India: Development and testing of the cryogenic stage intended for the upper stage of GSLV rockets has been completed

This is an important achievement for the Indian space industry that will increase its independence in space launches

The Indian space agency ISRO reported at the end of the week the successful completion of a significant step in its independent development program. It is about the development and testing of the cryogenic stage that should form part of the upper stage of its launch rockets called GSLV - Geosynchronous Satellite Launch Vehicle. Yesterday, an experiment was successfully carried out in the cryogenic phase which lasted 720 seconds and which took place at the Liquid Propulsion facility in Mahendragiri in the state of Tamil Nadu in South East India. With the successful completion of the experiment, the cryogenic phase was declared operational, and preparations are now beginning for the next launch using GSLV, which is planned for next year.

The cryogenic upper stage known as CUS is driven by a cooled cryogenic engine that operates on a combustion cycle and produces a thrust of 69.5 kN in a vacuum. Other systems at this stage include insulated tanks for the propellant, increased pumps, filling and draining systems, pressure systems, gas tanks, control units, spark plugs, combustion valves and cold gas based stabilization and positioning systems. Liquid oxygen and liquid nitrogen are fed from the tanks in which they are stored through individual elevated tankers to the main turbo pump that rotates at a speed of 39,000 revolutions per minute in order to ensure a flow at a rate of 16.5 kg per second of propellant materials to the combustion chamber. The turbine is primarily driven by hot gas produced in the pre-burner. Thrust control and mixture control are achieved through two independent steering mechanisms. Liquid oxygen and gaseous nitrogen are ignited by figurative igniters in the pre-burner as well as in the main engine and the steering engines.

Apart from the complexity of manufacturing the tanks of this stage, the engines, the subsystems and the control units, the CUS includes materials such as aluminum, titanium, nickel and other alloys, bimetallic materials and polyimides (polymers with extremely high resistance to chemical substances and high temperatures).