Launch Pad Explosion during Static Test Fire - Sept 1 2016

[lklundin]

Oh man, Elon tweeted a link to this article: https://theringer.com/ranking-poten...-musks-spacex-venture-ff66e7e2b23f#.n9q9yjyn4

If someone wants to be blame the Russians (and they can be blamed for a lot), then I want to join the party:

A Soviet era, silent caterpillar driven submarine, on its way to Cuba, surfaced off the coast of Florida and proceeded to let Edward Snowden out on its sail. Snowden, having for once been told the truth by the Russians that the rocket would launch a satellite belonging to the greatest spying platform in the world, had been issued a single 14.5mm incendiary round and a PTRD-41 with its stock having seven notches, one for each of the German tanks it had taken out when defending the Great Motherland against Western aggression. Convinced he was once again doing his country and the free world a great service, Snowden took out the rocket and with it its dangerous payload.

"The Americans know all about collateral damage. They will understand", he said in Russian as he carved an eighth notch and handed the rifle back to the captain, who had an uncanny resemblance to the actor Sean Connery.

 

[HVM]

I hope SpXers know this doc. by heart:
Design Guidelines for Avoiding Thermo-Acoustic Oscillations in Helium Piping Systems

 

[oneday]

Does anyone know what the process would be if SpaceX cannot identify what the cause of the fault was? If they can't, how long will they continue to investigate?

 

[HVM]

Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion

WASHINGTON — SpaceX is getting closer to finding the cause of a September pad explosion that destroyed a Falcon 9, and the company’s president remains confident the vehicle will return to flight later this year. In an Oct. 9 speech at the annual meeting of the National Academy of Engineering here, SpaceX President Gwynne Shotwell suggested that the Sept. 1 accident prior to a planned static-fire test on the company’s Cape Canaveral, Florida, launch pad was not a flaw in the vehicle’s design.

“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.”

Shotwell says SpaceX “homing in” on cause of Falcon 9 pad explosion - SpaceNews.com

...Operational error... My guess is that a new tanking process (test?) led to a temperature gradient which was too large for the helium system to handle. Either by different thermal expansion rates or, if rumors are true, with thermo-acoustic oscillations.

 

[ecarfan]

“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.”

Very interesting, thanks for posting. That is a hopeful statement. Perhaps SpaceX only has to modify how they handle loading fuel to avoid a recurrence.

 

[lklundin]

My guess is that a new tanking process (test?) led to a temperature gradient which was too large

That would be awesome and plausible given both the vehicle's otherwise good track record and SpaceX's learning-by-doing driven strategy (seen f.ex. in their development of their revolutionary booster retrieval).

I have read much more worrying speculation, that the subcooled LOX could cause the surrounding atmospheric oxygen to condensate on the outside of the cryogenic parts of the rocket (the atmospheric nitrogen would have done so in a separate step, basically a distillation process), and that such a highly reactive oxygen condensate could be ignited into a fast fire by f.ex. a little spark in a relay. This would be worrying, since the LOX per design is supposed to be subcooled and since the condensation would be hard to prevent (since you don't want to sacrifice payload on insulation).

So let's see what SpaceX comes up with.

 

[Cosmacelf]

Ha! My guess all along was that it had something to do with the colder fuel they use. It will be interesting to hear the details...

 

[Grendal]

Elon Musk talking to the NRO.

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

“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.”

So they've fired a bullet at the rocket? I'm going to assume that means they did it in a computer simulation.

 

[palmer_md]

That is a whole lot of bullet proof glass to install.

 

[Model 3]

So they've fired a bullet at the rocket? I'm going to assume that means they did it in a computer simulation.

Someone hurry up and count the number of used 1. stages that Tesla should have laying around! Then we find out if it was only a computer simulation

 

[ecarfan]

So they've fired a bullet at the rocket? I'm going to assume that means they did it in a computer simulation.

I also assume Elon was referring to a virtual bullet.

 

[Cosmacelf]

So they've fired a bullet at the rocket? I'm going to assume that means they did it in a computer simulation.

Actually no, they hauled off to a remote range somewhere, hired a sharpshooter, and did a real test - according to the reddit link above, before the entire reddit subforum got wiped.

 

[oneday]

I also assume Elon was referring to a virtual bullet.

Doesn't Elon believe all bullets are virtual/simulated bullets.

 

[ccutrer]

Actually no, they hauled off to a remote range somewhere, hired a sharpshooter, and did a real test - according to the reddit link above, before the entire reddit subforum got wiped.

Wait for reals? There's no way... they'd have to willingly expend not just a first stage (even if it's a used one, it's still worth millions), but also the fueling and support structure. And that's not something you can just set up over a weekend. That would have to be their test stand in McGregor. Which they need to use between now and March (how long it's going to take to rebuild pad 40).

 

[ccutrer]

Wait for reals? There's no way... they'd have to willingly expend not just a first stage (even if it's a used one, it's still worth millions), but also the fueling and support structure. And that's not something you can just set up over a weekend. That would have to be their test stand in McGregor. Which they need to use between now and March (how long it's going to take to rebuild pad 40).

Hmmm, and thinking more, to be a true test it would be the second stage you want to hit, not a first. Which might make it slightly more plausible since it's much smaller. But no used ones of those hanging around to test with.

 

[Cosmacelf]

Well, the Reddit poster seemed quite credible (about the rifle test). I mean, look at Elon's words (which admittedly aren't a true transcript IIRC). If it was a simulation, he probably would have said as much. I have no idea though, especially since the sub Reddit was wiped, which, when you think about it, is pretty interesting in itself.

 

[Cosmacelf]

You know, when they ever do get around to make a movie of Elon's life, it'll end up being a 12 part miniseries, and all of it damn interesting!

 

[ecarfan]

Well, the Reddit poster seemed quite credible (about the rifle test). I mean, look at Elon's words (which admittedly aren't a true transcript IIRC). If it was a simulation, he probably would have said as much. I have no idea though, especially since the sub Reddit was wiped, which, when you think about it, is pretty interesting in itself.

Hmmm...I never saw what was on Reddit and didn't realize it was not a real transcript.

It's not credible to me that SpaceX would have done a real world test of the sniper theory using a real first stage, fueled up and pressurized, and shot it with a rifle in the area where the explosion occurred. That is not plausible.

 

[glhs272]

Hmmm...I never saw what was on Reddit and didn't realize it was not a real transcript.

It's not credible to me that SpaceX would have done a real world test of the sniper theory using a real first stage, fueled up and pressurized, and shot it with a rifle in the area where the explosion occurred. That is not plausible.

Hmm... perhaps they actually did this test to a second stage LOX tank. The pictures of McGregor test site sure looks like they blew something up there....

 

[Cosmacelf]

Well, first of all, it was a second stage (much smaller). And who said anything about doing the test in the vicinity of the first explosion? Anyways, I'm not trying to convince anyone. Just reporting what I read.