3D-printed, semi-cryogenic Agnibaan rocket takes Indian space sector to new heights

Agnikul Cosmos, the IIT Madras-incubated start-up, launched the world’s first rocket with a single-piece 3D printed engine from Sriharikota at 7:15 am on Thursday. This remarkable feat has been achieved entirely through indigenous design and development. 

This Chennai-based space startup successfully conducted a sub-orbital test flight of its 3D-printed semi-cryogenic rocket, Agnibaan. The launch took place from its launch pad at Sriharikota, making Agnikul Cosmos the second private company in India to achieve this. The private company that first accomplished this was Skyroot Aerospace, which launched the Vikram S in November 2022. 

Interestingly this success came after multiple failed attempts. The test flight this morning was conducted without any live streaming and with fewer dignitaries present at the Sriharikota launch pad, which is located within ISRO’s Satish Dhawan Space Centre. ISRO announced in its post on  X: “Congratulations to Agnikul Cosmos on the successful launch of the Agnibaan SubOrbital Technological Demonstrator (SoRTed-01) mission from their launch pad. This is a major achievement as it marks the first controlled flight of a semi-cryogenic liquid engine made using 3D printing”. 

“Sub-orbital means a flight path that goes into space but doesn’t complete an orbit around Earth. The vehicle reaches space, typically above 100 kilometres, and then returns without circling the planet. 

The single-stage rocket, powered by the semi-cryogenic Agnilet engine, serves as a precursor (or prototype) to the  Agnibaan launch. Agnibaan is a two-stage launch vehicle designed to be highly customisable and capable of carrying a 300 kg payload to a 700 km orbit,” explained Space expert Girish Linganna. 

The Agnilet engine is the world’s first semi-cryogenic rocket engine that uses sub-cooled liquid oxygen. Developed locally, it is made from a single piece using 3D printing to power a launch vehicle. This engine runs on sub-cooled Liquid Oxygen (LOX) and Aviation Turbine Fuel (ATF). Additionally, the vehicle is equipped with four carbon composite fins that provide passive control. 

“Single piece using 3D printing means that the entire part was made as one continuous piece using a 3D printer, rather than being assembled from multiple parts. 3D printing is a process where a machine creates objects layer by layer from a digital model, using materials like plastic or metal. This method can make the part stronger and more reliable,” added Linganna. 

A semi-cryogenic engine uses liquid oxygen (which is very cold)  and regular fuel, like kerosene or ATF, while a cryogenic engine uses both liquid oxygen and liquid hydrogen, both of which are extremely cold. The main difference is that semi-cryogenic engines use less cold fuel, making them simpler and cheaper to handle and store compared to cryogenic engines. 

“Cryogenic engines are generally more powerful because liquid hydrogen provides a higher specific impulse, meaning more thrust per unit of fuel, making them more efficient for long-distance missions or heavier payloads. Semi-cryogenic engines are often used in the initial stages of a rocket for their cost-effectiveness and simpler handling, whereas cryogenic engines are used in the later stages for their higher efficiency and greater power needed to place satellites into higher orbits or for deep space missions. Semi-cryogenic engine technology has not yet been demonstrated by the Indian Space Research Organisation (ISRO) in any of its rockets,” remarked Linganna. 

This startup has prepared the vehicle with the first-ever ethernet-based avionics system and autopilot software fully developed in-house in India. Ethernet technology refers to a common system used for connecting computers and devices in a network, allowing them to communicate with each other quickly and reliably. In the context of a vehicle, it means using this technology to connect and control various onboard systems. 

“The Department of Space and ISRO congratulates Agnikul Cosmos on the successful launch of ‘Agnibaan  – SOrTeD’. The success involving many firsts including 3D-printed semi-cryogenic engine, flight control systems etc. demonstrates the prowess of indigenous design and innovation. It motivates ISRO  to support the Space startups and Non-governmental entities for innovation and Atmanirbharata to create a vibrant space ecosystem in the country,” remarked  ISRO Chairman S Somanath. 

Srinath Ravichandran, co-founder and CEO, Agnikul Cosmos, said that the successful launch was the culmination of 1000s of hours of reviews and hard work by the team. “We are blessed to have had the opportunity and the full support of  IN-SPACe and ISRO to design and build original space-worthy hardware in India,” remarked Ravichandran. 

Pawan Goenka, chairman of IN-SPACe, lauded the efforts of Agnikul Cosmos. “It marks a significant moment for private players who are contributing to growing India’s space sector. Today it is the power of young innovators and entrepreneurs who are leading from the front, innovating with cutting-edge technology such as the world’s first 3D-printed semi-cryogenic engine, that is driving the transformation of  India’s space sector. At IN-SPACe, we are committed to support these young pioneers as they help to propel India to a leadership position in the global space arena,” remarked Goenka. 

The Agnikul Cosmos team consists of over 200 engineers and is associated with NCCRD at IIT Madras. Additionally, the team is guided by  45 former scientists from ISRO who bring invaluable expertise to the endeavour of democratising access to space.