ISRO advances nextgen rocket power with successful semi cryogenic engine test

ISRO advances nextgen rocket power with successful semi cryogenic engine test
by Simon Mansfield
Sydney, Australia (SPX) Apr 01, 2025

ISRO has taken a significant step forward in its efforts to develop a powerful semicryogenic engine, a key component intended to upgrade the LVM3 launch vehicle. On March 28, 2025, the space agency successfully completed the first hot test of the Engine Power Head Test Article (PHTA) at the ISRO Propulsion Complex in Mahendragiri, Tamil Nadu.

The Liquid Propulsion Systems Centre (LPSC) is spearheading the development of the SE2000 semicryogenic engine, which will produce 2000 kN of thrust. This engine will be used in the SC120 stage, replacing the current L110 liquid core stage in the LVM3 rocket. By utilizing liquid oxygen and kerosene - propellants that are both non-toxic and non-hazardous - ISRO expects improved performance and a higher payload capacity, raising LVM3's GTO capability from 4 to 5 tonnes.

Core elements of the SE2000 engine include a thrust chamber, turbo pump set, pre-burner, ignition system, and control mechanisms. It operates on an oxidizer-rich staged combustion cycle, reaching combustion chamber pressures of 180 bar and propellant feed pressures up to 600 bar. With a specific impulse of 335 seconds, the engine is engineered with advanced materials to endure extreme thermal and chemical environments. Its components, along with space-grade kerosene, are developed in collaboration with Indian industry partners.

Due to the complexity of the system, ISRO constructed a new facility - the Semicryogenic Integrated Engine Test (SIET) facility at Mahendragiri - dedicated to the engine and stage's qualification tests. Inaugurated by Prime Minister Narendra Modi on February 27, 2024, this facility is capable of managing high-pressure propellant storage and performing rigorous engine tests up to 2600 kN. It includes an advanced control system and a PLC-based data acquisition setup, all developed domestically.

Before the full engine hot tests, ISRO is conducting validation tests using intermediate setups like the Power Head Test Article (PHTA), which includes all engine systems except the thrust chamber. The recent 2.5-second hot fire was designed to assess the integrated functioning of the turbo pumps, pre-burner, startup systems, and control units. These subsystems had undergone thorough qualification before being assembled into the test article.

A separate unit, the Pre-burner Ignition Test Article (PITA), was also developed to refine the ignition sequence for the PHTA. Testing with PITA allowed engineers to determine the optimal startup procedure. The results of the March 28 test confirmed that the engine ignited as expected and transitioned smoothly into bootstrap mode operation.

Following this successful milestone, ISRO plans to carry out additional tests on the PHTA to fine-tune performance parameters before completing the integrated engine. This progress marks a major leap toward deploying high-thrust semicryogenic propulsion in future ISRO missions.