• Forum
• SITREP
• Military
• WMD
• Intelligence
• Homeland Security

• Space

• Introduction
• Systems
• Facilities
• Agencies
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• Public Eye

GSLV Mark-II Cryogenic Upper Stage (CUS)

GSLV-MK II uses the indigenously developed Cryogenic Upper Stage (CUS) that develops 9 ton of thrust against 7.5 ton of the Russian CUS and carries 15 ton of propellant against 12.5 ton. The objective of the Cryogenic Upper Stage (CUS) Project is to develop and qualify an indigenous restartable cryogenic stage employing liquid oxygen as oxidizer and liquid hydrogen as fuel for the upper stage of GSLV. The ISRO used the indigenously developed Cryogenic Upper Stage (CUS) for the first time since the launch of the mega shuttle, GSLV-D3, in April 2010. The first flight of the India designed tested and produced small cryogenic rocket engine failed to properly start-up and ignite on April 15, 2010 setting back the ISRO intent to have its own cryogenic engine for the GSLV use. Defining the technical issues that prevented its engines ignition and their resolution was anticipated to take about a year before it will again be flight tested, although ISRO iniitally indicating it may be flight tested again before 2010 is over or early in 2011. In the mean time India returned to using purchased Russian cryogenic engines to assure GSLV continued operations.

A comprehensive technical assessment of CUS-3 flight stage by National Panel of Eminent Experts was carried out and recommendations were implemented. Accordingly, the margins on fuel booster turbo pump speed were demonstrated in ground test. Ground preparation of the stage was satisfactory and achieved the required lift off conditions. On board chilling of feed lines, maintenance of the propellant tank pressures during flight etc., were successfully demonstrated and required conditions for the engine ignition were achieved.

The expected performance of the stage was not achieved due to the anomaly in the Fuel Booster Turbo-Pump (FBTP). Subsequently, Fuel Booster Turbo Pump (FBTP) failure simulation tests were conducted at SET facility considering various suspected failure scenarios in GSLV D3 mission. Later, based on FAC & Expert Committee recommendations, FBTP was modified with increased seal clearances & qualification tests were carried out. Also, engine level tests were also conducted using A4 Main Engine, wherein modified OBTP was flight acceptance tested & performance of modified FBTP was assessed.

The Flight Main engine (A7) was realized & two cold start tests were conducted to finalize the parameters for flight acceptance hot test. Flight acceptance testing of steering engines (SE18 & SE 22) was successfully conducted at SET-HAT, LMF. Fuel & Oxidizer booster turbo pumps were realized and flight acceptance tested. Indigenous LOX & LH2 level sensors were realized &flight acceptance tested. Stage structures viz. modified Lower Stub Adaptor (LSA), Lower Truss (LT) and Inter Tank Truss (ITT) were realized & delivered for flight stage integration.

The Luna-Resource mission was expected to be launched in 2013 on the Indian GSLV mark-2 booster that was un-successfully flown indigenous design tested in April 2010 or GSLV-3 mark-3 was also suggested as the booster to be used. The international payload launch will be from India ’s Satish Dhawan Space Center, Sriharikota. Testing is continuing to resolve the liquid hydrogen stages ignition systems issues.

The GSLV-D5 vehicle carrying 2018 kg GSAT-14 would have the configuration (4 L40H+S139) + L37.5H + CUS-12 + 3.4 m diameter payload fairing. All the recommendations from Failure Analysis Committees of GSLV-F06 and GSLV-D3 have been incorporated and implemented. Modifications in Fuel Booster Turbo Pump (FBTP) and Oxidiser Booster Turbo Pump (OBTP) were carried out along with improvements in Cryogenic Upper Stage (CUS) elements. The CUS lower shroud was redesigned and strengthened. Wind tunnel configuration was modified by extending its length. The lanyard connector mounting bracket was relocated from the lower shroud to truss member.

GSLV-D5 aerodynamic characterisation was revisited. Force measurements, Steady and Unsteady Pressure measurements and aero elastic tests were conducted using wind tunnel models at National Aerospace Laboratory, Bangalore and Glavkosmos, Russia. Computational Fluid Dynamics (CFD) simulations were carried out in-house for incremental effects on protrusion, overall aerodynamic load distribution and distribution on protrusions.

All the motor segments of S139 stage were realised and cleared for flight. All the four L40 stages are positioned at SDSC, SHAR. GS2 stage is under preparation at LPSC Mahendragiri Facility (LMF). Assembly of cryogenic flight stage is in advanced stage of completion after successful completion of acceptance test and post test inspection of flight engine at LPSC Mahendragiri. To demonstrate cryogenic engine ignition under vacuum condition, preparation for the test in High Altitude Test (HAT) facility at LPSC Mahendragiri is progressing well. In parallel, assembly of GSLV-D5 at Vehicle assembly building of Second Launch Pad commenced on January 31, 2013 and the launch was targeted for June 2013.

The Indian Space Research Organization called off the much-awaited Aug 19, 2013 launch of GSLV-D5 after scientists detected a leak in the second stage liquid propellant tank. The mission was called off about an hour before the designated lift-off at 4.50pm on Monday. GSLV-D5, powered by an indigenous cryogenic engine, was to launch telecommunication satellite GSAT-14 from Sriharikota. The flight-test of GSLV with indigenous cryogenic engine was now expected to take place only in December,

The Geosynchronous Satellite Launch Vehicle GSLV-D5 was launched from the Satish Dhawan Space Centre in Sriharikota 05 January 2014. It included an indigenous cryogenic rocket stage. From January 2014, the vehicle achieved four consecutive successes.

On August 12, 2021, the launch of GISAT-1, an earth observations satellite onboard India's GSLV Mk 2 rocket had failed barely 350 seconds after its launch from India's spaceport. According to ISRO's initial analysis on launch day, it was caused due to "a technical anomaly in the cryogenic stage". However, the Indian space agency has now made public their Failure Analysis Committee(FAC) report and pinpointed the reason for the failure. The cryogenic stage refers to the final and third stage of the GSLV rocket and it is responsible for injecting the satellite into the desired orbit. As the name suggests, the cryogenic stage is powered by a cryogenic engine that burns Liquid Hydrogen(LH2) as fuel and Liquid Oxygen (Lox) as oxidizer. The combined burning of the two liquified(super-cooled) gases is among the most efficient methods of propelling a rocket engine. A multi-stage rocket essentially functions like a relay race, where each runner performs their task and hands over the task to the next runner, and eventually the final runner takes the baton to the finish. In this GSLV mission, while the first and second stage of the rocket performed their part and imparted necessary velocity to the launch vehicle, the third stage (Cryogenic) couldn't carry forth the work and impart the final velocity required, owing to the anomaly. "The FAC concluded that the lower LH2 tank pressure at the time of CUS(cryogenic upper stage) engine ignition, caused by the leakage of Vent & Relief Valve (VRV) resulted in the malfunctioning of the Fuel Booster Turbo Pump (FBTP) leading to mission abort command & subsequent failure of the mission. The most probable reason for the leakage of VRV valve is attributed to the damage in the soft seal that could have occurred during the valve operations or due to contamination and valve mounting stresses induced under cryogenic temperature conditions" read the statement from ISRO. The cryogenic stage of the GSLV rocket had two main tanks - one for storing Liquid Hydrogen (fuel) and another for Liquid Oxygen (oxidizer). In this mission, the leak from a component (Vent and relief Valve) connected to the hydrogen tank had eventually led to the failure.