Author Topic: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD (2)  (Read 542685 times)

Offline glennfish

  • Full Member
  • ***
  • Posts: 388
  • Liked: 281
  • Likes Given: 169
Thread 2 for discussion of the Falcon 9 (AMOS-6) Static Fire Failure.

Thread 1


Update to start Thread 2:

http://www.spacex.com/news/2016/09/01/anomaly-updates

Quote
September 23, 1:00pm EDT

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.



Resources:

NSF Threads for AMOS-6 : Discussion / Updates / L2 Coverage (pre-failure) /  / ASDS / Party
NSF Articles for AMOS-6 : Booster prep (1) / Booster prep (2) / Falcon 9 explodes during AMOS-6 static fire test

September 01 2016, 0907 Local (1307 UTC) : Launch vehicle (Falcon 9-29) and payload destroyed during testing at SLC-40


Failure Articles:

Static Fire Failure

Update 2 with 39A focus

Update 3 Status Update


L2

L2 SpaceX Section
L2 Coverage (post-failure)



Other SpaceX resources on NASASpaceflight:
   SpaceX News Articles (Recent)
   SpaceX News Articles from 2006 (Including numerous exclusive Elon interviews)
   SpaceX Missions Section (with Launch Manifest and info on past and future missions)
« Last Edit: 09/23/2016 10:48 PM by Chris Bergin »

Online guckyfan

  • Senior Member
  • *****
  • Posts: 6676
  • Germany
  • Liked: 1732
  • Likes Given: 1695
So the COPV but they rule out any connection with the former incident which is important.

They still want to fly again in November which sounds optimistic.


Offline kevin-rf

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8646
  • Overlooking the path Mary's little Lamb took..
  • Liked: 1113
  • Likes Given: 243
And it is on a Friday....
If you're happy and you know it,
It's your med's!

Offline rockets4life97

  • Full Member
  • ****
  • Posts: 546
  • Liked: 247
  • Likes Given: 223
It is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware.

edit: I meant narrowed the root cause to the COPV as the press release clearly states.
« Last Edit: 09/23/2016 05:52 PM by rockets4life97 »

Offline somepitch

  • Full Member
  • *
  • Posts: 172
  • Vancouver
  • Liked: 179
  • Likes Given: 407
It is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware.

On the contrary, they have not identified the root cause and are still working through the fault tree.


Offline Joaosg

Jim was right (again). SpaceX should hire Jim.

Hope they can solve the ressonance issue and launch again in the "November" timeframe

Offline PahTo

  • Full Member
  • ****
  • Posts: 1536
  • Seattle
  • Liked: 171
  • Likes Given: 513
It is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware.

Root cause has not been ID'd.  They have isolated it to a very complex subsystem (and I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7).

Offline kevin-rf

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8646
  • Overlooking the path Mary's little Lamb took..
  • Liked: 1113
  • Likes Given: 243
So the way that was worded, it did not say if it originated inside or outside of the LOX tank.

So could the first visible flash be an effect, not the cause? Common bulkhead failure before the LOX tank burst due to a sudden pressure increase in the LOX tank.
If you're happy and you know it,
It's your med's!

Offline ellindsey

  • Member
  • Posts: 43
  • New Jersey
  • Liked: 29
  • Likes Given: 0
SpaceX has taken some steps in their design to make sure that a single engine failure does not bring down the entire vehicle.  The engines have firewalls separating them from each other and the rest of the rocket, there are blowout panels to direct pressure outward, and automatic shutoff valves to isolate dead engines.  They've had one first stage engine failure that did not result in a mission failure due to this precaution.  They have however now had two mission failures related to the second stage helium system.  Would it be at all possible for them to make design changes so that a single COPV failure would not being down the rocket?  I expect it would take a major redesign of the LOX tanks to do so, but two failures with similar causes might mean that has to be done.

Offline SWGlassPit

  • I break space hardware
  • Full Member
  • ****
  • Posts: 511
  • Liked: 330
  • Likes Given: 43
SpaceX has taken some steps in their design to make sure that a single engine failure does not bring down the entire vehicle.  The engines have firewalls separating them from each other and the rest of the rocket, there are blowout panels to direct pressure outward, and automatic shutoff valves to isolate dead engines.  They've had one first stage engine failure that did not result in a mission failure due to this precaution.  They have however now had two mission failures related to the second stage helium system.  Would it be at all possible for them to make design changes so that a single COPV failure would not being down the rocket?  I expect it would take a major redesign of the LOX tanks to do so, but two failures with similar causes might mean that has to be done.

I'm not sure how you can do that without abandoning the "LOX-immersed COPV" concept entirely.  These are pretty good sized tanks, charged with a very lightweight gas at several thousand psi.  If one of those fails, chances are high that it will do so spectacularly.  If it's inside the tank, there's not much you can do.

Offline Mike_1179

  • Member
  • Full Member
  • ****
  • Posts: 557
  • New Jersey
  • Liked: 226
  • Likes Given: 50
I know we generally are not supposed to talk about what is on /r/SpaceX here but they have a thread about COPV harmonics being the root cause.  That would be a bad thing, I think.

How much performance/density would they lose if they moved the COPV tanks outside of the tank?

IF that is indeed the case, harmonics per se isn't the problem - resonance is. And resonant frequency is easy to change in a system. Those tiny lead weights around the rim of your wheels? Those are there to provide a counteracting mass to damp out resonance in your spinning wheels. So, IF the problem is a harmonic resonance in the COPV tanks (e.eg., vibrations set up in response to rapidly loading propellants, THEN the solution is equally-simple. Add a tiny bit of mass, or simply change the physical arrangement of whatever part was oscillating, to damp the vibration and prevent the resonance.

Why would this not have been seen (detected by strain gauges in the system) during filling in McGregor prior to full-duration test firing there? Even if LC-40 GSE is different and fills at a different rate, the resonant frequency of the helium system doesn't change based on the force used to excite it, right?

Offline Mike_1179

  • Member
  • Full Member
  • ****
  • Posts: 557
  • New Jersey
  • Liked: 226
  • Likes Given: 50

I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7.

CRS-7 failure was due to a strut holding the COPV failing - if they now have strain gauges (or some other method) monitoring those struts they may be able to show it wasn't that.

Offline ugordan

  • Senior Member
  • *****
  • Posts: 7504
    • My mainly Cassini image gallery
  • Liked: 1725
  • Likes Given: 377
Jim was right (again). SpaceX should hire Jim.

Sure. He must have been the only one here (and at SpaceX) to think that the high pressure helium system was the most plausible source of stored energy to drive a rapid failure...

P.S. Occam called, he wants his razor back. At least now we won't have to sift through any more pages of contrived scenarios all designed to move the failure to the strongback.
« Last Edit: 09/23/2016 06:03 PM by ugordan »

Offline cebri

  • Full Member
  • *
  • Posts: 124
  • Spain
  • Liked: 150
  • Likes Given: 86
Hopefully is not tracked to lack of good quality controls this time. I really hope this time they get to the root to the cause to the point FAA and NASA agree with the conclusions of the investigation.

Offline JamesH65

  • Full Member
  • ****
  • Posts: 791
  • Liked: 511
  • Likes Given: 8
It is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware.

Root cause has not been ID'd.  They have isolated it to a very complex subsystem (and I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7).

You don't need to understand why - you just need to read the statement which says they are unconnected. I tend to believe the engineers doing the investigating, since they have access to all the information.



Offline mme

  • Full Member
  • ****
  • Posts: 1240
  • Santa Barbara, CA, USA, Earth, Solar System, Milky Way Galaxy, Virgo Supercluster
  • Liked: 1516
  • Likes Given: 4097
I know we generally are not supposed to talk about what is on /r/SpaceX here but they have a thread about COPV harmonics being the root cause.  That would be a bad thing, I think.

How much performance/density would they lose if they moved the COPV tanks outside of the tank?
My main hesitation with this is that SpaceX just released a statement that they were still working the fault tree.  On the one hand, I expect that no matter what they will work through the entire fault tree (even if/when they determine the root cause.)  On the other, I think that if they had any level of confidence that a specific failure was the root cause they would have mentioned that in their update.
Space is not Highlander.  There can, and will, be more than one.

Online punder

  • Full Member
  • ****
  • Posts: 459
  • Liked: 361
  • Likes Given: 226
Assuming (you know what they say) it was a COPV, how extensive a redesign to replace with, what, titanium tanks?

Offline rockets4life97

  • Full Member
  • ****
  • Posts: 546
  • Liked: 247
  • Likes Given: 223
On the other, I think that if they had any level of confidence that a specific failure was the root cause they would have mentioned that in their update.

That isn't the way PR works. You say just enough to update folks, but not get ahead of the investigation team. There is a reason Elon isn't out their tweeting updates to the same extent like the last time (CRS-7). He is learning to let his communication team take the lead.

They will finalize the results when the official report comes out. From the sound of it, that could be in the next couple months. If RTF November/December is really in the cards.

Offline eriblo

  • Full Member
  • **
  • Posts: 282
  • Sweden
  • Liked: 158
  • Likes Given: 107
It is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware.

Root cause has not been ID'd.  They have isolated it to a very complex subsystem (and I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7).

You don't need to understand why - you just need to read the statement which says they are unconnected. I tend to believe the engineers doing the investigating, since they have access to all the information.
Last time they identified the root cause as "this strut broke due to bad materials/manufacturing". If they now have that strut laying bent and sooty but unbroken in a hangar I think they are allowed to state that...

Online Chris Bergin

Also consider the timing. This will have been aimed - in part - at avoiding reporters badgering Elon for an update at the IAC, allowing him to maybe make a passing reference before getting into his main speech.

Anyhoo, I think this is a good jump off point for a second thread, as thread one is way too long.

And done. Starting with the first posting of the official update and expanded the post into a resource.
« Last Edit: 09/23/2016 06:45 PM by Chris Bergin »

Tags: