HUNTSVILLE, Alabama – Workers have completed the construction of a critical test stand at Marshall Space Flight Center that will be used by NASA engineers to push the limits of the fuel tanks for the Space Launch System (SLS), the most powerful rocket ever developed.
Structural Test Stand 4697 is now being outfitted with special equipment and instrumentation. At this stand, the 196,000-gallon cryogenic liquid oxygen taken in the SLS’s giant core stage will be subjected to the extreme stresses of a deep-space mission to Mars.
“The forces the tank will experience in the test stand are as close as you can get on Earth to what the tank will experience on its way to space,” said Scott Chartier, primary test engineer over the stand for Marshall’s propulsion systems test branch.
“During the series of tests, the tank will endure up to 9 million pounds of compressive, up-and-down loads, and up to 300,000 pounds of shear or ‘twist’ loads.”
To accomplish these SLS tests and for future testing, Marshall teams will outfit the stand with sophisticated fluid transfer and pressurization systems, hydraulic and electrical control and data systems, fiber optics cables and instrumentation over the next few months.
“While the SLS tank will be the first piece of hardware in the stand, this and the other new Marshall test stand can be used for a variety of vehicles and testing needs, including commercial rockets or other large spacecraft structures needed for deep space exploration,” Chartier said.
The test article, which includes the liquid oxygen tank, will be produced using exactly the same materials and processes as a flight version, but with additional equipment that will simulate the tank’s connections to the SLS rocket.
A barge will carry the test article from NASA’s Michoud Assembly Facility in New Orleans to Marshall next summer, Chartier said.
‘SPIDERS’ AND LONG ARMS
Test Stand 4697 is shaped like an 85-foot-tall “L” with 90-foot-long arms. Three cage-like pedestals will be positioned in a broad circle on the foundation in the crook where the arms meet.
When the 28-foot-diameter, 70-foot-tall test article arrives at the stand, it will be carefully lifted and then positioned inside the circle of pedestals — there is only about a foot of clearance for the tank sides. The test article will sit atop a “spider” and special ring that will be bolted into the stand’s foundation.
A similar spider and ring will be mounted at the top of the test article.
When testing gets under way in late summer 2017, hydraulic cylinders and “load lines” attached to the spiders’ arms, the pedestals and the steel of the stand will push, pull and apply varying combinations of pressure to the tank, which will be filled with varying amounts and temperatures of fluid.
Each test scenario and combination simulates a different phase of an SLS launch and flight, Chartier said.
“We haven’t seen this magnitude of testing since we tested the Saturn rockets and the space shuttle,” Chartier said. “These test facilities will serve NASA well as we continue on the Journey to Mars. I can’t wait to take my kids to an SLS launch and see the hardware we helped develop on these test stands — sturdy stands even their generation can use as they continue exploring space.”
TEST STAND 4693
Nearby, work continues on Test Stand 4693, where the SLS core stage’s liquid hydrogen tank will be tested. The construction phase for 4693, rising 215 feet, will end later this year.
The construction project has a strong Alabama connection. Birmingham-based Brasfield & Gorrie is serving as general contractor, while Goodwin Mills and Cawood of Montgomery is one of the architects. Steel fabricator North Alabama Fabricating Co. of Birmingham is also working on the project.
Brasfield & Gorrie says the test stands project involves 7,216 yards of concrete foundations and 4,537 tons of structural steel.