Bangalore-based Othisis has achieved a major milestone by successfully hot-firing its regeneratively cooled, fully cryogenic, 3D-printed rocket engine delivering 5 kN thrust.

This breakthrough positions the start-up at the forefront of India’s private space sector, with the engine designed to power a reusable vertical take-off and landing rocket for small- to medium-sized satellite launches.

The cryogenic engine runs on liquid oxygen and methane, propellants known for their efficiency and cleaner combustion compared to traditional fuels. The design incorporates regenerative cooling, where propellant flows through channels around the combustion chamber, absorbing heat before injection. 

This prevents thermal damage to the chamber walls and ensures sustained performance during long-duration burns.

The engine was fully 3D-printed at Othisis’s Whitefield facility in Bangalore. Additive manufacturing allowed the integration of complex cooling channels directly into the chamber walls, reducing assembly complexity and improving reliability.

The modular pintle injector architecture enables adaptability, allowing thrust levels to be changed by swapping a single component, making the platform versatile for different mission requirements.

The hot-fire test delivered a nominal thrust of 5 kN at a chamber pressure of 35 bar, with a total impulse of 100 kN·s. The team conducted over 20 test cycles, including three failed ignition attempts, before achieving a successful sustained burn. This rigorous testing validated the robustness of the design and the reliability of the control and data acquisition systems developed in-house.

Building the test facility itself was a remarkable achievement. Othisis established the infrastructure from an empty plot of land in just three months, including the propellant feed system, cryogenic-rated valves, and custom electronics. Water-flow and cold-flow tests preceded ignition, ensuring system integrity before live firing.

The reusable rocket program aims to provide domestic launch options for smallsat and mediumsat customers, reducing reliance on ISRO’s limited slots or foreign providers. By focusing on reusability, Othisis aligns with global industry trends pioneered by companies like SpaceX, aiming to lower launch costs and increase mission frequency.

Cryogenic propulsion offers significant advantages for reusability. Methane and liquid oxygen produce cleaner combustion, reducing soot and thermal stress, which enhances engine longevity. This makes the technology ideal for vertical take-off and landing rockets, where engines must withstand repeated cycles of ignition and shutdown.

India’s private space sector has seen rapid growth, with startups such as Skyroot, Agnikul, and Bellatrix pushing boundaries in propulsion and launch systems.

Othisis’s achievement adds momentum to this ecosystem, positioning Bangalore as a hub of advanced space innovation.

The successful hot-fire test demonstrates that Indian startups can build world-class cryogenic propulsion systems within tight timelines and limited resources.

The upcoming flight of Othisis’s reusable hopper rocket later this year will be a crucial demonstration. If successful, it will validate the company’s technology and open pathways to scaling up for orbital-class vehicles capable of commercial satellite launches and potentially deep-space missions.

Agencies