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SpaceX Return to Fight and what was the anomaly

Discussion in 'SpaceX' started by Grendal, Sep 13, 2016.

  1. Grendal

    Grendal Active Member

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    I'm posting a more optimistic thread with real answers (or the best they can determine) from SpaceX as to what caused the anomaly and the progress for a Return to Flight (RTF).

    First information from SpaceX on RTF:

    Peter B. de Selding on Twitter

    Peter B. de Selding‏@pbdes 2h2 hours ago

    SpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.

    So SpaceX is moving forward and will use Pad 39A and Vandenberg for launches until SLC-40 can be repaired.

    A further comment from Gwynne: Nov return to flight is our best hope. We still haven't isolated the cause or whether its origin was rocket or ground.
     
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  2. Att1cus

    Att1cus Member

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    Thanks for the update. Great to hear F9 will return to flight this year. I'm very curious to know the root cause on this one.
     
  3. ecarfan

    ecarfan Well-Known Member

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    Thanks for the update! Very mysterious. Nothing about the cause of the explosion but if their launch customers and insurers are willing then they must have given them some news.

    Anyway, I'm glad that the F9 will be flying again soon!
     
  4. RDoc

    RDoc S85D

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    Unfortunately she said a few moments later that that was a hope and they still didn't know what the problem was.
     
  5. Cosmacelf

    Cosmacelf Active Member

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  6. oneday

    oneday Member

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    Seeing as they couldn't figure out the anomaly seems to me next launch might as well be ses10 on an already proven booster. J/S
     
  7. HVM

    HVM Savolainen

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    Anomaly Updates

    September 23, 1:00pm EDT

    Anomaly Updates

    "Three weeks ago, SpaceX experienced an anomaly at our Launch Complex 40 (LC-40) at Cape Canaveral Air Force Station. This resulted in the loss of one of our Falcon 9 rockets and its payload.

    The Accident Investigation Team (AIT), composed of SpaceX, the FAA, NASA, the U.S. Air Force, and industry experts, are currently scouring through approximately 3,000 channels of engineering data along with video, audio and imagery. The timeline of the event is extremely short – from first signs of an anomaly to loss of data is about 93 milliseconds or less than 1/10th of a second. The majority of debris from the incident has been recovered, photographed, labeled and catalogued, and is now in a hangar for inspection and use during the investigation.

    At this stage of the investigation, preliminary review of the data and debris suggests that a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place. All plausible causes are being tracked in an extensive fault tree and carefully investigated. Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.

    The teams have continued inspections of LC-40 and the surrounding facilities. While substantial areas of the pad systems were affected, the Falcon Support Building adjacent to the pad was unaffected, and per standard procedure was unoccupied at the time of the anomaly. The new liquid oxygen farm – e.g. the tanks and plumbing that hold our super-chilled liquid oxygen – was unaffected and remains in good working order. The RP-1 (kerosene) fuel farm was also largely unaffected. The pad’s control systems are also in relatively good condition.

    SpaceX’s other facilities, from the Payload Processing Facility at the Cape, to the pad and hangar at LC-39A, are located several miles from LC-40 and were unaffected as well. Work continues at Pad 39A in preparation for bringing it online in November. The teams have been in contact with our Cape Canaveral and Kennedy Space Center partners and neighbors and have found no evidence of debris leaving the immediate area of LC-40.

    At SpaceX headquarters in Hawthorne, CA, our manufacturing and production is continuing in a methodical manner, with teams continuing to build engines, tanks, and other systems as they are exonerated from the investigation. We will work to resume our manifest as quickly as responsible once the cause of the anomaly has been identified by the Accident Investigation Team. Pending the results of the investigation, we anticipate returning to flight as early as the November timeframe.

    Other efforts, including the Commercial Crew Program with NASA, are continuing to progress. Getting back to flight safely and reliably is our top priority, and the data gathered from the present investigation will result in an even safer and more reliable vehicle for our customers and partners."
     
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  8. ecarfan

    ecarfan Well-Known Member

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    Thanks for posting that. I tentatively interpret that to mean that the 2nd stage LOX tank cooling system (not the LOX tank itself) suffered a mechanical failure, a rupture. Since helium is not combustible, is it possible that the rupture produced fragments of material that were propelled into the LOX tank causing it to rupture which resulted in the explosion?

    My next question is, was the cryogenic helium system failure caused by a spontaneous failure of a component of that system within the rocket, or was it caused by a force from outside the rocket? Apparently SpaceX has not yet determined that, or if they have they didn't mention it in their news release.
     
  9. thegruf

    thegruf Member

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    How can Spacex conceivably launch again if ...

    "a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place"

    surely the root cause of that failure has to be identified to eliminate it for the future?

    I want SpaceX to succeed and get back to flight soon as much as anyone else here, but is there something not being said, any potential failure within the rocket itself or indeed shore based failure, just has to be conclusively tested and I don't see how that can happen in these timescales.

    All the best to SpaceX nonetheless.
     
  10. HVM

    HVM Savolainen

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    This is 2nd stage's LOX tank. Arrows point the struts and black thing in between is a helium bottle: Composite overwrapped pressure vessel (COPV)

    741dc2bcf5762a48.jpg
    There is no cooling system, just sheer volume LOX is keeping it cool. Exec. boiling oxygen is vented out. Helium is mainly there for propellant tank(s) pressurization (and for separation systems etc.). Also LOX is keeping helium in cryogenic state for better density. Pure pneumatic force of COPV breach (~x000 psi) is enough to breach the LOX tank's walls and common bulkhead. Although exploding COPV is not short of fragments:
    2014 incident may provide clue to cause of SpaceX Falcon 9 failure
     
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  11. HVM

    HVM Savolainen

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    There is no simple reason yet. Vibrations during tanking process and the helium system's resonance frequencies, e.g. "weird harmonics" are rumored be the cause...
     
  12. Grendal

    Grendal Active Member

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    Does anyone know if SpaceX actually makes their own COPV's? The consensus on Facebook seems to be that SpaceX buys these vessels from the same vendors as ULA and other launch companies. They have been thoroughly tested by NASA in the past as possible problem issues. I know that SpaceX prefers to make everything in house so it is possible that they are making these things themselves.

    Composite overwrapped pressure vessel - Wikipedia, the free encyclopedia
     
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  13. Doug_G

    Doug_G Lead Moderator

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    A rupture of the helium tank would cause an overpressure of the LOX tank, causing it to fail in turn. That's what happened in the previous launch incident, though due to a different root cause.

    It would be an internal cause. Something failed.
     
  14. Nikxice

    Nikxice Member

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    If SpaceX has narrowed the anomaly to a fuel tank, this might be the one to have. Would seem simpler and quicker to engineer a fix for a large breach in a small helium tank rather than a small breach in a large LOX tank. They'll certainly be looking back on all the the previous QC inspections on every one of these tanks and system components.

    The in flight oxygen tank failure during the Apollo 13 mission was traced back to technicians that had accidentally dropped it a mere two inches. Future tanks were redesigned. Hope this can become SpaceX's version of a successful failure!
     
  15. ecarfan

    ecarfan Well-Known Member

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    Thanks to everyone for their comments, I'm learning a lot. If the cryogenic helium COPV ruptured that then ruptured the LOX tank and then...a big mess.

    So it sounds like SpaceX has narrowed down the cause of the explosion to the helium tank failing, now they have to figure out why it failed. Which could be very difficult to do. But at least they have something to focus on.

    The photo of the inside of the LOX tank that @HVM posted is certainly strange looking. The helium COPV looks like it is built into the sidewall of the LOX tank?
     
  16. ggr

    ggr Roadster R80 537, SigS P85 29

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    I'd say "onto" rather than "into", but yes. Remember, there's no "LOX tank" as such. The side walls of the tank are the outside of the rocket, so everything inside, like wiring, goes through the tank.
     
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  17. HVM

    HVM Savolainen

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    COPV after orbital reentry:
    IMAG0013.JPG
    Upper stage's (LOX tank's) walls are behind slosh baffles and are barely visible:
    lox_tank.jpg
    Wires and pipes not needed inside tank(s), are installed outside...
    wiring_pipes.jpg
     
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  18. ecarfan

    ecarfan Well-Known Member

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    Okay, understand. Interesting.

    And that photo of the COPV tank after it came back to earth, surviving atmospheric heating, wow! Those things are tough.
     
  19. Grendal

    Grendal Active Member

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    Elon talking to the NRO:

    Details from Elon's speech at the NRO • /r/spacex

    Addressing the anomaly:

    “We are close to figuring it out. It might have been formation of solid oxygen in the carbon over-wrap of one of the bottles in the upper stage tanks. If it was liquid it would have been squeezed out but under pressure it could have ignited with the carbon. This is the leading theory right now, but it is subject to confirmation. The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket. We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.”

    Addressing return to flight:

    “The plan is to get back to launch in early December and that will be from pad 39A at the Cape and we will be launching around the same time from Vandenberg as well. Pad 40 will probably be back in action around March or April next year. Probably around May or so is when we will launch Falcon Heavy. We are going to re-fly the first returned core December or January. We have test fired one of the returned cores 8 times and it looks good. That is promising for testing re-flight.”

    Other interesting points:

    -3D printing works fine for super-dracos, but too much work is needed to make it feasible on Raptors.

    -Elon envisions Mars as a direct democracy, not a representative democracy.

    -Still wants communication satellite constellation to provide revenue for Mars.

    -In talking about the IAC, “Crazy people are a lot faster to the mic than scientists.”

    Lots of good information.... Elon is optimistic and he thinks December RTF. Let's hope.
     
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  20. GoTslaGo

    GoTslaGo Learning Member

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    The top comment from the link has a great explanation about the solid oxygen and how it may have caused the explosion.

    Sorry I can't seem to copy and paste anymore on my IPad after IOS update...
     
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