Indian space startup Agnikul Cosmo has been granted a patent for the design and manufacture of a single-piece 3D printed rocket engine

Recently, according to Mohou.com, Indian aerospace startup Agnikul Cosmo was granted a patent for the design and manufacture of a single3D-printedrocket engine. The engine consists of the five main components of a rocket engine and is produced as a single component in a single run. The advanced semi-cryogenic liquid propulsion engine can be manufactured in 96 hours and is designed to support the company's satellite launch vehicle called Agnibaan, but can also be used for satellites and other space exploration tools.

△AgnikulCosmos' single-piece 3D printed engine. Image courtesy of AgnikulCosmos

Under traditional manufacturing methods, a rocket engine has to be carefully assembled at least 100 times using techniques such as welding, which is demanding in terms of labor, equipment and cost. Like many space technology companies, Agnikul felt that assembling engine components using traditional processes would be tedious and cumbersome, so it identified the need for a single integrated propulsion engine that could be effectively optimized for space vehicle design and manufacturing using 3D printing technology. Based on these needs, the small Chennai-based rocket company filed a patent application for its 3D-printed engine in late 2020.

After two years, the Indian Patent Office issued a patent for the invention, which aims to provide a highly reliable, single-piece, lightweight integrated engine for space vehicles. According to Agnikul Cosmos, the engine includes a combustion chamber to burn fuel, an injection plate to inject fuel into the chamber, an igniter to ignite the fuel mixture, a nozzle to generate thrust through hot gases, and a cooling channel for regenerative cooling.

However, in the original documents published by the Office of the Superintendent of Patents, Designs and Trademarks, Agnikul did not specify whether the single-piece engine also included other subcomponents of the rocket motor. And while Agnikul's founders have been posting information about their latest milestone on social media, fellow space industry experts have asked whether the engine is indeed "fully" 3D printed, as the company claims. In particular, Tim Berry, head of manufacturing and supply chain at California space startup Launcher, asked in a post on Agnikul, "Are the tubes, valves, electronics, etc. all molded in one piece?"

He added, "If it's just the nozzle, chamber and injector, then "it's not a complete rocket motor and it's not a new discovery."

Berry may be alluding to the fact that other space startups have gone public with the manufacture of 3D-printed rocket engines in the past few years. Last April, for example, Launcher demonstrated the full thrust of its E-2 engine - which has a fully 3D-printed chamber - for the first time; RocketLab is also known to use 3D-printed engines, while rocket engine maker UrsaMajor is focused solely on developing 3D-printed rocket propulsion systems, and the UK-based startup Orbex even commissioned AMCM to build a high-volume 3D printer for the overall manufacture of its rocket engines. With so many companies turning to 3D printed rocket propulsion systems, and space agencies like NASA and the European Space Agency (ESA) advancing their own rocket engine technology through additive manufacturing, it looks like tough competition ahead.

Agnikul, however, is confident that it can offer a quick turnaround for its rocket engines because everything is 3D printed and shaped in a single pass. The startup, incubated at the Indian Institute of Technology Madras (IIT Madras) research park, has reached impressive goals thanks to its one-piece 3D printed rocket engine. Since 2019, the company says it has "automated" the engine making process, which involves zero components, and has tested its 3D-printed engine in 2021.

△ AgnikulCosmos' 3D printed rocket engine patent. Image courtesy of AgnikulCosmos.

Agnikul notes that by using laser powder bed fusion and advanced aerospace materials such as copper and its alloys, Inconel, Monel and titanium, all components of the engine can be integrated during the construction process.

With no bolts, screws or welds, the engine is very light (5 to 6 kg) compared to engines with similar thrust ratings, which can weigh up to 25 kg. Thus, by utilizing 3D printing, Agnikul believes this will help reduce the mass of the space vehicle, the cost of the launch vehicle, and even the cost of the mission. In addition, manufacturing the engine as a single piece helps to identify errors more easily than traditional multi-component assembled engines. As a result, qualification is easier and faster, as described by the startup in its patent specification section.

As has happened in almost every industry that utilizes additive manufacturing, volume production has become faster and the time required to assemble a multi-component part has decreased. In addition, Agnikul says that with less machining work and manual intervention, they managed to speed up the turnaround time for the manufacturing process to three days and qualify the engine for flight in less than a week. This faster turnaround time for engine manufacturing allows for a faster assembly process and ultimately helps increase launch frequency.

Commenting on this latest achievement, Agnikul co-founder and CEO Srinath Ravichandran said on social media, "When we started the journey of designing the engine, we had no idea how far 3D printing could help us. Now, after many successful launches, 3D printing simply seems to be the best option for rocket engine manufacturing. Incredibly, we have a team that developed this original design from scratch in-house, simulating every aspect of it, having it built to push metal sintering to its limits, and ultimately testing it multiple times."

Agnikul looks forward to test-launching its Agniban rocket by the end of 2022, which will carry a payload of about 100 kilograms into a 700-kilometer-high orbit for customers sometime next year. Meanwhile, the startup has partnered with 3D printing technology company EOS India to expand the potential of its 3D printed rockets and subsystems and has opened a new facility, Rocket Factory-1, to 3D print its rocket motors at scale and has set up EOS's 3D printer on site, enabling it to create the required hardware in-house.