Computational engineering Algorithm Autonomously Designs 20-Ton Rocket Engine

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LEAP 71, a pioneer in the field of computational engineering, and HBD, a manufacturer of large-format metal 3D printers, have developed and manufactured one of the most complex aerospace propulsion systems in the world—and did so without traditional CAD, instead using an autonomous algorithm.

The engine designated XRA-2E5 was developed with the help of Noyron, LEAP 71’s large “computational engineering” model. Put simply, it is a design AI that calculates complex 3D geometries not through manual modeling, but purely algorithmically based on physical requirements and manufacturing rules. The software uses these principles to generate functional designs completely autonomously and without human intervention. 

“Aerospikes are often considered the Holy Grail of space propulsion,” explains Josefine Lissner, CEO of LEAP 71 and chief architect of Noyron. “They promise major performance advantages over conventional engines, but their complex geometry has made design, manufacturing, and operation extremely difficult in the past. By combining computational engineering with advanced additive manufacturing, we can finally get them flying.”

The new engine shares its development DNA with two earlier Aerospike engines generated by Noyron, which LEAP 71 has already subjected to hot-fire tests over the past 15 months. The current 200 kN design is reportedly the largest 3D-printed Aerospike ever produced and is specifically suited for the upper stages of large reusable launch vehicles.

The constructive challenge: “inside-out” architecture

Aerospike engines use an annular (toroidal) combustion chamber and a central spike. To cope with the enormous thermal loads from the combustion gases, the XRA-2E5 employs a complex regenerative cooling strategy that, thanks to software design and 3D printing, has been integrated directly into the structure. Unlike conventional engines with bell-shaped nozzles, aerospikes maintain high efficiency from sea level to vacuum. This makes them particularly attractive for fully reusable next-generation launch systems in which the booster and upper stage return to Earth. This requires propulsion systems that operate efficiently in all atmospheric layers and can be deeply throttled (deep throttling).

Manufacturing at the limit of what is feasible

HBD printed the monolithic engine in one piece in a record time of 289 hours. “Just a year ago it would have been impossible to manufacture such an engine at this scale,” emphasises Kevin Chen, Marketing Director at HBD. “The physics-driven geometry of the aerospike, with shallow overhangs and highly complex internal structures, pushes even advanced metal printing processes to their limits. The fact that the engine could be produced successfully on the very first print attempt demonstrates the stability and precision of our large-format additive manufacturing platform.”

The close collaboration between the two companies ensured that Noyron’s algorithmic design strategy was optimally aligned with the manufacturing capabilities of the HBD system. The result is a fully integrated monolithic engine, printed from the Inconel 718 alloy. The XRA-2E5 marks an important milestone in validating manufacturing within LEAP 71’s multi-year propulsion development project with Aspire Space for the fully reusable Oryx spacecraft, and now provides the hardware needed to move into the qualification phase with hot-fire testing.

About HBD
HBD (Shanghai Hanbang United 3D Tech Co., Ltd.) is a leading Chinese manufacturer of industrial metal 3D printers (LPBF technology) headquartered in Shanghai. Founded in 2007, the company has already installed more than 1,000 systems worldwide. Its portfolio ranges from small platforms to large-format multi-laser systems for industries such as aerospace, automotive, medical technology, and robotics.
 

About LEAP 71
LEAP 71 (Dubai, UAE), founded in 2023 by aerospace engineer Josefine Lissner and serial entrepreneur Lin Kayser, is a pioneer in the field of computational engineering. At the heart of the company is Noyron—an algorithmic software model that designs physical components such as spacecraft propulsion systems fully autonomously and without human intervention. This software generates finished designs in a matter of minutes, optimally tailored to modern manufacturing processes such as industrial 3D printing.