Indian Startup 3D Prints Rocket Engine in Just 72 Hours

Agnikul’s successful launch is a step toward “on-demand” rocket launches

A rocket featuring the world’s first rocket engine 3D printed as a single piece blasted off from India’s east coast in late May. Startup Agnikul fabricated the engine in just 72 hours and hopes the approach could open the door to “on-demand” rocket launches for operators of small satellites.

The Chennai-based company isn’t the only private space operation to rely heavily on 3D printing—both Relativity Space and Rocket Lab use the approach extensively to build their launch vehicles. What sets Agnikul apart is that its engine is printed in one go, rather than as multiple components that have to then be stitched together, which significantly speeds up manufacturing time.

On 30 May, the company carried out its first suborbital launch powered by the engine. A single-stage rocket lifted off from the Indian Space Research Organisation’s Satish Dhawan Space Center on Sriharikota island in Andhra Pradesh, reaching an altitude of 6.5 kilometers before splashing down into the ocean.

 “It performed very successfully,” says cofounder and chief operating officer Moin SPM. “It met all the objectives of the mission so we have a lot of confidence in the technologies that we have built.”

The company’s first commercial product will be a two-stage rocket called Agnibaan, which will be 18 meters tall, feature eight engines in total and able to carry a 300-kilogram payload to an altitude of around 700 km. The launch vehicle used in May’s test was only 6 meters tall and featured just a single engine, making it roughly equivalent to Agnibaan’s second stage.

The launch acted as a technology demonstrator to test out all of the key subsystems necessary for an orbital launch. Those included the flight computer, avionics, guidance, and navigation systems, as well as the launchpad itself, which was purpose-built for the mission.

The team hit its target of 6 kilonewtons of thrust and was able to successfully carry out a wind-biasing maneuver, in which the rockets trajectory is adjusted midflight to account for the affects of wind. Besides validating the technology, SPM says they gained valuable experience in both manufacturing processes and launch operations.

This 3D-printed rocket engine was used in Agnikul’s first successful launch.  Agnikul

The launch also vindicated the company’s unconventional manufacturing approach. Constructing a rocket engine using conventional approaches can take months, followed by extensive qualification testing to ensure it meets the required specifications. Using a metal 3D printer from German company EOS, Agnikul produced its engine in roughly three days. Agnikul printed the engine out of inconel, a high-performance alloy of nickel and chromium that can withstand high temperatures and mechanical loads. The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification.

Assembling the rest of the rocket and integrating the engine took roughly two weeks. The company says that opens the door to providing low-cost, “on-demand” launch services to operators of small satellites, which otherwise need to wait for a ride share on a bigger rocket.

The big challenge now will be going from a single engine to a cluster of seven on Agnibaan’s first stage, says cofounder and CEO Srinath Ravichandran. This raises all kinds of challenges, from balancing thrust across the engines at lift-off to managing engine plume interactions when the engines gimbal to alter the trajectory. “But these are problems that people have figured out,” he says. “We believe that we should just be able to fine-tune it for our mission and go.”

The company is currently building facilities to carry out ground tests of engine clusters, says Ravichandran, and is targeting its first orbital launch for this time next year.

Source