By Express News Service

It’s been two decades of roller-coaster ride for India in mastering the critical but complex cryogenic technology. After Russians cancelled cryogenic technology transfer agreement in 1993, the Indian Space Research Organisation (ISRO) has now completed long duration stage test for 640 seconds earlier this month and is inching towards the historic launch of first developmental flight of GSLV Mk-III, the third generation launcher that has greater load carrying capability, on April 20.



Express spoke to S Ramakrishnan, who guided the ‘game changing’ project from cradle stage to adulthood. As its director, Ramakrishnan steered the GSLV Mk-III project during the crucial phase of design, engineering and realisation of first-off hardware for development test from 2002 to 2006. He also played a lead role in the formulation of Indian Human Spaceflight (HSP) project and completion of system concept reviews.

Excerpts from the interview

How motivated where you when you took charge as GSLV Mk-III project director, since cryogenic stage was coming from April 2010 failure?



GSLV Mk-III or LVM3 project began in 2002, and when I took charge as the first project director, indigenous cryo stage was yet to be realised. It was decided early on that the cryogenic upper stage would be fully indigenous.

All through the project, a deliberate decision was taken to avoid shortcuts such as clustering already indigenised cryo engine when a heavier thrust engine was required. Instead, a totally indigenous engine was built from scratch — CE20. The then chairman, G Madhavan Nair, was firm that we have to take this route to master the technology and become fully self-reliant.

Could you elaborate on the difficulties to undertake this, from drawing to design to fabrication of sub-systems?



This 20-tonne thrust engine (CE20) is not only bigger, but also adopts a different operating cycle. We did not have any engine design or drawings to refer to. We started from scratch, first drawing up the specifications and sizing the subsystems.

The engineering and fabrication drawings were all conceived in-house.We carried out well planned subsystem level tests to validate the components before attempting the integrated engine test, which required planning and commissioning of test facilities at ISRO Propulsion Complex (IPRC), Mahendragiri.

Some unique facilities were established for the cryo stage development. The recent accomplishment of integrating the cryo stage and carrying out ground qualification firing was a stupendous task. Realising a cryogenic turbo-pump fed rocket engine and stage is a most challenging area in the field of chemical rockets.

Why did it take 15 years for ISRO to develop desi cryogenic stage?

The failure of GSLV-D3 in 2010, where the first indigenous Cryogenic Upper Stage (CUS) was flight-tested, impacted the C25 stage programme due to the priority assigned for the additional investigation tests and added qualification tests demanded on CUS engine systems. Still the C25 Project crossed many milestones.



As the propulsive stages were being developed, the vehicle systems were also undergoing design finalisation. Being a new vehicle, several configuration changes and course corrections were part of maturing process in vehicle engineering area. Remember, development of a turbo-pump fed rocket engine of 20 tonne thrust is indeed a breakthrough accomplishment.

How difficult was it for ISRO to realise sub-scale cryo engine and later flight version after US pressured Russia not to transfer cryogenic tech to India?



Russia’s decision to cancel cryogenic technology transfer agreement motivated the ISRO to constitute the CUS development project in 1995 to sustain the GSLV operational flights after the Russian-supplied cryo stages were used up. It was extremely difficult because Russians stopped sharing information on further modifications they were carrying out in their cryo engine/stage, and flatly refused to give clarifications on specific critical elements. However, that paved way or forced us to launch our own fully indigenous cryo project. So, no regrets.

How crucial was the industry contribution?

The engine and cryo stage hardware were all fabricated at Indian industries. For this programme, indigenous materials and processes were adopted and industries contributed in establishing unique facilities at Mahendragiri for integrating and testing the new engine and stage.

About the key members and how you built the team in initial years

I took charge as the first project director of LVM3 programme in October 2002 from PSLV Continuation Programme, which I was steering till that time. I had very competent handpicked team with me, a mix of veterans and youth with proven record.

What future holds for GSLV Mk-III?

The GSLV Mk-III has the mandate to meet the requirement of deploying 4 tonne to the orbit. The avenues for further enhancement beyond 4 tonnes will definitely be explored once the vehicle stabilises after a few successful missions. However, without touching the lower propulsive stages and the overall vehicle architecture, the payload may not go beyond 5 tonne.

There are programmes ongoing to increase this to 6 tonnes. Mk-III is identified as the launcher for Indian Human Space Flight mission and as such the man rating of this vehicle is the immediate task to be addressed.