Aerospace 3D printing went Mach 5 this week, with Orbital ATK announcing that it has successfully tested a printed hypersonic engine combustor at NASA's Langley Research Center in Virginia. A key scramjet component, the 3D-printed combustor spent 20 days undergoing high-temperature hypersonic flight conditions as well as one of the longest duration propulsion wind tunnel tests for such a component.

The combustor was assembled at the company's Ronkonkoma, New York facility and the Allegany Ballistics Laboratory in Rocket Center, West Virginia using an additive manufacturing process known as Powder Bed Fusion (PBF). In this, a layer of metal alloy powder is laid down by the printer and a laser or electron beam fuses areas of it by following a digital pattern. As each layer is fused, a second is laid down until the process is completed. The excess powder is then removed and the component is smoothed and polished.

The company says that PBF printing is necessary because of the complex design of the combustor, which would otherwise require multiple parts and a much longer and expensive manufacturing process. Through this fabrication method, Orbital ATK says new and otherwise impractical features can be prototyped, and potentially tested quickly and cheaply.

The scramjet combustor is used to hold and maintain a stable combustion under volatile hypersonic conditions in a scramjet engine operating at speeds in excess of Mach 5 (3,800 mph, 6,125 km/h). The tests were used not only to observe how effective the 3D printing process was, but also to see if the finished product met mission objectives. Orbital ATK says that it met or exceeded all of the test requirements.

"Additive manufacturing opens up new possibilities for our designers and engineers," says Pat Nolan, Vice President and General Manager of Orbital ATK's Missile Products division of the Defense Systems Group. "This combustor is a great example of a component that was impossible to build just a few years ago. This successful test will encourage our engineers to continue to explore new designs and use these innovative tools to lower costs and decrease manufacturing time."