Apr 22, 2016 | By Kira

NASA has successfully tested a 3D printed rocket engine turbopump using liquid methane in place the previously tested liquid hydrogen. The tests proved that the highly-complex 3D printed component could pump 600 gallons of liquid methane per minute, enough to power an engine capable of generating 22,500 pounds of thrust. These extremely promising results which could now pave the way for future, methane-fueled Mars landers.

Turbopumps are critical rocket engine components consisting of two turbines that spin at extremely fast speeds and can generate more than 2,000 horsepower—twice the horsepower of a NASCAR engine. However, they are also some of the most complex rocket engine parts to manufacture.

Luckily, metal additive manufacturing—specifically, selective laser melting, or SLM—has been a key technology in allowing NASA not only to build advanced rocket engine turbopumps, but to do so more quickly and efficiently than possible with traditional manufacturing methods.

“Additive manufacturing allowed us to build the turbopump with 45 percent fewer parts,” said Nick Case, the propulsion engineer who led the testing at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “This made it affordable to build two turbopumps, get them on the test stand quickly, and get results.”

“NASA is making big advances in the additive manufacturing arena with this work," added Marty Calvert, Marshall’s design lead for the turbopump. “Several companies have indicated that the parts for this fuel pump were the most complex they have ever made with 3-D printing.”

What is even more exciting, however, is the fact that these 3D printed turbopumps were successfully tested with liquid methane, which is considered to be an ideal propellant for fueling Mars landers and other spacecraft.

Whereas previously, NASA tested its 3D printed turbopump using liquid hydrogen, liquid methane is much more suited to life on Mars. As NASA explains, liquid methane is cooled to 255 degrees below zero Fahrenheit (-159°C), whereas liquid hydrogen is cooled to 400 degrees below zero Fahrenheit (-240°C).

That 145-degree difference means liquid methane boils off more slowly, and can be stored for longer periods of time—a major bonus for future Mars missions. Furthermore, methane rocket fuel can be manufactured from carbon dioxide, which is found in abundance on the Red Planet.

During the full power test, the 3D printed turbopump’s turbines generated 600 horsepower, while the fuel pumps got its ‘heartbeat’ racing at more than 36,000 revolutions per minute, delivering 600 gallons of liquid methane per minute. That is enough power to fuel an engine producing over 22,500 pounds of thrust. Three other tests were completed at lower levels, and all helped to ensure that the 3D printed parts would operate successfully under the extreme and harsh conditions found in space.

“Methane propulsion and additive manufacturing are key technologies for the future of exploration including NASA’s journey to Mars,” said Graham Nelson, a Marshall propulsion engineer who helped with the testing. “We’re excited to complete testing that advances both these technologies at the same time and improves the capabilities of future missions.”

NASA added that by demonstrating that the 3D printed turbopump could work with different types of fuel, they have proven that a common design can work for engines fuelled by either methane or hydrogen. This is a crucial finding that will pave the way for even more complex 3D printed rocket engine parts.

Artist’s concept of a Mars lander whose fuel tanks are filled with liquid methane, liquid oxygen, and engine nozzles.

The next step for NASA will be to test the liquid methane turbopump with other 3D printed engine components in a similar configuration to the liquid hydrogen tests.

“Designing, building, and testing a 3-D printed rocket part as complex as the fuel pump was crucial to Marshall’s upcoming tests of an additively manufactured demonstrator engine made almost entirely with 3-D printed parts,” said Mary Beth Koelbl, deputy manager of Marshall’s Propulsion Systems Department, during the initial testing in August. “By testing this fuel pump and other rocket parts made with additive manufacturing, NASA aims to drive down the risks and costs associated with using an entirely new process to build rocket engines.”

NASA has been at the forefront of bringing 3D printing to the final frontier, exploring the unprecedented potentials of metal additive manufacturing in its rocket engine and aerospace components. The national space giant has previously tested 3D printed F-1 rocket engine parts, 3D printed RS-25 rocket engines, and is currently working with Made in Space on Archinaut, an in-orbit robotic 3D printing demo.

Watch the 3D printed methane-powered turbopump test in action in this video by NASA:

Posted in 3D Printing Application

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