The Russian-made ‘RD-191’ semi-cryogenic rocket engines are being transferred to Indian industry through the Department of Space of the Indian Government. With the help of this knowledge transfer, Indian businesses will be able to produce Russian-made rocket engines there.

This increases the likelihood that the made-in-India “RD-191” engines will be exported and used in India’s biggest rocket, the LVM3, to increase its payload carrying capacity. According to reports, India and Russia have been negotiating the sale of ‘RD-191’ engines for a very long time.

The ‘RD-191’ is a powerful rocket engine that runs on liquid oxygen and kerosene. It belongs to the semi-cryogenic category since its oxidizer, liquid oxygen, must be maintained at super-cold temperatures (below -150 degrees Celsius) while its fuel, kerosene, can be kept at ambient temperature.

India presently uses three different types of engines on its operational rockets: cryogenic (where liquid oxygen and hydrogen are stored at extremely low temperatures) and solid-fuelled.

Andrey Elchaninov, First Deputy Director General of the Russian Space Agency Roscosmos, was recently questioned regarding the potential sale of RD-191 engines to India in an interview with the Russian News Agency Interfax.

He had stated that Russia and India were talking about the specifics, features, and range of RD-191 engine supplies. The signing of a contract is something we expect to do soon. We do not halt our relationships with anyone, and we welcome all overseas clients, he added.

The Indian Space Agency ISRO is preparing for the first test of its homegrown semi-cryogenic engine, a 2000kN engine driven by kerosene and liquid oxygen, as negotiations for the Russian-origin semi-cryogenic engine are ongoing.

The ISRO Liquid Propulsion Systems Centre in Thiruvananthapuram is creating a semi-cryo engine known as SCE-2000. Although the engine is a stand-alone part, it eventually combines with fuel tanks and other parts to form what is known as a rocket stage. ‘SC-120’ is the name of ISRO’s semi-cryo stage. ISRO has created a kerosene-based fuel known as “ISROSENE” specifically for this engine.

ISRO stated that “the development of seven out of eight engine subsystems has been completed” in its most recent annual report. The engine’s intermediate configuration (the Power Head Test Article) has been realised, and all of the subsystems were produced by Indian businesses.

For the semi-cryogenic stage, one ISROSENE propellant tank and two sets of LOX propellant tanks have been realised through industry and successfully undertaken proof pressure testing. “We are preparing for the SCE-200’s first-ever test.” ISRO Chairman Dr. S. Somanath told WION.

Although the most effective cryogenic fuel combination is liquid hydrogen and liquid oxygen, storing liquid hydrogen in tanks is a very difficult and complex engineering achievement. Hydrogen gas is expensive to create and explosive by nature.

Kerosene for rockets is easier to handle because it can be kept at room temperature and can be kept in moderately sized tanks in big amounts due to its high density. Due to the low density of liquid hydrogen, enormous tanks are needed to store even a tiny amount of it, which expands the rocket stage’s size and mass.