3D Printed hypersonic ramjet engines soar to new heights
Aerospace and defense giant Lockheed Martin, metal 3D printing specialist Velo3D, and aerospace part inspection company Vibrant have joined forces with the US Department of Defense’s (DoD) LIFT Institute in a groundbreaking initiative. These sophisticated engines, unlike their turbojet counterparts, have minimal moving parts but possess an incredibly intricate interior structure. They generate high pressure by forcing external air into the combustor using the aircraft’s forward speed. This compression occurs through a series of shockwaves and internal geometry, ultimately decelerating the air until it becomes subsonic within the combustion section.
To create these engines, the team employed Velo3D’s laser powder bed fusion (LPBF) technology. The components underwent Vibrant’s acoustics-based Process-Compensated Resonance Testing (PCRT), evaluating critical physical properties such as stress state, part integrity, geometry, and surface finish. The project has been deemed a success, with the team now shifting their focus to the next phase: examining the fatigue behavior of 3D printed components and moving towards producing “born-certified” parts. Dr. John Keogh, LIFT’s Engineering Director, expressed his satisfaction with the project’s outcome, highlighting the collaboration’s potential in certifying additive manufacturing (AM) components for mission-critical and safety-critical applications. This initiative aligns with the growing demand in the defense and aerospace sectors for propulsion systems capable of achieving supersonic and hypersonic flight speeds. 3D printing technology has proven instrumental in crafting these complex, single-piece engine designs more efficiently and economically than traditional methods. The LIFT Institute, the DoD is actively investing resources to determine whether these additively manufactured engines can withstand the extreme environmental conditions encountered during hypersonic flight. This particular ramjet project is participating in the “Hypersonic Challenge,” an initiative funded by the DoD’s Manufacturing Technology Program. The long-term objective of this challenge is to identify the most efficient materials and manufacturing processes for developing vehicles and missiles capable of hypersonic flight.
During the ramjet project, the team gathered extensive data during the LPBF 3D printing process, conducting experiments to interpret these data streams. The engine was 3D printed using Velo3D’s Sapphire 1 MZ LPBF 3D printer and Inconel 718 metal alloy. Velo3D’s technology, equipped with Intelligent Fusion and patented technology, eliminated the need for support materials during the 3D printing process. The team believes that with some minor adjustments, their ramjet engine could be converted into a scramjet, offering the potential for hypersonic velocities exceeding Mach 5. The team also 3D printed various material test parts, each serving a unique purpose in testing and evaluation. Vibrant’s PCRT process, using ultrasonic frequencies, played a pivotal role in assessing the printed components. This non-destructive testing approach provided insights into material state, mechanical properties, and manufacturing consistency. Dr. Keogh praised this approach for its ability to complement additive manufacturing effectively. It offers a rapid, volumetric solution without the need for destructive testing, providing valuable information about porosity, surface defects, geometry aberrations, and more.
The collaboration between Lockheed Martin, Velo3D, Vibrant, and the DoD’s LIFT Institute signifies a significant stride in the aerospace industry. Their successful exploration of 3D printing hypersonic ramjet engines not only addresses critical challenges in propulsion but also points toward a future where AM technologies play a pivotal role in developing advanced aerospace components. This innovative approach promises to revolutionize aerospace manufacturing, ushering in a new era of efficient and sustainable propulsion systems.