Gaganyaan mission-qualified C20 cryogenic engine of ISRO aces key test

New Delhi, Dec 12 The Indian Space Research Organisation (ISRO) on Thursday announced that its C20 cryogenic engine, which had qualified for Gaganyaan mission, has successfully aced a crucial test.

The Indian space agency noted that the test features restart enabling systems that are important for space missions.

“ISRO achieves a major milestone! The C20 cryogenic engine successfully passes a critical test in ambient condition, featuring restart enabling systems -- a vital step for future missions,” the county’s space agency said in a post on X on Thursday.

The key test was “successfully carried out the sea level hot test of its CE20 Cryogenic Engine featuring a nozzle area ratio of 100 at ISRO Propulsion Complex in Mahendragiri, Tamil Nadu on November 29,” ISRO said in a statement.

The indigenous CE20 cryogenic engine is being developed by engineers at the ISRO’s Liquid Propulsion Systems Centre. The engine will be used to power the upper stage of the LVM3 launch vehicle. It has also been qualified to operate at a thrust level of 19 tonnes.

This engine has successfully powered the upper stage of six LVM3 missions so far.

Recently, the engine was also qualified for the Gaganyaan mission with a thrust level of 20 tonnes and also to an uprated thrust level of 22 tonnes for the future C32 stage, ISRO said.

The test demonstrated the performance of a multi-element igniter that is required for engine restart capability.

Further, testing the CE20 engine at sea level also posed considerable challenges, because of the high area ratio nozzle which has an exit pressure of approximately 50 mbar.

“The flow separation inside the nozzle can lead to severe vibrations and thermal problems at the flow separation plane leading to possible mechanical damage of the nozzle,” ISRO explained.

However, to mitigate the issue, the engineers are performing the “flight acceptance tests for CE20 engines at the High-Altitude Test (HAT) facility”. Even as this added complexity to the acceptance testing procedure, the teams devised a sea-level test utilising an innovative Nozzle Protection System. This paved the way for a cost-effective and less complex procedure for acceptance testing of the cryogenic engines.

“Restarting a cryogenic engine is a complex process. Major challenges are vacuum ignition without nozzle closure and use of multi-element igniter,” ISRO said.

The space agency had in earlier ground tests demonstrated vacuum ignition of the CE20 engine without nozzle closure.

In the latest test, the multi-element igniter performance was also evaluated. While only the first element was activated, the health of the other two elements was monitored.

“During this test, both the engine and facility performance were normal, and the required engine performance parameters were achieved as anticipated,” ISRO said.