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Forum:Commercial Space - Military Space
Topic:SpaceX Crew Dragon test anomaly (4.20.19)
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cspgThere's a video on Twitter. The capsule apparently blew up.

dom
quote:
Originally posted by Cozmosis22:
If so, that will likely push back a crewed launch into some time next year.

Surely we're looking at a significant delay if the capsule has actually BLOWN UP!!!

issman1I'm no SpaceX apologist or supporter and would also criticise Boeing for its constant delays and excuses.

But it seems that neither company was in any position to safely return NASA astronauts to low earth orbit. In fact, I fear both have shortcomings which endangers the ISS and those Americans being forced to launch and land on Soyuz and spend almost a year in space simply because it is expedient than rational.

Fra MauroAnomaly... that's an understatement. Not a disaster or tragedy for sure, but NASA speak doesn't fit the event.
space1I recall an Aviation Week magazine cover in 1986 about the Space Shuttle Challenger "loss." Not accident, not tragedy, or anything more dramatic.
Ken HavekotteWas the Crew Dragon the exact same flight crew version #2 spacecraft set to fly, or was it a prototype for the launch escape system as I have not been following this event thus far, having been away last week from the Cape area? If it was the same #2 vehicle, by all means, it could be a major setback to say the least.
Robert PearlmanSpaceX has not officially said, but multiple sources say is was the Demo-1 Crew Dragon that was destroyed, the same spacecraft that flew to the International Space Station in March and that SpaceX was planning to use for its in-flight abort test.

The Demo-2 Crew Dragon that is to launch Bob Behnken and Doug Hurley is still under construction at SpaceX's assembly facility in Hawthorne, California.

Ken HavekotteThanks Robert as that makes more sense. I didn't think the Demo-2 Crew Dragon vehicle was even ready for her maiden flight and why use it for the abort test firing. Still surprised a bit to hear that it was the Demo-1 spacecraft that had been used, though. Hopefully SpaceX can quickly resolve the failure and have it corrected before the next abort test firing, however, what vehicle would they use for it now?
Robert PearlmanThat would seem to be one of the issues; SpaceX may have to build a new vehicle for the in-flight abort test.
SkyMan1958Originally the Crew Dragon was supposed to return to Earth on land, and be reused. SpaceX scratched that when they decided to focus their funding on the Super Heavy/Starship for human flight. So, SpaceX decided to do water landings, for Crew Dragon. The concern was that water landings would not be good for the Super Draco thrusters, and therefore all manned Crew Dragons would be new spacecraft.

Assuming it's the Super Dracos that blew up, this concern with the effects of seawater on the Super Draco engines appears to be justified. I am guessing that since all Crew Dragons will theoretically be new spacecraft, that this is not too much of a show stopper, although it's obvious they'll want to do some more testing on the engines.

SpaceAngelI cannot believe this was the same spacecraft involved the the demo flight last month...
Robert Pearlman
quote:
Originally posted by SkyMan1958:
...with the effects of seawater on the Super Draco engines
You are, of course, assuming the issue was seawater intrusion, as opposed to something unrelated. Until more information is known about the cause, it is probably impossible to gauge how major or minor a problem this is for going forward.
denali414The last explosion for SpaceX was a helium leak in the tank. It could again be something with the tanks.
Jim Behling
quote:
Originally posted by SkyMan1958:
Assuming it's the Super Dracos that blew up, this concern with the effects of seawater on the Super Draco engines appears to be justified.
There is no data to support that statement.
astro-nutWhere is the Landing Zone 1 area at Cape Canaveral? Which launch pads or blockhouses is it located by?

I am trying to figure out by which launch pad did this unsuccessful event take place at? Any help would be appreciated. Thank you.

Robert PearlmanLanding Zone 1 is located on the site of the former Cape Canaveral Air Force Station Launch Complex 13 (LC-13). It is located between the Mercury-Atlas LC-14 pad and Atlas-Agena LC-12 pad and is southeast of the active 39A and LC-40 launch complexes.
Robert PearlmanNASA's Aerospace Safety Advisory Panel discussed the anomaly during its meeting today (April 25).
"The event occurred during a static fire test conducted prior to the in-flight abort test," said Patricia Sanders, chairwoman of the panel charged with ensuring that NASA has a healthy safety culture and mitigates risks where possible during spaceflight.

The Crew Dragon capsule in question is the same one that successfully flew a demonstration mission to the International Space Station in March. On Saturday, the spacecraft was being prepared for a launch-abort flight this summer. During the abort flight, the Dragon would have launched from Florida on a Falcon 9 booster and then fired its powerful SuperDraco engines to show that the Dragon could pull itself safely away from the rocket in case of a problem with the booster before or during flight.

"The firing was intended to demonstrate integrated systems SuperDraco performance in two times vehicle level vibro-acoustic-like for abort environments," Sanders said. Here, Sanders explains that the test was simulating the Falcon 9 rocket below the spacecraft breaking apart, and triggering an abort.

"Firing of 12 service section Dracos were successfully performed," she said, noting that the 12 smaller Draco engines used for in-space maneuvering functioned normally. "Firing of eight SuperDracos resulted in an anomaly," Sanders concluded. This suggests the anomaly occurred during or just after the SuperDraco test. Sanders also noted that SpaceX followed all safety protocols for the test and that no one was injured.

issman1The silence from Mr. Musk and Ms. Shotwell are deafening while Mr. Bridenstine is being starry-eyed. Understandable as his agency has invested so much in SpaceX.
Robert PearlmanHans Koenigsmann, SpaceX's vice president for mission assurance, said today that the cause of the April 20 Crew Dragon anomaly is not yet known.

A review of the initial data indicates that the anomaly took place during SuperDraco activation, but there is no sign that the issue is with the thrusters themselves. SpaceX has high confidence in the SuperDraco after extensive previous testing.

Robert PearlmanSpaceX release
In-Flight Abort Static Fire Test Anomaly Investigation Statement

On Saturday, April 20, 2019 at 18:13 UTC, SpaceX conducted a series of static fire engine tests of the Crew Dragon In-Flight Abort test vehicle on a test stand at SpaceX's Landing Zone 1, Cape Canaveral Air Force Station in Florida.

Crew Dragon's design includes two distinct propulsion systems – a low-pressure bi-propellant propulsion system with sixteen Draco thrusters for on-orbit maneuvering, and a high-pressure bi-propellant propulsion system with eight SuperDraco thrusters for use only in the event of a launch escape. After the vehicle's successful demonstration mission to and from the International Space Station in March 2019, SpaceX performed additional tests of the vehicle's propulsion systems to ensure functionality and detect any system-level issues prior to a planned In-Flight Abort test.

The initial tests of twelve Draco thrusters on the vehicle completed successfully, but the initiation of the final test of eight SuperDraco thrusters resulted in destruction of the vehicle. In accordance with pre-established safety protocols, the test area was clear and the team monitored winds and other factors to ensure public health and safety.

Following the anomaly, SpaceX convened an Accident Investigation Team that included officials from the National Aeronautics and Space Administration (NASA), and observers from the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB), and began the systematic work on a comprehensive fault tree to determine probable cause. SpaceX also worked closely with the U.S. Air Force (USAF) to secure the test site, and collect and clean debris as part of the investigation. The site was operational prior to SpaceX's Falcon Heavy launch of STP-2 and landing of two first stage side boosters at Landing Zones 1 and 2 on June 25, 2019.

Initial data reviews indicated that the anomaly occurred approximately 100 milliseconds prior to ignition of Crew Dragon's eight SuperDraco thrusters and during pressurization of the vehicle's propulsion systems. Evidence shows that a leaking component allowed liquid oxidizer – nitrogen tetroxide (NTO) – to enter high-pressure helium tubes during ground processing. A slug of this NTO was driven through a helium check valve at high speed during rapid initialization of the launch escape system, resulting in structural failure within the check valve. The failure of the titanium component in a high-pressure NTO environment was sufficient to cause ignition of the check valve and led to an explosion.

In order to understand the exact scenario, and characterize the flammability of the check valve's titanium internal components and NTO, as well as other material used within the system, the accident investigation team performed a series of tests at SpaceX's rocket development facility in McGregor, Texas. Debris collected from the test site in Florida, which identified burning within the check valve, informed the tests in Texas. Additionally, the SuperDraco thrusters recovered from the test site remained intact, underscoring their reliability.

It is worth noting that the reaction between titanium and NTO at high pressure was not expected. Titanium has been used safely over many decades and on many spacecraft from all around the world. Even so, the static fire test and anomaly provided a wealth of data. Lessons learned from the test – and others in our comprehensive test campaign – will lead to further improvements in the safety and reliability of SpaceX's flight vehicles.

SpaceX has already initiated several actions, such as eliminating any flow path within the launch escape system for liquid propellant to enter the gaseous pressurization system. Instead of check valves, which typically allow liquid to flow in only one direction, burst disks, which seal completely until opened by high pressure, will mitigate the risk entirely. Thorough testing and analysis of these mitigations has already begun in close coordination with NASA, and will be completed well in advance of future flights.

With multiple Crew Dragon vehicles in various stages of production and testing, SpaceX has shifted the spacecraft assignments forward to stay on track for Commercial Crew Program flights. The Crew Dragon spacecraft originally assigned to SpaceX's second demonstration mission to the International Space Station (Demo-2) will carry out the company's In-Flight Abort test, and the spacecraft originally assigned to the first operational mission (Crew-1) will launch as part of Demo-2.

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