a duration of 3.5 seconds, that validated the engine start-up sequence. During the test, the engine was successfully ignited and operated up to 60% of its rated power level, demonstrating stable and controlled performance.
These tests are part of a planned series of evaluations designed to validate the design integrity and performance of critical subsystems, including the low-pressure and high-pressure turbo pumps, pre-burner and associated control systems. The results provided crucial data to finalize the operational sequencing of the full Semicryogenic engine.
Further qualification tests are scheduled to comprehensively validate the engine system, ultimately paving the way for its induction into ISRO's launch vehicles.
ISRO successfully conducted a short duration hot test of Semicryogenic Engine
April 26, 2025
A short duration hot test of the Semicryogenic Engine was successfully conducted at the test facility in ISRO Propulsion Complex (IPRC), Mahendragiri on April 24, 2025. This ignition test is the second milestone after the successful first hot test on March 28 ,2025, that was a major breakthrough in the testing of the Semicryogenic engine test programme.
In this test, the Engine Power Head Test Article, encompassing all engine systems except the thrust chamber, was subjected to a hot test for a duration of 3.5 seconds, that validated the engine start-up sequence. During the test, the engine was successfully ignited and operated up to 60% of its rated power level, demonstrating stable and controlled performance.
These tests are part of a planned series of evaluations designed to validate the design integrity and performance of critical subsystems, including the low-pressure and high-pressure turbo pumps, pre-burner and associated control systems. The results provided crucial data to finalize the operational sequencing of the full Semicryogenic engine.
Further qualification tests are scheduled to comprehensively validate the engine system, ultimately paving the way for its induction into ISRO's launch vehicles.
ISRO successfully conducted a short duration hot test of Semicryogenic Engine