Author Topic: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD (1)  (Read 1190855 times)

Offline Kabloona

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #580 on: 09/01/2016 08:32 PM »
Wise words from Jeff Foust.

Quote
1h1 hour ago
Jeff Foust ‏@jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.

Offline wtrix

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #581 on: 09/01/2016 08:32 PM »
One more nail to the coffin of FTS theory. FTS consists of small linear charge designed to rupture the pressure vessel. It is not designed to explode into a giant fireball 30 feet across in a split second.

There's a remote possibility that FTS initiated on charge detonator level and this caused fuel-air explosion nearby in a very unlikely event. But in order this to happen very unlikely things have to happen.
« Last Edit: 09/01/2016 08:34 PM by wtrix »

Offline ugordan

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #582 on: 09/01/2016 08:32 PM »
Made a little gif. Don't know how accurate it is:


It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.

That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.

Online ellindsey

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #583 on: 09/01/2016 08:35 PM »
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage.  This failure was too localized to be FTS.
That exactly looks like what happened. The whole stack just exploded really fast.
No, it doesn't.  There was a very bright and fast event on the second stage near the oxygen tank.  That opened the kerosene tank, and then the burning fuel and debris falling downward tore apart and ignited the first stage.  A FTS trigger would have been simultaneous on the first and second stages, not starting on the second stage and then proceeding downward like this was.

Offline SWGlassPit

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #584 on: 09/01/2016 08:36 PM »
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage.  This failure was too localized to be FTS.
That exactly looks like what happened. The whole stack just exploded really fast.

It really didn't.  There was a localized explosion in the second stage with a relatively slow progressive failure down the stack.  If it was FTS, the whole vehicle would have ceased to exist in the span of two or three frames.

Offline wtrix

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #585 on: 09/01/2016 08:36 PM »
Made a little gif. Don't know how accurate it is:


It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.

That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.

Sorry, but in this case, those spikes (actually in-lens reflections) show the average center of the oversaturated fireball. Nothing else.

Offline intrepidpursuit

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #586 on: 09/01/2016 08:37 PM »
The biggest thing I don't understand is what is the ignition source? Even if the O2 tank had an overpressure, underpressure, or any other failure mode, why would the first thing we see be blinding fire? Some static or something would probably catch it eventually, but without the engines running you could mix O2 and RP-1 and it would still not self detonate.

Am I missing something? I realize my optimism toward SpaceX might make me favor the least damaging outcome, but I just don't see how anything other than an explosive charge could have detonated so quickly. TEA-TEB or hypergolics could easily cause a bad day, but they don't appear to have been involved unless they were being loaded into S2 by the umbilical at the time.

Offline mlindner

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #587 on: 09/01/2016 08:39 PM »
Wise words from Jeff Foust.

Quote
1h1 hour ago
Jeff Foust ‏@jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.

Agreed, thus why I explicitly put a low emphasis in my post.
Internal combustion engine in space. It's just a Bad Idea.TM - Robotbeat

Offline mlindner

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #588 on: 09/01/2016 08:40 PM »
Made a little gif. Don't know how accurate it is:


It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.

That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.

Yes this was exactly what I was doing (I was still reading 20 pages back at the time and hadn't seen the gif yet).
Internal combustion engine in space. It's just a Bad Idea.TM - Robotbeat

Offline iamlucky13

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #589 on: 09/01/2016 08:40 PM »

FH is worst case equivalent to 196 tons of TNT. The HIF is 1900 feet from LC-39A, and at that range the only effect should be some broken windows, and possibly some falling flamey bits - but neither are likely to cause major damage to a steel building or anything reasonably sturdy inside it.

There's not really a practical way to get a similar burn rate of separate fuel and oxidizers as you get for TNT. Most of that energy is, as can be seen, is consumed in deflagration, not detonation, so the worst case is not nearly as bad as the TNT equivalent.

That said, according to HYDEsim, 0.2 kT of TNT can damage buildings 1900 feet away, but in this case we're talking about LC-40. The hangar for LC-40 is much closer than that, isn't it?
http://meyerweb.com/eric/tools/gmap/hydesim.html?dll=28.56212,-80.57729&mll=28.56246,-80.57759&yd=0.2&zm=15&op=156

I'm going to speculate wildly here (Mod, please delete if inappropriate);

Point 1; The CRX7 failure occurred in the second stage.
Point 2; This explosion *appears* to have originated in the second stage.

Speculation: to my eyes, this event appears to have been highly energetic from the first moment it appears.

Further speculation; would a COPV failure (sudden release of He into the LOX) fit observations?

You are not the first person to suspect this. In my opinion, it appears consistent with overpressurization, but a problem with GSE  or the valve that handles boiloff might also result in overpressurization.

The CRS-7 failure is believed to have been due to buoyant forces under several G's of loading. The buoyant forces while on the pad are far lower. Even if it was a COPV failure, I would be surprised if it was due to tank buoyancy breaking a strut.

Regardless, don't get too attached to the theory. For almost every high-visibility aerospace accident like this, there's usually half a dozen reasonable-sounding theories proposed early on. Most (sometimes all) of them turn out to be wrong.

Some notes:
1. There's no similarity to CRS-7 event. "Excessive venting" that some people claim here is probably mostly due to the fact that surrounding air was almost saturated with moisture. Pressure vessel overpressure rupture would have caused massive cloud initially, which then would have perhaps detonated. Not the other way around.

A failure of the common bulkhead would have allowed ignition to begin inside the tank.

Watching this in slow motion, it appears that in the first frame with fire that there is a long downward finger of flame and smoke that dissipates as the fire ball erupts.  Is there an umbilical that could have come off and sprayed something downward?

I originally had a similar thought, but the speed of the explosion progression makes me think more likely its due to the tanks failing along a vertical seam (either initial, or after a bulkhead failure). That is why I've started leaning towards over-pressurization, although I'm pondering whether an accidental FTS activation would look the same. A partial vehicle FTS firing seems extremely unlikely, but not completely impossible.

Offline wtrix

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #590 on: 09/01/2016 08:41 PM »
Wise words from Jeff Foust.

Quote
1h1 hour ago
Jeff Foust ‏@jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.

Agreed, thus why I explicitly put a low emphasis in my post.

BTW, this applies to all amateur accident investigations.

Offline Kabloona

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #591 on: 09/01/2016 08:41 PM »
Wise words from Jeff Foust.

Quote
1h1 hour ago
Jeff Foust ‏@jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.

Agreed, thus why I explicitly put a low emphasis in my post.

I wasn't singling you out; that was for all of us, me included. ;-)

Offline ugordan

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #592 on: 09/01/2016 08:42 PM »
Made a little gif. Don't know how accurate it is:


It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.

That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.

Sorry, but in this case, those spikes (actually in-lens reflections) show the average center of the oversaturated fireball. Nothing else.

Sorry, but there is oversaturation and then there is oversaturation. According to you, those spikes should simply be as wide as the whited-out region, which is clearly not the case. My point is that it takes even more light intensity to produce spiking than it takes to saturate the detector at a region and that it was reasonable to assume that the highest physical brightness point corresponds to the point of origin. The spikes convey additional useful information about the brightness profile above the whited-out region precisely because they are more tightly constrained.
« Last Edit: 09/01/2016 08:44 PM by ugordan »

Offline SWGlassPit

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #593 on: 09/01/2016 08:42 PM »
The biggest thing I don't understand is what is the ignition source? Even if the O2 tank had an overpressure, underpressure, or any other failure mode, why would the first thing we see be blinding fire? Some static or something would probably catch it eventually, but without the engines running you could mix O2 and RP-1 and it would still not self detonate.

Am I missing something? I realize my optimism toward SpaceX might make me favor the least damaging outcome, but I just don't see how anything other than an explosive charge could have detonated so quickly. TEA-TEB or hypergolics could easily cause a bad day, but they don't appear to have been involved unless they were being loaded into S2 by the umbilical at the time.

If the fuel-oxygen mix is right, it only takes a tiny spark.  Electrostatic discharge, a momentary arc from a switch opening or closing, really anything.  If you read the history (don't have a link handy, but it's out there) of when they built LC-39A, they had a LOX leak at the pad one day and discovered it when people's cars started bursting into flame.

Offline vanoord

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #594 on: 09/01/2016 08:42 PM »
Sorry, but in this case, those spikes (actually in-lens reflections) show the average center of the oversaturated fireball. Nothing else.

Albeit there's probably a correlation between the centre of the lens flare, the brightest point of the image - and by derivation the hottest point of the fireball, which - given there's about 1/30 of a second between the start of the event and the explosion / lens flare - has a very good chance of being the initial point at which the event occurred.

Occam's Razor; or "if it look like a duck and quacks like a duck, then it probably is a duck".

*Why* it's a duck is a bit more problematic. The video footage almost certainly gives us the location of the failure - but certainly not the cause.

Offline Moderas

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #595 on: 09/01/2016 08:43 PM »
The vehicle is sitting in a cloud of concentrated, evaporating oxygen and is holding thousands of kilograms more on board. A small leak and a spark is all that is needed to cause an event big enough to rupture the tanks leading the chain reaction. Oxygen is abundant in this scenario - we don't need an explosive to turn the situation bad.

Offline intrepidpursuit

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #596 on: 09/01/2016 08:44 PM »
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage.  This failure was too localized to be FTS.
That exactly looks like what happened. The whole stack just exploded really fast.

It really didn't.  There was a localized explosion in the second stage with a relatively slow progressive failure down the stack.  If it was FTS, the whole vehicle would have ceased to exist in the span of two or three frames.

FTS isn't designed to obliterate the vehicle as much as it is to release the fuel to get rid of its mass, momentum, and explosive potential. When we've seen FTS before it causes a slow conflagration fireball just like we see here after that initial pop at the top of S2. It looked very much like the fireball we saw on GH2, although with a much better vantage point to see details.

For those saying FTS wouldn't cause a fireball, well, what other ignition source was there? We didn't see a green flash.

Offline Robotbeat

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #597 on: 09/01/2016 08:45 PM »
The biggest thing I don't understand is what is the ignition source? Even if the O2 tank had an overpressure, underpressure, or any other failure mode, why would the first thing we see be blinding fire? Some static or something would probably catch it eventually, but without the engines running you could mix O2 and RP-1 and it would still not self detonate.

Am I missing something? I realize my optimism toward SpaceX might make me favor the least damaging outcome, but I just don't see how anything other than an explosive charge could have detonated so quickly. TEA-TEB or hypergolics could easily cause a bad day, but they don't appear to have been involved unless they were being loaded into S2 by the umbilical at the time.

If the fuel-oxygen mix is right, it only takes a tiny spark.  Electrostatic discharge, a momentary arc from a switch opening or closing, really anything...
Indeed. You might call this a *static*fire*. Heh.
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Online rcoppola

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #598 on: 09/01/2016 08:52 PM »
Wonder how the Dragon2 Trunk/Capsule would have dealt with this 2nd Stage RUD in a Pad Abort scenario?
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Offline mulp

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Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #599 on: 09/01/2016 08:53 PM »
Ok, the cost to SpaceX for the rocket is manufacturing cost plus the direct opportunity cost of the lost use of its pad and personnel, all readily quantifiable, plus the harder to measure opportunity cost of loss of sales, plus some liability to the customer.

We know SpaceX rocket costs and launch capacity are transitioning to "volume".

The customer cost is the satellite hardware plus opportunity cost of the delay.

How much of the satellite hardware is in "volume" production?

Are things like antennas 3d printed or laser Cut?

Creating the specs for AMOS-6 might take years, but making the parts and integrating them only months. Or the process might still be in the stage of sending out orders for each part to be made custom.

Any idea where the satellite production is for AMOS-6 and for the majority in general?

I'm thinking of PBS NBR special reports this week on the multiple satellite Silicon valley startups getting tens of billions of cash to build satellites in volume, plus all the launcher startups.

Is the destruction of this hardware a really huge cost, or just a lot of labor cost flushed, but easily replaced by everyone working a few more hours a week for awhile and using the overtime to buy new boats?

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