NASA recently built and successfully tested an additively manufactured, or 3D-printed, rocket engine nozzle made of aluminium. The nozzle is lighter than conventional nozzles and thus paves the way for space flights that can carry more payload. The new aluminium components should make it possible to carry more cargo into space in the future – for example for missions to the Moon or Mars.
NASA innovation: With aluminium to Moon and Mars
NASA's innovative rocket nozzle paves the way for deep space missions
Less is more: lighter rockets for more payload
NASA's goals of travelling to the Moon and Mars require the ability to carry more cargo into space. The new innovation could play a decisive role here, as it enables the production of lighter rocket components that can also withstand high structural loads.
As part of the "Announcement of Collaborative Opportunity", engineers from NASA's Marshall Space Flight Center in Alabama have teamed up with experts from the company Elementum 3D to develop a weldable type of aluminium that is heat-resistant enough for use in rocket engines. Compared to other metals, aluminium has a lower density and enables high-strength, lightweight components. The novel weldable type of aluminium is the latest development from NASA as part of the RAMFIRE (Reactive Additive Manufacturing for the Fourth Industrial Revolution) project.
Project RAMFIRE: Reactive Additive Manufacturing for the Fourth Industrial Revolution
The RAMFIRE project is funded by NASA's Space Technology Mission Directorate (STMD) and focuses on the development of lightweight, additively manufactured rocket nozzles made of aluminium. These nozzles are equipped with small internal channels that keep them cool enough to prevent them from melting. Conventional manufacturing processes can require up to a thousand individual parts for a nozzle, whereas the RAMFIRE nozzle is made from a single piece, requiring far fewer joints and significantly reducing manufacturing time.
Over the course of this summer, two RAMFIRE nozzles have already undergone multiple hot-fire tests at Marshall's test site using liquid oxygen and liquid hydrogen, as well as liquid oxygen and liquid methane propellant configurations. With pressure chambers exceeding 825 pounds per square inch (psi) – more than the expected test pressures – the nozzles achieved 22 starts and 579 seconds of run time, or nearly ten minutes. This result demonstrates that the nozzles can perform under the most demanding conditions in space.
The RAMFIRE nozzle performs a hot fire test at Marshall’s East test area. The nozzle, made of the novel aluminium alloy 6061-RAM2, experiences huge temperature gradients. As hot gasses approach 6000 degrees Fahrenheit and undergo combustion, icicles are forming on the outside of the engine nozzle.
Novel aluminium variant A6061-RAM2
As part of the RAMFIRE project, NASA and Elementum 3D first developed the novel aluminium variant A6061-RAM2 to build the nozzle and modify the powder used with LP-DED (Laser Powder Directed Energy Deposition) technology. Another commercial partner, RPM Innovations (RPMI), used the newly invented aluminium and the special powder to produce the RAMFIRE nozzles with their LP-DED process. In addition to building and testing the rocket engine nozzles, the RAMFIRE aluminium material and additive manufacturing process were also used to build other advanced large components for demonstration purposes. These include a 36-inch diameter aerospike nozzle with complex integrated cooling channels and a vacuum jacketed tank for cryogenic liquid applications.
NASA and its industry partners are also already working to share the data and process with commercial stakeholders and the academia. Several aerospace companies are evaluating the novel alloy and the LP-DED additive manufacturing process and are looking at ways they can be used to manufacture components for satellites and other applications.
Seen here at the Marshall Space Flight Center in Alabama, developed with the same 6061-RAM2 aluminium material used under the RAMFIRE project, is a vacuum jacket manufacturing demonstrator tank. The component, made for cryogenic fluid application, is designed with a series of integral cooling channels that have a wall thickness of about 0.06 inches.