SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD (2)

[Geron]

Does anyone have link to shotwell talk October 9?

[ChrisWilson68]

And let's not forget Shuttle was eventually shut down after the inherent risk in its design made further operation outrageously expensive.

I believe Shuttle was shut down because a review board wanted the shuttle to be re-certified which made it expensive.

Incorrect.  Review boards don't have the power to require anything.  They can only write recommendations.

The shut-down was a political decision of the president and Congress.

[Space Ghost 1962]

... SpaceX blew up the rocket by doing something different in the Hotfire on September 1 that they had not done in prior tests and launches. Either they changed procedures or there was a procedural error.

... or there was a case that wasn't anticipated in a new vehicle's procedures that had unintended consequences.

[MP99]

And let's not forget Shuttle was eventually shut down after the inherent risk in its design made further operation outrageously expensive.
Ariane got fixed and it cost them lots of work on the Vinci 2 engine to do so and pretty much testing, too.
Things that SpaceX will now have to do, too, and which will obviously add to their cost structure as well.

Shuttle had a crew, but no LAS.

Cheers, Martin

[Jet Black]

... SpaceX blew up the rocket by doing something different in the Hotfire on September 1 that they had not done in prior tests and launches. Either they changed procedures or there was a procedural error.

... or there was a case that wasn't anticipated in a new vehicle's procedures that had unintended consequences.

how well is the physics of subcooled LOX understood, compared to normal LOX?

[spacekid]

And let's not forget Shuttle was eventually shut down after the inherent risk in its design made further operation outrageously expensive.

I believe Shuttle was shut down because a review board wanted the shuttle to be re-certified which made it expensive.

Incorrect.  Review boards don't have the power to require anything.  They can only write recommendations.

The shut-down was a political decision of the president and Congress.

I did not say they required it. They wanted it (recommendation) and the President and Congress going along with it made it expensive.

[woods170]

Get back on track please. Shuttle, LAS and political decisions to kill shuttle are all very much OFF-TOPIC to this thread.

Thank you.

[Norm38]

Why is the COPV filled before the oxygen tank is? After the oxygen cools the helium, you'd need to do much more He filling since the tank would have depressurized with the lower temperatures. Unless the He is precooled to the expected  60K tank temperature even before LOX is loaded. But if that's true then all the theories here mentioning  heat stress, thermoacoustic hammers, and temperature gradients are  invalid.

Take an empty 2 liter bottle, cap it, put it in the freezer. Then examine the result. Don't want to do that to the helium system.

[Googulator]

Sdoes helium expand as it freezes? IIRC water is one of the few substancea to do that.

[ames]

I'm sure the empty (vacuum) He system can withstand negative ~15 psi (sea level atmospheric pressure)

[envy887]

Sdoes helium expand as it freezes? IIRC water is one of the few substancea to do that.

There's no frozen helium anywhere in the Falcon or it's ground support systems.

[SWGlassPit]

I'm sure the empty (vacuum) He system can withstand negative ~15 psi (sea level atmospheric pressure)

Maybe.  I wouldn't be so sure.  Fiber-wound pressure vessels use high-strength fibers to resist tensile loads associated with high pressure.  These slender fibers cannot resist compressive loads (you can't push a rope).  Consequently, pretty much all of the resistance to negative pressure would be provided by the epoxy matrix and the liner.  If the COPV is autofrettaged, the liner will already be under compression at zero pressure, so the additional negative 15 psi is probably not a huge difference.  Depending on other environmental factors, though, you could see debonding or delamination of the composite material.

My take: probably not a huge deal, but it's not what they were designed for, so I can't say "I'm sure" about it.

[Navier–Stokes]

Full quote from Jeff Foust's summary article on SpaceNews (Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion):

“We’re homing in on what happened,” she said. “I think it’s going to point not to a vehicle issue or an engineering design issue but more of a business process issue.”

Note: emphasis mine.

[Jim]

Full quote from Jeff Foust's summary article on SpaceNews (Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion):

“We’re homing in on what happened,” she said. “I think it’s going to point not to a vehicle issue or an engineering design issue but more of a business process issue.”

Note: emphasis mine.

Meaning what? Trying to save a little time in the countdown to shorten the launch campaign?  Doing something to save some time/money?  Who is in charge of making such decisions.  And what was the risk vs reward?  As for not being a vehicle or an design issue, it is something worse, it is a cultural issue.  What other "short cuts" are being done without rigorous engineering review.

She used some bad words there

[pippin]

Full quote from Jeff Foust's summary article on SpaceNews (Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion):

“We’re homing in on what happened,” she said. “I think it’s going to point not to a vehicle issue or an engineering design issue but more of a business process issue.”

Note: emphasis mine.

Am I the only one thinking that's actually worse news for SpaceX than a vehicle issue?
I mean: a vehicle issue is something you find and then fix. Happens.

But business processes is where SpaceX see their competitive advantage. They claim due to their leaner business processes they can be more cost effective than OldSpace.

If these leaner business processes now turn out to cause mission or payload losses it means they will have to change them, probably for something more expensive.
That may gradually move their cost structure towards OldSpace's and might simply mean there's sometimes a reason others are doing things they way they are doing them...

[Mike_1179]

From the Update Thread:

Full quote from Jeff Foust's summary article on SpaceNews (Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion):

“We’re homing in on what happened,” she said. “I think it’s going to point not to a vehicle issue or an engineering design issue but more of a business process issue.”

Note: emphasis mine.

Meaning what? Trying to save a little time in the countdown to shorten the launch campaign?  And what was the risk vs reward?  As for not being a vehicle or an design issue, it is something worse, it is a something worst, it is a cultural issue.  What other "short cuts" are being done without rigorous engineering review.

Jim brings up a really good point - I don't want it to get lost if there's discussion over in the Update thread.

Wayne Hale wrote a few days ago about asking "why" seven times as part of a root cause investigation. Identifying the proximate cause is good, but if the underlying defects that allowed it to happen without being caught are fixed, then you're just waiting for another failure to happen.

Not stating that this was the case, just curious however about what sort of cultural / procedural actions can cause a company to miss something like we discussed above (thermo-acoustic resonance coupling to mechanical resonance)?

[meekGee]

Well since nobody knows what "business process" she's talking about, what's the point second guessing her, and then attacking the very speculation you just made as if it were fact?

[envy887]

From the Update Thread:

Full quote from Jeff Foust's summary article on SpaceNews (Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion):

“We’re homing in on what happened,” she said. “I think it’s going to point not to a vehicle issue or an engineering design issue but more of a business process issue.”

Note: emphasis mine.

Meaning what? Trying to save a little time in the countdown to shorten the launch campaign?  And what was the risk vs reward?  As for not being a vehicle or an design issue, it is something worse, it is a something worst, it is a cultural issue.  What other "short cuts" are being done without rigorous engineering review.

Jim brings up a really good point - I don't want it to get lost if there's discussion over in the Update thread.

Wayne Hale wrote a few days ago about asking "why" seven times as part of a root cause investigation. Identifying the proximate cause is good, but if the underlying defects that allowed it to happen without being caught are fixed, then you're just waiting for another failure to happen.

Not stating that this was the case, just curious however about what sort of cultural / procedural actions can cause a company to miss something like we discussed above (thermo-acoustic resonance coupling to mechanical resonance)?

The main "business procedure" type issue I can think of is running new operations with the customer's payload mounted. I get that they want to test any procedural "tweaks" in as close to operational conditions as possible, but then do the static fire without the bird on top.

I also don't like that they didn't find this earlier at McGregor. Sounds to me like they implemented operational changes on the static fire without adequately testing them on the test stand.

[Jim]

Well since nobody knows what "business process" she's talking about, what's the point second guessing her, and then attacking the very speculation you just made as if it were fact?

Ok, then spin it another way to make it a positive thing that she said

[D_Dom]

  If the COPV is autofrettaged, the liner will already be under compression at zero pressure,

Not sure what you mean here. Guessing is not within my comfort zone but in your context is "autoclaved" a good term?