Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3  (Read 807150 times)

Offline AnalogMan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #780 on: 05/01/2016 12:53 AM »
I saw nothing on Marinetraffic for EIII today or yesterday when the three ships were splashing around the harbor.  Kinda odd considering Marinetraffic has a receiver bolted to Fishlips.  I only see one current hit and no path / track from EIII on Vesselfinder.  Is anyone seeing better with the other services?

I see a track on both vesselfinder.com and marinetraffic.com

Position data seems to have been available since 00:28 UTC.  Currently heading about 120 degrees at 5 knots.

Offline Johnnyhinbos

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #781 on: 05/01/2016 03:31 AM »
Yes! Our girl Elsbeth III now transmitting and outbound. I hope her crew is even half as interested in her activity as we are...
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Offline CameronD

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #782 on: 05/01/2016 11:45 PM »
From the CRS-8 update thread;
Wow - SpaceX just tweeted a 360 degree video of the stage landing on OCISLY. You have to view it on YouTube, but if viewed with smartphone you can move your phone around to adjust viewing angle...

It's a shame they didn't leave the camera running..  What would have been even more interesting in 360deg would be the sight of the safing crew coming aboard and doing their thing.
 
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 Zed_Noir

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #783 on: 05/02/2016 01:17 AM »
From the CRS-8 update thread;
Wow - SpaceX just tweeted a 360 degree video of the stage landing on OCISLY. You have to view it on YouTube, but if viewed with smartphone you can move your phone around to adjust viewing angle...

It's a shame they didn't leave the camera running..  What would have been even more interesting in 360deg would be the sight of the safing crew coming aboard and doing their thing.
 

Maybe they have the footage, just no released yet.

Online meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #784 on: 05/02/2016 01:26 AM »
From the CRS-8 update thread;
Wow - SpaceX just tweeted a 360 degree video of the stage landing on OCISLY. You have to view it on YouTube, but if viewed with smartphone you can move your phone around to adjust viewing angle...

It's a shame they didn't leave the camera running..  What would have been even more interesting in 360deg would be the sight of the safing crew coming aboard and doing their thing.
 

And since this was a topic elsewhere - no sonic boom in the video...  Obvious why, but still cool.
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« Last Edit: 05/02/2016 01:41 AM by Ronsmytheiii »
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Offline CameronD

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #786 on: 05/02/2016 02:46 AM »
Go Quest heading out to sea:

http://www.marinetraffic.com/en/ais/details/ships/shipid:450521/mmsi:367564890/imo:1155515/vessel:GO_QUEST

Edit: Same for Go Searcher

http://www.marinetraffic.com/en/ais/details/ships/shipid:426008/mmsi:366584000/imo:9591648/vessel:GO_SEARCHER

Interesting to note that Marinetraffic's reporting AIS source in this instance is operated by "PTZtv and Fishlips".  Sounds like they've more invested in Port Canaveral than just a few cameras.


EDIT:  Go Searcher increasing speed..
« Last Edit: 05/02/2016 02:50 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.

Online Lar

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #787 on: 05/02/2016 02:51 AM »
if both Go sisters are going does that mean fairing recovery work?
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #788 on: 05/02/2016 03:39 AM »
if both Go sisters are going does that mean fairing recovery work?

That's our working thoery, at least for fairing tracking if not yet recovery.

So far, GO Searcher has been dispatched on missions only with fairings, and stayed at home for CRS-8 (carrying Dragon instead of payload fairing).
« Last Edit: 05/02/2016 04:27 AM by Kabloona »

Offline Ohsin

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #789 on: 05/02/2016 06:13 AM »
What is the yellow apparatus at the starboard rear of OCISLY? Seems like it has two vertical bars in back, a cylinder inside, and perhaps a ladder on the deck side? It seems to be overhanging the stern slightly.

I noticed that thing too, I think it may be new. Got good screen shots of it, but don't think I can post them for IP reasons. On the other hand, it is not an angle we usually see Ocisly from.

Matthew

I couldn't see departure so all I have are these still frames...anyway.

http://www.portfever.com/webcam_player_pcw.php?date=20160430&start=1141&end=1200

Frame 1159 onwards. Yes a ladder and guard rails on top. What could be its function? Also there is a roof shielding over space behind blast shield at stern where they keep jacks, gas cylinders, work platform and cherry picker etc . Nice to see Droneship evolution after every attempt! they have colored the mini shields protecting the hydraulic lines to thrusters as yellow too.

Adding an image I found on Instagram by user '_adamgoodwin'

https://www.instagram.com/p/BE0DaEmBzPM/

« Last Edit: 05/02/2016 06:15 AM by Ohsin »
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Offline leetdan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #790 on: 05/02/2016 06:22 AM »
And since this was a topic elsewhere - no sonic boom in the video...  Obvious why, but still cool.

Except there was a sonic boom... Did you watch the same video?  Check your volume maybe ;)  There's ambient noise from the gensets, then three quick pops immediately followed by rocket sounds that persist until cutoff.  The mic on this setup lacks sufficient dynamic range, so the boom and thrust sounds don't sound much louder than the ambient noise on the recording.  I'm sure it's quite different in person :)

I can believe there being three pops at minimum range... During Orbcomm I heard two from State Road 3, and Jim heard 1 from wherever he was.

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #791 on: 05/02/2016 07:04 AM »
And since this was a topic elsewhere - no sonic boom in the video...  Obvious why, but still cool.

Except there was a sonic boom... Did you watch the same video?  Check your volume maybe ;)  There's ambient noise from the gensets, then three quick pops immediately followed by rocket sounds that persist until cutoff.  The mic on this setup lacks sufficient dynamic range, so the boom and thrust sounds don't sound much louder than the ambient noise on the recording.  I'm sure it's quite different in person :)

I can believe there being three pops at minimum range... During Orbcomm I heard two from State Road 3, and Jim heard 1 from wherever he was.
Yes  - but not very boom like...  Could be the mikes.  Or that along the flight axis you get a much weaker "boom".

EDIT:
It took 17 seconds from that ratatat to touchdown.   If that happened at 340 m/s, then the stage was accelerating at 20 m/s, so had a T/W = 3.0, on average.

right?
« Last Edit: 05/02/2016 07:17 AM by meekGee »
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Offline Ohsin

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #792 on: 05/02/2016 08:08 AM »


Posted by ugordan https://forum.nasaspaceflight.com/index.php?topic=38149.msg1464456#msg1464456

Had boom hit 13 sec before lights out so sonic boom hitting 17 seconds earlier on bulls eye sounds right and that is when Mr Seagull hitching a free ride on droneship decided not to be roasted so nothing too bothersome happened before the beginning of 360 video.
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Offline cscott

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #793 on: 05/02/2016 12:17 PM »
if both Go sisters are going does that mean fairing recovery work?

That's our working thoery, at least for fairing tracking if not yet recovery.

So far, GO Searcher has been dispatched on missions only with fairings, and stayed at home for CRS-8 (carrying Dragon instead of payload fairing).
I'm a fan and proponent of that working theory.  Just to play devil's advocate, though: all the "with fairing" missions have been GTO attempts, right?  It's *possible* that the second Go * ship is there for some other GTO-related reason, maybe even just downrange distance, say.  We'll really get confirmation if we see it going out for a LEO-with-fairing mission... or if it comes back with bits of fairing on deck. ;)

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #794 on: 05/02/2016 01:39 PM »
if both Go sisters are going does that mean fairing recovery work?

That's our working thoery, at least for fairing tracking if not yet recovery.

So far, GO Searcher has been dispatched on missions only with fairings, and stayed at home for CRS-8 (carrying Dragon instead of payload fairing).
I'm a fan and proponent of that working theory.  Just to play devil's advocate, though: all the "with fairing" missions have been GTO attempts, right?  It's *possible* that the second Go * ship is there for some other GTO-related reason, maybe even just downrange distance, say.  We'll really get confirmation if we see it going out for a LEO-with-fairing mission... or if it comes back with bits of fairing on deck. ;)

Yes, Searcher has done only GTO missions so far.

But hopefully they can perfect fairing recovery on GTO launches, not just LEO, otherwise there's really no point in trying since vast majority of fairings used will be on GTO's.
« Last Edit: 05/02/2016 01:44 PM by Kabloona »

Offline leetdan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #795 on: 05/02/2016 01:57 PM »
Rewatching my landing video, I remembered wrong, it was also 3 pops in about the same cadence as this new video.

Here's how the Orbcomm landing's sonic boom was modeled; obviously the boom for an ASDS landing could be different for any number of reasons, but I'd say there's no chance of there not being a boom at ground zero.

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #796 on: 05/02/2016 03:13 PM »
Rewatching my landing video, I remembered wrong, it was also 3 pops in about the same cadence as this new video.

Here's how the Orbcomm landing's sonic boom was modeled; obviously the boom for an ASDS landing could be different for any number of reasons, but I'd say there's no chance of there not being a boom at ground zero.
Yes, agreed.

So if a vehicle is moving towards you at some constant supersonic speed, how far ahead is the sonic boom?

(Then we can talk about a decelerating vehicle)

We should take this to a different thread, but if this is a way to figure out the deceleration during final approach, that will be cool.

EDIT:
https://en.m.wikipedia.org/wiki/Sonic_boom
« Last Edit: 05/02/2016 03:17 PM by meekGee »
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Offline cscott

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #797 on: 05/02/2016 03:23 PM »
The sonic boom travels at the speed of sound, naturally.  Typically it would be behind you; the only way it can arrive *before* you is if you are decelerating, such that the sonic boom catches up to you and passes you.  I think someone upthread already did the math assuming constant deceleration.

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #798 on: 05/02/2016 03:25 PM »
Rewatching my landing video, I remembered wrong, it was also 3 pops in about the same cadence as this new video.

Here's how the Orbcomm landing's sonic boom was modeled; obviously the boom for an ASDS landing could be different for any number of reasons, but I'd say there's no chance of there not being a boom at ground zero.
Yes, agreed.

So if a vehicle is moving towards you at some constant supersonic speed, how far ahead is the sonic boom?

(Then we can talk about a decelerating vehicle)

We should take this to a different thread, but if this is a way to figure out the deceleration during final approach, that will be cool.

EDIT:
https://en.m.wikipedia.org/wiki/Sonic_boom
So as I remembered (see picture), a sonic boom is only heard behind the vehicle, along a cone whose angle depends on the speed of the vehicle (and the speed of sound).   So for every speed you get a different angle, but it's always backwards of the vehicle.

But, if you look at the illustrations, there's another degenerate case - exactly at Mach 1.0  Then you get a boom directly in front of the vehicle, but only during the moment of crossing the speed of sound.

Remember that a sonic boom is not a "thing".  It's just the place where a bunch of shock fronts have constructive interference.  It doesn't "propagate" because it doesn't exist outside of that location.

I am not sure what we're hearing at ground level.  Maybe it's a shock wave from the stage doing Mach>1 while still having a horizontal component...
 
But the most curious thing here is that 2g average deceleration.  I thought our estimate for the "slam" in hoverslam was about 1g.
« Last Edit: 05/02/2016 05:05 PM by meekGee »
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Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #799 on: 05/02/2016 06:27 PM »
Quote
So as I remembered (see picture), a sonic boom is only heard behind the vehicle, along a cone whose angle depends on the speed of the vehicle (and the speed of sound).   So for every speed you get a different angle, but it's always backwards of the vehicle.

That is true only for a body which continues on at M>1 or M=1.  cscott is correct above that if the vehicle is decelerating, the shock waves it created at supersonic speed *can* pass ahead of it. So the sonic boom *can* be heard directly "ahead" of a body decelerating below supersonic.

This is analogous to your M>1 diagram in which the point source (the center of the circles) suddenly slows below M=1 and stops creating more shock "circles." But the existing shock "circles" continue to propagate outward in all directions, including "ahead" of the last point where the body was supersonic.

This is why the sonic boom could be heard right on the landing pad, directly "ahead" of the incoming, now-subsonic stage...if only there were someone on the pad to actually hear it...  :)


« Last Edit: 05/02/2016 06:41 PM by Kabloona »

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