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

What They Built

Othisis, a startup based in Bengaluru, India, has moved from concept to hardware faster than most space companies manage. The team successfully hot-fired a 5 kN rocket engine that runs on cryogenic propellants. The entire engine was manufactured using selective laser melting, a powder bed fusion process that fuses metal layer by layer.

The engine produces a total impulse of 100 kNs. That number matters because it directly determines how much payload the engine can push to orbit or how effectively it can slow a vehicle down for landing. For a reusable hopper rocket, both numbers need to be credible. Othisis claims both are.

Why SLM Printing Matters Here

Traditional rocket engine manufacturing relies on milling, forging, and extensive assembly. Complex internal channels, regenerative cooling passages, and injector geometries often require dozens of parts welded together. SLM printing turns many of those parts into single pieces. The geometry Othisis printed would have been expensive and time-consuming to produce any other way.

SLM also lets the team iterate faster. If a combustion chamber geometry underperforms in testing, they can revise the CAD file and print a new version without retooling an entire production line. For a startup burning through budget and calendar months, that flexibility is worth more than the material cost savings.

The Reusable Hopper Plan

The test fire was not an end in itself. Othisis plans to use this engine to launch and land a reusable hopper rocket later in 2026. A hopper is essentially a suborbital vehicle that lifts off, performs a controlled ascent, and then returns to the launch pad. It is a proven stepping stone toward full reusability, and it requires an engine that can fire, shut down cleanly, and restart on command.

That last requirement is the hardest part. Cryogenic engines are temperamental. They need to handle extreme temperature swings without warping or losing seal integrity. A 3D-printed engine that survives multiple restarts under those conditions would prove that additive manufacturing is ready for prime time in orbital-class hardware.

What This Means for the Industry

3D-printed rocket engines are not new. Rocket Lab has flown its 3D-printed Rutherford engine for years. Blue Origin's BE-4 and SpaceX's Raptor both use additively manufactured components. What Othisis is showing is that a small team with limited resources can now build a flight-capable cryogenic engine from scratch, largely because metal 3D printing has dropped below the threshold where only governments and billion-dollar corporations can afford it.

If the hopper flight succeeds, expect more Indian and global startups to adopt similar SLM-based development cycles. The barrier to entry for serious propulsion work has just dropped again.