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SpaceX – Launch Vehicle Failure

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Re: SpaceX – Launch Vehicle Failure

#311

Post by GreenPlastic »

demachina wrote: post #305
hackuser wrote: post #289

Earlier quoted context omitted.

> it is fair to note that this is the "current generation" Atlas and Delta. The first Atlas was used during the Mercury program, so they've had more than 50 years of design refinement to get to that point. This perspective surprises me. From my perspective, I wonder why it matters to me how long SpaceX has had to design their rocket? Wouldn't I prefer the one with 50 years of refinements? Someone else posted a simila…

The SpaceX design should be dramatically suprior to the aging Atlas and Delta designs because they are designed to be cheaper to build in the first place and they will be game changing if they manage to land the first stage and immediately turn it around for multiple launches. Atlas and Delta are certainly good platforms for high reliability but they are expensive and they aren't making much effort to bring the costs…

ULA is already dead in the water. The only reason why they're around is because of the monopoly they have with US military launches.

Re: SpaceX – Launch Vehicle Failure

#312

Post by grinich »

TeMPOraL wrote: post #303
51Cards wrote: post #179

From Elon just now via Twitter: "There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause. That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis."

I wonder if "overpressure event" is a significant information, or is it just an euphemism for "explosion"?

Usually they call those RUD, or "rapid unplanned disassembly." ;)

I imagine this was literally an overpressure event, where perhaps something occurred with the 2nd stage tank mixers. (The explosion occurred close to MECO.)

Re: SpaceX – Launch Vehicle Failure

#313

Post by phkahler »

51Cards wrote: post #179

From Elon just now via Twitter: "There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause. That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis."

>> "That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis."

You're supposed to do the fault tree analysis before you build the rocket Elon. The safety critical systems on your car have these done. Or perhaps they never did one for over pressure because it seems implausible for the pressure to increase.

Re: SpaceX – Launch Vehicle Failure

#314

Post by 001sky »

TrevorJ wrote: post #229
001sky wrote: post #189

Earlier quoted context omitted.

The lack of fragmentation from the first event suggests event #2 would have been range control. 23:44 23:52 https://www.youtube.com/watch?v=ZeiBFtkrZEw&t=23m38s

They said in the press conference that it wasn't a commanded event.

Press conference said that range safety didn't command the FTS (flight termination system) and there is no data (yet) that FTS enabled, but that's doesn't mean the on-board FTS didn't activate itself. It certainly looked like a controlled explosion...

Comment from Reddit that may be useful.

https://www.reddit.com/r/space/comments/3bejxp/spacex_crs7_h...

Re: SpaceX – Launch Vehicle Failure

#315

Post by phkahler »

danbruc wrote: post #63
n_coats wrote: post #49

Earlier quoted context omitted.

I saw two big puffs of smoke and initially thought it was the boosters releasing.

On the video it looked to me like a tank ruptured somewhere in the top half of the rocket, probably the second stage, and set free all the fuel. The rocket kept its course for some time until it suddenly disintegrated.

I was impressed with how long the first stage kept going with all that happening up above.

Re: SpaceX – Launch Vehicle Failure

#316

Post by hackuser »

GreenPlastic wrote: post #311
demachina wrote: post #305

Earlier quoted context omitted.

The SpaceX design should be dramatically suprior to the aging Atlas and Delta designs because they are designed to be cheaper to build in the first place and they will be game changing if they manage to land the first stage and immediately turn it around for multiple launches. Atlas and Delta are certainly good platforms for high reliability but they are expensive and they aren't making much effort to bring the costs…

ULA is already dead in the water. The only reason why they're around is because of the monopoly they have with US military launches.

Looking at SpaceX's and Orbital Science's recent performances, ULA seems to be in good shape.

Re: SpaceX – Launch Vehicle Failure

#317

Post by [deleted] »

phkahler wrote: post #313
51Cards wrote: post #179

From Elon just now via Twitter: "There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause. That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis."

>> "That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis." You're supposed to do the fault tree analysis before you build the rocket Elon. The safety critical systems on your car have these done. Or perhaps they never did one for over pressure because it seems implausible for the pressure to increase.

[deleted]

Re: SpaceX – Launch Vehicle Failure

#318

Post by fnordfnordfnord »

hackuser wrote: post #249

Costs and catastrophic failures:[1] * United Launch Alliance (Boeing and Lockheed Martin): 0 "outright failures" and 83 successful launches, ~$110 million/launch * SpaceX: 1 failure and 18 successful launches, $60 million/launch If you are looking for someone to launch your assets into orbit, who do you choose? [1] http://www.cbsnews.com/news/spacex-falcon-9-rocket-destroyed...

>If you are looking for someone to launch your assets into orbit, who do you choose?

The first thing you do is be very glad that you have a choice. Then you can start price shopping. If there is only one domestic option, then you either pay what the sole-source wants, or you pursue international options if those are available to you, many times they will not be.

Re: SpaceX – Launch Vehicle Failure

#319

Post by robzyb »

phkahler wrote: post #313
51Cards wrote: post #179

From Elon just now via Twitter: "There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause. That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis."

>> "That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis." You're supposed to do the fault tree analysis before you build the rocket Elon. The safety critical systems on your car have these done. Or perhaps they never did one for over pressure because it seems implausible for the pressure to increase.

> You're supposed to do the fault tree analysis before you build the rocket Elon.

How can you do a fault tree analysis before things go wrong?

Maybe fault tree analysis means something different to you.

According to Wikipedia, it is "a top down, deductive failure analysis in which an undesired state of a system is analyzed using Boolean logic to combine a series of lower-level events."

There needs to be an undesirable (and presumably unforeseen) state to be analysed before you do the fault tree analysis.

Re: SpaceX – Launch Vehicle Failure

#320

Post by HeyLaughingBoy »

robzyb wrote: post #319
phkahler wrote: post #313

Earlier quoted context omitted.

>> "That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis." You're supposed to do the fault tree analysis before you build the rocket Elon. The safety critical systems on your car have these done. Or perhaps they never did one for over pressure because it seems implausible for the pressure to increase.

> You're supposed to do the fault tree analysis before you build the rocket Elon. How can you do a fault tree analysis before things go wrong? Maybe fault tree analysis means something different to you. According to Wikipedia, it is "a top down, deductive failure analysis in which an undesired state of a system is analyzed using Boolean logic to combine a series of lower-level events." There needs to be an undesirabl…

I'm no Risk expert, but going from memory, you hypothesize potential failures based on experience and knowledge of the module. Then you use the FTA to understand what faults may result in the failures under examination.

FTA can be used either pre- or post- event.

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