A team of NASA scientists has moved a step closer to building a completely 3-D printed, high-performance rocket engine. They manufactured engine parts and test fired them with oxygen and cryogenic liquid hydrogen to produce about 9 tons (20 000 pounds) of thrust.
Today, 3-D printing is a key technology in space design and manufacturing, which enables affordable exploration missions. It has the potential to influence spacecraft built for leaving Earth and spaceships and landers for visiting other destinations. Further plans include engine testing with methane and oxygen - the components for Martian landers, because methane and oxygen production is a probability on the Red Planet.
A team at NASA’s Marshall Space Flight Center in Huntsville, Alabama tested 3-D printed rocket engine parts connected in the same fashion that they would work in a rocket engine. The parts performance rivaled that of traditionally manufactured engine parts. During six separate tests, the engine generated up to 20,000 pounds of thrust. Credit: NASA/MSFC
“We manufactured and then tested about 75 percent of the parts needed to build a 3-D printed rocket engine,” said Elizabeth Robertson, the project manager for the additively manufactured demonstrator engine at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “By testing the turbopumps, injectors and valves together, we’ve shown that it would be possible to build a 3-D printed engine for multiple purposes such as landers, in-space propulsion or rocket engine upper stages.”
Over past few years, the Marshall team has worked with various vendors to make 3D printed parts, like turbopumps and injectors, including the testing of the parts. They connected the parts to test them so they could work same as they do in a real engine. However, they are not packaged together like the typical engine, what one would see on a test stand.
“In engineering lingo, this is called a breadboard engine,” explained Nick Case, the testing lead for the effort. “What matters is that the parts work the same way as they do in a conventional engine and perform under the extreme temperatures and pressures found inside a rocket engine. The turbopump got its “heartbeat” racing at more than 90 000 revolutions per minute (rpm) and the end result is the flame you see coming out of the thrust chamber to produce over 20 000 pounds of thrust, and an engine like this could produce enough power for an upper stage of a rocket or a Mars lander.”
The team performed seven tests, the longest lasting about 10 seconds. During the tests performed, 3-D printed engine experienced all the extreme conditions and environments inside the rocket engine, where the fuel is burned at least on 3 300 degrees Celsius (6,000 degrees Fahrenheit) to produce the thrust. Turbopump's "duty" is to deliver the liquid hydrogen, which is cooled down to -240 degrees Celsius (-400 degrees Fahrenheit). These tests were performed with cryogenic liquid hydrogen and liquid oxygen, the mainstays of spaceship propulsion systems.
Despite the fact that methane and oxygen are chosen for Martian mission, the combination of liquid hydrogen and oxygen produces the highest temperatures and this enabled the team to test the limits of 3-D printed engine. In addition to the methane testing, the team has plans to add other key components to the testing engine, which includes cooled combustion chamber and nozzle and a turbopump for liquid oxygen.
An unmanned aerial vehicle captured this view of a 3-D printed rocket engine test. The test laboratory at NASA’s Marshall Space Flight Center in Huntsville, Alabama, uses aerial cameras to contribute to imagery data analyzed after tests. Credit: NASA/MSFC
“These NASA tests drive down the costs and risks associated with using additive manufacturing, a relatively new process for making aerospace quality parts,” said Robertson. “Vendors who had never worked with NASA learned how to make parts robust enough for rocket engines. What we’ve learned through this project can now be shared with American companies and our partners.”
“This new manufacturing process really opened the design space and allowed for part geometries that would be impossible with traditional machining or casting methods,” said David Eddleman, one Marshall’s propulsion designers. “For the valve designs on this engine, we used more efficient structures in the piece parts that resulted in optimized performance.”
All data of these parts can be found here.
NASA propulsion engineer Nick Case explains how engineers configured engine parts to make and test additively manufactured engine parts as a system. Credit: NASA/MSFC
A GoPro camera feels the force of 20 000 pounds of thrust during a test of 3-D engine rocket components tested together. Credit: NASA/MSFC
Featured image: During a series of test firings at NASA’s Marshall Space Flight Center in Huntsville, Alabama, 3-D printed rocket engine parts worked together successful under the same conditions experience inside rocket engines used in space. The turbopump was tested at full power, pumping 1,200 gallons of liquid hydrogen per minute and the injector produced 20,0000 pounds of thrust. Credits: NASA/MSFC/David Olive