3D Printing and Coatings Help Rocket Engineers to Reach for The Stars

Don’t call the founders of LENA Space rocket scientists, even though they technically are. Instead, call them rocket engineers.

The company develops space technology with the ultimate goal of end-to-end rocket propulsion systems for launch vehicles that could bring satellites or other payloads into orbit. Co-founders CEO Edward Fletcher and CTO Lee Giles consider themselves engineers with a focus on space.

Rather than moving directly from theory to a final product, the LENA team develops initial concepts based on the science. Then it moves into engineering.

“It’s often better to apply the theories to a certain point, run an experiment to test, then move on incrementally from there,” said Fletcher. Such development, with new rounds building on what was learned in previous ones, lets LENA’s team keep improving their results. And with help from multiple divisions of Oerlikon, the company has efficiently and economically moved forward.

Following a successful research and development grant application for funding with the UK Space Agency, the team started work on key propulsion hardware. The technology is also expected to have spin-off uses in energy, environment and transportation applications on Earth.

In 2017, the team first focused on developing what is known as a turbopump, which is like the fuel pump of a car. LENA is also considering two potential proof-of-concept terrestrial applications: improved pumping performance on existing firefighting trucks and lightweight high-performance pumps for flood control.

From supercars to rocket engines
Fletcher and Giles met as part of a land-speed record project developing a rocket-powered supersonic car. “We founded LENA Space after a discussion about developing rocket propulsion hardware outside the USA,” Giles said.

The entire LENA staff comes from an engineering background in rapid — and unusual — forms of transportation. Fletcher worked on jetpacks in New Zealand and hybrid airships in the U.K. Giles worked in automotive research and development (R&D), including concepts to eventually be included in supercar projects from McLaren Automotive. Many of the other team members came out of the race car industry.

The engineers at LENA face some interesting challenges in their current work. A turbopump pulls propellant from storage tanks and delivers the fuel to the rocket motor. But the conditions it faces are far more difficult. Designed to support a 13-tonne (28,660-pound) thrust engine, the turbopump has to move 60 kilograms (132 pounds) of propellant per second under a crushing pressure of 1,015 pounds per square inch, which is like being more than 700 meters (2,300 feet) under water.

The turbine portion has to spin nearly 20,000 revolutions-per-minute, or about three times a normal car engine. The turbopump must also bear up under extraordinary temperature differences of thousands of degrees between the liquid fuel and burning gases.

Finding the balance between performance and costs
The company’s iterative design-test-improve approach offers distinct advantages for moving toward optimized products. But it creates its own challenges. Building multiple prototypes can get expensive, especially when the subject is the turbopump, commonly counted as half the development cost of an entire rocket engine.

LENA needed to control costs during the iterative design process while providing the strength, resilience, and endurance to meet performance requirements. Oerlikon was able to help in rapid prototype construction and materials selection through Oerlikon AM, the division for additive manufacturing, more popularly known as 3D printing. In addition, Oerlikon Metco provided high-end thermal barrier coatings (TBC) for the parts.

One of LENA’s newest developments is regenerative rocket nozzles. Cold liquid propellant flows through a cooling jacket around the outside of the engine, in the process controlling temperature before the fuel burns and comes out through the inside of the nozzle at temperatures surpassing those of a blast furnace. Historically, the cooling channels that initially carry the propellant would be pipe, either brazed or welded to the exterior of the nozzle. The traditional approach adds weight and makes for a complicated and more expensive manufacturing process.

“With additive manufacturing, it is possible to create the complex geometry of the cooling channels far more easily,” Fletcher said. “It’s also possible to simplify the design and reduce costs. Instead of a series of parts assembled with seals and bolts, we can produce the unit as a single piece,” Giles added. Fewer parts also mean lighter products, fewer potential points of failure for improved reliability, and improved performance.

Oerlikon provided the prototyping services using its in-house equipment. More importantly, the company’s deep expertise in materials science helped it develop the mix of alloys that will provide the necessary strength and heat characteristics.

But those alloys still face tremendous heat. To bear up under temperatures that exceed what you’d find in blast furnaces, Oerlikon Metco and Oerlikon Balzers surface coatings gave critical added resistance and endurance.

Collaboration for disruptive innovation
Fletcher and Giles both knew Dan Johns, Chief Technology Officer at Oerlikon AM, through mutual work on the supersonic car project. “Dan introduced us to the capacities of additive manufacturing, including how and when to exploit AM techniques,” Fletcher said. “We’ve been really impressed with the range of skills of Oerlikon.”

In addition, Oerlikon’s expertise helped speed development, and the ability to get materials and manufacturing simplified LENA’s supply chain. “We were able to stick to our strengths at LENA and allow Oerlikon to stick to theirs,” Giles said.

“Working with LENA Space gives us the opportunity to solve extremely hard technical challenges by bringing together Oerlikon AM, Oerlikon Metco, and Oerlikon Balzers,” Johns said. “The three brands work together to accelerate innovation. We learn faster and inspire each other to think in new different ways. It is also a fantastic example of how our concept of ‘Open Collaboration’ really works to break down conventional thinking. I haven’t heard anyone say, ‘We’ve tried that before and it didn’t work’. To welcome disruptive innovation is one challenge. Achieving it is another. This collaboration shows we can accomplish both.”

As far as the future goes, it’s not sky-high, but space-high.

Source: oerlikon