Aug 27, 2015 | By Alec

3D printing is being increasingly used in the aerospace industry for a variety of parts, but few of those projects are as innovative or as intimidating as NASA’s attempts to 3D print rocket engines. However, even here 3D printing turns out to be a very suitable technology, as NASA has just successfully tested a 3D printed turbopump for in a rocket engine at their Marshall Space Flight Center in Huntsville, Alabama. During the test with liquid hydrogen propellant, the turbopump was able to generate and withstand more than 90,000 revolutions per minute (or rpms).

As ever, NASA can be found at the forefront of technological innovation, even where 3D printing is involved. Only a few months ago, they unveiled a 3D printed copper combustion chamber liner, but this turbopump and its ‘heartbeat racing seems to be even more impressive. Like its predecessor part, it is all part of NASA’s drive for Mars through affordable missions, but this is the most complex 3D printed rocket part to date.

So what exactly is a turbopump? Well, it’s a critical rocket engine part that revolves around a spinning turbine. This generates lots and lots of horsepower: 2,000, or at least twice that of a NASCAR engine. And this set of 15 tests unequivocally proves that it works; when reaching full power, it is capable of delivering 1,200 gallons of cryogenic liquid hydrogen per minute. More than enough, NASA says, to power an upper stage rocket engine to produce 35,000 pounds of thrust. During these tests, the pump was also exposed to the extreme environments typical of rocket activity. Think 6,000 degrees Fahrenheit (or 3,315 degrees Celsius), while the liquid hydrogen itself is cooled down to 400 degrees Fahrenheit (or -240 degrees Celsius).

Now as you can imagine, this is a very complex engine component. Traditionally manufactured versions consist of hundreds of separate parts, but this 3D printed innovation took that number down by 45 percent. ‘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,’ Mary Beth Koelbl explained on the NASA website, who is deputy manager of Marshall’s Propulsion Systems Department. ‘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.’

To design it, NASA teamed up with four suppliers, and leveraged their expertise to build the necessary parts – each 3D printed separately using SLS metal 3D printing technology. ‘NASA is making big advances in the additive manufacturing arena with this work,’ said 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.’

Nick Case, who is a propulsion engineer and worked on the turbopump, explained that the design and testing phase for this fuel pump took about two years to complete. ‘If we used traditional manufacturing processes, it would have taken us double that time. Using a completely new manufacturing technique allowed NASA to design components for an additively manufactured demonstration engine in a whole new way,’ he says.

Finally, what will it be used for? Primarily, this is part of a test engine to fully understand how 3D printed parts operate under such harsh conditions. Test data will therefore be made available to American companies specializing in aerospace manufacturing. All of this will be compiled in NASA’s Materials and Processes Technical Information System, called MAPTIS. In the near future, this data will hopefully be used to develop future spaceflight engines. To make that happen, all the performance parameters have been specifically made applicable to the Block II advanced configuration of NASA’s Space Launch System. This will become the most powerful launch vehicle ever made, intended for use in trips to Mars and beyond.

Posted in 3D Printing Applications

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