Indian Startup Othisis Hot-Fires a 3D-Printed Cryogenic Rocket Engine

A Five-Kilonewton Engine Built by a Three-Person Student Team

A startup called Othisis has hot-fired a fully cryogenic, 3D-printed rocket engine delivering 5 kN of thrust. The test took place in Bangalore, and the engine now sits on the critical path for a reusable hopper rocket launch and landing trial later this year.

The engine uses regeneratively cooling, which is standard on orbital launchers but rare in student and startup programs. Liquid propellant circulates through tiny channels machined inside the combustion chamber wall before injection, pulling heat away from the metal and keeping the engine from melting itself during burn. That cooling geometry is difficult to make with conventional machining, which is why Othisis turned to additive manufacturing.

Copper Alloy, Printed Channels, and a 6-Kilogram Engine

The finished hardware weighs roughly 6 kg and is about the size of a large pineapple. It completed five clean, stable hot fires in a single day, including throttling runs, and reached a maximum thrust of 5.4 kilonewtons. That output is comparable to a small lunar lander engine.

The engine is printed in a copper alloy selected for thermal conductivity and its tolerance of high heat flux. Additive manufacturing lets the team embed the micro cooling channels directly in the chamber wall, a geometry that would be prohibitively expensive or impossible to drill by hand. The design reduces production time and cost while allowing the complex internal passages that regenerative cooling requires.

The hopper rocket this engine will power is meant to demonstrate vertical takeoff and vertical landing. Hopper systems are the stepping stone most reusable launchers use before scaling to full orbital vehicles. If Othisis can pull off a controlled landing later this year, it will mark a tangible milestone in India's private space sector.

Where It Fits in the Global Picture

Student and startup teams around the world are reaching the same threshold. A University of Melbourne team, supported by CSIRO's Lab 22, recently won the LOX bipropellant category at Race2Space with a 5.4 kN regeneratively cooled engine nicknamed Slinky. That engine was printed on a Nikon SLM Solutions system using a copper alloy, with CSIRO advising on material selection and post-processing.

The parallel is not accidental. Copper alloys remain difficult to process by laser powder bed fusion, and the teams that are pulling this off are the ones with access to industrial metal printers and national lab expertise. Othisis did not disclose which printer it used, but the technical result is the same: a startup in Bangalore is now competing with university teams that have national laboratory backing.

The honest test comes next. A hot-fire on a test stand proves the engine survives combustion. A reusable hopper flight proves the engine survives the thermal and mechanical shock of ascent, descent, and touchdown. Othisis plans to attempt that flight later in 2026.