Dynetics recently verified the structural design of an affordable booster concept by successfully performing a proof and burst test of the Space Launch System (SLS) Advanced Booster Engineering Demonstration and/or Risk Reduction (ABEDRR) tank, according to a company statement.
Dynetics, the prime contractor on the ABEDRR contract, completed the design and fabrication of the full-scale cryogenic tank late last year. The tank is the largest flight-weight cryogenic tank built at NASA Marshall Space Flight Center, Ala., since the Apollo Saturn era. It is an 18-foot diameter friction-stir welded aluminum structure weighing 10,000 pounds and composed of some of the thickest roll-formed material ever welded on NASA Marshall’s friction stir weld tools.
Dynetics SLS Program Manager Andy Crocker said Monday in an email a proof test is a demonstration of the load-bearing capability of a structure, or in this case, a tank. For a tank, he said, pressure inside the vessel is increased to a specified level to prove the ability of the vessel to hold that pressure without failing. Crocker said a proof test is usually performed at a load (or pressure) well beyond where the structure (or tank) is expected to actually operate.
Following assembly, the team transported the tank to Dynetics’ test facility in Iuka, Miss. Several tests were conducted to prove out the design and fabrication methods. The team started with a hydrostatic proof test (with water), followed by a proof test using cryogenic fluid and finished with another hydrostatic proof and a planned burst test. Crocker said a hydrostatic proof test uses water as a test medium. Water inside the pressure vessel is pressurized to the specified pressure.
In a press release, Crocker said the burst occurred at a pressure well above some conservative estimates and right about where Dynetics had predicted. Crocker said in the email a structural analysis had suggested that the tank could burst at as low as 133 pounds per square inch, gauge (psig); but he said Dynetics knew that was a somewhat conservative estimate. He said the actual tank burst pressure was over 180 psig. Crocker added the planned operating pressure for a tank like the one tested would be around 50 psig, although that depends on the final vehicle design.
These tests were the last planned activities for this tank, Crocker said, as the activity was conducted ABEDRR contract and both manufacturing and test demonstrations have been completed. The data from these efforts, however, will be used for future hardware designs for NASA.
This work is being performed in partnership with Aerojet Rocketdyne [AJRD] to reduce risks for advanced boosters that could help meet SLS’ future capability needs.