LEAP 71
LEAP 71 is scaling its computational engineering approach to rocket design and manufacture with two large reference engines: a 200kN aerospike and a 2000kN bell-nozzle.
The company hopes to have conducted hot fire tests for the aerospike engine before 2027 and the bell-nozzle engine by 2029.
Having successfully validated its Noyron Large Computational Engineering Model through a series of hot fire tests - including a 5kN engine test that TCT attended last year - LEAP 71 is now looking to enhance Noyron's capacity in line with customer demand.
Noyron has been developed to enable the generation of manufacturable hardware directly from a consistent and physics-informed model framework, with LEAP 71 primarily using metal additive manufacturing technology to produce the computationally engineered parts.
The XRA-2E5 (200kN aerospike) and XRB-2E6 (2000kN bell-nozzle) reference engine development tracks will represent different nozzle architectures but are not entirely separate developments. Both will be developed using the same computational DNA within Noyron, and are considered 'distinct phenotypes' expressed from a shared set of physics models, engineering logic, and manufacturability constraints. This approach will allow LEAP 71 to explore, compare and validate multiple engine classes without duplicating the effort across 'fundamentally similar systems.'
"Our customers want larger engines," LEAP 71 co-founder Lin Kayser told TCT. "So we said, 'Okay, what do you actually have to do to create these larger engines?' It's a more sophisticated model because these engines are more complex in terms of their behaviour, but in a way, it's the same DNA. The practical side of things gets more complex, but the theoretical side is more or less the same. It's probably going to take a few more months to get there."
So far, LEAP 71 customers have only asked for 1000kN engines, but Kayser and co-founder Josefine Lissner see value in setting their sights beyond that current demand. The company is buoyed by the advancements in metal additive manufacturing, citing the increased size of build volumes, enhanced quality, and potential for costs to come down as a result of increased Chinese competition. All together, this will allow LEAP 71 to pursue 'extreme functional integration,' reducing part counts and eliminating many of the complexities of multi-part assemblies.
"I've been waiting for this for basically a decade," Kayser said.
So too have the customers LEAP 71 is partnering with. While LEAP 71 is to work on the reference engine projects independently, there will be significantly overlap with ongoing customer projects.
"The reference designs are for us internally. They're designs we work on independent of direct customer engagement," Kayser explained. "But, of course, they share the DNA with concrete customer projects and these concrete customer projects differ in various aspects from these reference designs. They use different propellants or they have different thrust levels or they use different engine cycles."
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Because of the nature of the Noyron computational model, LEAP 71 is going to be able to leverage learnings from the reference engines into customer projects, just as it has already done with the various hot fire test findings being fed back into Noyron. This will continue to be the case as LEAP 71 carries out for hot fire tests of smaller engines in the short term, with the company seeing it as an effective way to better ready Noyron for the development of larger engines without going through costly manufacturing and testing cycles. This will also mean that when the time comes, the design of the 2000kN bell-nozzle engine, for example, will harness years' worth of data and intelligence.
"It's a game-changer because it's never been done before," Kasyer said. "If you are targeting a two mega newton engine in four years, your CAD engineers will start drawing one today."
That won't be the case for the XRB-2E6 reference engine. LEAP 71 has set itself a target of carrying out a hot fire test of this engine - designed for the more complex full-flow staged combustion cycle -by 2029, with the smaller 200kN aerospike slated for a hot fire test within the next 18 months. The final design for both engines will be computationally produced as close to the test day as possible.
Both reference engines are envisioned as complete propulsion systems. They are not limited to combustion chambers and nozzles, but will include the turbomachinery required to power them. The Noyron computational model is targeting advanced engine cycles such as full-flow staged combustion and is said to already include much of the foundational physics required to support this. However, LEAP 71 recognises that fully realising such complex cycles will be a multi-step journey — one that will involve intermediate testing with simpler configurations like open gas generator cycles to validate critical aspects of the system along the way.
The company's next steps involve the development and testing of a 600 mm diameter injector head for XRB-2E6 and a nozzle requiring approximately 1.5 m diameter for sea-level operation, with the 'living DNA' of the computational model being refined as they go. LEAP 71 anticipates hundreds of tests, if not thousands, being carried out across the next four years, experimenting with various sizes and aspects of components, as well as different additive manufacturing systems, to test the limits of its approach.
Confidence is not in short supply at LEAP 71, however. The company believes its computational approach lends itself well to companies looking to scale the size of their engines quickly. Kayser suggests using traditional design approaches for this scale up is like 'starting from scratch', whereas all LEAP will have to do is 'focus on what is really different for a large engine.'
"[Typically,] you can't [just] scale up a blueprint of the old engine to a large one," he said. "You're basically sitting down and, of course, you've gained insights and experience, engineers are better than before, but it's a completely new development. It's not like you can generate a new engine and then only focus on the things that are significantly different for a larger engine. We hope to be able to do that.
"Our hope is that we can dramatically accelerate the convergence from smaller engines to larger engines using the same computation model because the production process is similar. It's just a larger printer, and hopefully by then the process is controllable enough that it doesn't give us completely different results, and the computation model in its base model is robust enough that all we have to do is focus on what is really different for a large engine."
