At the end of last week (28 August) NASA confirming that it had successfully tested two 3D-printed rocket injectors, which mix liquid oxygen and hydrogen gas together and send it into the engine.
The injectors were tested on stand at NASA’s Marshall Space Flight Center in Huntsville, Alabama. They ran for five seconds (see picture), burning fuel at temperatures greater than 6,000°F and producing 20,000lb of thrust, and performed “exceptionally well”, according to Chris Singer, director of Marshall’s engineering directorate.
NASA worked with two additive manufacturers – Solid Concepts in California and Directed Manufacturing in Texas – to design and create the injectors, and to explore how the 3D printing fabrication process itself could change how rocket engines are built in future.
“We wanted to go a step beyond just testing an injector and demonstrate how 3D printing could revolutionise rocket designs for increased system performance,” confirmed Singer.
The designers were able, for example, to create an injector with 40 individual spray elements that generated complex geometric flow patterns allowing oxygen and hydrogen to swirl together before combusting at 1,400lb per square inch.
Furthermore, NASA confirms that additive manufacturing helped to cut costs related to materials and fabrication time.
The parts were built using selective laser melting, where metal powder is built up in layers and fused together with a laser. This enabled the designers to manufacture the injectors in two parts, where using traditional methods it would need 163 individual parts to be made and assembled.
The injectors were similar in size to those that power small rocket engines and close in design to those for large engines, such as the RS-25 engine which will power NASA’s space launch system (SLS) rocket and, hopefully, take humans to Mars.
Propulsion engineer Jason Turpin said: “We are working with industry to learn how to take advantage of additive manufacturing in every stage of space hardware construction from design to operations in space. We are applying everything we learn about making rocket engine components to the SLS and other space hardware.”
For all those involved in the manufacture and supply of components to the aerospace sector NASA’s approach will make very interesting reading. If additive manufacturing proves to be a safe bet for space travel it seems only a matter of time before OEMs and their supply chains begin to explore making more complex parts in this way.
In March, for example, Airbus signed an agreement with China’s North Western Polytechnical University to work together to identify new applications for 3D printing technology in commercial aviation.
It seems that not even the sky will be the limit for additive manufacturing.