ISRO Successfully Tests 3D-Printed Liquid Rocket Engine for 665 Seconds

On May 9, 2024, the Indian Space Research Organization (ISRO) successfully conducted a long-duration hot test of a 3D printed liquid rocket engine. The tested engine, known as PS4, is typically used in the fourth stage of the Polar Satellite Launch Vehicle (PSLV), one of ISRO’s main rockets.

The PSLV is used to send satellites into space. Since its first flight in 1993, it has completed many successful missions. It can carry satellites to different orbits, making it useful for various space projects. Now, with its 3D printed components, the PSLV is being modernized for the next generation of space missions.

Traditionally, the PS4 engine has been produced using conventional machining and welding techniques. However, by leveraging additive manufacturing (AM), ISRO has achieved considerable improvements in efficiency and sustainability.

For this project, ISRO chose laser powder bed fusion (LPBF), which allowed it to reduce the number of engine parts from 14 to a single piece, eliminating the need for 19 weld joints and cutting the production time by 60%. Accordingly, the raw material required per engine dropped dramatically from 565 kg (roughly 1245.56 pounds) of forgings and sheets to just 13.7 kilograms (30.20 pounds) of metal powder.

ISRO’s 3D printed PS4 engine. Image courtesy of ISRO.

ISRO’s Liquid Propulsion Systems Centre, or LPSC, was responsible for redesigning the engine to make it compatible with Design for AM (DfAM). After the redesign, Wipro 3D, a division of Wipro Infrastructure Engineering and an Indian leader in AM services, took over manufacturing. Wipro 3D uses advanced 3D printing machines from various leading brands to provide its services.

Wipro 3D expressed excitement over the 3D printed PS4 engine on social media, highlighting AM’s environmental and efficiency benefits, including saving 97% of raw materials and significantly reducing production time.

“ISRO recently achieved a milestone by successfully conducting a hot test of a 3D-printed liquid rocket engine, a key step in validating its performance and reliability. This progress emphasizes ISRO’s commitment to developing sustainable technologies that meet the stringent demands of future space missions,” highlights Wipro 3D on its LinkedIn account. “This accomplishment marks a giant leap forward in sustainable space exploration.”

The performance of the 3D printed PS4 engine during the long-duration test is shown in this graph. Image courtesy of ISRO.

Once the PS4 engine was ready, it underwent rigorous evaluation. The successful hot test, conducted at the ISRO Propulsion Complex in Mahendragiri, lasted 665 seconds, during which the engine’s performance was assessed. The PS4 engine operates using a bipropellant combination of Nitrogen Tetroxide as the oxidizer and Mono Methyl Hydrazine as fuel in a pressure-fed mode, where the propellants are pushed into the combustion chamber using pressure rather than pumps. Other space missions by NASA and the European Space Agency (ESA) have used similar bipropellant systems due to the reliable ignition and stable performance of this combination.

As shown in the graph above, titled “AM Engine Long Duration Development Hot Test,” the 3D printed PS4 engine shows stable performance throughout the 665-second test. Both the red and blue lines remain consistent, indicating stable thrust and chamber pressure. At the 665-second mark, there is a sudden drop in all parameters, indicating the end of the test. This stability in performance demonstrates the engine’s reliability over the test duration.

Before the long test, the injector head was built and tested, and ISRO performed detailed simulations to ensure its reliability. Four shorter tests totaling 74 seconds validated the engine’s performance, explains ISRO. However, the final 665-second test confirmed that the engine met all expectations.

ISRO plans to integrate this 3D printed PS4 engine into its regular PSLV program, proving the potential of using AM in specific applications within the space sector. This achievement also aligns with global trends in space exploration, where agencies and private companies are increasingly turning to AM to develop next-generation technologies, help make space exploration more viable, and democratize the sector.

This success builds on ISRO’s ongoing exploration of 3D printing for other components and applications. The organization has used 3D printing to manufacture satellite parts, enhancing efficiency and reducing launch costs. ISRO is also working on 3D printing components for other rocket engines, including cryogenic engines, which use super-cooled fuels. ISRO is investigating the potential use of 3D printing technologies for constructing habitats on the Moon or Mars, potentially using local materials to build necessary infrastructure for long-term missions. By adopting these techniques, ISRO aims to meet the stringent demands of future space missions.