Rocket engines are normally developed in long iteration loops of sizing, design, manufacturing, and testing. LEAP 71 now reports having taken two very different methalox engines from requirements to a first hot-fire test in less than three weeks. Both units are designed for the 20 kN thrust class and burn cryogenic methane with liquid oxygen—a propellant pair typical for orbital launch vehicles.
The special aspect lies in how the geometries were created. The designs were generated entirely by the “Noyron Large Computational Engineering Model,” which translates requirements into a manufacturable design.
“Noyron is our ongoing attempt to comprehensively encode the process of engineering into a computational model that can operate independently of humans — radically compressing iteration times and making objects possible that were previously unfeasible. These physical tests — literally hot-firing the engines — generate crucial data that can only be obtained in the real world,” said Lin Kayser, Co-Founder of LEAP 71.
A classic engine with a bell nozzle and a full-scale aerospike were tested. The latter uses a toroidal combustion chamber and a central spike to “shape” the exhaust jet using ambient pressure. In testing, the aerospike reportedly reached the full chamber pressure of 50 bar, but due to issues during the start transients it could only be ignited once. The conventional engine, by contrast, ran in steady-state operation at nominal pressure and thrust and achieved more than 93% combustion efficiency in its first campaign.
“Methane is a complex propellant to model,” said Josefine Lissner, CEO of LEAP 71 and Principal Architect of Noyron. “Contrary to the kerosene fuel we tested in the past, it undergoes significant density changes under different temperatures and pressures. So Noyron’s predictions need to be spot on in order to produce working hardware. Also, the increased size of the engines comes with its own operational challenges.”
Both engines were manufactured fully additively from a high-temperature copper alloy (CuCrZr) by the German AM specialist Aconity3D.
Josefine Lissner said: “In the last 12 months we tested kerolox engines from 1.5 to 7.5 kN, using different materials and configurations. Noyron now delivers first-time-right rocket thrusters for kerosene and cryogenic liquid oxygen. We are confident that we are close to achieving the same for cryogenic methane. This test was an important step for us, validating that we can radically reduce the time for our customers to get to the launch pad with Noyron-generated engines.”
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