SpaceX Falcon 9 : CRS-16 (Dragon SpX-16) : December 5, 2018 - DISCUSSION

[ugordan]

Booster out of the water and the crew is starting to show up. Should be interesting seeing the legs removed.

Looks like the one leg collapsed backward and dented an engine bell...
Clearly not possible on impact, so most likely a failed attempt at pulling with a line from it?

Why would it not be posible on impact, specifically during tipover if the leg broke off and the weight of the rocket came down on it? The dent lines up nicely with the way the leg bulges outward around the centerline.

[kdhilliard]

Booster out of the water and the crew is starting to show up. Should be interesting seeing the legs removed.

Are the blue stands supporting the stage on either end something we have seen before?

[Jakusb]

Booster out of the water and the crew is starting to show up. Should be interesting seeing the legs removed.

Looks like the one leg collapsed backward and dented an engine bell...
Clearly not possible on impact, so most likely a failed attempt at pulling with a line from it?

Why would it not be posible on impact, specifically during tipover if the leg broke off and the weight of the rocket came down on it? The dent lines up nicely with the way the leg bulges outward around the centerline.

Because the leg would be pushed up against the side as the water would push it back up, not down...
Unless it made lateral move before falling over, but it clearly did not..
Also the piston would first have to come off before it would be able to hit the engine bell..
To me it correlates more with a failed attempt to attach a line to it and then ripping off the piston first and the leg falling down on the engine bell both by gravity and a tug pulling the line.

It also explains the clear instructions towards the recovery crew to absolutely NOT attach anything to the legs as they would break... I was wondering how they would be so clear minded on warning them in advance but now I think it might be a response to it actually being just experienced in practice..

[Wolfram66]

Booster out of the water and the crew is starting to show up. Should be interesting seeing the legs removed.

Adjusted CygnusX112 for clarity & exposure

[Johnnyhinbos]

Some reflections...

- Clearly see the load spreader on the sling I referred to yesterday.

- Strange seeing the booster “post recovery” with the grid fins deployed.

- strange seeing the booster horizontal with (most) legs deployed.

[SDSmith]

I only see 3 grid fins.

[pb2000]

In the interests of science and combustion instability testing (or just for sh|ts and giggles), I think that bent merlin needs to be hooked up on the test stand and fired one last time before its retired.

[mainmind]

Does anyone know the operational constraint that required the back-away from capture volume because Comm with the ground was going to go down? The astronauts are driving the SRMS and the Dragon is in closed-loop communications with the station directly. Why couldn't they press for capture and wait to continue berth operations until comm was restored? This seems really wasteful.

Re-upping this question so it doesn't get lost among the booster recovery talk. What is the constraint that they had to do a Dragon back-away to the 30m hold when they weren't going to have TDRSS at the planned capture time? Abundance of caution? Is the command to send Dragon to free drift right before grapple coming in over TDRSS and not a direct command from ISS? It sounded  like the back-away command was sent from ISS.

Thank you

[ellindsey]

I only see 3 grid fins.

I think the fourth one is still there, just hidden behind the blue cradle that the booster is resting on.

[ugordan]

In the interests of science and combustion instability testing (or just for sh|ts and giggles), I think that bent merlin needs to be hooked up on the test stand and fired one last time before its retired.

If only test stands were as disposable.

[CorvusCorax]

I only see 3 grid fins.

No you don't.
You see 2 grid fins.
The thIrd grin fin is behind the booster, not visible, on the other side and you assume its there because it was visible in earlier photos.

( But if they are actually working on removing the fins, we cannot simply assume that its there either )

The 4th grid fin would be on the bottom on the booster and currently hidden by that rack thongy they put underneath to support its weight.

From the current angle we can't tell if its there or not. It was not visible in previous photos since it was under water. ( or too dark )
So there is some mystery around it, but not enough evidence to say wether its actually missing

[oiorionsbelt]

Is the similarity of shape between the grid fin attachment points and the "ice" that was liberated on ascent just a coincidence?

https://twitter.com/w00ki33

[CorvusCorax]

Is the similarity of shape between the grid fin attachment points and the "ice" that was liberated on ascent just a coincidence?

https://twitter.com/w00ki33

Probably not. That ice obviously formed around some sort of port in ring shape, so it matches that shape like a negative imprint. But its not necessarily from the grid fin attachment point. All 4 gridfins were still there, there would have been no way for it to cone off in one piece without the grid fin coming off first.

Are there umbilical attachments or other ports near or underneath the grid fins or at the botton.of the 1 st stage that have a similar shape?

[ugordan]

Is the similarity of shape between the grid fin attachment points and the "ice" that was liberated on ascent just a coincidence?

They're both ring-like, that's about it. The grid attachments actually have a cover on during flight which was apparently taken off here for purposes of fin removal.

It's more likely that the ice formed around one of the interstage vents that dumps various MVac GOX/LOX bleeds during prop load and 1st stage flight. I.e. the flexible hoses you can see flapping around inside the interstage after stage sep.

[deruch]

It's SpX internal investigation, or with NASA?

As booster recovery isn't a NASA requirement, I assume it is a purely SpaceX investigation

I'm pretty sure there will be some sort of landing mishap investigation.  It will likely be SpaceX only with possible involvement/positions for USAF Range Safety and the FAA as those are the two organizations responsible for approving RTLS landings operations.  And maybe an observer from NASA just to keep their hand in.  The technical focus of exactly what failed and why won't be of much interest to any one but SpaceX.  However a review of the performance of in-place safety rules/precautions for RTLS and an examination of potential areas of improvement or needed changes will be of interest to the other groups.  If Range Safety and FAA aren't actually represented on the board, for sure they will be CC'd on the report as well as be doing their own analysis as to safety impacts.

[Patchouli]

In the interests of science and combustion instability testing (or just for sh|ts and giggles), I think that bent merlin needs to be hooked up on the test stand and fired one last time before its retired.

If only test stands were as disposable.

Yah it could damage the test stand.
Though I think just the nozzle extension is damaged which I think is replaceable.
If all else fails it could make an interesting lawn decoration for one of their buildings.

[gongora]

It's SpX internal investigation, or with NASA?

As booster recovery isn't a NASA requirement, I assume it is a purely SpaceX investigation

I'm pretty sure there will be some sort of landing mishap investigation.  It will likely be SpaceX only with possible involvement/positions for USAF Range Safety and the FAA as those are the two organizations responsible for approving RTLS landings operations.  And maybe an observer from NASA just to keep their hand in.  The technical focus of exactly what failed and why won't be of much interest to any one but SpaceX.  However a review of the performance of in-place safety rules/precautions for RTLS and an examination of potential areas of improvement or needed changes will be of interest to the other groups.  If Range Safety and FAA aren't actually represented on the board, for sure they will be CC'd on the report as well as be doing their own analysis as to safety impacts.

I agree with this, it would be a missed opportunity for the FAA and USAF ranges not to review what happened on this flight.  They definitely have an interest in the SpaceX landing processes.

[CorvusCorax]

The thing is, something obviously went wrong. It didn't go "horribly" wrong. SpaceX inherently safe landing approach procedure worked, and some aspects of their flight control software got a very rare chance to demonstrate how awesome they are. It also demonstrated that propulsive landing can still work even if aerodynamic control fails ( that will come up again, when the discussion of propulsive versus horizontal airplane like landing comes up again, for example with that point 2 point passenger idea with BFR )

But ultimately this mishap will have had both root cause and contributing factors, some of which might affect launches too, not just landings.

Some component didn't work as it should have, and it wasn't noticed until that component was needed in flight.

Obviously adding redundancy might help. But if an investigation comes to the conclusion that overlooking something in assembly or during test procedures contributed to a faulty part ending up on an operational flight, this might end up with suggestions for operational, test or QC procedure changes that have implications for other flight hardware, relevant to commercial and possibly crewed launches too.

That does not necessarily mean someone did something wrong. Sometimes its just that theres a way stuff could have been done even better.

If SpaceX really wants to reach Air-travel-like reliability, they will want and have to go that route. And the more partners they could get into the investigation, the better. NASA, FAA, Airforce, NTSB even?

It doesn't look like they'd have to stand down or delay launches until the result of that investigation. After all, nothing bad happened and theres no indication that theres anything inherently wrong with SpaceX hardware or procedures. But that doesnt mean the investigation should be any less thorrough than if a launcher had blown up.

Its definitely going to be easier though. After all they recovered the core mostly intact and can look in depth at all data as well as the components itself. Should be fun.

[weepingdragon]

Looks like the one leg collapsed backward and dented an engine bell...
Clearly not possible on impact, so most likely a failed attempt at pulling with a line from it?

Landing damage does seems wrong angle. Though landing could have done damage to that leg.

Likely leg caught on a sandbar (or bottom in shallow water). Gives right angle to damage engine bell.  And current/wind was really moving the booster south at a nice clip considering where/when it's movement was finally arrested compared to where it hit the water.

[weepingdragon]

Re-upping this question so it doesn't get lost among the booster recovery talk. What is the constraint that they had to do a Dragon back-away to the 30m hold when they weren't going to have TDRSS at the planned capture time? Abundance of caution? Is the command to send Dragon to free drift right before grapple coming in over TDRSS and not a direct command from ISS? It sounded  like the back-away command was sent from ISS.

Thank you

info probably over here SpaceX CRS-16 Dragon - RNDZ, ISS Ops, EOM - UPDATES