Exclusive: India to buy Russia’s ‘RD-191’ semi-cryo rocket engines?

To enhance the lifting power of its spacefaring rockets, India is likely to purchase a limited number of Russian-origin Semi-cryogenic engines of the ‘RD-191’ variant, WION has learnt. If this deal goes ahead, this would mark the second time that India is purchasing spacefaring rocket engines from Russia. Back in the early 1990s, India purchased seven ‘KVD-1’ cryogenic engines from Russia. The ‘KVD-1’ engines were used in the upper stage of the early versions of India’s then heaviest rocket, GSLV.

This latest deal for rocket engines is likely to take shape as Russian President Vladimir Putin visits India on Thursday, (4th Dec), for a two-day State visit hosted by Prime Minister Narendra Modi. Back in April 2023, this author had reported on such negotiations regarding the ‘RD-191’ engine having been underway and the possibility of manufacturing technology being transferred to India.

Also Read: Exclusive: India-Russia discuss tech transfer, making of 'RD-191' semi-cryo rocket engine

On Wednesday, (3rd Dec), a day ahead of President Putin’s visit, Russian space agency Roscosmos’ Director General Dmitry Bakanov said that Russia is preparing to announce “good news about space sector cooperation with India”. He elaborated that the areas of cooperation would include rocket engines, human spaceflight (astronaut missions), and collaboration on the development of national space stations. However, he did not offer specific information.

In recent years, India-Russia space cooperation has been steadily growing. Four years ago, Russia provided astronaut training for India’s four ‘Gaganyaan’ astronaut candidates at Star City, near Moscow. When Indian astronauts undertake their space missions as part of Gaganyaan, they will be wearing the Russian Sokol KV2 suit manufactured by Zvezda, which the Indian candidates had familiarised themselves with during training in Russia.

About the ‘RD-191’ rocket engine

The ‘RD-191’ is a high-performance rocket engine fuelled by Kerosene and Liquid oxygen. It falls under the category semi-cryogenic, as its fuel rocket-grade Kerosene can be stored at room temperature; and the oxidizer liquid oxygen has to be stored at super-cooled cryogenic temperatures (below -150 degrees Centigrade). India’s existing rockets are powered by engines that burn: solid-fuel, liquid-fuel, and cryogenic fuel (where liquid hydrogen and liquid oxygen are stored at super-cooled temperatures). Though efforts have been underway to develop a semi-cryogenic engine dubbed ‘SE-2000’, India does not possess a flight-ready engine as of now.

Developed by NPO Energomash, the ‘RD-191’ is a workhorse engine used in Russia’s Angara series of rockets. ‘RD-191’ is also a throttleable engine, which means that it can significantly reduce or increase its thrust mid-flight, a crucial capability that enables precise flight control, recovery, and reuse of rocket stages. While Russia itself does not possess reusable/vertical landing rockets, ‘RD-191’ offers some of the basic capabilities required in that regard.

The RD-191 is approximately two-and-a-half times more powerful than ISRO’s workhorse Indo-French Vikas engine. While the Vikas engine delivers about 60-80 tonnes of thrust, the ‘RD-191’ is known to deliver between 200 and 220 tonnes of thrust. The Vikas engine is used in India’s PSLV, GSLV, and LVM3 rockets.

Why does India need the ‘RD-191’?

The Indian space agency ISRO’s largest and most powerful homegrown rocket LVM3 can lift only 4,000 kg to the Geosynchronous transfer orbit, which is a higher orbit into which communication satellites are launched. Likewise, the LVM3 is said to be capable of lifting around 8,000-10,000 kg to low earth orbit, which is about 500 km above the earth’s surface. India’s most powerful rocket LVM3 has a very modest lift capability when compared to its global peers operated by government-run space agencies or private firms.

India’s rocketry muscle power deficiency has been evident on multiple occasions. In recent years, despite having its own rockets, India has had to pay foreign entities like Europe’s Arianegroup and America’s SpaceX to launch heavy satellites built in India. This was done because the satellites weighed much more than 4,000 kg, which is the maximum lifting capability of India’s LVM3 rocket.

As India’s growing space ambitions include the Gaganyaan human spaceflight programme (astronaut mission), proposed Bharatiya Antariksh Station (Indian crewed space station), envisioned crewed moon landing, the country is in dire need of more rocketry muscle power. Designing and developing all-new rockets and rocket engines could take decades or longer, which is why India is looking to purchase the powerful ‘RD-191’ engine from Russia, WION has learnt.

How would India utilise the ‘RD-191’ engines?

While the Indian Space Research Organization (ISRO) wishes to design and develop powerful rockets for the future, India’s immediate priority is to enhance the lifting capability of the LVM3. To accomplish this, ISRO can use the Russian ‘RD-191’ engine and associated systems to replace the existing L110 or second stage of the three-stage LVM3 rocket. This is one step towards significantly enhancing the lifting power of the LVM3 rocket.

Also, the LVM3’s lifting power can be further bolstered by using a more powerful C32 Cryogenic upper stage developed in-house by ISRO. This would help ISRO to launch satellites heavier than 4,000 kg from home soil on its own rocket, while reducing dependence on foreign rockets.

In the foreseeable future, the LVM3 rocket powered by the Russian semi-cryogenic engine and the Indian C32 cryogenic engine could be used for various missions that were earlier not possible for ISRO due to the rocketry muscle power deficiency.

ISRO’s future rockets can be designed and developed based on the capabilities offered by the ‘RD-191’ engine. In heavy-lift rocketry, multiple engines are used in a cluster to deliver high amounts of lifting power. Therefore, a single rocket would require a dozen or more engines. In such cases, production of the engine in India under licence would be a necessity. Which is why India and Russia have also been exploring the possibility of making the ‘RD-191’ in India, in partnership with homegrown industry, WION has learnt.