Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3  (Read 486980 times)

Offline matthewkantar

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3/4" thick based on what? I have seen lots of speculation about deck thickness, but no authoritative citation.

Matthew

Offline Arb

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Is that a landing leg?

Offline CameronD

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3/4" thick based on what? I have seen lots of speculation about deck thickness, but no authoritative citation.

Refer OxCartMark's post back 5..

FWIW, I still think it's more likely on the 1/2" side of things - but I could be wrong. :)
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline OxCartMark

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Just noticed a thing or two in the pictures that Kabloona posted above.  That hole is in one of the compartments at the edge of the Marmac barge.  Beyond that is deck extension.  Hmm.  Let's back up and think about the impact slam event.  After the rocket scrap broke through the deck it would have done essentially a belly flop into the swimming pool below which had approximately 10 feet of water standing in it.  If it hit slowly then no big deal.  But if it had substantial remaining speed then it could have generated significant hydraulic pressure bulging out the plates around the impact.  That could be the bottom plate, the plates between compartments, or now I understand it could also be the plate on the side of the hull.  That plate is at the base of a number of deck extension braces.  I tried to go back to look at the side of the hull in the images we have of it coming into port but the image quality and lighting don't allow any conclusions.  http://forum.nasaspaceflight.com/index.php?topic=36326.msg1501108#msg1501108

Then we have the tank walls themselves which could have been directly impacted by the rocket coming down on their edge.  And internal bracing / structure may have been hit.

Below I'm re-re-posting some images that have been posted here before, both by meself and Ohsin depicting the tank divisions.  These are for only the Marmac barge, not the deck extensions.  I've added an approximately 12' red circle for scale but its location in the fore-aft direction is anybody's guess.

And then there's the dark spot approximately 1' in diameter just inside the cones and tape (Kabloona's picture above).  That is at the edge of the Marmac barge.  One might just hypothesize that it too is a hole.  One of the caps to the ballast tanks has been removed, that's what I observed.

I'm thinking that its probable that there will be multiple plates and structures that need to be replaced.  But still, relatively easy going with flat rectangular low carbon steel.

As for the image of the welders and stuff on the truck, I think some of those welders are plasma cutters.  The number of them would seem to indicate that they aren't planning to replace just the deck plate.  And that bundle of other stuff being lifted off the truck, not plate, something else.

« Last Edit: 03/11/2016 12:32 PM by OxCartMark »

Offline OxCartMark

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There's absolutely no doubt, and never has been, that it's a steel deck.

Offline OxCartMark

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Hmm, I just stumbled into another predecessor to this thread

Honorary thread 0b: http://forum.nasaspaceflight.com/index.php?topic=31452.0
Topic: First stage recovery at down-range locations  (Read 89853 times)

Offline CameronD

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Below I'm re-re-posting some images that have been posted here before, both by meself and Ohsin depicting the tank divisions.  These are for only the Marmac barge, not the deck extensions.  I've added an approximately 12' red circle for scale but its location in the fore-aft direction is anybody's guess.

And then there's the dark spot approximately 1' in diameter just inside the cones and tape (Kabloona's picture above).  That is at the edge of the Marmac barge.  One might just hypothesize that it too is a hole.

OxCartMark, I think you're a compartment too far aft.

Looking at the photo again and comparing the ballast tank diagram, the last compartment is at the stern and the stage hit is 8'-10' forward of the bulkhead (the one in line with the ends of the wings).  It looks to me like the stage hit took out a deck beam - right across the center of the hole - and damaged another aft of it.

I can't see any other damage that isn't part of the one big hole..

 
« Last Edit: 03/11/2016 01:44 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline OxCartMark

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Like rocket catching barges?  Got some time?  Try punching in "marmac 303" or "marmac 304 in this link and hitting search.  http://www.eagle.org/safenet/record/record_vesselsearch

Among other things you get inspection records and the type of steel used, which is 'ABS Grade A', which itself is a search term that will send you off to some interesting reading.
__________

Six portable welders and a dude.
You're going to need more dudes.
« Last Edit: 03/11/2016 02:49 AM by OxCartMark »

Offline the_other_Doug

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To try and illustrate a couple of things, I'm attaching a marked-up detail of Craig's aerial-view post.

First, the yellow lines define the distance between the aft-most extent of the hole (almost exactly at the level of the wing "roots") and the end of the barge.  Looks to me like Mark's estimate in terms of which compartment was holed is pretty good, but I would think his first marked-up diagram, showing the hole to fore of the frame between the aftmost compartment and the one to fore of it, is more correct.  I think the wall between those compartments is just aft of the wing roots, not fore of them.

The yellow lines give a really good feel for the extent of distance between the aft end of the barge and where the hole was punched.  And it looks to me like the fore line, still aft of the hole, would be fore of the first compartment bulkhead.

Second, what seems to be being referred to as "the second hole" is a very dark area, somewhat similarly shaped to the obvious hole, just across the barge from the obvious hole.  I've circled it in red.  This area was covered by debris and tarps on the earlier aerial views, and seems to be one of the foci of the tire scuffs and drag marks that result from the piling up of the debris and its subsequent removal.

I'd be willing to bet that this really dark spot is a place where the decking had been extremely thoroughly washed.  Perhaps some type of fluid came out of the debris and pooled here, and either discolored the deck or required a very thorough cleaning?

Edit to correct picture attribution (oops, sorry) and to point out that I drew the yellow lines, and yes, I know the aft yellow line is about five feet behind the barge.  It was more visible there... :)
« Last Edit: 03/11/2016 02:17 AM by the_other_Doug »
-Doug  (With my shield, not yet upon it)

Offline CyndyC

FCC permit for CRS-8 transmitters:

https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=69496&RequestTimeout=1000

ASDS location is given as 30.5 degrees N, 78.5 degrees W.

Permit does not guarantee an ASDS landing attempt on CRS-8, but it is apparently an option if they can get the repairs done fast enough.

So it's back to east of Jacksonville, about 173 mi off that coast and about 192 mi from Port Canaveral.
"Once a Blue, always a Blue." -- USN/USMC Flight Demonstration Squadron

Offline CameronD

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Like rocket catching barges?  Got some time?  Try punching in "marmac 303" or "marmac 304 in this link and hitting search.  http://www.eagle.org/safenet/record/record_vesselsearch

Among other things you get inspection records and the type of steel used, which is 'ABS Grade A', which itself is a search term that will send you off to some interesting reading.

Drat!  The secret is out..  :-X

Seriously though: Yes, that's the place to go for details of any ABS-approved vessel.. and that's most commercial vessels in the USA.  In the case of our target-barges however, you'll find more recent updates on the USCG PSIX site (google it) because, in the case of the Marmacs, the USCG organise the inspections on behalf of ABS.

« Last Edit: 03/11/2016 04:44 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Kabloona

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Quote
I'd be willing to bet that this really dark spot is a place where the decking had been extremely thoroughly washed.  Perhaps some type of fluid came out of the debris and pooled here, and either discolored the deck or required a very thorough cleaning?

Hydraulic fluid from the grid fin reservoir ?

Offline OxCartMark

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what seems to be being referred to as "the second hole" is a very dark area, somewhat similarly shaped to the obvious hole, just across the barge from the obvious hole.  I've circled it in red.  This area was covered by debris and tarps on the earlier aerial views, and seems to be one of the foci of the tire scuffs and drag marks that result from the piling up of the debris and its subsequent removal.

That is not the potential hole I was speculating as maybe being a hole.  I've marked up the first image below to show what I thought might be a hole.  But then I had a revelation.  It isn't another rocket puncture hole, its a hole. It is one of the many small holes with removable covers that the barge has for access to the ballast tanks.  Its placement along the edge is a guarantee of that, final answer.  The last three images I'm posting are of some of these holes from previous discussion.  Case closed (before it was much open).  Even the green garden hose seems to be the same.
« Last Edit: 03/11/2016 02:42 AM by OxCartMark »

Offline Ohsin

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Thanks for those amazing images Craig_VG :) First stage took out two ballast compartments and it did that to what I assume is second most strong region on barge deck first would be where four compartments meet.

If it lande.. I mean ploughed through middle of ballast compartment damage might have been much more.

Hole aligns to covered bollard box on sides(3rd from stern)
« Last Edit: 03/11/2016 06:27 AM by Ohsin »
"Well, three cheers to Sharma, but our real baby is INSAT."

Offline OxCartMark

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First stage took out...
I feel you know more about ASDS anatomy than anyone on this board so its hard to argue with you but according to your dimensioned diagram that I reposted above that cross ship bulkhead, the second from the rear that you think was hit is 79' 9" forward of the stern.  I have a hard time scaling that distance using something of known width such as the 8.0 foot wide shipping containers.

Hole aligns to covered bollard box on sides(3rd from stern)
What is a bollard box?  You might have to point this feature out.  Not knowing the answer to this it appears  to me that your line across the deck is based on following a pre-existing line across the deck, presumably a weld line?  Which would presumably be on top of a bulkhead as you say(?)

And as a reminder to everyone, the red circles I posted above are very approximate in their fore-aft placement, I'm not suggesting any accuracy there.  There may be some degree of accuracy in the diameter of the circle and its cross ship placement.



Offline cscott

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From the exploration tower photos it appears that the on-site forensics are done and they are well into the cleanup phase.  I see wood packing crates scattered over the deck, each filled with "Falcon droppings" and then another large blue steel shipping container which appears to have the "big stuff" (tank panels, etc).  As noted above, they've already cut off some of the peeled back steel, pumped the ballast tanks dry, and ordered a bunch of welders and/or cutters for the repair work.  There are some open boxes near the "down" Thrustmaster which might be repair parts. The urgency might give us a clue as to whether OCISLY might be used for CRS-8.

I'm a little disappointed: I was hoping for some bottom hull fix-up, and that MARMAC 300 might be recalled for the job.  I was imagining MARMAC 300 getting some timbers lashed to the top, being submerged under OCISLY, and then triumphantly refloated, lifting OCISLY, to be the new temporary work area.  Aw, never mind---I can see it so clearly in my head I don't need for it to happen in real life. ;)
« Last Edit: 03/11/2016 02:24 PM by cscott »

Offline Ohsin

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I was imagining MARMAC 300 getting some timbers lashed to the top, being submerged under OCISLY, and then triumphantly refloated, lifting OCISLY, to be the new temporary work area

While singing "He ain't heavy...he is my brother"  ::)

@Mark

Luxury of posting here is everyone can be barge scientist till CameronD tells you how it really is  ;D I didn't get into measurements for this at all. 'Bollard box' is a technical term I just invented.. on edge there are these recessed bollards/cleats and wing covers them up. These 'boxes' are exactly where compartments meet as in the second image you posted. Using container width for reference will give more error, better would be to use whole barge length and see if hole is at 26% of it from stern. I think its close to it.

With your model what should be the length of these compartments? See if it matches to those.
« Last Edit: 03/11/2016 05:45 PM by Ohsin »
"Well, three cheers to Sharma, but our real baby is INSAT."

Offline OxCartMark

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Random hypothetical question from nowhere;

If there were to be an F9 flight two days from now (surprise!) and assuming that SpaceX were willing to take the chance that one of the landing leg feet might step into the hole in the deck could ASDS OCISLY report for duty or is it legally grounded?  And if grounded is there appeal wiggle room since there is no endangerment and its such a badass program that the CG is already partway involved in?

@Mark ... With your model what should be the length of these compartments? See if it matches to those.
IIRC, the longitudinal placement of the bulkheads in my model was done with little regard to being anatomically correct as I was going for weight and (other than the front bulkhead which is on the sloping bow) the longitudinal placement has no affect on bulkhead area or weight.
« Last Edit: 03/11/2016 11:19 PM by OxCartMark »

Offline John Alan

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I take it you mean CG would insist OCISLY is repaired 100% before leaving port...
No... she could sail now if they wanted to... IMHO...

There are many stories (IIRC) of boats being patched seaworthy and going back to sea...
It was not damaged beyond use... since it relies on EIII to provide propulsion and guidance... 
My guess  ;) is CG considers if boat is a hazard or could easily become a hazard if taken out as is...

Of course I differ to those who know the regs better then me...   :)
« Last Edit: 03/12/2016 12:02 AM by John Alan »

Offline llanitedave

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Think of the Yorktown before the Battle of Midway.




Not sure this is quite as compelling...
"I've just abducted an alien -- now what?"

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