NASA Langley runs more wind tunnel tests on Space Launch System rocket models
The SLS rocket model is sleek and silver, standing 6 feet and then some inside the atmospheric wind tunnel at NASA Langley Research Center.
Research aerospace engineer David Chan is inside the tunnel, holding a long, hollow metal wand. At a signal, a big fan begins to pump outside air through the 14-by-22-foot tunnel cavity. A river of cool wind starts to gust over Chan and the rocket model, rapidly building to a tsunami of 35 mph.
Test engineer Les Yeh sends propylene glycol coursing into the wand, which heats the clear fluid to 270 degrees till it turns to smoke and ejects from the wand's tip like something out of "Harry Potter."
A line of smoke streams toward the rocket and the model launch tower standing beside it. Most of it flows past and disappears downstream. Some of it eddies and whirls around the rocket. And it all gives Chan and his colleagues more data on how ground winds can affect the real SLS booster when it stands on the launch pad at Cape Canaveral in Florida in a year or two and during the initial moments of liftoff.
"What we're trying to do is collect aerodynamic data to see how ground winds from various directions can affect the rocket," Chan said. "Basically, we're interested in crew safety. We don't want the rocket as it's lifting off to be pushed into the tower and contact the tower."
Dave Piatak, deputy lead for the SLS aerodynamics team at Langley, likens it to sticking your hand out the window of a car traveling at a high speed.
"There's a significant drag force," Piatak said. "And if you move your hand around the sideview mirror, you can find some areas where there's a little vortical flow and very unsteady. So it can not only push your hand back but buffet it."
Traveling at Mach 1, or 768 miles an hour at sea level, creates even harsher drag and flow environments.
"Even after decades of flying to orbit, to reaching that 17,500-mile-an-hour mark to get to orbit, we're still constantly learning new things as we test new configurations," Piatak said. "So new shapes of vehicles dictate a whole new aerodynamic database that needs to be developed."
The 14-by-22 is one of two wind tunnel tests on SLS models that NASA is running at its research center in Hampton.
The other is at the center's hypersonic Unitary Plan Wind Tunnel, where another smaller model is about to be subjected to blistering speeds of Mach 4, or four times the speed of sound.
There again, the idea is to ensure crew safety — this time when the twin solid rocket boosters separate from the core, said aerospace engineer Courtney Winski.
"It's a very short time period during the actual flight," said Winski, lead researcher for the SLS solid rocket booster test. "But it's an important piece of the flight."
Important because when those empty boosters have done their job, spent their fuel and dropped away, any inadvertent recontact with the core rocket carrying a crew capsule or critical cargo could be catastrophic.
"That would be a bad day for all," Piatak said.
The Unitary Plan Wind Tunnel is one of a group of unique facilities created by an act of Congress in 1949 to test experimental aircraft, missiles and rockets at near-hypersonic speeds. NASA Langley's version has two test sections, one with a Mach range from 1.5 to 2.9, and the other from 2.3 to 4.6. The test section for the SLS model is about 4-foot square. But looks can be deceiving.
"You're only seeing a small portion of the massive industrial complex that surrounds us right now," Piatak said.
The entire complex includes six giant compressors powered by two massive motors capable of generating a combined 100,000 horsepower, said Winski. The compressors shoot air through huge steel pipes that snake throughout the facility. Other far smaller compressors and heat exchangers are installed along the tunnel piping. Nozzles control the air flow into the test chambers — one of which contains an SLS model being readied for its Mach 4 workout.
The SLS is the Space Launch System of super heavy-lift rockets that NASA has been developing with its commercial partners. The idea is to get space vehicles with enough oomph to send crews on deep-space missions and launch massive amounts of payload to assemble structures in space or colonize other planets or the moon.
The SLS system is expected to include the most powerful rocket ever built.
Of the four variants under development so far, two are intended to carry crew while the others are to haul up to 130 metric tons of cargo. They range in size from 322 to 365 feet. By comparison, the Saturn V rocket built to boost astronauts to the moon stood at 363 feet.
The model being tested now at NASA Langley represents the bigger of the crew versions, called SLS Block 1B Crew. The real thing could be boosting an Orion capsule carrying crew into lunar orbit as early as 2021 on what's known as Exploration Mission 2, or EM-2.
But prior to that, the smaller version, or SLS Block 1 Crew, is scheduled for a test flight to the moon in late 2018 or early 2019. That version has already been tested at Langley.
It's unclear yet if that EM-1 mission will have test pilots aboard.
"The official word on that is the White House has requested an assessment of whether or not we could put a crew earlier than we had planned on that first EM-1 flight," Piatak said.
He, his team and others have made recommendations on whether it would be feasible based on economics and scheduling. He declined to say what their recommendations were.
Quelle: Daily Press
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Update: 11.05.2017
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NASA investigating damaged SLS tank section
A Space Launch System liquid oxygen tank confidence article in the Vertical Assembly Center at the Michoud Assembly Facility in 2016. Part of a qualification model of an SLS liquid oxygen tank was damaged in a mishap there May 3. Credit: NASA/Michoud/Steven Seipel
WASHINGTON — NASA and Boeing are investigating a recent mishap at the Michoud Assembly Facility that damaged a portion of a liquid oxygen tank being developed for the Space Launch System.
Kim Henry, a spokesperson for NASA’s Marshall Space Flight Center, said May 10 that NASA and Boeing, the prime contractor for the SLS core stage, have established independent investigation teams to review an incident at Michoud one week earlier involving the rear dome of a liquid oxygen qualification tank. The mishap was first reported by NASA Watch.
The agency didn’t provide additional details about the incident, which took place in the Vertical Assembly Center at Michoud, used to weld large components of the SLS. The Vertical Assembly Center was shut down when the incident took place, Henry said. “NASA is evaluating next steps to safely resume operations.”
The damage was limited to the one dome section of the tank, which was not yet welded to the rest of the tank. “Assessments are ongoing to determine the extent of the damage,” she said.
Henry said that the incident was classified as a “Type B” mishap. Such a mishap, according to NASA documents, covers incidents that cause between $500,000 and $2 million in damage. No one was injured, she said.
The liquid oxygen tank involved in the incident was a qualification model, intended for testing, and not flight hardware. Henry said it wasn’t immediately clear how long the investigation would take.
The accident comes as other factors, some outside of NASA’s control, have threatened to delay development of the SLS. A tornado struck Michoud in February, damaging some buildings used for SLS and Orion work there. Agency officials estimated in March the repairs would delay work by two to three months.
The schedule for that launch may also depend on a decision to put a crew on EM-1, which is currently planned to fly without astronauts on board. NASA officials said last month that a report studying the feasibility of placing a crew on EM-1 has been completed and briefed to agency leadership and the White House, but no decision has been announced yet.
Quelle: SN
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Update: 13.05.2017
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NASA decides not to place a crew on first SLS/Orion mission
NASA said a study concluded it was technically feasible to fly a crew on the first SLS/Orion mission, but that cost, schedule and risk concerns led them to stick with original plans to fly it uncrewed. Credit: NASA
WASHINGTON — NASA has decided it will not add astronauts to the first flight of the Space Launch System, a launch now delayed until some time in 2019.
In a media teleconference May 12, agency leaders said that while it was technically feasible to place a crew on the Exploration Mission (EM) 1 flight of SLS and Orion, cost, schedule and risk issues led NASA and the White House to decide to keep with current plans to fly the mission without astronauts.
“At the end of the day, we found it technically feasible to fly crew on EM-1, as long as we had a commitment of additional resources and schedule,” NASA Acting Administrator Robert Lightfoot said. However, after assessing what it would take to implement that plan, officials “decided that, while it was technically feasible, they really reaffirmed that the baseline plan we had in place was the best way for us to go.”
That decision, Lightfoot said, was made jointly by NASA and the White House. “We definitely sat with them after we heard the feasibility study and came to this conclusion together,” he said. He added that the new administration has been “incredibly supportive” of the study and NASA’s overall exploration plans.
NASA announced Feb. 24 that it had started a study to examine the feasibility of putting astronauts on EM-1. That study stemmed out of discussions with the agency review team, or “landing team,” assigned to NASA by the incoming Trump administration after the November election, particularly after concerns that technical issues could delay the planned November 2018 EM-1 launch.
Bill Gerstenmaier, NASA associate administrator for human exploration and operations, said that the study turned up fewer technical issues with putting a crew on EM-1 than he originally expected. “What I was surprised by was that I thought there would be a whole lot of really negative work that would actually maybe make this not very attractive to us,” he said.
“But when Robert and I look at this overall, it does add some more risk to us, because it’s the first crew on the vehicle,” he said. The work to add crew to EM-1 would have cost NASA an additional $600–900 million, and delay the launch likely to the first or second quarter of 2020.
“The culmination of changes in all three of those areas said that overall, probably the best plan we have is actually the plan we’re on right now,” Gerstenmaier said. “When we looked at the overall integrated activity, even though it was feasible, it just didn’t seem warranted in this environment.”
Gerstenmaier said a variety of issues with SLS and Orion contributed to the delay to 2019. “The fact that we’re running into some production problems is typical of almost any major development of this complexity,” he said. He added that the tornado that damaged the Michoud Assembly Facility in New Orleans in early February “really set us back in a big way.”
“This was a significant event for us,” Gerstenmaier said, but one he said will likely not have a major effect on the overall schedule.
NASA has not announced a more specific launch date for EM-1 yet other than 2019. Gerstenmaier said the agency would wait until a mishap investigation board at Michoud concludes its study of the tank accident. “We’re probably a month or two away from coming up with a final schedule,” he said.
The EM-1 delay could also push back EM-2, the first mission to carry a crew. That mission will also use an upgraded version of the SLS with the more powerful, and larger, Exploration Upper Stage, which requires some reconfiguration of ground systems at the Kennedy Space Center.
“We’ve been carrying, tentatively, an August 2021 date for EM-2,” Gerstenmaier said. “It will probably move somewhere to the right because of the relationship between EM-1 and EM-2.” A revised date for EM-2, he said, should come several months after the new date for EM-1.
“We continue to have a good dialogue with the White House. The administration has been very supportive of our plan,” he said. “They have not asked us to go to Mars by 2024.”
Quelle: SN
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Update: 17.05.2017
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A massive barge got this SLS part to Alabama, now NASA will crunch it
NASA barge Pegasus at Redstone Arsenal dock in Huntsville, Ala. delivering the engine section test article for NASA's Space Launch System to Marshall Space Flight Center after a month long trip from NASA's Michoud Assembly Facility in New Orleans. (Bob Gathany / bgathany@AL.com)
The first large test section of NASA's Space Launch System core will roll slowly to an Alabama test stand this week in what's being called a key step toward America's next deep-space rocket.
"It's been a long time since the agency's had a program make it this far," Space Launch System program manager John Honeycutt said at Marshall Space Flight Center Tuesday.
Honeycutt spoke inside NASA's Pegasus barge, enlarged for its new SLS mission and docked now on the Tennessee River. The Pegasus had just brought a 40,000-pound engine core from NASA's Michoud Assembly Facility near New Orleans to Marshall for stress testing. If it passes, the part is "qualified" for spaceflight.
"The engine section is kind of the back part of the rocket," Honeycutt said, "where all the plumbing, if you will, gets connected to the RS-25 engines."
Marshall technicians will move the core "at a walking pace" approximately 7 miles from the river landing to Building 4619. There, it will be fitted with 3,000 data channels and 55 hydraulic lines. It will have a test stand basically built around it.
The hydraulic lines will apply controlled pressure to test the core's ability to survive launch pressure by squeezing, bending and crushing it. The test program will take until early next year to finish.
It took 17 days to get the test part upriver from Michoud to Marshall by way of the Mississippi, Ohio and Tennessee rivers. "What we did not expect was all the rain we had up the Mississippi in the St. Louis area," Pegasus barge team leader Alan Murphy said.
The crew had to park the barge for five days while water levels dropped low enough to insure its 213 feet height would make it under every bridge going downriver. "We did not want to hit a bridge," Murphy said. "It we hit a bridge, it's not going to be an 'oops,' it's going to be nationwide."
The engine core is the first of four core parts of the SLS heading for Marshall for stress testing in the coming year. All are being built in the Michoud facility near New Orleans.
Why not build new test stands there - as NASA is doing in Alabama - and test a few hundred yards from the manufacturing facility?
"You've got to look at your resources, the people, all of your moving equipment," said Tim Flores, SLS core stage integration manager. "It was much cheaper to just barge the equipment here and have these stands built here where we are actually a center of excellence for structural engineering."
"This is a milestone," Honeycutt said of the test part's arrival at the Marshall Space Flight Center. "It helps me to where I'm one step closer to that flight readiness review ... to say this rocket's ready to fly."
Honeycutt said SLS will share the load of space exploration with rockets built by commercial space companies such as SpaceX and Blue Origin.
"We need all of us to do the space exploration the nation has charted out for us to go do," he said. "The president and the Congress support SLS. SLS will give us the capability to deep space exploration for decades to come."
As for where Tuesday's barge docking puts NASA in the years' long process of building SLS, Honeycutt said he sees his current team "as the team that has got to close this out. If you want to do a baseball analogy, we're the closers."
Quelle: AL
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Update: 20.05.2017
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Report criticizes development of SLS test stands
Todd May, director of NASA's Marshall Space Flight Center, speaks at a December 2015 event to mark progress on the construction of Test Stand 4693 that will be used for the Space Launch System. Credit: NASA/MSFC/Emmett Given
WASHINGTON — A rush to complete two test stands needed for development of the Space Launch System caused their cost to nearly double, even as the overall program suffered delays, according to a new report.
The May 17 report by NASA’s Office of Inspector General (OIG) found that the cost of the two test stands built at the Marshall Space Flight Center for testing SLS propellant tanks increased by more than 87 percent, to $76 million, as the agency overlooked potential long-term cost savings in a effort to expedite their construction.
NASA entered into an agreement with the U.S. Army Corps of Engineers in August 2013 to construct Test Stands 4693 and 4697 at Marshall, on the grounds of the Army’s Redstone Arsenal. The Corps of Engineers then awarded a contract to an Alabama construction company, Brasfield & Gorrie, to build the stands. The stands are large steel structures designed to perform load testing on the rocket’s liquid oxygen and liquid hydrogen tanks to simulate the conditions the tanks will experience during launch.
At the time of the contract award, NASA sought to have Test Stand 4693, for liquid hydrogen tank testing, done by May 2015 and Test Stand 4697, for liquid oxygen tank testing, by September 2015. NASA paid a $7.6 million premium for a compressed construction schedule in order to meet a planned December 2017 deadline for the first SLS launch.
The development schedule for SLS slipped, though, pushing back the first launch to November 2018 and, more recently, to some time in 2019. NASA was unable to recoup that premium because of the fixed-price nature of the contract.
The OIG report concluded that costs also increased because of changes in the design of the test stands. Those design changes were in large part caused when testing requirements for the tanks matured as the program advanced.
NASA had originally budgeted $30 million and $10.5 million for Test Stand 4693 and Test Stand 4697, respectively. The final costs for the two stands, OIG found, were $53.7 million and $22.3 million, with the construction completed in late 2016. The $76 million total cost represented an increase of 87.6 percent over the original budget.
“In short, rushing the decision regarding the test stands to support a December 2017 first flight raised the cost of constructing the stands by tens of millions of dollars,” the report concluded.
The report also criticized the decision to build the stands at Marshall without seriously considering alternative sites, notably the Stennis Space Center in Mississippi. The cost of building the liquid hydrogen tank stand at Stennis, Marshall officials said, was 23 percent more than the original cost of Test Stand 4693, but the OIG report noted that estimate was not originally documented and had to be recreated for the audit.
That analysis also did not take into account the lifecycle costs of the stands, in particular transportation costs. The tanks, built at the Michoud Assembly Facility in New Orleans, must be transported by barge to Marshall, a circuitous route that takes two weeks and costs $500,000. Transporting the tank to Stennis would take less than one week and cost $200,000.
“Without a thorough analysis of alternative construction sites, including complete life-cycle cost analysis to include operations and maintenance costs, as well as transportation of test articles through the expected useful life of the stands, it remains unclear whether NASA made the most cost effective decision for the Program and the Agency in the long run,” the report stated.
