Skyroot's Fully 3D-Printed Dhawan-III Methalox Engine Passes 145-Second Hot-Fire Test

Skyroot Aerospace successfully hot-fired its fully 3D-printed Dhawan-III methalox engine for a continuous 145-second run, producing 2.3 kilonewtons of thrust at sea level and 2.8 kilonewtons in vacuum. Indian Defence News reported that "Dhawan-III was tested at level conditions and achieved an impressive 2.3kN of thrust and 2.8kN in vacuum," and that "the engine fired for 145 seconds of continuous run and it proved stable combustion and efficiency."

The engine is built entirely with metal additive manufacturing in Inconel, a superalloy chosen "to withstand extreme heat and pressure." India Today described the hardware as "Fully 3D-printed from Inconel … designed for multiple restarts" and noted the test was conducted on an "in-house mobile stand." Skyroot and press images show the combustion plume with vivid electric-blue color and clear shock diamonds; an original report described the firing as "showcasing perfect combustion with electric blue flames and Mach diamonds. The test highlights rapid progress in private Indian space tech using advanced AM. CEO shared stunning visuals of the per"

Dhawan-III demonstrated shut-off and multi-restart capability, a functionality flagged by Indian Defence News as "a critical capability for SkyRoot's future reusable launch vehicles." The company and press accounts frame the restart ability as essential for reusable upper stages and precision orbital insertion. Indian Defence News added that "During the test, the engine demonstrated stable combustion and met the targeted performance parameters for thrust and efficiency."

Dhawan-III joins a family of cryogenic engines named for Dr. Satish Dhawan. Earlier iterations include Dhawan-I, a 1.0 kN engine, and Dhawan-II, which underwent a 200-second endurance firing and delivered roughly 3.5 kN vacuum thrust in tests on 31 March 2023 at Solar Industries' propulsion test facility in Nagpur using an indigenously developed mobile cryogenic engine test pad. The Dhawan series uses methane-family fuels and liquid oxygen; YouTube and published program notes for Dhawan-II specify LNG as more than 90 percent methane, and India Today and Indian Defence News classify Dhawan-III as a methalox engine using liquefied natural gas or methane plus liquid oxygen.

Industry observers and program notes underscore the technical hurdles Skyroot addressed: cryogenic propellants require handling below -150°C where materials can become brittle and standard lubricants fail, and pumps and seals require bespoke engineering. Sources note metal 3D-printing reduces part count and lead times while maintaining the structural integrity needed for high-pressure combustion.

Skyroot built Dhawan-III with support under the Aatmanirbhar Bharat ARISE-ANIC initiative by NITI Aayog, and Indian Defence News concluded that "These results provide the engineering team with the necessary data to proceed towards integrated stage testing." The firm now has thrust, duration, restart and materials data to feed into the next phase of integrated stage qualification.