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

[rsdavis9]

Speculation:  Shooting the rocket is one branch of the fault tree.  I suspect they wanted to rule it out by showing it would result in different signatures than observed.  This would be very hard to do analytically, so they tried it in Texas.  To their surprise, it gave exactly the same signatures as what they saw.  (Again, this is speculation...)

Could be that the shooting exercise could provide information on how rockets can fail. If just a bullet piercing the LOX tank could cause it, it seems that a piece of COPV exiting the tank would be similar. Depends if the bullet hit the fuel tank too.

I'm hoping we see a video of the bullet and oxygen tank test. If the sharpshooter selects the correct round the bullet and the aluminum should vaporize. We should then get a aluminum and oxygen explosion very much like we see in the uslaunch video. The rest is the mixing with fuel and burn.

[Rocket Science]

Is "shooting" now part of this main thread now? I'm just asking since some posts that were removed so I'm a bit confused...

[Kabloona]

Is "shooting" now part of this main thread now? I'm just asking since some posts that were removed so I'm a bit confused...

Elon reportedly said they were able to reproduce the observed phenomena by shooting a stage mockup, but they don't believe that's what caused the AMOS-6 vehicle to fail:

http://forum.nasaspaceflight.com/index.php?topic=41252.msg1598513#msg1598513

[Jet Black]

Is there anything in the rumors that this may have involved polyurethane foam? or is that something that should be restricted to the wacky thread?

[envy887]

Oxygen plus carbon plus pressure = boom.

But this would just be a spontaneous thing?  It's sitting there, then boom?

Yes, it's spontaneous. Oxidizer and fuel will autoignite once they reach a critical pressure - the exact pressure depends on the type of fuel and oxidizer, and the temperature. This is the operating principal of the diesel engine, which does not have or need an ignition source to start combustion of the fuel-air mixture.

[Jim]

We should then get a aluminum and oxygen explosion very much like we see in the uslaunch video.

What aluminum and oxygen explosion?

[rsdavis9]

We should then get a aluminum and oxygen explosion very much like we see in the uslaunch video.

What aluminum and oxygen explosion?

In the case of a bullet which vaporizes itself and target upon collision. Supposedly something spacex did at mcgregor. You should get a oxy aluminum explosion.
Maybe that would look similar to what we see in the uslaunch explosion. In the case of the static fire when a copv goes thru the oxygen tank is there a aluminum/oxygen ignition?

[rsdavis9]

Oxygen plus carbon plus pressure = boom.

But this would just be a spontaneous thing?  It's sitting there, then boom?

Yes, it's spontaneous. Oxidizer and fuel will autoignite once they reach a critical pressure - the exact pressure depends on the type of fuel and oxidizer, and the temperature. This is the operating principal of the diesel engine, which does not have or need an ignition source to start combustion of the fuel-air mixture.

But from what I know about diesels is that the pressure raises the temperature to the ignition point for diesel fuel.

So in the case of carbon or urethane with lox is it the pressure or temperature rise from the pressure that ignites?

[Rocket Science]

Is "shooting" now part of this main thread now? I'm just asking since some posts that were removed so I'm a bit confused...

Elon reportedly said they were able to reproduce the observed phenomena by shooting a stage mockup, but they don't believe that's what caused the AMOS-6 vehicle to fail:

http://forum.nasaspaceflight.com/index.php?topic=41252.msg1598513#msg1598513

Ok, thanks!

[Kabloona]

Is there anything in the rumors that this may have involved polyurethane foam? or is that something that should be restricted to the wacky thread?

You may be referring to this post, which says urethane adhesive (rather than epoxy) is the "glue" that holds the carbon fibers together in the COPV overwrap. (If you've ever used the original amber-colored Gorilla Glue, that's urethane adhesive.)

http://forum.nasaspaceflight.com/index.php?topic=41252.msg1598604#msg1598604

[HMXHMX]

Is there anything in the rumors that this may have involved polyurethane foam? or is that something that should be restricted to the wacky thread?

You may be referring to this post, which says urethane adhesive (rather than epoxy) is the "glue" that holds the carbon fibers together in the COPV overwrap. (If you've ever used the original amber-colored Gorilla Glue, that's urethane adhesive.)

http://forum.nasaspaceflight.com/index.php?topic=41252.msg1598604#msg1598604

For clarification, it is not urethane foam.  It is polyurethane adhesive, such as is used by the automotive industry to manufacture composite bumpers for automobiles – just as epoxy is used in conventional carbon-epoxy structures.

[Jet Black]

Is there anything in the rumors that this may have involved polyurethane foam? or is that something that should be restricted to the wacky thread?

You may be referring to this post, which says urethane adhesive (rather than epoxy) is the "glue" that holds the carbon fibers together in the COPV overwrap. (If you've ever used the original amber-colored Gorilla Glue, that's urethane adhesive.)

http://forum.nasaspaceflight.com/index.php?topic=41252.msg1598604#msg1598604

Aah ok. I'd heart it with reference to the GSE side of things, so perhaps they had it wrong. Thanks for pointing to the relevant bit of the conversation.

[CyndyC]

  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.”

That is plain paranoia.  There always has been that threat.

Then as they say on Dancing with the Stars, Jim, you're safe.

Anyone who cares to speculate very far on this theory publicly, and happens to zero in on a real saboteur, may not be left standing just as the rocket wasn't.

However, I will be brave enough to say this. I've narrowed down my own list to only 2 who's, and ULA won't be added to my list unless I start hearing about similar events happening, such as Publix taking out a Walmart delivery truck.

[Robotbeat]

No way ULA as a company would do it. The leadership of the company are all space geeks. And no one with a financial interest (such as LM or Boeing) would be insane enough to do it, since if it were revealed, there'd be so much worse impact than just some competition with SpaceX.

People who could do it:
Authoritarian regimes, maybe. Anti-Israeli folks, maybe. Some random disgruntled person who has whipped themselves up, maybe.

I seem to remember security personnel with big guns protecting Shuttle launches. As Jim said, this isn't new. But it also isn't likely in the least.

[Herb Schaltegger]

Seriously, did anyone actually read the excerpts from the Reddit post? You're all acting as if SpaceX decided the root cause was a gun shot. Jeez, come on.

[cro-magnon gramps]

No way ULA as a company would do it. The leadership of the company are all space geeks. And no one with a financial interest (such as LM or Boeing) would be insane enough to do it, since if it were revealed, there'd be so much worse impact than just some competition with SpaceX.

People who could do it:
Authoritarian regimes, maybe. Anti-Israeli folks, maybe. Some random disgruntled person who has whipped themselves up, maybe.

I seem to remember security personnel with big guns protecting Shuttle launches. As Jim said, this isn't new. But it also isn't likely in the least.

I seem to remember foreign fishing trawlers taking an interest in the coastal waters of Florida during launches, and I suspect, though never mentioned, Coast Guard and Navy ships of America would be shadowing them... nope nothing here folks, let's move on...

[virnin]

Does oxygen expand when it freezes? Most substances do not. Water is unusual.

The compression doesn't come from the frozen oxygen crystals.  It come from pressurizing the COPV which stretches the aluminium inner skin.  Metal stretches, carbon fiber composite does not so the crystals are crushed between.

[CyndyC]

Does oxygen expand when it freezes? Most substances do not. Water is unusual.

The compression doesn't come from the frozen oxygen crystals.  It come from pressurizing the COPV which stretches the aluminium inner skin.  Metal stretches, carbon fiber composite does not so the crystals are crushed between.

How are you thinking LOX crystals would get between the liner and the carbon overwrap? They're trying to say the crystals got pressured into the overwrap weave.

[Grendal]

Speculation:  Shooting the rocket is one branch of the fault tree.  I suspect they wanted to rule it out by showing it would result in different signatures than observed.  This would be very hard to do analytically, so they tried it in Texas.  To their surprise, it gave exactly the same signatures as what they saw.  (Again, this is speculation...)

Could be that the shooting exercise could provide information on how rockets can fail. If just a bullet piercing the LOX tank could cause it, it seems that a piece of COPV exiting the tank would be similar. Depends if the bullet hit the fuel tank too.

I'm hoping we see a video of the bullet and oxygen tank test. If the sharpshooter selects the correct round the bullet and the aluminum should vaporize. We should then get a aluminum and oxygen explosion very much like we see in the uslaunch video. The rest is the mixing with fuel and burn.

I am not hoping to see a video.  I would not want to see such a thing become generally known.  It will give too many wackos ideas that I do not want to be spread around.

[LouScheffer]

Does oxygen expand when it freezes? Most substances do not. Water is unusual.

The compression doesn't come from the frozen oxygen crystals.  It come from pressurizing the COPV which stretches the aluminium inner skin.  Metal stretches, carbon fiber composite does not so the crystals are crushed between.

How are you thinking LOX crystals would get between the liner and the carbon overwrap? They're trying to say the crystals got pressured into the overwrap weave.

The idea is the that helium tank liner is colder than the freezing point of oxygen (perhaps since the tank was being loaded with very cold helium).  The LOX soaks through the overwrap, hits the cold metal liner, and freezes into a crystal(s).  Then pressurizing the tank continues, and compresses the LOX crystal against the overwrap as the tank liner expands due to increased pressure.  If the LOX was liquid, then it can squeeze out the way it came in.  But the crystal is solid and can't get out, so it gets compressed until it explodes.