Author Topic: BFR ASDS  (Read 11338 times)

Offline Ludus

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BFR ASDS
« on: 09/30/2017 02:13 AM »
The BFR ASDS shown at the 2017 SpaceX presentation at the Adelaide IAU conference seems pretty distinct from the ASDS used with Falcon.

It’s intended to really live up to the “Spaceport”, including the same Booster launch and landing mount and the same launch tower with hammerhead crane shown in the 2016 IAU video at pad 39a for ITS.


Online groknull

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Re: BFR ASDS
« Reply #1 on: 09/30/2017 03:45 AM »
For scale, the ferry in the video appears to be based on the Austal 102m trimaran "Condor Liberation".

Offline su27k

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Re: BFR ASDS
« Reply #2 on: 09/30/2017 04:10 AM »
We need to put some ships (ADSD, oil tanker, container ship) around this thing to get a sense of scale.

Also, no flame trench?

BTW, this finally fulfills Elon's twitter musing about just land the first stage on the barge, fill it up and fly it back. He really doesn't want to give up that idea  :D

Offline Coastal Ron

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Re: BFR ASDS
« Reply #3 on: 09/30/2017 04:23 AM »
We need to put some ships (ADSD, oil tanker, container ship) around this thing to get a sense of scale.

We know the diameter of the rocket - isn't that enough to scale everything else?

Quote
Also, no flame trench?

In the video the exhaust appeared to exit out from the bottom area of the barge, but yeah, it's not clear.

Quote
BTW, this finally fulfills Elon's twitter musing about just land the first stage on the barge, fill it up and fly it back. He really doesn't want to give up that idea  :D

The whole idea about colonizing Mars has had many chances to die, yet he won't let it. He is tenacious...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Zed_Noir

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Re: BFR ASDS
« Reply #4 on: 09/30/2017 06:21 AM »
There is space on top of the crane hammerhead for a small helo pad.

Offline vaporcobra

Re: BFR ASDS
« Reply #5 on: 09/30/2017 06:56 AM »
Just realized that I quite literally cannot screenshot in 4K because I don't have a 4K monitor :( But, regardless, here's a 4K version of the video shown in the livestream that will provide you much more detailed renders of the BFR ASDS/platform.

spaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaace

Offline Ludus

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Re: BFR ASDS
« Reply #6 on: 09/30/2017 09:46 PM »
It seems to be at least 300m x 100m with on board Liquid Methane and LOX tanks. Otherwise the system looks exactly the same as the pad 39a Version. The launch and landing mount for the Booster presumably is over a flame duct that channels it out the side. There would be quite a bit of space available below deck. Power for thrusters and general ops could come from turbines using the same Methane as the rocket.

It really fits “Autonomous Spaceport Drone Ship”. This is a general purpose Spaceport that can be built in a shipyard and moved where needed around the world.

It seems like 39a will be the first BFR pad but this ASDS might be the second. It might be intended for a location like Boca Chica but this approach allows a lot more flexibility.

Offline vaporcobra

Re: BFR ASDS
« Reply #7 on: 09/30/2017 09:57 PM »
It seems to be at least 300m x 100m with on board Liquid Methane and LOX tanks. Otherwise the system looks exactly the same as the pad 39a Version. The launch and landing mount for the Booster presumably is over a flame duct that channels it out the side. There would be quite a bit of space available below deck. Power for thrusters and general ops could come from turbines using the same Methane as the rocket.

It really fits “Autonomous Spaceport Drone Ship”. This is a general purpose Spaceport that can be built in a shipyard and moved where needed around the world.

It seems like 39a will be the first BFR pad but this ASDS might be the second. It might be intended for a location like Boca Chica but this approach allows a lot more flexibility.

It's most certainly trapped in whichever ocean it launches in if it's intended to be an actual vessel and not a fixed platform. Not necessarily a problem, but it definitely is a step beyond the current ASDS ;D
spaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaace

Offline darkenfast

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Re: BFR ASDS
« Reply #8 on: 10/01/2017 03:36 AM »
It seems to be at least 300m x 100m with on board Liquid Methane and LOX tanks. Otherwise the system looks exactly the same as the pad 39a Version. The launch and landing mount for the Booster presumably is over a flame duct that channels it out the side. There would be quite a bit of space available below deck. Power for thrusters and general ops could come from turbines using the same Methane as the rocket.

It really fits “Autonomous Spaceport Drone Ship”. This is a general purpose Spaceport that can be built in a shipyard and moved where needed around the world.

It seems like 39a will be the first BFR pad but this ASDS might be the second. It might be intended for a location like Boca Chica but this approach allows a lot more flexibility.

It's most certainly trapped in whichever ocean it launches in if it's intended to be an actual vessel and not a fixed platform. Not necessarily a problem, but it definitely is a step beyond the current ASDS ;D
Big oil rigs are towed all over the world.  They just have to go the long way around.  The oil industry has most of the answers to large floating launch and landing pads (see Sea Launch for an example), whether it's a barge or a elevated platform. 

While I don't think the structure will be a problem, it's still going to be hard to find a stretch of water close enough to major populations but big enough to close off the necessary exclusion zone for this sized rocket.  Aren't we talking a circle 6+ miles in diameter?

This is the one part of Elon's presentation that I have problems with.  Tourist flights, yes.  Multiple daily point-to-point flights will run up against an awful lot of hurdles, although I don't see any technical reasons why it wouldn't work. 

Offline IainMcClatchie

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Re: BFR ASDS
« Reply #9 on: 10/01/2017 04:01 AM »
The ASDS in the video shows a landing pad separate from the launch pad.

Are they still planning to land on the launch pad?  I think Elon said this during his Friday presentation.

Are they planning to land the BFS on a pad rather than a cradle?  If eliminating the landing gear saves booster mass, I'd think it would save orbiter mass as well.

Overall, my impression of the BFR/BFS announcement was
* meh, this is a downsized version of last year's presentation, and
* doesn't the BFS suffer the same problem that the Space Shuttle suffered, which was that you are essentially launching a mini space station into orbit on every launch?  Why not separate people and cargo?

I know, I know, Elon's idea is that the people are the cargo, but that's barely true for commercial aviation today, in a context where ships carry everything heavy.  In a context where his ride is the only ride, I have to believe there will be a huge amount more cargo than people.

Online KelvinZero

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Re: BFR ASDS
« Reply #10 on: 10/01/2017 04:06 AM »
"meh"? :)

Re the comparison to the shuttle, there are lots of differences (there is a cargo-only variant) but the full list definitely deserves it's own thread.

Offline biosehnsucht

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Re: BFR ASDS
« Reply #11 on: 10/01/2017 05:14 AM »
There's a landing pad for the BFS, but the BFR likely still intended to land on the launch mounts.

This may not be a mega-ASDS, it might be a fixed installation (or fixed in X-Y, able to be moved in Z to account for weather). Consider all those big spherical tanks probably can only store enough for one or two flights, and they need to bring more prop somehow. Likely underwater pipe, as there doesn't seem to be any large prop facility in sight (though in theory you could do some kind of massive floating solar + energy storage + CO2 capture + water  -> Sabatier > CH4 + LOx, it would take up more real estate than the "ASDS"). Perhaps floated to destination then anchored, or built on site, who knows.

Offline Ludus

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Re: BFR ASDS
« Reply #12 on: 10/01/2017 06:33 AM »
There's a landing pad for the BFS, but the BFR likely still intended to land on the launch mounts.

This may not be a mega-ASDS, it might be a fixed installation (or fixed in X-Y, able to be moved in Z to account for weather). Consider all those big spherical tanks probably can only store enough for one or two flights, and they need to bring more prop somehow. Likely underwater pipe, as there doesn't seem to be any large prop facility in sight (though in theory you could do some kind of massive floating solar + energy storage + CO2 capture + water  -> Sabatier > CH4 + LOx, it would take up more real estate than the "ASDS"). Perhaps floated to destination then anchored, or built on site, who knows.

Ships could supply LOX and Methane. Actual holding tanks on a 300 m ASDS could be pretty large, they might extend below water level.

The Adelaide presentation is the first time I heard Elon mention even in passing that ultimately SpaceX could use the same sort of solar electric driven ISRU that’s required on Mars to synthesize Methane from Co2 on earth so BFR could actually be zero net carbon. It’s expensive and not serious commercial scale still but worth attention.

That’s true, it could be fixed. Even if it’s floating but anchored I suppose it might not be called an ASDS.
« Last Edit: 10/01/2017 06:38 AM by Ludus »

Offline speedevil

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Re: BFR ASDS
« Reply #13 on: 10/01/2017 03:11 PM »
It's most certainly trapped in whichever ocean it launches in if it's intended to be an actual vessel and not a fixed platform. Not necessarily a problem, but it definitely is a step beyond the current ASDS ;D

Raptors need testing. The ASDS+ already has LOX and methane tanks. Problem solved.

Online meekGee

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Re: BFR ASDS
« Reply #14 on: 10/02/2017 12:02 AM »
An honest question. 

If they're thinking about a BFR ASDS - why bother with land pads at all?

Build the rockets at a ship yard, so they go directly from factory to ASDS, and that's the end of that.

No road transport of any kind ever.  ASDS can hang out just a couple of mile off shore, come in to load large cargo, go back out.

People and Fuel go out to the ASDS so it stays off shore.

No weather issues either, since the ASDSs are mobile.




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Offline CameronD

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Re: BFR ASDS
« Reply #15 on: 10/02/2017 01:21 AM »
An honest question. 

If they're thinking about a BFR ASDS - why bother with land pads at all?

Build the rockets at a ship yard, so they go directly from factory to ASDS, and that's the end of that.

No road transport of any kind ever.  ASDS can hang out just a couple of mile off shore, come in to load large cargo, go back out.

People and Fuel go out to the ASDS so it stays off shore.

No weather issues either, since the ASDSs are mobile.

There certainly will be weather issues with an ASDS system on any body of water anywhere in the world.  The clip shows take-off and landing in calm conditions, but, ignoring basic stability issues for a sec, there's no way you'll get passengers going up a tower on a floating platform in any kind of swell : with a total loss of spacial reference they'll be seasick before they get aboard!  If you doubt me, go up the mast of a yacht tied up alongside a wharf (that's as stable an analog as you'll get) and, after admiring the view, shut your eyes for 30 seconds or so and see how you feel about being there and then imagine the average passenger (not some mast-climbing thrill-seeker) in the same situation, but for longer...

Land pads vs ASDS:  (a) I'm no expert, but just can't see how the economics stack up.  It isn't cheap running ferries and fitting out an ASDS.  Given identical infrastructure requirements, surely a landing pad (a tiny? patch of real-estate and some concrete) has to be cheaper to buy and run?, and
(b) Given that a land pad doesn't move in a decent blow, surely there would be less cancelled flights from a land pad than an ocean-based one.. and
(c) People can drive to a land pad in their own car (or bus/train), no need to catch a ferry.


EDIT:  FWIW, similar concept discussion ended the era of the trans-oceanic flying boats.  As romantic as travel by flying boat was, the weather at either end made landing at a land pad (airport) a much more viable option better suited to the needs of the travelling public.
« Last Edit: 10/02/2017 01:48 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 KelvinZero

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Re: BFR ASDS
« Reply #16 on: 10/02/2017 01:30 AM »
Hmmm.. I just had a whole bunch of ideas of creating an area of calm water where the docking part is.. then I realised, we must do this all the time. Eg nice quiet bays. Has anyone ever done this for floating platforms before?

Offline CameronD

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Re: BFR ASDS
« Reply #17 on: 10/02/2017 01:33 AM »
Hmmm.. I just had a whole bunch of ideas of creating an area of calm water where the docking part is.. then I realised, we must do this all the time. Eg nice quiet bays. Has anyone ever done this for floating platforms before?

The ones we know of were called "flying boat bases" - built to serve the floating platforms called "flying boats".  They lasted until some guy built an all-weather airport on a patch of land nearby (how rude!).
« Last Edit: 10/02/2017 01:43 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 watermod

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Re: BFR ASDS
« Reply #18 on: 10/02/2017 01:53 AM »
It would make more sense to have a mini man built island or structure and have his TBMs drill tunnels to it to bring people, cargo and fuel to/from the platform.


Online meekGee

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Re: BFR ASDS
« Reply #19 on: 10/02/2017 02:46 AM »
If the ASDS is truly mobile, it can get away from bad weather spots.

You still need to get to it, but 100 miles in each direction is not a big deal.
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