Multiple NASA centers have partnered with Virgin Orbit to develop and to test a 3D printed combustion chamber.

Virgin Orbit air launches rockets carrying small satellites to space. The company partnered with NASA experts in combustion and additive manufacturing (3D printing) at NASA’s Marshall Space Flight Center in Huntsville, Alabama; Glenn Research Center in Cleveland; and Armstrong Flight Research Center in Edwards, California. The goal: to create a 3D printed combustion chamber that combines multiple materials and takes advantage of advanced manufacturing processes.

A 3D-printed rocket engine combustion chamber awaiting hot-fire testing at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Credits: NASA/Virgin Orbit

Traditionally, it takes many months to manufacture, test and deliver a conventional combustion chamber. We can reduce that time considerably. Additive manufacturing is primed to augment and enhance traditional processes. It provides new design and performance opportunities and yields a highly durable piece of hardware—and with this partnership, we’re advancing that capability even further.

—NASA senior engineer Paul Gradl, who leads the joint project at Marshall

The effort incorporates a proven NASA additive copper alloy—GRCop-84—which was developed at Marshall and Glenn in 2014 to successfully print and test the first full-scale 3D printed copper rocket engine part.

GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) is a new high-temperature copper-based alloy that possesses excellent high-temperature strength, creep resistance and low-cycle fatigue up to 700 ˚C (1292 ˚F) along with low thermal expansion and good conductivity.

GRCop-84 can also be processed and joined by a variety of methods including extrusion, rolling, bending, stamping, brazing, friction stir welding, and electron beam welding. Considerable mechanical property data has been generated for as-produced material and following simulated braze cycles. The data shows that the alloy is extremely stable during thermal exposures.

To strengthen this new engine thrust chamber further, Virgin Orbit used its own hybrid additive/subtractive machine to apply a second bimetallic super-alloy jacket and precisely machine the part.

Engineers test-fire a 3D-printed rocket engine combustion chamber at NASA’s Marshall Space Flight Center in Huntsville, Alabama. NASA is partnering with Virgin Orbit of Long Beach, California, to deliver advanced engine hardware that employs NASA and commercial additive manufacturing processes. Researchers will continue to explore advanced 3D-printing solutions, introducing even higher-performing alloys and further refining the printing process. Credits: NASA/Virgin Orbit

In late 2018 and early 2019, Marshall, in consultation with Glenn and Virgin Orbit engineers, tested the combustion chamber using high-pressure liquid oxygen/kerosene propellants. The test article delivered more than 2,000 pounds of thrust successfully in nearly two-dozen, 60-second test firings.

The combination of multiple optimized materials and additive manufacturing technologies we’ve employed represents a significant advancement from the compromises typically made in the production of 3D printed rocket engine combustion chambers.

Information gained from our partnership with NASA will be key in applying these technologies to further improve cost, performance and lead time of Virgin Orbit’s propulsion systems for the LauncherOne vehicle.

—Kevin Zagorski, Propulsion Advanced Manufacturing manager at Virgin Orbit

NASA’s goal is to continue working with industry to advance technology and improve access to space by making launch technology safer, faster and more cost effective, said Ed Hamlin, project manager at Armstrong.

At Marshall, that means refining 3D printed combustion devices even further by exploring even higher-performing copper alloys. In time, Gradl said, additive manufacturing solutions could support a variety of crewed or robotic deep space exploration missions, including lunar landers and advanced propulsion systems. Earth-based applications also may present themselves.

The collaborative partnership between NASA and Virgin Orbit, created via an Announcement of Collaborative Opportunity by NASA’s Space Technology Mission Directorate, seeks to advance technology across the commercial sector and benefit future NASA missions, reducing launch costs and enabling more robust scientific exploration of the Moon and Mars.