SkyRoot Aerospace has successfully conducted a significant test firing of its Dhawan-III cryogenic engine, marking a pivotal moment for India’s private space sector.

This power plant is specifically designed to propel the upper stage of the Vikram-II launch vehicle, which aims to provide cost-effective and reliable transport for small satellites into orbit. The successful test highlights the company’s growing technical maturity in handling the complexities of cryogenic propulsion.

The Dhawan-III engine operates on a combination of liquid natural gas (LNG) and liquid oxygen (LOX), a propellant choice that distinguishes it from more traditional rocket engines. LNG is predominantly composed of methane, making it a "cleaner" fuel option that reduces soot build-up within the engine components. This choice is not merely environmental; it simplifies the refurbishment process, making the technology more suitable for potential future reusability.

Dhawan-III was tested at level conditions and achieved an impressive 2.3kN of thrust and 2.8kN in vacuum. The engine fired for 145 seconds of continuous run and it proved stable combustion and efficiency.  This engine can shut-off and restart multiple times, a critical capability for SkyRoot's future reusable launch vehicles. Its fully 3D-Printed in Inconel, a superalloy that withstands extreme heat and pressure.

Cryogenic engines are notoriously difficult to develop because they require managing fuels at temperatures well below -150c. At these extremes, materials become brittle and standard lubricants fail, requiring bespoke engineering solutions for pumps and seals.

The Dhawan-III utilises advanced 3D-printing techniques to manufacture its core components, which significantly reduces the part count and lead times while maintaining the structural integrity needed to withstand high-pressure combustion.

During the test, the engine demonstrated stable combustion and met the targeted performance parameters for thrust and efficiency. These results provide the engineering team with the necessary data to proceed towards integrated stage testing. By mastering cryogenic technology, Skyroot is positioning itself to compete on the global stage, offering heavier payload capacities compared to its solid and liquid-fuelled predecessors.

Challenges in cryogenic technology remain formidable, including material selection for cryogenic compatibility, vibration management during start-up, and handling boil-off losses in propellants. 

SkyRoot overcame these through iterative testing and collaboration with domestic suppliers for high-strength alloys and advanced composites. The Bengaluru facility, equipped with state-of-the-art data acquisition systems, played a crucial role in real-time validation.

The transition from the previous Dhawan-II to this latest iteration involves improvements in thermal management and throttle control. As the private space race accelerates globally, the ability to domestically produce high-performance upper stages is essential for maintaining a competitive edge. This milestone reinforces the vision of a robust, privately-led aerospace ecosystem in India, supported by the country's evolving space policy.

SkyRoot X Handle