Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3  (Read 807449 times)

Offline NovaSilisko

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #460 on: 04/09/2016 03:26 AM »
So we're back to the good old pasttime of arguing about all the minutia SpaceX is doing wrong, eh?

Welding is cheap and quick. Just a loop of metal that sits over the very end of the leg and stops it from skidding or lifting up. I'm more worried about skidding than tipping. If it's tilting to the point that it actuall falls over, we're talking Poseidon Adventure level wave action, and you've probably got bigger issues (like the entire thing sinking)

Also, I'm pretty sure we saw the shoes before, somewhere. Buried in one of the old ASDS threads, no doubt.
« Last Edit: 04/09/2016 03:31 AM by NovaSilisko »

Offline Ohsin

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #461 on: 04/09/2016 04:25 AM »
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Also, I'm pretty sure we saw the shoes before, somewhere. Buried in one of the old ASDS threads, no doubt.

No we would know that. Also the idea of shoes going over tips and being welded isn't lost on me in fact it is intuitive just like for everyone else after listening and reading to Elon ... 'Steel' 'Over legs' 'Welded to deck' yep even more obvious I just find it odd that rocket sitting on jacks isn't worth mentioning..It is not something obvious and they visibly put work into it and stuck with them for many attempts. Mind it only one person here predicted them before they were seen on DSCVR attempt. So just trying to pick holes in the 'obvious' anyways..

To divert subject Mark mentioned in discussion thread that first stage maintains its roll such that the sides of square formed by joining leg tips are parallel to sides of deck. On Jason3 attempt this was true as well. So stage is simply adjusting its roll to reduce chances of one leg going overboard? If yes how does it determine orientation of ASDS?

Or ASDS is maintaining predetermined position as well as orientation? What factor decides what orientation ASDS should maintain? Is it something related to waves like aligning to have them along length than width.
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Offline Nomadd

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #462 on: 04/09/2016 04:46 AM »
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Also, I'm pretty sure we saw the shoes before, somewhere. Buried in one of the old ASDS threads, no doubt.


Or ASDS is maintaining predetermined position as well as orientation? What factor decides what orientation ASDS should maintain? Is it something related to waves like aligning to have them along length than width.
That's a good question. And a complicated one. Boats sitting still act nothing like boats moving. Bow into the waves on a still barge could make the thing pitch more than side to the waves. And, do they worry more about pitching and rolling or sliding sideways? Those Thrustmasters aren't instantaneous.

Offline OxCartMark

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #463 on: 04/09/2016 04:56 AM »
My guesses on how shoes would look;

Offline Ohsin

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #464 on: 04/09/2016 05:10 AM »
Or ASDS is maintaining predetermined position as well as orientation? What factor decides what orientation ASDS should maintain? Is it something related to waves like aligning to have them along length than width.
That's a good question. And a complicated one. Boats sitting still act nothing like boats moving. Bow into the waves on a still barge could make the thing pitch more than side to the waves. And, do they worry more about pitching and rolling or sliding sideways? Those Thrustmasters aren't instantaneous.

Maintaining position would be priority and they have less error margin along width.
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Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #465 on: 04/09/2016 09:30 AM »
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I just find it odd that rocket sitting on jacks isn't worth mentioning..It is not something obvious and they visibly put work into it and stuck with them for many attempts.

Maybe leg piston locks have been beefed up to the point they think legs alone can support the stage safely during transit with no need for jacks now.

Or maybe Elon just didn't bother to mention because in this case jacks won't be weighted down and thus are not really contributing to stability, just protecting against leg collapse.
« Last Edit: 04/09/2016 10:02 AM by Kabloona »

Offline MarekCyzio

Update: Elon confirmed Sunday arrival at press conference.


Thank you. I guess I will be spending my Sunday at the beach ;)

Wouldn't Fish Lips have a better view, or not? I finished my taxes after working all week on them, so might be a good way to reward myself. It would be about a 2 hr drive from Jacksonville.


Any place in the port will be good.

Offline MarekCyzio

Also Elon said ultimately it'll be at Port Canaveral but not sure if it is initial destination.


SpaceX installed special "rocket mount" in Port Canaveral. I suspect this mount may be required to unload the rocket. So I doubt SpaceX would divert to any other port.

Offline cambrianera

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #468 on: 04/09/2016 11:07 AM »
Also Elon said ultimately it'll be at Port Canaveral but not sure if it is initial destination.


SpaceX installed special "rocket mount" in Port Canaveral. I suspect this mount may be required to unload the rocket. So I doubt SpaceX would divert to any other port.

IMHO needed to remove the legs.
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Offline gadgetmind

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #469 on: 04/09/2016 11:07 AM »
Hmm, "refine", now there's a word. Trying to eliminate those last pesky traces of exploding on impact, falling over and exploding, punching big holes in the deck, and other miscellaneous minor refinements.

OK, now they can refine their landings!

Offline Chris Bergin

Set up a specific thread for the return to port tomorrow:
https://forum.nasaspaceflight.com/index.php?topic=40002.0

Offline cambrianera

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #471 on: 04/09/2016 12:41 PM »
Word is it may come back to JAX, not to the cape

I can see they might have wanted to get close to shore for overnight and/or ASAP, to get out of the higher winds offshore, and JAXPORT would have been closest to their position at the landing site, but why go to the trouble of offloading and trucking the stage from there when it's already loaded for transport on the drone ship. I think when when the stage comes in close to it's final resting place, it will be on the drone ship, not a truck.

They have experience of trucking the stage for thousand of km, they never experienced vertical barge transport.
That said, I don't put a dime on a JAX stop.
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Online litton4

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #472 on: 04/09/2016 01:45 PM »
I'm looping the landing, and it really looks to me as if it bounced/scooted just a bit on landing.  (As in, it looked like the initial landing point was actually closer to the center than the final resting point.)  Obviously, it would've been built for that, and it didn't hurt, but if it did translate just a bit, the targeting may actually be a smidge *better* than the resting stage makes it look.

I noticed this, too - very apparent in the 4K version. Wind taking it a metre or 3 to the left. Scary stuff.
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Offline OxCartMark

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #473 on: 04/09/2016 01:58 PM »
Regarding that bounce - If we knew the coefficient of friction between the deck and the foot pads we could use that to determine what that slide demonstrated in terms of tip over angle (assuming that there wasn't still any significant thrust at that time).  It wouldn't tell us the maximum angle that the stage could be at without tipping over but it would set a lower bound that we know we can survive, at least statically.  But seat of the pants, I think it demonstrates what they've been telling us all along, that the CG is way down low and we shouldn't worry about it.  Elon in the press conference said 6-8 degrees is OK and 8-9 was maybe possible.

Offline Herb Schaltegger

Regarding that bounce - If we knew the coefficient of friction between the deck and the foot pads we could use that to determine what that slide demonstrated in terms of tip over angle (assuming that there wasn't still any significant thrust at that time).  It wouldn't tell us the maximum angle that the stage could be at without tipping over but it would set a lower bound that we know we can survive, at least statically.  But seat of the pants, I think it demonstrates what they've been telling us all along, that the CG is way down low and we shouldn't worry about it.  Elon in the press conference said 6-8 degrees is OK and 8-9 was maybe possible.

I wonder how much of the "skid" on touchdown was due to wind on the settling stage, and how much due to motion of the barge from the sea state? At first blush it looks to me more that the deck of the barge moves under the stage (pitch and roll) as much as the stage moves while it settles.
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Online gongora

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #475 on: 04/09/2016 02:13 PM »
Do we know if a stand for the rocket is still in place at JAX?

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #476 on: 04/09/2016 02:18 PM »
Do we know if a stand for the rocket is still in place at JAX?

Last we saw, stands had been moved to Port Canaveral. But here they are, as originally installed in JAX.



Photo below taken by MarekCyzio at Port Canaveral. You can see they are the same stands, by the "ears" projecting from the top corners of the 2 stands on the left.
« Last Edit: 04/09/2016 03:21 PM by Kabloona »

Offline hans_ober

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #477 on: 04/09/2016 02:45 PM »
Regarding that bounce - If we knew the coefficient of friction between the deck and the foot pads we could use that to determine what that slide demonstrated in terms of tip over angle (assuming that there wasn't still any significant thrust at that time).  It wouldn't tell us the maximum angle that the stage could be at without tipping over but it would set a lower bound that we know we can survive, at least statically.  But seat of the pants, I think it demonstrates what they've been telling us all along, that the CG is way down low and we shouldn't worry about it.  Elon in the press conference said 6-8 degrees is OK and 8-9 was maybe possible.

Check out the barge around 30 seconds into .
(After the stage has landed).

The barge sways A LOT, definitely more than 10 degrees, but the stage seems pretty stable, no signs of movement, which is impressive. Looked close to 20 degrees.

Online gongora

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #478 on: 04/09/2016 03:03 PM »
Do we know if a stand for the rocket is still in place at JAX?

Last we saw, stands had been moved to Port Canaveral. But here they are, as originally installed in JAX. Second photo shows them in Port Canaveral.

Finally found picture from JAX where they had removed stands (only 227 pages into the previous thread).  Was wondering if they had just left stands in both places, if you already have to build 4 stands then building a 5th doesn't seem like a big deal.
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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
Reply #5656 on: 12/19/2015 04:24 PM

Offline OxCartMark

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #479 on: 04/09/2016 03:12 PM »
The barge sways A LOT, definitely more than 10 degrees, but the stage seems pretty stable, no signs of movement, which is impressive. Looked close to 20 degrees.
  No.  Elon addresses this in the press conference.  He said they were seeing 2-3 degrees.

The pictures are very definitive as to the history of the crane and Falcon Perch.  Both were at Jacksonville.  Both were gone from Jax on the next Carnival Fascination images we had after the ASDS departed.  Both have been seen in Port Canaveral since at least the beginning of March and in all probability back into February though I've not traced them back that far.  There isn't much wiggle room for other versions of reality on this.

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