ISRO says, GSLV's Cryogenic upper stage tested successfully

The ISRO said it has successfully tested its indigenously developed Cryogenic Upper Stage for GSLV MkIII.

It said the cryogenic stage, designated as C25, was tested for a flight duration of 640 seconds at ISRO Propulsion Complex at Mahendragiri in Tirunelveli district of Tamil Nadu, yesterday.

C25 stage had earlier been tested successfully for 50 seconds on January 25, 2017 to validate all the systems.

Stating that prior to stage development hot tests, three CE20 engines were realised and two engines were subjected to qualification tests in sea level conditions, ISRO said, this included 800 seconds duration hot test and the third engine identified for flight was tested in high altitude conditions for a duration of 25 seconds.

This stage test is a significant milestone as it is the last in a series of engine and stage development hot tests before the first development flight of GSLV MkIII, it said.

GSLV MkIII, the next generation launch vehicle of ISRO, is capable of launching four ton class satellites into Geosynchronous Transfer Orbit (GTO).

The GSLV MkIII vehicle integration activities are in progress at Satish Dhawan Space Centre or Sriharikota for its first development flight (GSLV MkIII-D1) targeted for April 2017.

The space agency described the C25 stage as the "most powerful" upper stage developed by ISRO which uses Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) propellant combination.

It said the stage carries 27.8 tonnes of propellants loaded in two independent tanks.

According to ISRO, development of a cryogenic stage has unique design challenges, with liquid Hydrogen stored at -253 deg C and liquid Oxygen stored at -195 deg C in its tanks.

The Cryogenic Stage development tests were carried out in two phases; first stage was subjected to fluid mock-up, wherein the stage preparation and servicing at launch complex in SDSC, SHAR, Shriharikota was completed to prove all the ground facilities established for servicing the cryogenic stage.

This was followed by testing of the Stage at ISRO Propulsion Complex, Mahendragiri. From the Stage realisation to completion of testing, the process was accomplished in four months.

The performance of the Stage during the hot test was as predicted, ISRO said, adding, successful hot test for flight duration qualifies the design of the stage and "robustness of the facilities conceived and established towards its development."

The flight cryogenic stage is in advanced stage of realisation and forms upper stage of GSLV MkIII, it added.