LEAP 71 hot fires additively manufactured rocket engine designed without human intervention

June 24, 2024

June 24, 2024

LEAP 71 has successfully test fired a liquid rocket engine created entirely through Noyron, the company’s large computational engineering model (Courtesy LEAP71)
LEAP 71 has successfully test fired a liquid rocket engine created entirely through Noyron, the company’s large computational engineering model (Courtesy LEAP71)

LEAP 71, a developer of AI-based engineering technology based in Dubai, United Arab Emirates, has announced the successful test firing of an additively manufactured liquid rocket engine developed without human intervention by Noyron, the company’s Large Computational Engineering Model.

The rocket engine was additively manufactured in copper by AMCM GmbH, Starnberg, Germany. It was then post-processed at the University of Sheffield, UK, and prepared for the test. The hot fire was performed at Airborne Engineering in Wescott, UK, where the engine generated the expected 20,000 horsepower and completed all tests, including a long-duration burn.

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Josefine Lissner, aerospace engineer and Managing Director of LEAP71 said, “This is an important milestone for us, but also for the entire industry. We can now automatically create functional rocket thrusters and directly move to practical validation. From final specification to manufacturing, the design of this engine took less than two weeks. In traditional engineering, this would be a task of many months, or even years. Each new engine iteration takes only minutes. Innovation in space propulsion is hard, and costly. With our approach, we hope to make space more accessible for everyone.”

Lin Kayser, co-founder of LEAP 71, added, “Our company is at the forefront of the new field of computational engineering, where sophisticated machines can be designed without manual work. The paradigm significantly accelerates the pace of innovation for real-world objects. The fact that the Noyron thruster operated nominally on the first try, confirms that the approach is working. The method can be applied to any field of engineering.”

The Noyron RP thruster ready for testing (Courtesy LEAP71)
The Noyron RP thruster ready for testing (Courtesy LEAP71)

Development of the rocket thruster

The development of the Noyron TKL-5 rocket thruster is an internal LEAP71 project to showcase the capabilities of the Noyron large computational engineering model. The design phase of the thruster was said to have taken less than two weeks from final specification to send-off to manufacturing. The generation of new design variations takes less than fifteen minutes on a regular computer.

LEAP71 chose a thrust level of 5kN (equivalent to 500 kg/1120 lbs lift mass or 20,000 horsepower). This is a relatively compact engine suitable for the final kick stage of an orbital rocket. The thruster runs on cryogenic liquid oxygen (LOX) and kerosene, a combination that is used by many advanced rocket systems, including the SpaceX Falcon 9 and the Saturn V moon rocket. LEAP71 intentionally made that selection despite the propellants being more challenging to operate than others commonly used for small engines.

The engine was manufactured from copper (CuCrZr) using an EOS M290 Laser Beam Powder Bed Fusion (PBF-LB) Additive Manufacturing machine. Copper has a low melting point, but enables compact high-performance engines, when actively cooled. If cooling failed, it would melt immediately.

The additively manufactured heat exchanger (Courtesy LEAP71)
The additively manufactured heat exchanger (Courtesy LEAP71)

The engine uses thin cooling channels that swirl around the chamber jacket, with variable cross sections as thin as 0.8 mm. The kerosene is pressed through the channels to cool the engine and prevent it from melting. Both propellants are then injected into the combustion chamber. The combustion temperature inside the engine is around 3000ºC, whereas the engine surface stays to below 250ºC, because of the active cooling.

The propellants are injected into the engine using a coaxial swirl injector head. This injector type is considered the most advanced. Additional film cooling is provided by directing a portion of the fuel through tiny holes near the wall of the combustion chamber.

A multitude of measurement ports for temperature and pressure data enable information to flow back into the Noyron computational model.

The testing stage

The engine was hot fired for an initial 3.5 seconds using an oxidiser to fuel ratio of 1.8, which is lower than the nominal 2.3. By using less oxidiser, the engine burns slightly les shot. After confirming that the engine performed well and all temperatures were in the expected range, the engine was tested for a full 12 second long-duration burn at a nominal oxidiser-to-fuel ratio of 2.3.

The engine was said to have performed as expected. It achieved steady-state, which means it can essentially be operated as long as needed. The burn time was only limited by the fuel supply at the test site.

Following the tests, the engine was disassembled at the University of Sheffield the next day, and careful inspection confirmed that it remained fully intact. The thruster will stay in the UK for future tests. Initial analysis of the data shows that the pressure drop (the resistance) of the cooling channels was higher than modelled due to the build’s actual surface roughness. The team will post-smooth the existing engine while Noyron’s cooling channel logic has already been updated to improve predictions and the design for future engines.

LEAP 71 intends to use the data from the successful test to further advance Noyron. The company is reportedly working with leading aerospace companies in the US, Europe and Asia on the commercialisation of the resulting rocket engines.


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June 24, 2024

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