Author Topic: BFR ASDS  (Read 20035 times)

Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
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.

Itís intended to really live up to the ďSpaceportĒ, 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

  • Member
  • Posts: 15
  • U.S. West Coast
  • Liked: 20
  • Likes Given: 70
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

  • Full Member
  • ****
  • Posts: 756
  • Liked: 462
  • Likes Given: 51
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

  • Senior Member
  • *****
  • Posts: 3585
  • I live... along the coast
  • Liked: 2329
  • Likes Given: 2948
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

  • Senior Member
  • *****
  • Posts: 2315
  • Canada
  • Liked: 306
  • Likes Given: 509
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

  • Full Member
  • ****
  • Posts: 637
  • Tacoma, WA
  • Liked: 813
  • Likes Given: 1456
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.

I report on commercial space!

Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
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 ďAutonomous Spaceport Drone ShipĒ. 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

  • Full Member
  • ****
  • Posts: 637
  • Tacoma, WA
  • Liked: 813
  • Likes Given: 1456
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 ďAutonomous Spaceport Drone ShipĒ. 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
I report on commercial space!

Offline darkenfast

  • Member
  • Full Member
  • ****
  • Posts: 762
  • Liked: 413
  • Likes Given: 877
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 ďAutonomous Spaceport Drone ShipĒ. 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

  • Full Member
  • **
  • Posts: 276
  • San Francisco Bay Area
  • Liked: 146
  • Likes Given: 265
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.

Offline KelvinZero

  • Senior Member
  • *****
  • Posts: 3599
  • Liked: 503
  • Likes Given: 128
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

  • Full Member
  • **
  • Posts: 217
  • Liked: 60
  • Likes Given: 86
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

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
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 thatís required on Mars to synthesize Methane from Co2 on earth so BFR could actually be zero net carbon. Itís expensive and not serious commercial scale still but worth attention.

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

Offline speedevil

  • Full Member
  • ****
  • Posts: 995
  • Fife
  • Liked: 468
  • Likes Given: 490
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

  • Senior Member
  • *****
  • Posts: 8000
  • N. California
  • Liked: 4244
  • Likes Given: 852
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.




ABCD - Always Be Counting Down

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
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.

Offline KelvinZero

  • Senior Member
  • *****
  • Posts: 3599
  • Liked: 503
  • Likes Given: 128
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

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
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

  • Full Member
  • ***
  • Posts: 380
  • Liked: 98
  • Likes Given: 116
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

  • Senior Member
  • *****
  • Posts: 8000
  • N. California
  • Liked: 4244
  • Likes Given: 852
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.
ABCD - Always Be Counting Down

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #20 on: 10/02/2017 03:50 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.

Unfortunately, 100 miles @ 5kts = 20 hours actually IS a big deal.. especially since that means your mobile platform is down for most of a day, meaning one day loss of customers - and that's assuming you have 100 miles of water you can move it and still get out of the weather system.

The video included cities like Hong Kong and Singapore where moving 100 miles in any direction would put you out of reach of your customers (travelling via high-speed ferry for 3-4 hours over a rough sea to get to a 30-minute flight to the other side of the world might make waiting in an airport lounge seem kinda comfortable: puke on the way to the flight, whilst boarding the flight, during the flight and after the flight.. yay! what fun!).

« Last Edit: 10/02/2017 04:07 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 Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #21 on: 10/02/2017 03:54 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.

Iíd think SpaceX would consider it. It makes sense to launch initially from 39a, but after that is it worth building a BFR launch site at Boca Chica (in addition to the F9/FH) vs offshore on the first BFR ASDS?

Mobile Spaceports open up a lot of possibilities. Scaling to a global system is obviously much easier. The Air Force and Navy will have an interesting sumo match over who has jurisdiction over this concept. Remote air and naval bases of strategic importance like Diego Garcia or Guam arenít so remote if they have a spaceport and installing such a thing is a lot easier in every respect if it just floats in from a shipyard and stays off the coast. Politics, environmental impact, long term budget issues are all much reduced.

On this one I get the sense that Elon had this in mind for some time. Heís not a big fan of acronyms but SpaceX insisted on ASDS despite the fact it was a barge with some capacity to hold position without anchoring. BFR ASDS seems like Ohhh I get it, that really is an Autonomous Spaceport.


Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #22 on: 10/02/2017 04:13 AM »
Let's just hope the Air Force / Navy wouldn't mistake an incoming BFR from Asia as hostile. :)
 
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 Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #23 on: 10/02/2017 04:13 AM »
Although it was shown in the context of the point to point express idea, it seems at least as important as a general purpose Spaceport.

Cargo launched to space might be put in a container in a facility on land, brought out by ship and the container loaded into the BFS cargo with the hammerhead crane.

That would apply to hyper express shipping, satellite dispensers, cargo to/from space stations or the Moon.

Online Archibald

  • Senior Member
  • *****
  • Posts: 2135
  • Liked: 245
  • Likes Given: 682
Re: BFR ASDS
« Reply #24 on: 10/02/2017 06:05 AM »
https://en.wikipedia.org/wiki/Mobile_offshore_base

The great thing is, you can land a BFR and then have an ATR-42 or 737 to carry the passengers to an airport.

Online meekGee

  • Senior Member
  • *****
  • Posts: 8000
  • N. California
  • Liked: 4244
  • Likes Given: 852
Re: BFR ASDS
« Reply #25 on: 10/02/2017 07:58 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.

Unfortunately, 100 miles @ 5kts = 20 hours actually IS a big deal.. especially since that means your mobile platform is down for most of a day, meaning one day loss of customers - and that's assuming you have 100 miles of water you can move it and still get out of the weather system.

The video included cities like Hong Kong and Singapore where moving 100 miles in any direction would put you out of reach of your customers (travelling via high-speed ferry for 3-4 hours over a rough sea to get to a 30-minute flight to the other side of the world might make waiting in an airport lounge seem kinda comfortable: puke on the way to the flight, whilst boarding the flight, during the flight and after the flight.. yay! what fun!).
I agree with the timeline, but not with the impact.

Think of the ASDS as truly mobile  basically an aircraft carrier.

Keep an eye out on the weather  and be constantly on the move. Whether you stop (relative to GPS? Relative to the water?) During launch/land is immaterial.

But if you're mobile by default, you can have calm conditions much more of the time.
ABCD - Always Be Counting Down

Offline DreamyPickle

  • Full Member
  • *
  • Posts: 157
  • Home
  • Liked: 66
  • Likes Given: 17
Re: BFR ASDS
« Reply #26 on: 10/02/2017 08:18 AM »
If they're thinking about a BFR ASDS - why bother with land pads at all?

You still need at least one land pad with large hangars for inspection and servicing, for example at Boca Chica or the Cape. Even if the floating pads have hangars at one end they would be small and doing all your maintenance at sea would get complicated and expensive.

Also it seem likely that any launches would require evacuating the pad of any personnel, or placing them in some sort of bunker. By measuring pixels in the video you get a ship length of ~300m, comparable to the some of the largest ships in the world. This is still a bit less than the distance between 39A and the HIF.

I wonder if they've actually begun to look into building such a thing. A prototype based on a retrofitted LNG barge could be used to land in the Gulf of Mexico from Boca Chica, refuel and fly back. This would be useful for early grasshopper-like testing if you want to test high horizontal velocity and reentry but can't turn around or get into orbit.

Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 2315
  • Canada
  • Liked: 306
  • Likes Given: 509
Re: BFR ASDS
« Reply #27 on: 10/02/2017 09:04 AM »
If they're thinking about a BFR ASDS - why bother with land pads at all?

....
I wonder if they've actually begun to look into building such a thing. A prototype based on a retrofitted LNG barge could be used to land in the Gulf of Mexico from Boca Chica, refuel and fly back. This would be useful for early grasshopper-like testing if you want to test high horizontal velocity and reentry but can't turn around or get into orbit.

It might be easier to convert a medium size VLCC into a BFR ASDS. Will still retain self-propel capability.

Offline DreamyPickle

  • Full Member
  • *
  • Posts: 157
  • Home
  • Liked: 66
  • Likes Given: 17
Re: BFR ASDS
« Reply #28 on: 10/02/2017 10:46 AM »
Quote
A prototype based on a retrofitted LNG barge could be used to land in the Gulf of Mexico from Boca Chica, refuel and fly back.
It might be easier to convert a medium size VLCC into a BFR ASDS. Will still retain self-propel capability.

LNG barges already have the required equipment for large-scale cryogenics on the high seas and they can use boiled-off methane for propulsion and power. However a lower flatter deck for easy handling might be more desirable than extra fuel storage.
« Last Edit: 10/02/2017 02:04 PM by DreamyPickle »

Offline speedevil

  • Full Member
  • ****
  • Posts: 995
  • Fife
  • Liked: 468
  • Likes Given: 490
Re: BFR ASDS
« Reply #29 on: 10/02/2017 01:40 PM »
Although it was shown in the context of the point to point express idea, it seems at least as important as a general purpose Spaceport.

Cargo launched to space might be put in a container in a facility on land, brought out by ship and the container loaded into the BFS cargo with the hammerhead crane.

That would apply to hyper express shipping, satellite dispensers, cargo to/from space stations or the Moon.

If you look carefully  at the video,, it shows 40 cabins, all around 8 feet cubes. Not - quite - the standard 8 foot shipping container (yes, you can get stubby ones), but remarkably similar.
If you added circular rails, and one vertical rail, then you can load and offload these automatically. I note that the video also shows cargo being unloaded on the moon, from a crane which appears to be in an opening around this size too.

Loading passengers and cargo onto these would be a whole lot nicer than having to have them go in the open air, as well as faster, especially relevant at sea.

In principle, also, you can have 3-4 8m long containers.
« Last Edit: 10/02/2017 02:23 PM by speedevil »

Offline JamesH65

  • Full Member
  • ****
  • Posts: 695
  • Liked: 418
  • Likes Given: 8
Re: BFR ASDS
« Reply #30 on: 10/02/2017 02:24 PM »
I'd do what Dubai did with the Palm Islands. They are entirely man made, the first jutting out 3.5M in to the Gulf. It has a monorail from one end to the other.

Wouldn't be too much of a stretch to make a 10mile causeway out to an artificial island - less work that these UAE islands.

Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #31 on: 10/02/2017 04:00 PM »
Just a thought that a mothership BFR ASDS might have several landing only ASDSs with it that are basically the same as current. It seems like a BFS could land on the current ASDS. This would allow more flexible operations than just one landing pad. The crane could lift BFSs from the smaller Landing ASDSs that come alongside.


Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #32 on: 10/02/2017 04:13 PM »
I'd do what Dubai did with the Palm Islands. They are entirely man made, the first jutting out 3.5M in to the Gulf. It has a monorail from one end to the other.

Wouldn't be too much of a stretch to make a 10mile causeway out to an artificial island - less work that these UAE islands.

Artificial islands though lose many of the benefits of manufactured ASDSs. They can only be built in a very limited range of locations in shallow water. They canít avoid storms. They canít be relocated once built. The canít be mass produced and deployed. They take much longer to put in place. They may not have suitable sites near some major ports or otherwise good locations.

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #33 on: 10/02/2017 10:29 PM »
Well... to repeat what was posted right here some months ago:  ::)

Since this is a la-la thread, why not...

Going with that theme.. ;)

IMHO, you'd be better off building an artificial island out there - or a cluster of really large oil platforms connected together, complete with lading pad(s), flyback facilities, helipads and as much crew accommodation as you need to run the entire show.

And by putting it out international waters, you could make it duty-fee and start your own country.



(The pic is from the movie "Waterworld" in case anyone was wondering)
« Last Edit: 10/02/2017 10:30 PM 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 meekGee

  • Senior Member
  • *****
  • Posts: 8000
  • N. California
  • Liked: 4244
  • Likes Given: 852
Re: BFR ASDS
« Reply #34 on: 10/05/2017 02:33 PM »
Well... to repeat what was posted right here some months ago:  ::)

Since this is a la-la thread, why not...

Going with that theme.. ;)

IMHO, you'd be better off building an artificial island out there - or a cluster of really large oil platforms connected together, complete with lading pad(s), flyback facilities, helipads and as much crew accommodation as you need to run the entire show.

And by putting it out international waters, you could make it duty-fee and start your own country.



(The pic is from the movie "Waterworld" in case anyone was wondering)
Btw, the la-la comment was from a thread about a hovercraft ASDS for F9, and I meant "la-la" as in "a fun hypothetical discussion not related to any actual plans"..

Just for context...
ABCD - Always Be Counting Down

Offline Flying Beaver

Re: BFR ASDS
« Reply #35 on: 10/05/2017 09:26 PM »
Some Hi-Rez Screenshots.

Its a VERY basic 3d placeholder model. A quick <30 min job.
« Last Edit: 10/05/2017 09:27 PM by Flying Beaver »
Saw OG-2 Booster Land in person 21/12/2015.

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #36 on: 10/05/2017 10:57 PM »
Btw, the la-la comment was from a thread about a hovercraft ASDS for F9, and I meant "la-la" as in "a fun hypothetical discussion not related to any actual plans"..

Just for context...

Yeah, I know.  Whilst looking for the pic above, I saw your la-la comment and, feeling a strong sense of deja vu, decided to post the entire thing as, you say, "a fun hypothetical discussion not related to any actual plans".  :)
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 meekGee

  • Senior Member
  • *****
  • Posts: 8000
  • N. California
  • Liked: 4244
  • Likes Given: 852
Re: BFR ASDS
« Reply #37 on: 10/06/2017 12:37 AM »
:)  The more of these the merrier..
ABCD - Always Be Counting Down

Online Archibald

  • Senior Member
  • *****
  • Posts: 2135
  • Liked: 245
  • Likes Given: 682
Re: BFR ASDS
« Reply #38 on: 10/06/2017 07:39 AM »
http://dynamic-positioning.com/proceedings/dp2003/design_berkeley.pdf

Quote
The Mobile Offshore Base (MOB) is a large, self-propelled, floating, pre-positioned ocean structure formed
of three to five modules and reaching up to 1,500 meters in length.
It must accommodate the landing and take-off  of  C-17  conventional  aircraft,  host  3000  troops,  carry  10  million  gallons  of  fuel  and  provide  3   million  square  feet  of  internal  configurable  storage.  The  alignment  of  the  modules  is  maintained  through   the use of slew-able thrusters and/or connectors.

Plenty of room for passengers, methane, LOX, and commuter aircrafts to carry the passengers. A C-17 is as big as an A350 or 787.
add some shopping malls, hotels, and other goodies.

Offline vanoord

  • Full Member
  • ****
  • Posts: 558
  • Liked: 332
  • Likes Given: 56
Re: BFR ASDS
« Reply #39 on: 10/06/2017 10:52 AM »
http://dynamic-positioning.com/proceedings/dp2003/design_berkeley.pdf

Quote
The Mobile Offshore Base (MOB) is a large, self-propelled, floating, pre-positioned ocean structure formed
of three to five modules and reaching up to 1,500 meters in length.
It must accommodate the landing and take-off  of  C-17  conventional  aircraft,  host  3000  troops,  carry  10  million  gallons  of  fuel  and  provide  3   million  square  feet  of  internal  configurable  storage.  The  alignment  of  the  modules  is  maintained  through   the use of slew-able thrusters and/or connectors.

Plenty of room for passengers, methane, LOX, and commuter aircrafts to carry the passengers. A C-17 is as big as an A350 or 787.
add some shopping malls, hotels, and other goodies.

Some of the models being tested bear a resemblance to Pioneering Spirit - https://allseas.com/equipment/pioneering-spirit/

That wouldn't be an entirely daft design to follow. The cost would be massive, but no reason that they would have to be entirely carried by SpaceX.
« Last Edit: 10/06/2017 10:56 AM by vanoord »

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 13052
    • Space Launch Report
  • Liked: 3880
  • Likes Given: 659
Re: BFR ASDS
« Reply #40 on: 10/06/2017 01:48 PM »
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?
Cruise ships use stabilizing systems designed to minimize seasickness of passengers.  Also, the deeper the below-surface draft of a ship, the more stable it can be, as I understand things.  Still, none of these ships have passengers sitting within the nose of a 350 foot tall rocket atop them!

 - Ed Kyle

Offline envy887

  • Senior Member
  • *****
  • Posts: 3177
  • Liked: 1506
  • Likes Given: 1023
Re: BFR ASDS
« Reply #41 on: 10/06/2017 01:57 PM »
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?
Cruise ships use stabilizing systems designed to minimize seasickness of passengers.  Also, the deeper the below-surface draft of a ship, the more stable it can be, as I understand things.  Still, none of these ships have passengers sitting within the nose of a 350 foot tall rocket atop them!

 - Ed Kyle

The oil and gas industry has taken 6 DOF stabilization in the open ocean down to an exact science. These are mostly solved problems; not cheap, but solved.

Offline speedevil

  • Full Member
  • ****
  • Posts: 995
  • Fife
  • Liked: 468
  • Likes Given: 490
Re: BFR ASDS
« Reply #42 on: 10/06/2017 02:10 PM »
Cruise ships use stabilizing systems designed to minimize seasickness of passengers.  Also, the deeper the below-surface draft of a ship, the more stable it can be, as I understand things.  Still, none of these ships have passengers sitting within the nose of a 350 foot tall rocket atop them!

The BFR for ASDS will be significantly larger than the one for F9.
Cruise ships use stabilisation to minimise motion, but most cruise ships are under 40m wide. The good cabins are often around half as high as the top of the BFS.

ASDS-BFR is around twice as wide as most cruise ships, will not operate close-in to shore, does not have to point in a specific direction, and the passengers have already experienced a much rougher high-speed ship.

In addition, they are all packed to the gills with seasickness medication, and are going to be launched into space immediately after boarding, at 3G, before a period of weightlessness and then 3G again. I suggest swaying may not be a huge concern.

In principle, if you're deploying passenger systems like this in numbers, a stabilised launch cradle would not be the hardest part of this system.


Offline intrepidpursuit

  • Full Member
  • ****
  • Posts: 516
  • Orlando, FL
  • Liked: 326
  • Likes Given: 212
Re: BFR ASDS
« Reply #43 on: 10/06/2017 05:09 PM »
http://dynamic-positioning.com/proceedings/dp2003/design_berkeley.pdf

Quote
The Mobile Offshore Base (MOB) is a large, self-propelled, floating, pre-positioned ocean structure formed
of three to five modules and reaching up to 1,500 meters in length.
It must accommodate the landing and take-off  of  C-17  conventional  aircraft,  host  3000  troops,  carry  10  million  gallons  of  fuel  and  provide  3   million  square  feet  of  internal  configurable  storage.  The  alignment  of  the  modules  is  maintained  through   the use of slew-able thrusters and/or connectors.

Plenty of room for passengers, methane, LOX, and commuter aircrafts to carry the passengers. A C-17 is as big as an A350 or 787.
add some shopping malls, hotels, and other goodies.

I think even in a high reliability world the ship will probably be evacuated during launch and landings. I also think that large scale (more than 1 or 2 launches) fuel storage would not be attached the launch platform. In the real world there may be a small flotilla of ships, including a launch and landing ship, a transportation/logistics/security ship, and a fuel tanker or two. Purpose built ships could turn this into a well oiled machine with ships converging and diverging in a tightly choreographed schedule to allow a point to point launch every 2 hours or so.

I doubt the same ship(s) could be used for space launch though. Much more careful packing of sensitive equipment for interplanetary travel, quick volleys of multiple tankers, and satellite encapsulation would all go counter to the requirements of an airliner-like workflow. A mars caravan launch campaign would interrupt point-to-point travel for at least a few days at a time if they tried to use the same platform and LEO/BEO ships would likely need more processing than would make sense to be done on a ship.

Offline R.Simko

  • Full Member
  • ***
  • Posts: 309
  • Liked: 2
  • Likes Given: 23
Re: BFR ASDS
« Reply #44 on: 10/06/2017 08:09 PM »
If Mr. Musk did choose to build an island for launching BFR, any thoughts of where the best location would be to build an island?

Offline RobLynn

  • Full Member
  • **
  • Posts: 240
  • Per Molestias Eruditio
  • London
  • Liked: 25
  • Likes Given: 25
Re: BFR ASDS
« Reply #45 on: 10/07/2017 12:25 AM »
With two ASDS ships they could launch from one and land on the other, then swap location for next launch etc, even if launch ASDA is tied up to end of a pier for easy access. Ships are incredibly cheap, typically only about $2000/tonne so being able to build majority of launch towers, cranes, fuel tanks etc in a shipyard might reduce their costs considerably.

I wonder about the possibility of using a variable buoyancy design - big catamaran with ballast tanks to sink almost entirely below sea surface for launch and landing so that little more than the landing cradle is exposed to rocket exhaust.  Catamarans are fast and very stable, and if submerged so that they have minimal water-line area they are very insensitive to waves.

I'm a "glass is twice as big as it needs to be" kinda guy

Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 2315
  • Canada
  • Liked: 306
  • Likes Given: 509
Re: BFR ASDS
« Reply #46 on: 10/07/2017 07:51 AM »
What does folks think of the idea to put vertical BFS protective hangars abreast of the crane on the BFR ASDS for storing 2 or 4 BFS?

For a simple dual hangar design. Two vertical cylindrical structures with one to the starboard and one to port side of the BFR ASDS crane with a hatch on top. You already got the crane aboard the ASDS to move the BFS. Internal service platforms could be fitted in the hangars.

Should speed up the tempo of launch. Especially with BFS tankers on a BFR ASDS with quad BFS hangars.

Also useful to shelter the BFS in bad weather.

Offline DOCinCT

Re: BFR ASDS
« Reply #47 on: 10/07/2017 04:45 PM »
...
* 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.
Why not do both?  Modern container ships have comfortable accommodations for up to 12 passengers, there are also conventional cargo freighters that have passenger accommodations.  If the spaceship was taking cargo or crew to the ISS (or equivalent), lot's of room for space tourists, who get to see the ISS before heading out on their orbital excursion (or cis-lunar excursion).

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #48 on: 10/09/2017 12:21 AM »
...
* 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.
Why not do both?  Modern container ships have comfortable accommodations for up to 12 passengers, there are also conventional cargo freighters that have passenger accommodations.  If the spaceship was taking cargo or crew to the ISS (or equivalent), lot's of room for space tourists, who get to see the ISS before heading out on their orbital excursion (or cis-lunar excursion).

It would certainly put a new slant on travelling "Freight" (a.k.a. Baggage Class).  ;D

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 RobLynn

  • Full Member
  • **
  • Posts: 240
  • Per Molestias Eruditio
  • London
  • Liked: 25
  • Likes Given: 25
Re: BFR ASDS
« Reply #49 on: 10/21/2017 12:52 AM »
With a big and relatively lightweight catamaran as a launch platform and ASDS they could utilise the ships thrusters to move the launch tower away from the launch vehicle immediately after takeoff, saving some launch tower complexity.  Could also use a big keel mass held up by a line to bow and stern of ship and at lift-off cut one of those lines so that keel mass swings pulling the ship fore or aft as it does so.
I'm a "glass is twice as big as it needs to be" kinda guy

Online docmordrid

  • Senior Member
  • *****
  • Posts: 4451
  • Michigan
  • Liked: 1612
  • Likes Given: 1
Re: BFR ASDS
« Reply #50 on: 10/21/2017 08:45 PM »
Or, water depth permitting, use one or several adjacent jack-up rigs.  Their legs would sit on the sea floor providing a very solid, yet still mobile if needed, platform.
« Last Edit: 10/21/2017 08:53 PM by docmordrid »
DM

Offline RobLynn

  • Full Member
  • **
  • Posts: 240
  • Per Molestias Eruditio
  • London
  • Liked: 25
  • Likes Given: 25
Re: BFR ASDS
« Reply #51 on: 10/25/2017 01:03 AM »
if you suspend a large mass on 3 long cables 100's of meters below a floating mass it acts as a 100's m long rigid keel preventing almost all pitching and rocking.  The keel cables can be wound in for ease of transport.

alternatively if you additionally use small water-line area - essentially submersed buoyant chambers with small struts extending through water surface to support an elevated platform then waves have almost no effect on the platform and high stability is maintained.
I'm a "glass is twice as big as it needs to be" kinda guy

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #52 on: 11/02/2017 09:26 PM »
Or, water depth permitting, use one or several adjacent jack-up rigs.  Their legs would sit on the sea floor providing a very solid, yet still mobile if needed, platform.

if you suspend a large mass on 3 long cables 100's of meters below a floating mass it acts as a 100's m long rigid keel preventing almost all pitching and rocking.  The keel cables can be wound in for ease of transport.

You guys might be forgetting that, whilst it indeed needs to be a stable platform for landing, this ASDS must also be able to move quickly in an emergency - out of the way of an incoming rock(et).

The current design achieves this in spades; the above suggestions possibly not so much..
« Last Edit: 11/02/2017 09:31 PM 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 biosehnsucht

  • Full Member
  • **
  • Posts: 217
  • Liked: 60
  • Likes Given: 86
Re: BFR ASDS
« Reply #53 on: 11/02/2017 09:35 PM »
The current design can barely maintain it's position in rough seas. It can't get out of  the way of an incoming rocket without at least a few minutes of warning, and that's assuming they can remotely retarget the ASDS (no reason they couldn't if they wanted to, just might not be a current feature).

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #54 on: 11/02/2017 09:49 PM »
The current design can barely maintain it's position in rough seas. It can't get out of  the way of an incoming rocket without at least a few minutes of warning, and that's assuming they can remotely retarget the ASDS (no reason they couldn't if they wanted to, just might not be a current feature).

We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

Truth is (a) they may have less than a few minutes warning and (b) they certainly can re-target the ASDS from the support ship - that's how they set the position now, once the tow is released.
« Last Edit: 11/02/2017 09:51 PM 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 speedevil

  • Full Member
  • ****
  • Posts: 995
  • Fife
  • Liked: 468
  • Likes Given: 490
Re: BFR ASDS
« Reply #55 on: 11/02/2017 10:17 PM »

You guys might be forgetting that, whilst it indeed needs to be a stable platform for landing, this ASDS must also be able to move quickly in an emergency - out of the way of an incoming rock(et).

The current design achieves this in spades; the above suggestions possibly not so much..

The existing platform can't move significantly in time to matter.
A BFR landing platform could not move significantly unless you actually put many raptors on it.

Moving the barge  when it's more than 10-30s or so up is basically pointless, as the size of the probable landing ellipse if the rocket becomes uncontrolled exceeds the size of the barge.

While I am for a flying barge, it seems unlikely.


Online AC in NC

  • Full Member
  • **
  • Posts: 269
  • Raleigh NC
  • Liked: 220
  • Likes Given: 238
Re: BFR ASDS
« Reply #56 on: 11/03/2017 03:18 AM »
We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

The IIP is off the Landing Target until they are committed to the attempt.  The booster decides to try to hit the ASDS if things look good.  The ASDS doesn't decide to try to dodge the booster if things look bad.

« Last Edit: 11/03/2017 03:20 AM by AC in NC »

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #57 on: 11/03/2017 05:00 AM »
We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

The IIP is off the Landing Target until they are committed to the attempt.  The booster decides to try to hit the ASDS if things look good.  The ASDS doesn't decide to try to dodge the booster if things look bad.

Are you implying by that that they start off with the ASDS off-target and move it in if all is good??  ???

Better go read https://forum.nasaspaceflight.com/index.php?topic=39766.0 and especially http://forum.nasaspaceflight.com/index.php?topic=36326.0 again..
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 octavo

  • Member
  • Posts: 95
  • Liked: 43
  • Likes Given: 78
Re: BFR ASDS
« Reply #58 on: 11/03/2017 05:25 AM »
We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

The IIP is off the Landing Target until they are committed to the attempt.  The booster decides to try to hit the ASDS if things look good.  The ASDS doesn't decide to try to dodge the booster if things look bad.

Are you implying by that that they start off with the ASDS off-target and move it in if all is good??  ???

Better go read https://forum.nasaspaceflight.com/index.php?topic=39766.0 and especially http://forum.nasaspaceflight.com/index.php?topic=36326.0 again..
No, the barge doesn't move at all. The booster changes its landing target to the preset asds coords once it is happy that a safe landing can be attempted.

Online Lars-J

  • Senior Member
  • *****
  • Posts: 3701
  • California
  • Liked: 2966
  • Likes Given: 1871
Re: BFR ASDS
« Reply #59 on: 11/03/2017 08:46 PM »
The current design can barely maintain it's position in rough seas. It can't get out of  the way of an incoming rocket without at least a few minutes of warning, and that's assuming they can remotely retarget the ASDS (no reason they couldn't if they wanted to, just might not be a current feature).

We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

Truth is (a) they may have less than a few minutes warning and (b) they certainly can re-target the ASDS from the support ship - that's how they set the position now, once the tow is released.

You are mistaken.

Online Lars-J

  • Senior Member
  • *****
  • Posts: 3701
  • California
  • Liked: 2966
  • Likes Given: 1871
Re: BFR ASDS
« Reply #60 on: 11/03/2017 08:51 PM »
We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

The IIP is off the Landing Target until they are committed to the attempt.  The booster decides to try to hit the ASDS if things look good.  The ASDS doesn't decide to try to dodge the booster if things look bad.

Are you implying by that that they start off with the ASDS off-target and move it in if all is good??  ???

Better go read https://forum.nasaspaceflight.com/index.php?topic=39766.0 and especially http://forum.nasaspaceflight.com/index.php?topic=36326.0 again..
No, the barge doesn't move at all. The booster changes its landing target to the preset asds coords once it is happy that a safe landing can be attempted.

Right... This is determined when the landing burn starts. If the landing engine(s) starts, it will aim for the landing point. Otherwise the consensus is that it will continue in its trajectory and crash near it. The landing burn starts pretty high so it is able to do that.

Online AC in NC

  • Full Member
  • **
  • Posts: 269
  • Raleigh NC
  • Liked: 220
  • Likes Given: 238
Re: BFR ASDS
« Reply #61 on: 11/04/2017 02:33 AM »
The booster decides to try to hit the ASDS if things look good.

Are you implying by that that they start off with the ASDS off-target and move it in if all is good??  ???  Better go read ... [snip] ... again...

How could you POSSIBLY conceive that implication from what I wrote?

In pictures.  Please don't insist that this Land Based diagram doesn't mean anything with respect to ASDS landing profile.  The ASDS doesn't try to dodge the booster in a worst-case scenario anymore than LC-1 does.

« Last Edit: 11/04/2017 02:37 AM by AC in NC »

Offline yokem55

  • Full Member
  • ****
  • Posts: 499
  • Oregon (Ore-uh-gun dammit)
  • Liked: 286
  • Likes Given: 12
Re: BFR ASDS
« Reply #62 on: 11/06/2017 04:20 AM »
We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

The IIP is off the Landing Target until they are committed to the attempt.  The booster decides to try to hit the ASDS if things look good.  The ASDS doesn't decide to try to dodge the booster if things look bad.

Are you implying by that that they start off with the ASDS off-target and move it in if all is good??  ???

Better go read https://forum.nasaspaceflight.com/index.php?topic=39766.0 and especially http://forum.nasaspaceflight.com/index.php?topic=36326.0 again..
No, the barge doesn't move at all. The booster changes its landing target to the preset asds coords once it is happy that a safe landing can be attempted.

Right... This is determined when the landing burn starts. If the landing engine(s) starts, it will aim for the landing point. Otherwise the consensus is that it will continue in its trajectory and crash near it. The landing burn starts pretty high so it is able to do that.
Except this didn't work with SES-9. My bet is that the 3-engine burn attempt didn't allow for enough time to retarget after knowing they had 3 good engines, so it was a committed attempt from the get go. When the engine(s?) failed the impact point was already on the ASDS and so poor OCISLY got Falcon-Punched at high speed.

Online guckyfan

  • Senior Member
  • *****
  • Posts: 6470
  • Germany
  • Liked: 1636
  • Likes Given: 1524
Re: BFR ASDS
« Reply #63 on: 11/06/2017 07:36 AM »
Except this didn't work with SES-9. My bet is that the 3-engine burn attempt didn't allow for enough time to retarget after knowing they had 3 good engines, so it was a committed attempt from the get go. When the engine(s?) failed the impact point was already on the ASDS and so poor OCISLY got Falcon-Punched at high speed.

I see this event as SpaceX willing to risk damage to the ASDS to prove they can hit the target even under extreme conditions. Which would help getting approval for land landing.

Offline JamesH65

  • Full Member
  • ****
  • Posts: 695
  • Liked: 418
  • Likes Given: 8
Re: BFR ASDS
« Reply #64 on: 11/06/2017 11:22 AM »
We've known about the requirement to splash a stage by moving out of the way ever since the first landing attempt - so it's not only a current feature, it's a primary one - and we've all seen what can happen after a bad  (non-emergency) landing.

The IIP is off the Landing Target until they are committed to the attempt.  The booster decides to try to hit the ASDS if things look good.  The ASDS doesn't decide to try to dodge the booster if things look bad.

Are you implying by that that they start off with the ASDS off-target and move it in if all is good??  ???

Better go read https://forum.nasaspaceflight.com/index.php?topic=39766.0 and especially http://forum.nasaspaceflight.com/index.php?topic=36326.0 again..
No, the barge doesn't move at all. The booster changes its landing target to the preset asds coords once it is happy that a safe landing can be attempted.

Right... This is determined when the landing burn starts. If the landing engine(s) starts, it will aim for the landing point. Otherwise the consensus is that it will continue in its trajectory and crash near it. The landing burn starts pretty high so it is able to do that.
Except this didn't work with SES-9. My bet is that the 3-engine burn attempt didn't allow for enough time to retarget after knowing they had 3 good engines, so it was a committed attempt from the get go. When the engine(s?) failed the impact point was already on the ASDS and so poor OCISLY got Falcon-Punched at high speed.

Experimental landing. Has it happened since? Not that I am aware of. So the experiment lead to changes to stop is happening again. R&D.

The ASDS doesn't move.

Offline envy887

  • Senior Member
  • *****
  • Posts: 3177
  • Liked: 1506
  • Likes Given: 1023
Re: BFR ASDS
« Reply #65 on: 11/06/2017 01:28 PM »
Right... This is determined when the landing burn starts. If the landing engine(s) starts, it will aim for the landing point. Otherwise the consensus is that it will continue in its trajectory and crash near it. The landing burn starts pretty high so it is able to do that.
Except this didn't work with SES-9. My bet is that the 3-engine burn attempt didn't allow for enough time to retarget after knowing they had 3 good engines, so it was a committed attempt from the get go. When the engine(s?) failed the impact point was already on the ASDS and so poor OCISLY got Falcon-Punched at high speed.

I thought the booster ran out of propellant on that attempt - which would happen after moving the impact point on target.

Online AC in NC

  • Full Member
  • **
  • Posts: 269
  • Raleigh NC
  • Liked: 220
  • Likes Given: 238
Re: BFR ASDS
« Reply #66 on: 11/06/2017 07:44 PM »
Except this didn't work with SES-9. My bet is that the 3-engine burn attempt didn't allow for enough time to retarget after knowing they had 3 good engines, so it was a committed attempt from the get go. When the engine(s?) failed the impact point was already on the ASDS and so poor OCISLY got Falcon-Punched at high speed.

Not sure what would lead one to believe that a 3-engine burn wouldn't allow enough time to retarget.  I don't think the details are public knowledge so I guess we're speculating either way, but I just don't know what suggests that the vertical distance involved in a 3-engine burn isn't plenty of room to retarget horizontally the necessary distance.


I see this event as SpaceX willing to risk damage to the ASDS to prove they can hit the target even under extreme conditions. Which would help getting approval for land landing.

SES-9 was after the first successful LZ-1 landing.


Offline UKobserver

  • Member
  • Posts: 9
  • Liked: 51
  • Likes Given: 10
Re: BFR ASDS
« Reply #67 on: 12/24/2017 04:53 PM »
Or SpaceX can build a fleet of BFR sized ASDS floating platforms after where ever they chose as the first BFR pad.
I think a floating platform to launch and land BFR/BFS is highly unlikely.  Way more issues here.  For a rocket that big, a floating platform would probably need to be huge, which would be really expensive.

Fixed launch pads several miles offshore seem much more likely.  These would have legs that physically connect with the ocean floor, with cables and pipelines connecting back to land.  This arrangement is very typical in the oil and gas industry, so it would probably be relatively economical.

Especially if they start the P2P (point to point) service with the BFR.
For this, Elon's presentation showed a small launch platform several miles offshore.  This implies a fixed launch platform that's physically connected to the ocean floor.  A floating platform for a BFR size rocket would probably need to be an order of magnitude larger.

Yes that's true, I hadn't thought about an offshore platform in Florida; if they opted for that then it wouldnít interfere with their current operations and my logic about building BC first wouldnít apply.

I guess Iíd assumed that they would experiment on land first, but in fairness SpaceX have shown they are willing to be bold and jump in with both feet (ASDS was a great example), so maybe they will indeed go straight for the offshore design from the beginning. As you say; it removes a lot of the red tape and removes most of the risk to people/property/wildlife that slows down land-based testing. The initial F9 landing tests and the prototype carbon BFS tank testing were good examples of the freedom the ocean can offer. I guess you could even argue that offshore is the most logical choice for their first prototype; any effort expended designing a land-based pad could have very limited further application, given that most or all of their initial point to point pads will likely need to be offshore for noise/safety/public confidence considerations. For all we know they could already have quietly commissioned a shipyard somewhere to start converting a used jack-up rig into their first prototype BFR pad. Makes you think!

The comments above have also got me thinking about the video images of their future offshore point to point pads; I assumed when I first saw the Adelaide presentation that we weren't meant to take every detail literally and that it was just to give us the basic concept - a vertical booster on a flat platform with tanks. But I'm starting to wonder. If you look closely, we see an elongated rectangular platform, which could be interpreted as a sea-going barge, ie. longer than it is wide. It clearly is sitting on legs resting on the sea bottom, but that could easily make it a jack-up vessel, as I suggested above (and I think others have before). I was originally thinking more like a stationary oil rig, but what if it is a barge/ship and intended to shuttle out to the launch site each time carrying everything it needs? I initially discounted that possibility because I was thinking a fueled, vertical booster would want to topple over at sea, but of course they wouldn't travel with it fueled, and I've only just realised they wouldn't travel with it integrated either. If we assume that for transit all the propellant is in the tanks (keeping most of the mass very close to deck level), and if we assume that the empty (ie. relatively light) BFS is parked on it's haunches on the spot marked X, and the empty (therefore also light) booster is parked on it's launch mount, then transiting out to the launch site wouldn't be any more challenging or any less sea-worthy than bringing a F9 back to shore on an ASDS is currently.

I know that would be too slow an evolution for the eventual point to point model, but for the first few years of experimentation, of Starlink launches, and even fuelling/launching the first few Mars missions, it would be fine. We're only talking a few miles offshore, so not the 24/48hr transits that OCISLY is currently doing, so we're only talking a few hours for them to crane the loaded BFS onto the barge, fill the barge tanks, move to the launch site, lift the BFS onto the BFR, fuel, launch, recover BFR (and maybe BFS too, or if it needs longer in space you instead recover the BFS that launched yesterday/whenever) and return to base. They could easily be back in port 18 hours after leaving, ready to swap the empty BFS for the next one loaded with satellites/fuel for the Mars journey. One launch a day is still an incredibly high launch rate, and removes any near term need to worry about pipelines. Suddenly the offshore option looks extremely simple, easier even than a land pad I would say.

BTW although I think the point to point idea is perfectly feasible and a potentially viable business (at least for long-haul), I don't see it happening overnight. I think it will start with just one or two niche long-distance city pair routes where the massive time-saving will make it attractive to premium customers, enough for some of them to overcome any anxiety they may have about the risk. I'm talking Shanghai to New York types of distance. And I suspect although we will see plenty of scepticism, disbelief and denial (as with booster re-use) and even outright refusal to allow it in some jurisdictions, what I think will win out is that some cities will see it as a way to put themselves on the map, as the place where the future is really happening now. Think how much extra tourism that first pair of cities is going to get.. How many people in the eastern US would fly to New York just so they could experience that flight, rather than using their nearest big airport to fly direct. I think that's how it will start. But I digress, sorry mods.
« Last Edit: 12/24/2017 05:04 PM by UKobserver »

Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #68 on: 01/01/2018 07:29 AM »
Quote
If you look closely, we see an elongated rectangular platform, which could be interpreted as a sea-going barge, ie. longer than it is wide. It clearly is sitting on legs resting on the sea bottom, but that could easily make it a jack-up vessel, as I suggested above (and I think others have before). ]

I wasnít sure what you were seeing, but when I looked at the posted picture I get it. Itís a pretty poor frame grab. What looks like legs are actually reflections in the water. The platform is at the sea surface like a barge with no legs showing.
« Last Edit: 01/01/2018 03:27 PM by Ludus »

Offline UKobserver

  • Member
  • Posts: 9
  • Liked: 51
  • Likes Given: 10
Re: BFR ASDS
« Reply #69 on: 01/02/2018 04:56 PM »
Quote
If you look closely, we see an elongated rectangular platform, which could be interpreted as a sea-going barge, ie. longer than it is wide. It clearly is sitting on legs resting on the sea bottom, but that could easily make it a jack-up vessel, as I suggested above (and I think others have before). ]

I wasnít sure what you were seeing, but when I looked at the posted picture I get it. Itís a pretty poor frame grab. What looks like legs are actually reflections in the water. The platform is at the sea surface like a barge with no legs showing.

Oh dear, that's embarrassing  :-[ Not sure how I missed that!

Offline IntoTheVoid

  • Full Member
  • **
  • Posts: 239
  • USA
  • Liked: 182
  • Likes Given: 56
Re: BFR ASDS
« Reply #70 on: 01/03/2018 03:59 AM »
I've read the talk of oil rigs, and barges, and jack-up rigs, but what about it not being a ASDS but a SPP (a SpacePort Pier) With the water as shallow as it is, how do the costs compare if they instead built it like a freestanding bridge pier. It would be the most stable option, and would eliminate the hull inspections, etc. Presumably there could be other inspections, but it's got to be more convenient to have them come to you.

Offline Steve D

  • Member
  • Posts: 78
  • Liked: 31
  • Likes Given: 1
Re: BFR ASDS
« Reply #71 on: 01/03/2018 03:53 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by. Not good if they start finding dolphins and endangered sea turtles washing up on the beach cooked......
« Last Edit: 01/03/2018 03:57 PM by Steve D »

Offline JamesH65

  • Full Member
  • ****
  • Posts: 695
  • Liked: 418
  • Likes Given: 8
Re: BFR ASDS
« Reply #72 on: 01/03/2018 05:13 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by. Not good if they start finding dolphins and endangered sea turtles washing up on the beach cooked......

Er what? They won't be directing the exhaust straight in to the water, surely?

I'm not a fan of the offshore pad, at least initially anyway. Its expensive just putting in a 5 mile causeway and launch pad....

Offline speedevil

  • Full Member
  • ****
  • Posts: 995
  • Fife
  • Liked: 468
  • Likes Given: 490
Re: BFR ASDS
« Reply #73 on: 01/03/2018 05:23 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by.
This is one thing you can pretty much ignore as a concern.
The rocket 'only' burns ten or twenty tons of methane while clearing the tower, this is enough to only heat to boiling 1000 tons of water.
Or 10m*10m*10m - around the same scale as the launchpad. It will heat a 100m*100m*10m patch on average by 1C.
(this assumes that all heat is efficiently transferred to water, which it will not be, and that this is the case for the first several seconds, and no water boils)
Close enough to the rocket to be thermally damaging will be extremely sonically damaging.

Offline whitelancer64

Re: BFR ASDS
« Reply #74 on: 01/03/2018 05:53 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by.
This is one thing you can pretty much ignore as a concern.
The rocket 'only' burns ten or twenty tons of methane while clearing the tower, this is enough to only heat to boiling 1000 tons of water.
Or 10m*10m*10m - around the same scale as the launchpad. It will heat a 100m*100m*10m patch on average by 1C.
(this assumes that all heat is efficiently transferred to water, which it will not be, and that this is the case for the first several seconds, and no water boils)
Close enough to the rocket to be thermally damaging will be extremely sonically damaging.

This. It'll be the noise killing wildlife, not the heat.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline Steve D

  • Member
  • Posts: 78
  • Liked: 31
  • Likes Given: 1
Re: BFR ASDS
« Reply #75 on: 01/03/2018 06:04 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by.
This is one thing you can pretty much ignore as a concern.
The rocket 'only' burns ten or twenty tons of methane while clearing the tower, this is enough to only heat to boiling 1000 tons of water.
Or 10m*10m*10m - around the same scale as the launchpad. It will heat a 100m*100m*10m patch on average by 1C.
(this assumes that all heat is efficiently transferred to water, which it will not be, and that this is the case for the first several seconds, and no water boils)
Close enough to the rocket to be thermally damaging will be extremely sonically damaging.

This. It'll be the noise killing wildlife, not the heat.

Well, dead is dead. I wonder if they plan on installing blast deflectors to divert the flame off to the side instead of straight down. It may help to minimize the affect of all of the noise and heat. But if endangered sea turtles which do nest in the area get killed you can be sure that the environmentalists will shut them down. Sea life is attracted to structures such as this. I have been diving on quite a few oil rigs off the Texas coast and they all have large amounts of fish and corals growing on them. 

Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #76 on: 01/03/2018 10:12 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by. Not good if they start finding dolphins and endangered sea turtles washing up on the beach cooked......

Er what? They won't be directing the exhaust straight in to the water, surely?

I'm not a fan of the offshore pad, at least initially anyway. Its expensive just putting in a 5 mile causeway and launch pad....

I havenít seen any mention or reason for a causeway. Whatís shown is like an ASDS but larger and set up for BFR launches as well as landings. That would be MUCH cheaper and more scalable than any land based launchpad where most of limitations, cost and time would be about local impact. Seaplatforms could be built in shipyards and towed into place.

Offline Ludus

  • Full Member
  • ****
  • Posts: 911
  • Liked: 354
  • Likes Given: 179
Re: BFR ASDS
« Reply #77 on: 01/03/2018 10:21 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by.
This is one thing you can pretty much ignore as a concern.
The rocket 'only' burns ten or twenty tons of methane while clearing the tower, this is enough to only heat to boiling 1000 tons of water.
Or 10m*10m*10m - around the same scale as the launchpad. It will heat a 100m*100m*10m patch on average by 1C.
(this assumes that all heat is efficiently transferred to water, which it will not be, and that this is the case for the first several seconds, and no water boils)
Close enough to the rocket to be thermally damaging will be extremely sonically damaging.

This. It'll be the noise killing wildlife, not the heat.

Well, dead is dead. I wonder if they plan on installing blast deflectors to divert the flame off to the side instead of straight down. It may help to minimize the affect of all of the noise and heat. But if endangered sea turtles which do nest in the area get killed you can be sure that the environmentalists will shut them down. Sea life is attracted to structures such as this. I have been diving on quite a few oil rigs off the Texas coast and they all have large amounts of fish and corals growing on them.

Unless itís a platform thatís elevated quite a bit above the surface, the thrust has to be ducted off to the side across the sea surface rather than directly into it.

There would be a lot of study put in on this issue. Sound is likely to be a bigger problem than any effect from heat. Sea turtles that nest on the beach there are more likely impacted by a launchpad on shore.

Offline JamesH65

  • Full Member
  • ****
  • Posts: 695
  • Liked: 418
  • Likes Given: 8
Re: BFR ASDS
« Reply #78 on: 01/04/2018 11:35 AM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by. Not good if they start finding dolphins and endangered sea turtles washing up on the beach cooked......

Er what? They won't be directing the exhaust straight in to the water, surely?

I'm not a fan of the offshore pad, at least initially anyway. Its expensive just putting in a 5 mile causeway and launch pad....

I havenít seen any mention or reason for a causeway. Whatís shown is like an ASDS but larger and set up for BFR launches as well as landings. That would be MUCH cheaper and more scalable than any land based launchpad where most of limitations, cost and time would be about local impact. Seaplatforms could be built in shipyards and towed into place.

Cheaper? Running costs would be large - how do you get the BFS to the pad? I'd expect its going to need to come back to dry land for all the initial flights. How do you get the fuel to the pad?

Once BFx is up and running, then maybe. But in the prototyping period, having a floating launch pad will be a PITA. You got to build it first, for starters! Of course, if they started now, they could have it ready in a couple of years I suppose.

Hmm, still not convinced. Just build a pad on the ground at BC or Florida.

Offline Dave G

  • Senior Member
  • *****
  • Posts: 2059
  • Liked: 775
  • Likes Given: 1064
Re: BFR ASDS
« Reply #79 on: 01/13/2018 01:38 PM »
how do you get the BFS to the pad? I'd expect its going to need to come back to dry land for all the initial flights.
By ship.  For a fixed launch site 5-10 miles offshore, this wouldn't be very expensive.  After the initial flights, BFS would just stay at the pad.

How do you get the fuel to the pad?
For a fixed launch site 5-10 miles offshore, I'm assuming underwater flexible pipelines.

Offline Dave G

  • Senior Member
  • *****
  • Posts: 2059
  • Liked: 775
  • Likes Given: 1064
Re: BFR ASDS
« Reply #80 on: 01/13/2018 01:45 PM »
One thing that bothers me about launching from off shore is the impact on marine life in the area of the launch pad. All of that  thrust blasting directly into shallow water is going to cook anything close by. Not good if they start finding dolphins and endangered sea turtles washing up on the beach cooked......

Er what? They won't be directing the exhaust straight in to the water, surely?

I'm also assuming some sort of underwater flame ducts, but unlike flame trenches for land-based pads, liquid cooling is free, so the flame duct material wouldn't need to be very thick.

« Last Edit: 01/13/2018 05:37 PM by Dave G »

Offline Dave G

  • Senior Member
  • *****
  • Posts: 2059
  • Liked: 775
  • Likes Given: 1064
Re: BFR ASDS
« Reply #81 on: 01/13/2018 01:46 PM »
Whatís shown is like an ASDS but larger and set up for BFR launches as well as landings.

What Elon presented at IAC 2017, I believe this is a fixed launch platform with legs that physically connect it to the ocean floor.  More like a man-made island than a ship.  Most coastal areas are relatively shallow for miles offshore, often less than 100 feet deep.  A fixed platform would probably have underwater cables for power and data, plus underwater pipelines that connect it with on-shore propellant depots.  All of this is commonly used in the oil and gas business, so it shouldn't be expensive.

If it were a floating platform, it would probably need to be an order of magnitude larger.  Remember, we're talking about 5,400 tons of thrust at takeoff.  To counteract that on a floating platform, it would need to be really, really huge.  For this reason, I believe a floating launch site for BFR is extremely unlikely.

Offline darkenfast

  • Member
  • Full Member
  • ****
  • Posts: 762
  • Liked: 413
  • Likes Given: 877
Re: BFR ASDS
« Reply #82 on: 01/14/2018 03:35 AM »
If that barge/platform/whatever is 900' long by 300' wide at the waterline (just an example, eyeballed from the screen-grab), it would take an increase of over 17 million pounds to sink it one foot deeper in the water. 

Edit to add: I'm not arguing one way or another, as I personally don't think SpaceX plans to seriously look at this for some years.  Just wanted to remind everyone why big barges can carry so much!
« Last Edit: 01/14/2018 03:40 AM by darkenfast »

Offline Dave G

  • Senior Member
  • *****
  • Posts: 2059
  • Liked: 775
  • Likes Given: 1064
Re: BFR ASDS
« Reply #83 on: 01/14/2018 04:16 AM »
If that barge/platform/whatever is 900' long by 300' wide at the waterline (just an example, eyeballed from the screen-grab), it would take an increase of over 17 million pounds to sink it one foot deeper in the water. 
Wouldn't that require it to be perfectly centered?

I'm not arguing one way or another, as I personally don't think SpaceX plans to seriously look at this for some years.
You're guess is as good as mine, but I'm leaning toward sooner.  BFR is a huge rocket, so there may be issues launching it from land.

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #84 on: 01/14/2018 11:04 PM »
I'm not arguing one way or another, as I personally don't think SpaceX plans to seriously look at this for some years.
You're guess is as good as mine, but I'm leaning toward sooner.  BFR is a huge rocket, so there may be issues launching it from land.

However difficult launching this thing from land may be, there will be more issues launching it from water:  The ocean is never still.. and, unlike on land where you can retreat into a nice cozy hangar, there is no place to hide if the mother-of-all-storms happens by.

IMHO, they'd be better advised to takeover a small island.. they've done that before!
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 Dave G

  • Senior Member
  • *****
  • Posts: 2059
  • Liked: 775
  • Likes Given: 1064
Re: BFR ASDS
« Reply #85 on: 01/15/2018 01:58 AM »
IMHO, they'd be better advised to takeover a small island.. they've done that before!
How about a man-made island 5-10 miles offshore?  More specifically, a fixed launch site with legs attaching it to the ocean floor.  I believe this is what Elon showed at IAC 2017.

However difficult launching this thing from land may be, there will be more issues launching it from water...
Assuming they can get permission to launch it from land.  BFR has 1.6x the thrust of a Saturn 5.  The thing is huge.

unlike on land where you can retreat into a nice cozy hangar, there is no place to hide if the mother-of-all-storms happens by.
I see it just the opposite.  When a hurricane storm surge hits, I'd guess a land-based launch pad near the shore would sustain more damage than a fixed launch site 5-10 miles offshore.

Also, for a fixed launch site 5-10 miles offshore, what prevents them from bringing the rocket back to the hangar?  There's always advance warning for severe weather.

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #86 on: 01/15/2018 02:33 AM »
unlike on land where you can retreat into a nice cozy hangar, there is no place to hide if the mother-of-all-storms happens by.
I see it just the opposite.  When a hurricane storm surge hits, I'd guess a land-based launch pad near the shore would sustain more damage than a fixed launch site 5-10 miles offshore.

Also, for a fixed launch site 5-10 miles offshore, what prevents them from bringing the rocket back to the hangar?  There's always advance warning for severe weather.

Heh.  I guess you've not experienced what hurricane-force winds can do 5-10 miles offshore.  :)  So let's just say that, assuming a 'fixed launch site' in shallow water of the style shown in the presentation actually remains floating during a hurricane (which is unlikely), there wouldn't be anything remaining above deck level worth consideration once the storm passes.

The advantage of small islands, especially ones with rocks and established trees, is that rocks are generally immovable and trees act as wind breaks (to some extent) limiting ground-level damage to some extent.  And an island is more likely to stay where you left it.

What prevents them from bringing the rocket back to the hangar?  The waves kicked up before the storm warning is broadcast.  The calm seas shown in the presentation is no accident.
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 Dave G

  • Senior Member
  • *****
  • Posts: 2059
  • Liked: 775
  • Likes Given: 1064
Re: BFR ASDS
« Reply #87 on: 01/15/2018 11:56 AM »
So let's just say that, assuming a 'fixed launch site' in shallow water of the style shown in the presentation actually remains floating..
remains floating ?  I'm not talking about a floating launch site.

As I said before, I believe the launch site Elon presented at IAC 2017 is more like a man-made island than a barge, with a rigid structure connecting it to the ocean floor.

I'm also not talking about a direct hit from a hurricane, which would likely damage any launch site.

I'm talking about the surge.  When a storm surge comes inland, it picks up cars and other large objects and slams them into buildings and other fixed structures.

Offline CameronD

  • Full Member
  • ****
  • Posts: 1286
  • Melbourne, Australia
    • Norton Consultants
  • Liked: 408
  • Likes Given: 307
Re: BFR ASDS
« Reply #88 on: 01/15/2018 09:14 PM »
I'm talking about the surge.  When a storm surge comes inland, it picks up cars and other large objects and slams them into buildings and other fixed structures.

So am I.  If you do your research on storm surge you'll discover it can be even more damaging to fixed structures at sea-level in shallow water not far off-shore.. before it's had an opportunity to expend some of it's energy on land.

IMO, a structure of the type shown in the presentation 'fixed' in some way to the sea floor can be expected to cop a real hiding.  That's a key reason oil rigs are generally anchored (not 'fixed').. they can ride this stuff out if necessary.
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 vanoord

  • Full Member
  • ****
  • Posts: 558
  • Liked: 332
  • Likes Given: 56
Re: BFR ASDS
« Reply #89 on: 01/16/2018 02:29 PM »
So let's just say that, assuming a 'fixed launch site' in shallow water of the style shown in the presentation actually remains floating..
remains floating ?  I'm not talking about a floating launch site.

As I said before, I believe the launch site Elon presented at IAC 2017 is more like a man-made island than a barge, with a rigid structure connecting it to the ocean floor.

I'm also not talking about a direct hit from a hurricane, which would likely damage any launch site.

I'm talking about the surge.  When a storm surge comes inland, it picks up cars and other large objects and slams them into buildings and other fixed structures.

The surge is the rise in water level - the stuff being thrown around is thrown around by the wind (and the resultant waves).

For an offshore platform, a surge is only of concern if it brings water to a level where it will cause damage - ie a 5ft surge makes no difference to a platform that is usually 15ft clear of the water as there's still 10ft clear below; and if it's offshore there shouldn't be anything around to be slammed into it.

Online MaxTeranous

  • Member
  • Posts: 40
  • Liked: 36
  • Likes Given: 5
Re: BFR ASDS
« Reply #90 on: 01/22/2018 01:45 PM »
There's thousands of offshore facilities in the Gulf of Mexico in the oil industry and they're hardly ever destroyed by Hurricanes. The oil industry has "solved" the challenge of big offshore installations that can handle the elements.

Tags: