Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2  (Read 2965165 times)

Offline Bob Shaw

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #820 on: 01/10/2015 11:41 pm »
It'd be much easier to accentuate the positive if so many people weren't trying to eliminate the negative. "Look at how far we've come" should always be tempered with how far there is still to go.


Certainly. But even hitting the barge is a helluva triumph. Really, really impressive. My day-to-day job is in that area, and *really* the SpaceX guys (and gals) (and whatevers) did so, so, well getting as far as they have. Trust me, they really did well - anything at sea is far more of a challenge than on terra firma. Add rockets, and...

Offline meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #821 on: 01/11/2015 01:16 am »
It'd be much easier to accentuate the positive if so many people weren't trying to eliminate the negative. "Look at how far we've come" should always be tempered with how far there is still to go.
I absolutely hate when people do that, but looking it at objectively, listing off which bits worked, which didn't, and why,  I count this as a very good result, one that I'd have signed up for in a heartbeat if offered to by the devil ahead of time.

EDIT: ok, maybe two heartbeats. I'm as greedy as the next guy. But still. Check marks on re-entry and all flight regimes, and fail on a (predictable)  triviality during terminal guidance? Don't need to be a amazing people to feel happy about that.
« Last Edit: 01/11/2015 01:19 am by meekGee »
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Offline mvpel

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #822 on: 01/11/2015 01:21 am »

Maybe SBIRS saw it's heat signature... Oh those SpaceX folks must be trying something new again... ;D

No "maybe" about it. ;)
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Offline Lars-J

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #823 on: 01/11/2015 02:40 am »
It'd be much easier to accentuate the positive if so many people weren't trying to eliminate the negative. "Look at how far we've come" should always be tempered with how far there is still to go.

Always? That is a ridiculous standard to apply to most things.
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Offline ChrisWilson68

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #824 on: 01/11/2015 03:30 am »
Sounds like the hydraulic system was likely made inoperable on one or two of the thrusters. Which would mean they'd be stuck in the down position. I guess they'll have to spend some time dealing with that. Might just connect new hyd hoses to quest temp and fold them up?

If you're taking this from Musk's tweet about running out of hydraulic fluid, he was referring to hydraulic fluid on the stage, not on the ASDS.

Offline ChrisWilson68

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #825 on: 01/11/2015 03:30 am »
So many questions..
Lightning protection? Is there any? , Are 'tie downs' ballast tank hatches?, What is the exclusion area around ASDS? If its 10miles do they let it go out of this radius and then it covers distance and station keep unassisted? Were they just topping off the tanks or they  really needed refueling , how much fuel it can consume during each outing as delays can really mess up recovery operation if it needs to be refueled frequently.. we know how much those thrusters can consume, how much those two generators may burn....etc etc

I can probably answer one of those:
The plan was to weld plates over the landing pads to secure them to the deck.
Now if they are to tie down the stage from higher up, they can simply weld plates with U-bolts or shackles to the deck and attach cables at some pre-determined attach point. but I doubt that's needed.

There might be pre-existing tie-down points if they plan to tie the stage down before starting welding.  Welding might be pretty quick, but tying down is even quicker, and they might want the stage as secure as possible before starting the welds.

Online robertross

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #826 on: 01/11/2015 03:40 am »
So many questions..
Lightning protection? Is there any? , Are 'tie downs' ballast tank hatches?, What is the exclusion area around ASDS? If its 10miles do they let it go out of this radius and then it covers distance and station keep unassisted? Were they just topping off the tanks or they  really needed refueling , how much fuel it can consume during each outing as delays can really mess up recovery operation if it needs to be refueled frequently.. we know how much those thrusters can consume, how much those two generators may burn....etc etc

I can probably answer one of those:
The plan was to weld plates over the landing pads to secure them to the deck.
Now if they are to tie down the stage from higher up, they can simply weld plates with U-bolts or shackles to the deck and attach cables at some pre-determined attach point. but I doubt that's needed.

There might be pre-existing tie-down points if they plan to tie the stage down before starting welding.  Welding might be pretty quick, but tying down is even quicker, and they might want the stage as secure as possible before starting the welds.


Doubtful, unless they are recessed. You wouldn't want anything that would cause the landing feet to get caught up during touchdown. It doesn't take long to weld keepers over the feet.

Offline meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #827 on: 01/11/2015 04:36 am »
Hey,

http://www.vesselfinder.com/?mmsi=367017460

seems to be from a few hours ago - am I reading it right?

EDIT: from the coordinates, it was about 120 miles out at the time, should be less than 100 by now.

EDIT2: So if they'll continue at the current speed, they'll hit port early morning.  Please let there be someone with a camera on the HWY 295 bridge.
« Last Edit: 01/11/2015 04:48 am by meekGee »
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Offline dorkmo

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #828 on: 01/11/2015 04:47 am »

Sounds like the hydraulic system was likely made inoperable on one or two of the thrusters. Which would mean they'd be stuck in the down position. I guess they'll have to spend some time dealing with that. Might just connect new hyd hoses to quest temp and fold them up?

If you're taking this from Musk's tweet about running out of hydraulic fluid, he was referring to hydraulic fluid on the stage, not on the ASDS.

Was talking about asds, there are a lot of thrusters and hydraulic systems on everything now lol. Really interesting to learn about the grid fin hydraulics. Looks like from the vessel finder that they weren't delayed much.
« Last Edit: 01/11/2015 05:00 am by dorkmo »

Offline dorkmo

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #829 on: 01/11/2015 04:56 am »
Hey,

http://www.vesselfinder.com/?mmsi=367017460

seems to be from a few hours ago - am I reading it right?

EDIT: from the coordinates, it was about 120 miles out at the time, should be less than 100 by now.

EDIT2: So if they'll continue at the current speed, they'll hit port early morning.  Please let there be someone with a camera on the HWY 295 bridge.

Interesting they are going 6-7 knots. Just a little faster than before.

Offline meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #830 on: 01/11/2015 05:05 am »
Hey,

http://www.vesselfinder.com/?mmsi=367017460

seems to be from a few hours ago - am I reading it right?

EDIT: from the coordinates, it was about 120 miles out at the time, should be less than 100 by now.

EDIT2: So if they'll continue at the current speed, they'll hit port early morning.  Please let there be someone with a camera on the HWY 295 bridge.

Interesting they are going 6-7 knots. Just a little faster than before.

Less fuel on board, and some extra rocket pieces.   ... and prevailing currents might play a tiny role :)

Any takers on guessing what rocket pieces are on board?

0-9 engines, plumbing, octaweb, tanks?
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Offline ChrisWilson68

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #831 on: 01/11/2015 05:14 am »
Any takers on guessing what rocket pieces are on board?

0-9 engines, plumbing, octaweb, tanks?

I'll guess it's 9 engines, all the plumbing, the octaweb, etc. -- all crumpled up but more-or-less everything present.  70%

Offline meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #832 on: 01/11/2015 05:17 am »
I'll throw my guess in then...

Because of the loss of the grid fins, the divert maneuver had to be very aggressive.  The rocket touched down with a horizontal velocity component, and at an angle (trying to stop), and skidded off.  Very little was salvaged.

So hope to be wrong.

EDIT:  Btw, in the profile picture for Elsbeth III on Vessel Finder, it is pushing the ASDS, either in the river or very near shore.

A) Cool that they updated the picture
B) Pushing ?
« Last Edit: 01/11/2015 05:23 am by meekGee »
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Offline cscott

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #833 on: 01/11/2015 05:25 am »
If it hit the barge at all, I'm guessing it hit it pretty much dead center.  And then tipped/pancaked.  So I don't see the heavy engines going anywhere.  I'm guessing there are nine engines, octoweb, and the heavy stuff, but little structure above that: too light, doesn't float well, melts in a fire, blows off the platform before the crew arrives.

All also wager that there's a dark soot mark touching the center and extending from there in the direction of travel.  I don't know exactly what direction that is, but since we're calling in our wild guesses, I'll say orthogonal to the ASDS, that is, across the barge the narrow way.

No significant damage to the equipment containers, but exterior hoses, wires and antennas have been baked/burned.   But no dents.

Offline ChrisWilson68

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #834 on: 01/11/2015 05:26 am »
I'll throw my guess in then...

Because of the loss of the grid fins, the divert maneuver had to be very aggressive.  The rocket touched down with a horizontal velocity component, and at an angle (trying to stop), and skidded off.  Very little was salvaged.

So hope to be wrong.

I think the control system was meant to use the grid fins all the way down.  I don't think it had a mode where it realized the fins weren't working and switched to gimbaling of the M1D and/or cold gas thrusters.  I think when the grid fins were lost, the rocket became uncontrollable.  Perhaps the engine even switched off.

I think if it had switched to a non-fin control mechanism, it very likely either would have missed the barge entirely or landed safely.
« Last Edit: 01/11/2015 05:26 am by ChrisWilson68 »

Online Jdeshetler

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #835 on: 01/11/2015 05:32 am »
At this pace, the ship should arrive at the St. Johns River around 6 to 7pm in the evening.
« Last Edit: 01/11/2015 05:33 am by Jdeshetler »

Offline meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #836 on: 01/11/2015 05:35 am »
I'll throw my guess in then...

Because of the loss of the grid fins, the divert maneuver had to be very aggressive.  The rocket touched down with a horizontal velocity component, and at an angle (trying to stop), and skidded off.  Very little was salvaged.

So hope to be wrong.

I think the control system was meant to use the grid fins all the way down.  I don't think it had a mode where it realized the fins weren't working and switched to gimbaling of the M1D and/or cold gas thrusters.  I think when the grid fins were lost, the rocket became uncontrollable.  Perhaps the engine even switched off.

I think if it had switched to a non-fin control mechanism, it very likely either would have missed the barge entirely or landed safely.

The grid fins lose authority as it slows down.  The final maneuver has to be GH-style, using the engine.

Also, if the good lord* gave you both hands and feet (control mechanisms on both ends of the rocket), you'd be pretty impertinent to shrug one of them off just because you've got the other

:)
« Last Edit: 01/11/2015 05:42 am by meekGee »
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Offline meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #837 on: 01/11/2015 05:38 am »
At this pace, the ship should arrive at the St. Johns River around 6 to 7pm in the evening.

IIANM:

It was 01:06 UTC, not EST. 

110 miles at 7 MPH is 15 hours, so 16:00 UTC, which is 11:00 EST.

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Offline Ohsin

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #838 on: 01/11/2015 05:38 am »
Go quest ( last updated loc Jan 11, 2015 06:26 UTC )

~60km off inlet @ 8.2 Kn
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Offline ChrisWilson68

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2
« Reply #839 on: 01/11/2015 05:42 am »
I'll throw my guess in then...

Because of the loss of the grid fins, the divert maneuver had to be very aggressive.  The rocket touched down with a horizontal velocity component, and at an angle (trying to stop), and skidded off.  Very little was salvaged.

So hope to be wrong.

I think the control system was meant to use the grid fins all the way down.  I don't think it had a mode where it realized the fins weren't working and switched to gimbaling of the M1D and/or cold gas thrusters.  I think when the grid fins were lost, the rocket became uncontrollable.  Perhaps the engine even switched off.

I think if it had switched to a non-fin control mechanism, it very likely either would have missed the barge entirely or landed safely.

The grid fins lose authority as it slows down.  The final maneuver has to be GH-style, using the engine.

Also, if the good lord gave you both hands and feet (control mechanisms on both ends of the rocket), you'd be pretty impertinent to shrug one of them off just because you've got the other :)

I never said it was meant to use only the grid fins.  But if the control system is expecting the grid fins to have some effect and they are not having that effect, it needs a mode where it can stop using them or else it will go out of control.

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