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THE LATEST RESEARCH AND DEVELOPMENT NEWS IN MANUFACTURING AND TECHNOLOGYTECH FRONT NASA Fired Up Over 3D-Printed Engine Components t A


NASA team is fi red up about getting closer to building a completely 3D-printed, high-performance rocket engine. They demonstrated this in December by assembling additive-made complex engine parts and fi ring them up with cryogenic liquid hydrogen and oxygen to pro- duce 20,000 pounds of thrust. “We manufactured and then tested about 75% of the parts needed to build a 3D-printed rocket engine,” said Elizabeth Robertson, the project manager for the additively manufactured demonstrator engine at NASA’s Marshall Space Flight Center in Huntsville, AL. “By testing the turbopumps, injectors and valves together, we’ve shown that it would be possible to build a 3D-printed engine for multiple purposes such as landers, in-space propulsion or rocket engine upper stages.” Over the last three years, the Marshall team has been working with various vendors to make 3D- printed parts, such as turbopumps and injectors, and test them individually. To test them together, they connected the parts so that they work the same as they do in a real engine.


“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,” explained Nick Case, the testing lead for the effort. “The tur- bopump got its ‘heartbeat’ racing at more than 90,000 rpm and the end result is … 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.” Seven tests were performed, with the longest tests lasting 10 seconds. During the tests, the 3D-printed demonstra- tor engine experienced all the extreme environments inside a fl ight rocket engine where fuel is burned at greater than 3315° C to produce thrust. The turbopump delivers the fuel in the form of liquid hydrogen cooled below -240° C. These tests were performed with cryogenic liquid hydrogen and liquid oxygen, mainstays of spaceship propulsion systems. Even if methane and oxygen prove to be the Mars propel-


lant of choice, the propellant combination of cryogenic liquid hydrogen and oxygen tests the limits of 3D-printed hardware because it produces the most extreme temperatures and exposes parts to cryogenic hydrogen, which can cause brittleness. In addition to testing with methane, the team plans to add other key components to the demonstrator engine including a cooled combustion chamber and nozzle and a turbopump for liquid oxygen.


During test fi rings at NASA’s Marshall Space Flight Center, 3D-printed rocket engine parts worked together successful under the same conditions experienced inside rocket engines used in space.


“These NASA tests drive down the costs and risks associ- ated with using additive manufacturing, which is a relatively new process for making aerospace quality parts,” said Rob- ertson. “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.” The 3D-printed turbopump, one of the more complex parts of the engine, had 45% fewer parts than similar pumps made with traditional welding and assembly techniques. The injector had over 200 fewer parts than traditionally manufac- tured injectors, and it incorporated features that have never been used before because they are only possible with addi-


February 2016 | AdvancedManufacturing.org 33


Photo courtesy NASA


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