NASA and Aerojet Rocketdyne have been working together for several years now to make RS-25 engines for the Space Launch System (SLS) heavy-lift rocket. Numerous updates have kept us intrigued, along with December’s eighth and final hot-fire test.
While the RS-25 was already extremely powerful, engineers have made some high-tech modifications to the engine for NASA, to include a 3D printed pogo accumulator assembly. This is their largest 3D printed rocket component so far and is similar in size to a beach ball.
The RS-25 engine is a design that has been functioning for over 40 years by NASA, used previously as main engines on space shuttles with 100 percent thrust. These levels have continued to rise due to requirements for launch. Now, NASA reports that they have powered the RS-25 to its highest level, at 113 percent thrust. Once again, this third full-duration test took place on the A-1 Test Stand at Stennis Space Center in Bay St. Louis, MS.
The test lasted for over 260 seconds total, and the SLS engines were at 113 percent for over half the time. NASA plans for four of the RS-25 engines to be used (providing two million pounds of thrust), along with two solid rocket boosters (with eight million pounds of thrust).
“Through the years, the engines were modified to provide additional thrust to 109 percent of its original designated level. For the larger, heavier SLS rocket, the engines are being modified again to operate at 111 percent of their original power level. Increased engine performance is crucial for enabling SLS missions to deep space as the rocket evolves to be larger and carry astronauts and heavy cargo on a single flight,” states NASA.
As plans for Mars continue, the SLS rocket is slated to carry both crew and ship’s cargo there, as well as to future trips to the moon. The original weight configuration for traveling as far as the moon is 26 metric tons, but that will be expanded to 45 metric tons.
Currently, engineers are busy in New Orleans at NASA’s Michoud Assembly Facility. There, the four RS-25s are attached to a core stage that stands 212 feet high.
“Increased thrust requirements for the RS-25 are just one of the many changes in the SLS rocket’s performance that will facilitate our nation’s deep space exploration goals and objectives. While we can analytically calculate engine performance and structural capabilities at these higher power levels, actually demonstrating that performance with an engine hot fire provides the added confidence that these engines will meet all specification requirements demanded of SLS,” said Dan Adamski, RS-25 Program Director at Aerojet Rocketdyne.
“In addition to achieving the higher thrust level, the Feb. 21 hot fire also featured a test of an RS-25 flight controller, as well as a 3D printed engine component,” states NASA. “The new flight controller is a major part of the RS-25 modifications, operating as the ‘brain’ of the engine to help it communicate with the SLS rocket and to provide precision control of engine operation and internal health diagnostics.”
NASA has been enjoying the benefits of 3D printing for decades, long before it hit the mainstream and the public was aware of the value of the technology, along with most other industrial leaders, engineers, and designers. And considering the astronomical costs of going into space, savings on budget with 3D printed parts is definitely one of the most enticing aspects—not to mention the ability to create super durable, lightweight parts, and often some that would not be possible otherwise. Along with the 3D printed pogo accumulator assembly, both NASA and Aerojet Rocketdyne will be continuing to test numerous 3D printed components for the RS-25.
During further testing, NASA also has plans to:
“The recent hot fire provided a key maximum flow level test of the current 3D component. Each RS-25 test moves the agency closer and closer to its return to deep space exploration, to such destinations as the moon and Mars,” states NASA. “Earlier this month, the space agency completed testing of all four new RS-25 engine flight controllers needed for the second flight of the SLS rocket. The Exploration Mission-1 (EM-1) flight will test the new rocket and carry an uncrewed Orion spacecraft into space beyond the moon. Exploration Mission-2 (EM-2) will be the first flight to carry humans aboard the Orion spacecraft, returning astronauts to deep space for the first time in more than 40 years.”
- Evaluate the SLS core stage for the EM-1 mission at the south Mississippi site.
- Install the flight stage on the B-2 test stand.
- Simulate a true launch, firing all the RS-25 engines at one time.
While Aerojet Rocketdyne is the contractor for the RS-25 engines, testing at Stennis is also performed by teams from NASA and Syncom Space Services (the Stennis facilities and operations contractor).
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