Falcon 9 / Dragon CRS-7 ISS Resupply (mission thread)


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DocM

Yeah, their durability during that event was amazing. It'll be interesting to see what the actual cause of the S2 failure was; IDA, a popped COPV tank or plumbing.

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FloatingFatMan

shattered like broken glass ... damn, that's difficult to watch. I've grown fond of those rockets.

 

Imagine how I felt.  I was at the Challengers last launch. :(

 

Seeing another ship explode, even though it was unmanned, brought back some unpleasant images. :s

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Unobscured Vision

Imagine how I felt.  I was at the Challengers last launch. :(

 

Seeing another ship explode, even though it was unmanned, brought back some unpleasant images. :s

Good grief, I can't imagine actually being there. :( I was in 8th grade at the time, and a classmate had watched the launch (Science across the hall) while I and many others were in Band Class. He ran in and literally screamed that the Shuttle had exploded, then broke down crying. Everything stopped right then and there in the whole school the rest of the day. All of us were watching CNN in the rest of the classes from that point on.

 

I still watch that footage of the Challenger disaster sometimes and I re-live that morning like it just happened last week. Crazy how something that happened almost 30 years ago will leave such an impact on you.

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Unobscured Vision

The one thing that caught my attention was stage one, all engines firing........with all this chaos occurring right on top........and she was still pushing away while getting the "hell" hammered out of her. That........is what I call........ "one tough stage".....then we have Dragon, still (what seemed) intact as well.....that was a "heavy weight" fight........

Expanding on these comments ...

 

It was the LO2 that made it "shatter", or appear to do so. That bird held on for as long as it was able to, but the thing about Oxygen is it is extremely reactive, and causes everything else to become extremely reactive as well (except for, iirc, Xenon gas, which reacts to nothing at all). LO2 is, quite honestly and counter-intuitively, some nasty stuff in its' raw form. It'll kill almost anything and everything imaginable, and explosively too.

 

Now we make it a liquid-gas combination, rapidly aerosolizing near an open, raging ignition source as it was during the 15 seconds of the Falcon 9's failure incident. Give credit where it's due, indeed -- the Falcon 9 and Dragon put up a hell of a fight against one of the gnarliest, most corrosive elements in the Universe. Sadly, the LO2 won the battle, but it wasn't going to simply take the Falcon 9 or the Dragon just like *that*. It's a tribute to the robustness of the platform -- 15 seconds (roughly) of pure abuse and torture. A crewed vehicle in this scenario would have survived via the Launch Abort System.

 

If anything, this is a demonstration of just how good the Falcon 9 really is. Any other rocket would never have stood up to the challenge.

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DocM

They have to debug the last few milliseconds of the telemetry the old school way - in a hex editor.

Something loose in the Trunk could take out the S2 avionics and transmitters on its way to the top dome of the LOX tank. They're housed at the top of the stage.

There's a support/encouragement thread at NSF for SpaceXers. My $0.02

Hang in there guys! I'll simply leave you with one of my favorite quotes,

Far better is it to dare mighty things, to win glorious triumphs, even though checkered by failure... than to rank with those poor spirits who neither enjoy nor suffer much, because they live in a gray twilight that knows not victory nor defeat.

~ Theodore Roosevelt

Now, go git 'em

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tompkin

Imagine how I felt.  I was at the Challengers last launch. :(

 

Seeing another ship explode, even though it was unmanned, brought back some unpleasant images. :s

I was living in D.C. at the time of the Challenger explosion.

I remember being on the subway. Normally, subway riders are a pretty dispassionate group but you could just see the shock on everyone's face. 

The thing that got to me about that more than anything was that "Teacher In Space" program that they had going on. Just imagining all those students seeing the rocket explode that their teacher was on.  :(

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SarK0Y

They have to debug the last few milliseconds of the telemetry the old school way - in a hex editor.

Something loose in the Trunk could take out the S2 avionics and transmitters on its way to the top dome of the LOX tank. They're housed at the top of the stage.

There's a support/encouragement thread at NSF for SpaceXers. My $0.02

 

such event must be easily tracked because payload has to have live-checking marks to control its position.

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SarK0Y

lox tank, afaik, is over-chilled, so it'd explode if there was cracked thermal insulation.

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DocM

That depends.

We know the last few milliseconds of data was corrupted, and the avionics/telemetry hardware sits directly over the LOX tanks upper dome.

Telemetry goes through an encoding (for video), encryption (for security), and buffering process. If the event were fast enough the hardware could have been destroyed before the pertinant date was transmitted.

Upper stage showing avionics & telemetry hardware

secondstage.jpg

The S2 LOX tank has no insulation, the LOX being topped off before launch, and gassified LOX vented before and after launch.

LOX would boil off rapidly if the tank were compromised, which would explain the large O2 cloud around S2. If gassified LOX collected inside Dragon's Trunk it could also cause it to fail and Dragon to pop off as observed.

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SarK0Y

 

Telemetry goes through an encoding (for video), encryption (for security), and buffering process. If the event were fast enough the hardware could have been destroyed before the pertinant date was transmitted.

DocM, how payload displacement could be too fast??? +there has to be backup ties.

 

If gassified LOX collected inside Dragon's Trunk it could also cause it to fail and Dragon to pop off as observed.

such event must be in telemetry too.

 

We know the last few milliseconds of data was corrupted, and the avionics/telemetry hardware sits directly over the LOX tanks upper dome.

doubtfully it could give something valuable. 

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Unobscured Vision

That depends.

We know the last few milliseconds of data was corrupted, and the avionics/telemetry hardware sits directly over the LOX tanks upper dome.

Telemetry goes through an encoding (for video), encryption (for security), and buffering process. If the event were fast enough the hardware could have been destroyed before the pertinant date was transmitted.

Upper stage showing avionics & telemetry hardware

secondstage.jpg

The S2 LOX tank has no insulation, the LOX being topped off before launch, and gassified LOX vented before and after launch.

LOX would boil off rapidly if the tank were compromised, which would explain the large O2 cloud around S2. If gassified LOX collected inside Dragon's Trunk it could also cause it to fail and Dragon to pop off as observed.

If gassified/venting LOX entered the Trunk then that likely means there was a point of entry -- a puncture in the bottom, a substantial one; which could also indicate that something got loose inside. With the forces we're talking about during launch, especially near the end of S1 Burn before tail-off, we're talking at least 3.5-4.5G if not slightly more, and inertia, impacts, etc can behave strangely (read: counter-intuitively) during a launch.

 

Something to consider. *shrug*

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DocM

DocM, how payload displacement could be too fast??? +there has to be backup ties.

such event must be in telemetry too.

Boeing used 3 trunions to attach IDA. IF they let go, which hasn't been established yet, with a vehicle still accelerating at nearly 5G a suddenly free (and unpowered) 500kg mass is going to slam that avionics/telemetry dome 2-3 meters away fast & hard.

doubtfully it could give something valuable.

You can often reconstruct the data in hex because of ECC applied to the packets.

That's what SpaceX is doing now, and how an NSF crowdsource team reconstructed an earlier corrupted stage landing video. It took weeks but the NSF team took a garbled mess and turned it into a viewable stream.

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Unobscured Vision

Something that SpaceX may want to consider in the future, if it was indeed a strike event from something that came loose in the Dragon's Trunk, is some nice, aerospace-grade Impact Shielding for the top of the S2 to protect that LOX tank. It'll add weight, yes, but save a mountain's worth of headaches and lost revenue.

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SarK0Y

 

Boeing used 3 trunions to attach IDA. IF they let go, which hasn't been established yet, with a vehicle still accelerating at nearly 5G a suddenly free (and unpowered) 500kg mass is going to slam that avionics/telemetry dome 2-3 meters away fast & hard.

well, it's about 0.3sec before hit -- seems not too fast.

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Unobscured Vision

That's 3 tenths of a second to travel 2-3 meters. With that mass (500kg) and that inertia (4.5-5G), it's going to hit that Avionics/Telemetry Package like a car travelling at autobahn speeds (150km/hr or more), and push that gear into the LOX tank at roughly the same force or slightly lower due to transferrence losses. If it was indeed the IDA that broke loose, or even a portion of it and it kilted out of position far enough and fast enough (which is what seems to have happened).

 

Nope ... that LOX tank never stood a chance of resisting a puncture against those forces. Even if it did, the S2 was critically damaged at that point and wouldn't have responded to commands. It's avionics/control systems were destroyed.

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SarK0Y

That's 3 tenths of a second to travel 2-3 meters. With that mass (500kg) and that inertia (4.5-5G), it's going to hit that Avionics/Telemetry Package like a car travelling at autobahn speeds (150km/hr or more), and push that gear into the LOX tank at roughly the same force or slightly lower due to transferrence losses. If it was indeed the IDA that broke loose, or even a portion of it and it kilted out of position far enough and fast enough (which is what seems to have happened).

 

Nope ... that LOX tank never stood a chance of resisting a puncture against those forces. Even if it did, the S2 was critically damaged at that point and wouldn't have responded to commands. It's avionics/control systems were destroyed.

i mean it's not too fast to miss valuable data of telemetry.

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DocM

Yes, it could be. See my comment above about encoding, encryption etc. That can add a fraction of a second between acquisition and transmission. More than enough time for the avionics/telemetry package to get hammered by whatever happened.

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Unobscured Vision

Ahh. True, but if the Telemetry Package got nailed then it wouldn't matter. :p

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SarK0Y

Yes, it could be. See my comment above about encoding, encryption etc. That can add a fraction of a second between acquisition and transmission. More than enough time for the avionics/telemetry package to get hammered by whatever happened.

well, agreed -- any piece of data gotta be processed.
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Draggendrop

I'm not saying what did the damage, but with loose cargo being one of many scenario's, I found this picture of IDA-1 being prepped for Dragon...

 

post-546174-0-70028100-1435812512.jpg

 

This is prior to shipping......

 

post-546174-0-60410500-1435812800.jpg

 

Both these photo's show the shipping mounts...........I assume the trunk mounts would hook into the three upper gimble shaft's.......This unit is heavy and it would only take 1 point of 3 to let loose......

 

With 3000 sensor channels, these channels would have redundancy, built in test equipment (ie: calibration), time stamps and 1 pass error encoding. The video will be bandwidth demanding. What I am curious about is if all sensor's where in one "operational basket for processing" or at least split for fault tolerance between many sections in case of "sectional compromise". I imagine we may have a chance to generalize later with some data released.... although the design would be proprietary and I can't see SpaceX revealing a work in progress.

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DocM

It's been assumed the trunion sensors were only for confirming IDA-1's release during its removal from the Trunk by Canadarm2. They may not have been in the telemetry stream.

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Draggendrop

General media info for 1st July 2015....

 

 

 

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Unobscured Vision

Oh man. I really want to see how IDA-1 was flight secured for the trip uphill now. I was looking at how it was secured for cross-country shipping and I was like "Oh HELL no, they didn't send it to space like THAT, did they?!".

 

A couple of "red flags" for me, looking at the mounting pipes on the side of IDA-1 -- three to be exact. There's no way I would have signed off on that piece of equipment being secured by those three alone, from an Engineering standpoint.

 

See those mounting pipes holding the IDA-1 onto it's shipping arms? The hollow ones? They look quite small and flimsy relative to the IDA-1, don't they? My guess is that those were meant to be used in flight to secure the IDA to the Dragon. Not SpaceX's design or origin, of course. This item weighs 500 kg - 1,100 lbs. Half a ton. At flight inertia it will consistently weigh 3-5 times that much, as far as mass, the rocket (and gravity) is concerned.

 

There's absolutely no way that those three mounting pipes alone could (or would) bear the entire 3,300-5,500 pound (counting inertial mass) load during launch. Dry weight, on the ground, sure. In flight, not for long -- as we saw. I suspect the designers of the IDA-1 forgot that fairly important piece of information when they designed this thing. It needed at least three more hardpoints to remain secure, and double the thickness of each of those pipes holding it in place to prevent (or at least minimize) stress warpage.

 

I suspect that these pipes warped under stress during launch due to additional inertial mass loads that they were not designed to withstand. Eventually one of them either snapped or warped beyond a certain threshold and the IDA simply slid off the other two (or its' hardpoints) that were still attached. The IDA then fell downward, punched through the Dragon's Trunk sideways, crashed through the Avionics/Telemetry Package of the Falcon's S2 (destroying it) and impacted the LOX tank, rupturing it.

 

That's what I think happened.

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Draggendrop

We also don't know the design parameters, how many sub contractors were used and if so, how much data was supplied to them. The larger the hierarchy, the more problem prone...did any one know the whole process and checked for all variables....not likely. Just manufactured to station specs...throw a bunch of brackets at it and go...not our problem...built as requested......Hindsight is always easy but lessons will be learned on this one.......Boeing won't due SpaceX any favors............ :(

 

post-546174-0-04121200-1435822506.jpg

 

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malenfant

If the IDA is involved I doubt it was so straightforward. Perhaps it was a resonance -a sympathetic vibration - that couldn't be modeled or ground tested, that lead to a failure somewhere. I'm betting on a COPV or a line letting go. On the other hand theres enormous flight experience with helium and all manner of payloads.

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