Author Topic: SpaceX Falcon 9 : CRS-16 (Dragon SpX-16) : December 5, 2018 - DISCUSSION  (Read 247887 times)

Offline AC in NC

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Just get the stage transportation truck and dollies. Tow the rocket to a boat launch. Treat it like a bass boat.

***snort*** Can you imagine backing up that big bastard?

Offline wardy89

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Monitoring Port Canaveral marine radio.

Just heard "they have a line on it by the "nozzles" and need someone to get a photo to prove they got it first."

(salvage rights). Also mentioned that they have a sea anchor if needed.

Did somebody else than SpaceX get to the rocket first!?


Don't think so - I believe it's more of a formality in case someone claims they got to it first (somehow).

Boy though, wouldn't that be something if someone else claims salvage rights...

I might be wrong, but i was under the impression that space hardware because of ITAR regulations is exempt from normal marine salvage laws and remains property of the manufacturer?

Offline OxCartMark

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Marine traffic over the last 2 minutes

Its ~2 miles north of the port entry near bouys ?3,4,5,6?  Should be entering port mouth in 1-1/2 hours (someone said) But also there's word that "they won't let me put a line on it", waiting for Eagle to get in here from far out.  Someone else pointed out that there's a cruise ship set to leave soon.
Actulus Ferociter!

Offline whitelancer64

Monitoring Port Canaveral marine radio.

Just heard "they have a line on it by the "nozzles" and need someone to get a photo to prove they got it first."

(salvage rights). Also mentioned that they have a sea anchor if needed.

Did somebody else than SpaceX get to the rocket first!?


Don't think so - I believe it's more of a formality in case someone claims they got to it first (somehow).

Boy though, wouldn't that be something if someone else claims salvage rights...

I might be wrong, but i was under the impression that space hardware because of ITAR regulations is exempt from normal marine salvage laws and remains property of the manufacturer?

Under the Outer Space Treaty, anything launched into space remains the property of the nation that launched it into space, regardless of where it ends up if it falls back to Earth.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline 1

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Monitoring Port Canaveral marine radio.

Just heard "they have a line on it by the "nozzles" and need someone to get a photo to prove they got it first."

(salvage rights). Also mentioned that they have a sea anchor if needed.

Did somebody else than SpaceX get to the rocket first!?


Don't think so - I believe it's more of a formality in case someone claims they got to it first (somehow).

Boy though, wouldn't that be something if someone else claims salvage rights...

I might be wrong, but i was under the impression that space hardware because of ITAR regulations is exempt from normal marine salvage laws and remains property of the manufacturer?

My understanding of maritime law is admittedly limited, but I don't think salvage rights apply here as the item is question is clearly not abandoned. As such, the only entity with a "right" to approach is whomever has a towing contract with SpaceX. I agree that this is more about formality, specifically formally showing intent to recover rather than abandon. Even if someone zipped out and got there first, I don't believe they'd have any legal claim to the booster.

Offline Rocket Science

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If a stuck grid fin caused the roll I would say that the slowdown in speed had more to do with stopping the roll than any transfer of momentum from the leg deployment. At slow speed the reaction control thrusters could counteract the aerodynamic forces.

Nope. With the legs extended the "wider momentum" makes it much harder for the RCS fins to affect roll. This is another reason why the legs are deployed at the last second. Sure, lower speed helps in that it makes the stuck grid fins less effective, but note the timing of the leg deploy and the slowdown of the roll. It's all from the legs.

It makes sense what you say, but we probably need to wait for an analysis of the telemetry before we can state so categorically what caused what.
What does Lars like to tell others when analyzing video feed "better keep your day job"... He now needs to take his own advice... ;)
"The laws of physics are unforgiving"
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Online punder

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What was it they launched, again? Everything going okay with whatever it was?

 ???

Offline Rocket Science

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What was it they launched, again? Everything going okay with whatever it was?

 ???
A-OK!
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline tonya

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You can't claim salvage rights on something that hasn't been officially abandoned at sea (this is the same reason that Spain keeps claiming treasure from Spanish wrecks that are centuries old). I 100% guarantee this booster has not been abandoned by SpaceX.

If I were Jeff Bezos, I'd still be so tempted to tweet that I was going fishing.

Offline eriblo

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Regarding adding a second pump and lines vs. making the present one more robust; for F9 operation, I agree with those above who say making the single pump more robust is better. However, there's probably more than F9 at play here; there's BFR to consider. IMHO, they might be going redundant for that (especially BFS) so it'd make sense to go that route now.

IMHO, the fact the F9 managed to survive supersonic loss of control and then touch down and end up intact is utterly astounding.
A single pump is likely the lightest solution but you can shift the failure probabilities by using smaller redundant pumps which would be more reliable except for the cases where the maximum torque is needed. A simple two pump example: twice the chance of a failure like today but grid fins then operating at half torque instead of failing competently completely  ::).
« Last Edit: 12/05/2018 09:46 pm by eriblo »

Offline vanoord

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1 (known) pump failure in 38 attempts (plus the water landings - perhaps a dozen more).

If the issue can be traced if/after the core is fished out, it may be possible to rectify the fault and keep flying with one pump - and accept a 1/100 or so probability of it happening again.

Offline OxCartMark

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Eagle:

I'm going to come around the buoy and get a line on it somehow and shackle it to my line and take it in somewhere.  <question from another vessel (GQ? who is also out there?))> My office gave me permission to put a line on it.


Me: I can't believe they're willing to approach with so little severe caution.  I can't believe you can just pull something so potentially energetic and seemingly unstable or at least in an unknown state into a busy port.  Unless maybe communications with it are so good that they were able to bleed pressure and safe it in the normal manner.  But then how can you vent the tank pressure without making it structurally vulnerable.?.

And then there's the legs.  Its seemingly all mariners coming up with a plan.  How are they gonna get them out of the way for passage into shallower water?

More from the radio:
"she's floating well"
"DIDN'T WILE E. COYOTE PRETTY MUCH BLOW THIS THEORY OUT OF THE WATER"
"who's coming?"
"Eagle, Searcher, and three of her little boats"
"We're just holding the line and drifting with it"
"S.W. corner of the rocket"
"Would you be comfortable with me approaching and passing me the line"
"Yes"
Actulus Ferociter!

Offline acsawdey

Eagle:

I'm going to come around the buoy and get a line on it somehow and shackle it to my line and take it in somewhere.  <question from another vessel (GQ? who is also out there?))> My office gave me permission to put a line on it.


Me: I can't believe they're willing to approach with so little severe caution.  I can't believe you can just pull something so potentially energetic and seemingly unstable or at least in an unknown state into a busy port.  Unless maybe communications with it are so good that they were able to bleed pressure and safe it in the normal manner.  But then how can you vent the tank pressure without making it structurally vulnerable.?.

And then there's the legs.  Its seemingly all mariners coming up with a plan.  How are they gonna get them out of the way for passage into shallower water?

More from the radio:
"she's floating well"
"DIDN'T WILE E. COYOTE PRETTY MUCH BLOW THIS THEORY OUT OF THE WATER"
"who's coming?"
"Eagle, Searcher, and three of her little boats"
"We're just holding the line and drifting with it"
"S.W. corner of the rocket"
"Would you be comfortable with me approaching and passing me the line"
"Yes"

Elon tweeted that the flight computer was running after it fell over and that it completed the safing process. [OK, I must be misremembering because I can't find that tweet now. But see below for possibly the RP-1 tank venting.]

Also:

https://twitter.com/elonmusk/status/1070446975642812416

I think the blast of fire you see after it sets down in the water is from venting the fuel tank which must have had some RP-1 vapor and/or droplets which were ignited by something down by the engines. It seems too controlled to have been the tank springing a leak.
« Last Edit: 12/05/2018 09:46 pm by acsawdey »

Offline mlindner

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It's amazing watching the entire structure flex and bend from the torques being put on the grid finds and then the whole structure twist when it impacts the water but holds together! That's some incredible engineering!

I think most of the bending is actually the camera not being firmly enough attached to the stage. (due to G-forces)

No, the camera doesn't move with respect to the rocket body, only the fins twist.

Look again. Or point out where you see bending. The camera is certainly shaken loose in the water impact.



T+7:30 You can see the whole rocket body flex and bend as the grid fins bend out of location compared to the rocket body.
LEO is the ocean, not an island (let alone a continent). We create cruise liners to ride the oceans, not artificial islands in the middle of them. We need a physical place, which has physical resources, to make our future out there.

Offline eriblo

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Eagle:

I'm going to come around the buoy and get a line on it somehow and shackle it to my line and take it in somewhere.  <question from another vessel (GQ? who is also out there?))> My office gave me permission to put a line on it.


Me: I can't believe they're willing to approach with so little severe caution.  I can't believe you can just pull something so potentially energetic and seemingly unstable or at least in an unknown state into a busy port.  Unless maybe communications with it are so good that they were able to bleed pressure and safe it in the normal manner.  But then how can you vent the tank pressure without making it structurally vulnerable.?.

And then there's the legs.  Its seemingly all mariners coming up with a plan.  How are they gonna get them out of the way for passage into shallower water?

More from the radio:
"she's floating well"
"DIDN'T WILE E. COYOTE PRETTY MUCH BLOW THIS THEORY OUT OF THE WATER"
"who's coming?"
"Eagle, Searcher, and three of her little boats"
"We're just holding the line and drifting with it"
"S.W. corner of the rocket"
"Would you be comfortable with me approaching and passing me the line"
"Yes"

Elon tweeted that the flight computer was running after it fell over and that it completed the safing process. [OK, I must be misremembering because I can't find that tweet now. But see below for possibly the RP-1 tank venting.]

Also:

[tweet]

I think the blast of fire you see after it sets down in the water is from venting the fuel tank which must have had some RP-1 vapor and/or droplets which were ignited by something down by the engines. It seems too controlled to have been the tank springing a leak.
Hans stated in the post-launch presser that it went trough the whole safing procedure and kept on communicating (intermittently only due to line of sight issues).

Offline MattBaker

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In the video just posted by Musk on twitter it looks like the engines touch water, presumably shut down, stage starts tipping over and then there's a small fireball, what's up with that?

I presume the booster started venting its fuel and it somehow ignited? But first where would it ignite, looks like the engines are shut down at this point, can LOX or RP-1 just ignite of the hot smoke around it like that?

And second, is the stage really venting like two seconds after what would have been a landing if it'd be on the ground? Or is this another "well, that wasn't supposed to happen like that"? Or does it have an automatic "emergency vent" mode when it thinks it landed but starts tipping over to prevent a large explosion.

Offline Stan-1967

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I think today's events merit an edit of SpaceX's "How Not to Land an Orbital Rocket Booster" reel.  This landing can push the time to the 3 minute mark.


Offline speedevil

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Regarding adding a second pump and lines vs. making the present one more robust; for F9 operation, I agree with those above who say making the single pump more robust is better. However, there's probably more than F9 at play here; there's BFR to consider. IMHO, they might be going redundant for that (especially BFS) so it'd make sense to go that route now.

IMHO, the fact the F9 managed to survive supersonic loss of control and then touch down and end up intact is utterly astounding.
A single pump is likely the lightest solution but you can shift the failure probabilities by using smaller redundant pumps which would be more reliable except for the cases where the maximum torque is needed. A simple two pump example: twice the chance of a failure like today but grid fins then operating at half torque instead of failing competently.

Mass on the first stage is around a fifth penalty to payload for reusable flights.
If they are committed to launching a lot of Starlink in 2019, this may be an acceptable penalty.
Two small pumps mean you now have to dig into your control software and get it so that it is stable under both pressure conditions in the event of a failure.

Plus - as was raised by the other poster, now you can tear down the failed pump.

Offline OxCartMark

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Small boat to ?Eagle: "from the point we have it ~near the legs~ the line is very weak, you have to be very careful in towing it, its like 3/8" chain"

I'm not going to pull it in I'm just going to hold it here until everyone comes up with a plan"

"I hope just everybody stays safe out here this evening with this thing"

position: 28 24.3, 80 30.8

approximate quotes
Actulus Ferociter!

Offline freddo411

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I was under the impression that the center engine had essentially zero roll control.   Am I wrong?

Tags: CRS-16 
 

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