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Developing, maturing and advancing 3D printing, or additive manufacturing, technology for application within the aerospace industry has been underway at Aerojet Rocketdyne for more than 20 years. For use in the extreme environments of a rocket engine, there’s a whole lot more engineering that goes into producing a flight-qualified 3D printed part than just hitting the print button.

Equipped with some of the nation’s brightest engineers, Aerojet Rocketdyne is leveraging its industry leading 3D printing capabilities to design, test, qualify and deliver an affordable American-built AR1 rocket engine that will replace the Russian-built RD-180 by 2019.

One of the AR1 team members working hard to deliver the engine is AR1 Preburner Team Lead, Nate Scholten (pictured). For nearly two years, Scholten and his team have been fabricating the different elements of the AR1 preburner, a key component of staged combustion cycle rocket engines. With staged combustion, a share of the propellant is first combusted in a preburner and the resulting gases are then used to power the engine’s turbines and pumps before being consumed in the main combustion chamber. Use of 3D printing has been a key enabler to allow rapid design, fabrication and hot-fire test iterations to arrive at the best preburner element design.

“It is rewarding to be a part of the team that is using additive manufacturing technology to help the AR1 program make advancements in product development like we have never seen before,” said Scholten. “The beauty of 3D printing is that we have been able to go from completed design, to manufacturing to test of a single element injector in one month, and a subscale injector in just three months.”

Why is 3D printing so critical to the AR1 engine? It could take up to six months to produce a single element injector using traditional manufacturing processes, and more than a year to produce a full-scale preburner injector. A single element only has one injector, while the full-scale preburner has many injector elements. The end result is a significant reduction in development schedule and cost, and a significantly lower unit cost for the flight preburner. 3D printing will enable Aerojet Rocketdyne to deliver an affordable AR1 engine with the proven reliability needed to support critical NASA, DOD and Intelligence Community missions.

Within the last 18 months, Scholten and his team have conducted more than 150 hot fire tests on 18 single element injectors and four subscale injectors; all built using 3D printing, for the AR1 program at facilities in Sacramento, California; Marshall Space Flight Center in Alabama; and at Stennis Space Center in Mississippi.

Beyond testing the AR1 hardware, Nick Mule, Engineering Process and Tool Development lead for additive manufacturing, is leading a team focused on transitioning 3D printing technology from a development environment into a production environment that is focused on delivering flight-qualified hardware.

“3D manufacturing has matured significantly over the past few years,” said Mule. “It is exciting to be involved with a technology that is developing in such a fast paced environment. It’s not very often that a technology comes into the market that can make such a vast reduction in the cost associated with producing hardware for large scale liquid rocket engines.”

Mule’s work has affirmed his conviction that Aerojet Rocketdyne can meet the stringent technical and quality requirements demand by the National Security Space launch customer for AR1 hardware that is produced using 3D printing technology.

Mule holds a bachelor’s degree and a master’s degree in Mechanical Engineering from California Polytechnic State University in San Louis Obispo, California. He began his career at Aerojet Rocketdyne more than eight years ago working on the Space Shuttle Main Engine, RS-68 and J-2X programs.

Scholten holds a bachelor’s degree and master’s degree in Aerospace Engineering from the University of Michigan. He started at Aerojet Rocketdyne more than eight years ago and has done work for the company’s hypersonic, F-1, J-2X, CCtCap and Exoatmospheric Kill Vehicle programs.

Through Scholten’s and Mule’s leadership, Aerojet Rocketdyne is positioned to implement 3D printing on AR1 that meets the stringent requirements of the most demanding missions, and closing the business case required to deliver affordable, assured access to space. The results will be on display in the coming months at Stennis Space Center, building on testing that has already been conducted there.