Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2  (Read 2397310 times)

Online cartman

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #240 on: 12/24/2014 11:02 PM »
What sticky trap material, can you elaborate? I think we are just seeing rain water, like we see at the dock next to the ASDS.

Offline Lars-J

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #241 on: 12/24/2014 11:28 PM »
What sticky material?? Source?

Online Helodriver

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #242 on: 12/24/2014 11:44 PM »
The extensions don't fold up. It is clear.
Docking at the bay, they don't fold.

They're probably safety nets then. If the Booster is only guaranteed to stay within the outer circle and people might have to be that close to the edge, they'd be required.

I'm guessing they are boarding ramps basically?

We see people standing on them in some of EER's canon pics, and they are horizontal, not vertical.
I'm guessing the deck "wings" which horizontal deck structure would not stand up well to repeated bumping into of the pier, or onto the top of the dock. Ships, and barges for other goods such as Grain or Coal usually have sides that vertical, and more conducive to being "tied up" to a pier.

We can see from the cruise ship web cam that the barge is kept from direct contact with the pier/dock, thus creating a gap.

The extensions on the side are outside of the low perimeter retaining wall and will be the only place that people will be able to stand near the central deck once the liquid polymer sticky trap material has flooded the main part of the deck within the yellow retaining wall.  You can see over the course of the day that they have begun to flood the deck with the sticky trap material.  This morning it was only visible as a small puddle near the point of application near the right rear corner but as the day has gone on I've been watching the puddle of sticky trap material get larger and larger though it still hasn't covered the entire surface of the deck within the yellow wall.  I wonder how deep they plan to install the stuff?  I wonder if they are using the slow, medium, or fast version?  Both the fast and medium curing versions have a solvent smell that stinks to high heaven, which is probably why the cruise ship left. Eer, did you smell it?   The application and curing should be done by the first week of January for the landing but they never could have had it installed and cured by the launch last week.  Maybe that's the real reason they delayed the launch.?.

Mark

The world's largest glue trap? A good theory, but its much more likely that they will simply rub the barge with a giant zeppelin sized balloon and have the rocket just stick to the deck with static electricity.

Offline OxCartMark

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #243 on: 12/24/2014 11:48 PM »
What sticky material?? Source?
The source seems to be near the corner of the deck that is closest to the shore and furthest from the cruise ship.  What sticky material??? Just look at the stuff, there must be hundreds of gallons of it there!  Probably MIL-STD-1394-BS-4/1 since it appears to be clear. Heaven help any pelicans or sea gulls that land in it.

Mark

Offline mme

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #244 on: 12/24/2014 11:50 PM »
What sticky trap material, can you elaborate? I think we are just seeing rain water, like we see at the dock next to the ASDS.
What sticky material?? Source?

Dihydrogen Monoxide.  A near universal solvent and when consumed in large quantities it's been known to cause death via Hyponatremia.  Nasty stuff, though it's not usually considered sticky on its own.
Space is not Highlander.  There can, and will, be more than one.

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #245 on: 12/25/2014 12:15 AM »
What sticky material??? Just look at the stuff, there must be hundreds of gallons of it there!  Probably MIL-STD-1394-BS-4/1...

Oh, aha. As in MIL-STD-Bullsh**-April Fools Day?    ::) Watch for lump of coal in your Christmas stocking...
« Last Edit: 12/25/2014 12:21 AM by Kabloona »

Offline Mader Levap

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #246 on: 12/25/2014 01:05 AM »
I still think there is grid. This photo shows that whole contraption on top of barge is half-translucent - difference between "wings" (showing water under it) and main body (showing barge under it) are clearly visible.
If there is no grid, how this difference is explained?

Optical illlusion.

Maybe what happened is that SpaceX didn't bother to repaint the old black paint on the main barge deck. But when they added the wings, obviously those new wings had to be painted, black to match the original black paint on the deck. (...) But all you're seeing is the difference between old paint on the original deck and new paint on the wings.
I must say it is pretty convincing, especially considering right-bottom of barge is pretty much blending of wing and main body.
CORRECTION: you seem to think this is actual main body of barge itself with wings added. I think landing part is separate contraption mounted on top of barge. Visual difference still needs explanation, but puddles prove definetely that surface of this contraption is solid.

Well this image shows pretty conclusively that it is not a grid, or if it is then the holes are smaller than the size of the H2O molecule
You mean puddles? Yep, that would be pretty good evidence that surface of contraption is solid, OxCartMark's poor joke (at least I hope it was joke) notwithstanding.
« Last Edit: 12/25/2014 12:38 PM by Mader Levap »
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Offline Comga

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #247 on: 12/25/2014 01:28 AM »
What sticky material?? Source?
The source seems to be near the corner of the deck that is closest to the shore and furthest from the cruise ship.  What sticky material??? Just look at the stuff, there must be hundreds of gallons of it there!  Probably MIL-STD-1394-BS-4/1 since it appears to be clear. Heaven help any pelicans or sea gulls that land in it.

Mark
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Online meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #248 on: 12/25/2014 01:53 AM »
I still think there is grid. This photo shows that whole contraption on top of barge is half-translucent - difference between "wings" (showing water under it) and main body (showing barge under it) are clearly visible.

If there is no grid, how this difference is explained?

My 2c:

When you look at your linked image, you see a large highlight on the water (sun reflection) that is partially obscured by the upper corner or the barge.

If the deck was partially transparent, you'd have been able to see some trace of this bright highlight.  Instead, you only see the dark color that you interpret as "dark water showing through" but can in fact be anything from a different coat of paint to a different temperature and thus different amount of humidity.
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Offline CJ

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #249 on: 12/25/2014 02:45 AM »
My take on the pics of the ASDS deck; it has a retaining wall (yellow) around it. I agree with other posters that it's an I beam, but, in some pics (thanks and a shout out to Eer and others who have provided pics!!!) there's standing water.

Okay, let's touch on nautical design; in general, seagoing craft prefer to keep the sea on the outside, rather than on the inside, or on top. The latter is due to to weight issues; especially in a storm, you don't want extra mass topside. (this is why ships have to be mindful of icing). Think of that barge in high seas if there's no way to rapidly drain that deck; a wave hits, flooding the deck. That yellow I beam looks to be about two feet high, so that gives us a possibility of two feet of water. ballparking the deck area at 230x170 feet, so 78200 gallons of water, at 8.55 pounds per, for a mass of 334 tons. And worse than just mass, it's mass on the move.

Therefor, unless you want a barrier that'll hold water, you'd put in scuppers. These could be as simple as cutting a hole in your I-beam every couple of feet (this would not actually significantly weaken the I beam). I don't see any sort of scuppers, so, it looks to me as if the deck might be designed to flood. Perhaps with water, perhaps with foam, but with something. So, my guess; the I beam is both a liquid barrier and a physical barrier (to help contain a slipping stage, perhaps).



The world's largest glue trap?

It makes sense; they had to do something about all those mice from CRX-4.

@mme, I think it's at least possible that the ASDS will use dyhydrogen monoxide during an operational mission, though it'll probably have a bit of Cl and Na in the mix. That mix is corrosive, as well as dangerous if inhaled, so I think they'd prefer to keep it well below deck level.

 


Online speedevil

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #250 on: 12/25/2014 04:54 AM »
Okay, let's touch on nautical design; in general, seagoing craft prefer to keep the sea on the outside, rather than on the inside, or on top. The latter is due to to weight issues; especially in a storm, you don't want extra mass topside. (this is why ships have to be mindful of icing). Think of that barge in high seas if there's no way to rapidly drain that deck; a wave hits, flooding the deck. That yellow I beam looks to be about two feet high, so that gives us a possibility of two feet of water. ballparking the deck area at 230x170 feet, so 78200 gallons of water, at 8.55 pounds per, for a mass of 334 tons. And worse than just mass, it's mass on the move.

As context - the barge has tanks that can hold 13000 tons of ballast water.
I think these tanks are mostly full now - due to the relatively low freeboard.

334 tons is nothing.
And it can't meaningfully be on the move - if it can only tilt 1:150 before spilling half of it out.

Offline cambrianera

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #251 on: 12/25/2014 07:49 AM »
I'm the only one to see rows of holes on the deck?
Look left of the red lines.
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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #252 on: 12/25/2014 09:00 AM »
I'm the only one to see rows of holes on the deck?
Look left of the red lines.

Yes, I do wonder why we don't see them also in other pictures. Especially those from directly above provided by SpaceX.

Another point. Yes the puddles of water indicate strongly that there is no grid. However some argued the difference in texture is due to the central part is the original deck only painted over. Is that really likely? It seems to me they would have built the whole deck surface to their needs and it would not be the original deck. Would the original barge deck that flat without any surface structures?

Offline cambrianera

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #253 on: 12/25/2014 09:07 AM »
I'm the only one to see rows of holes on the deck?
Look left of the red lines.

Yes, I do wonder why we don't see them also in other pictures. Especially those from directly above provided by SpaceX.
Lack of resolution? Holes (if any) doesn't seem that big.

And they can be seen in some other pictures from Eer.
« Last Edit: 12/25/2014 09:08 AM by cambrianera »
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Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #254 on: 12/25/2014 11:59 AM »
It seems to me they would have built the whole deck surface to their needs and it would not be the original deck. Would the original barge deck that flat without any surface structures?

Let's rephrase the question. SpaceX knew they wanted a barge with nothing on the deck. So why wouldn't they buy a barge with nothing on the deck? And if there was something, cut it out and weld a plate in.

Many barges are built like this so heavy equipment and commodities can be on/offloaded easily without obstruction. In fact, there's an entire such class of barges called "deck" barges. Check Google Images for "flat deck barge" and you'll find hundreds of them. Here's just one for reference:

« Last Edit: 12/25/2014 12:10 PM by Kabloona »

Offline Nomadd

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #255 on: 12/25/2014 01:34 PM »
 It's not too likely they're going to land a rocket on the thin steel of the main deck unless they're trying to sink the barge. That deck is a main structural component and you really don't want to weaken parts of it by heating it with an M1D.

Offline Avron

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #256 on: 12/25/2014 01:52 PM »
I'm the only one to see rows of holes on the deck?
Look left of the red lines.

That answers the question of how they will tie the vehicle onto the Barge

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #257 on: 12/25/2014 02:22 PM »
It's not too likely they're going to land a rocket on the thin steel of the main deck unless they're trying to sink the barge. That deck is a main structural component and you really don't want to weaken parts of it by heating it with an M1D.

Do we know what the deck plate thickness really is? I saw one used "heavy duty" barge for sale with a deck thickness listed as 1".

The Marmac 300 has some specs listed online but I wasn't able to find a deck thickness spec. FWIW, the site below calls Marmac 300 a "heavy deck" barge.

http://www.marinelink.com/maritime/MARMAC

And this paper from some MIT students seems to suggest a nominal thickness of 20 mm for a Marmac-400-class barge.

http://ocw.mit.edu/courses/engineering-systems-division/esd-77-multidisciplinary-system-design-optimization-spring-2010/projects/MITESD_77S10_paper04.pdf

So it seems possible that the Marmac 300 "heavy deck" barge could have a deck plate thickness around 3/4" or so.
« Last Edit: 12/25/2014 02:34 PM by Kabloona »

Offline cambrianera

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #258 on: 12/25/2014 02:23 PM »
I'm the only one to see rows of holes on the deck?
Look left of the red lines.

That answers the question of how they will tie the vehicle onto the Barge
Maybe.
Maybe they are only sinkholes to keep the level constant (with a continuous recirculation of water, ejected from side nozzles toward center of the deck).
Maybe they can be dual use, maybe something we don't imagine.

Well, I think everybody here hopes to see soon what they are for  ;)
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Online speedevil

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #259 on: 12/25/2014 02:44 PM »
It's not too likely they're going to land a rocket on the thin steel of the main deck unless they're trying to sink the barge. That deck is a main structural component and you really don't want to weaken parts of it by heating it with an M1D.

The deck is a main structural component.
Sure.
However.
The total mass of the rocket is ~22 tons, the engine has a minimum thrust of ~40 tons.
The rocket ends up supported by three legs ~25m apart or so - 15m away from the weakened area.
The deck is normally specified for 20 tons or so a square meter.

Assuming 1G decelleration. (it's likely to be somewhat higher than this, due to the control system being designed to have flexibility to both increase and reduce throttle.)

The engine is ~2m away from the deck when landed - and it will be 6m away from the deck about one second before landing.
Two seconds, it's 25m up.
The engine exhaust is _very_ collimated - but steel has poor thermal conductivity - you simply can't heat it all the way through in 2 seconds, for a deck that can support 20 tons/m^2.

Yes, you may buckle a patch, but that patch is at most perhaps 3m in diameter, and to suggest this risks the barge is utterly ridiculous.

Without actually doing the numbers - I expect you can hit the deck to wash the area just after landing with the flood gun, and end up needing to only repaint.
« Last Edit: 12/25/2014 02:46 PM by speedevil »

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