ISRO successfully tests boot-strap mode start on CE20 cryogenic engine

The ISRO on Wednesday announced that it has successfully demonstrated the boot-strap mode start test of the CE20 Cryogenic engine, which powers the upper stage of the Launch Vehicle Mark -3 (LVM3) rocket.

The test was conducted for 10 second under vacuum conditions at the High-Altitude Test (HAT) facility at ISRO Propulsion Complex, Mahendragiri on November 7, it said.

According to ISRO, the CE20 cryogenic engine is already qualified for operation at thrust levels between 19 and 22 tonnes with a single start in flight and is cleared for use in the Gaganyaan missions.

Under normal conditions, the engine ignition begins under tank head pressure, followed by a turbopump start up using a stored gas start-up system, the space agency said. For future missions, multiple in-flight restarts of the CE20 engine will be required for mission flexibility, towards multi-orbit missions.

With the current configuration, each restart requires an additional start-up gas bottle and associated systems, leading to a reduction in vehicle payload capability, it said. "Hence, achieving boot-strap mode start - where the engine builds up to steady operation without external start-up assistance - is essential."  During the test, a multi-element igniter was employed in both the thrust chamber and gas generator to facilitate boot-strap starting, the agency added.

"In this test, following the ignition of the thrust chamber, the gas generator was ignited under tank head conditions, and the turbopumps were started without the use of the start-up system. Subsequently, boot-strap mode build-up and steady-state operation of the engine were successfully demonstrated," it said.

"With this achievement, ISRO has successfully demonstrated boot-strap mode starting of a gas-generator cycle cryogenic engine without any auxiliary start-up system, perhaps for the first time in the world - a significant milestone towards enhancing the restart capability and mission flexibility of future LVM3 flights," it added.