Author Topic: Starship Ocean Platform; Advantages and Difficulties  (Read 34446 times)

Offline OTV Booster

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The SH/SS prototype testing thread was clogging up with platform and barge speculation that is better split off for separate discussion.


An offshore launch and landing platform presents both advantages and difficulties. This threads purpose is to discuss the need or lack of need for a platform and to explore options and techniques that make a platform both physically possible and operationally sound, if the need is there.


Because current StarShip testing is limited to Boca Chica we'll limit discussion to operations in that vicinity - for now.


Be good to each other


Phil
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Offline yoram

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #1 on: 12/28/2020 05:13 pm »
One potential problem is regulatory, as in getting the FAA and environmental reviews etc. to sign off. Is it known how much trouble SeaLaunch had in this regard?

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #2 on: 12/28/2020 05:57 pm »
One potential problem is regulatory, as in getting the FAA and environmental reviews etc. to sign off. Is it known how much trouble SeaLaunch had in this regard?
speculation: environmental issues should be less. After all, the gulf is filled with drilling rigs and there's no nearby wildlife refuge. The fuel is clean in the sense that it would evaporate or burn clean with no residue. Greenhouse issues don't change with location.


I also think that the FAA would be happier with a platform for safety reasons. The FCC might even be happier with ops moved away from the RF rich mainland.
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Offline punder

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #3 on: 12/28/2020 06:08 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Offline dchenevert

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #4 on: 12/28/2020 06:20 pm »
at what distance from the beach does FAA authority end? i.e., 10 miles offshore? 1 mile south of the border with Mexico?

Offline DigitalMan

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #5 on: 12/28/2020 06:27 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

A while back I was talking with someone about launching Starships from ocean platforms. A nearby little birdie laughed at the idea that it would bypass environmental concerns.

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #6 on: 12/28/2020 06:37 pm »
The physical difficulties of ocean landing are not insignificant.


Landing would reasonably be on a barge or platform. Other option ideas are welcome. If on a platform there must be a way to transfer the rocket on and off to a barge or other vessel. The transfer vessel needs to be large enough to carry the rocket safely in less than perfect seas. The rocket needs to be moved onto land and eventually transferred to the Boca Chica facility. And propellant has to be available at the launch location. Feel free to point out anything I've missed.


This is collectively, a big job. Each element offers challenges, but AFAIK, nothing that breaks new engineering ground.


One difficulty that always shows up in these threads is where in development an idea applies. Concepts that might fit in for a fully developed system are often way out of line for a first try. We need to be clear where an idea fits in to avoid the back and forth that keeps missing the mark.


We need to look at the individual elements but we also need to look at a notional final system to know the elements to be considered. And there will be a feedback loop between both ends of the system changing both the final concept and the elements it is comprised of. And we need to find a reasonable development path. Where your ideas fit into this picture is important so please, don't skimp on this tidbit of information.


Edit: while I was putting this together several posts came in. Just pretend this is the second post.  8)
« Last Edit: 12/28/2020 06:40 pm by OTV Booster »
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #7 on: 12/28/2020 06:46 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.
AIUI, high power sonar sends dolphins into a tizzy. I imagine it's like somebody setting off a fire trucks siren next to you while eating dinner. Sonar is high frequency. Rocket engines are mostly low frequency.


Johnneyhinbos. If you're listening, you're our go to guy on this type of question.
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #8 on: 12/28/2020 06:53 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

A while back I was talking with someone about launching Starships from ocean platforms. A nearby little birdie laughed at the idea that it would bypass environmental concerns.
I doubt the EPA would issue an automatic pass but without a reef nearby and clean propellants, my gut sez your birdie friend  might have been trolling a bit. I mean hey, they've got oil rigs down there.


A Johnnyhinbos Q again.
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

Offline DigitalMan

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #9 on: 12/28/2020 07:32 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

A while back I was talking with someone about launching Starships from ocean platforms. A nearby little birdie laughed at the idea that it would bypass environmental concerns.
I doubt the EPA would issue an automatic pass but without a reef nearby and clean propellants, my gut sez your birdie friend  might have been trolling a bit. I mean hey, they've got oil rigs down there.


A Johnnyhinbos Q again.

Environmental reviews and concerns don't necessarily mean denials. Fail to mitigate? That is another story.
« Last Edit: 12/28/2020 07:32 pm by DigitalMan »

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #10 on: 12/28/2020 08:31 pm »
Landing and takeoff are both desirable for ocean ops (opinion). Takeoff requires fueling so my guess is that landing only will be done for early testing.

But what will they land on? Barge and platform are the only options that come to mind. A barge landing means no transfer from a platform. OTOH, a platform can be bigger and more stable in higher seas. If they referb a drilling platform that isn't stripped it will already be tricked out for hoisting, but with an unknown weight capacity. Height might be fine.

A barge is still needed to move the ship back to land with platform landing but it could be a simpler build. With no landing platform on it, a lower CG. No or minimal GSE. No heatshielding. No precision station keeping (maybe). Less electronics (maybe). And with a less expensive build more can be built to make a pipeline that would support a later higher launch tempo.

Still, for earliest testing, one of the F9 barges might be Good Enough. Personally, they feel too small for a final cut. I'm addicted to margin.


Edit: added a word (underlined).

« Last Edit: 12/28/2020 08:36 pm by OTV Booster »
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Offline JohnLloydJones

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #11 on: 12/28/2020 09:32 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.
AIUI, high power sonar sends dolphins into a tizzy. I imagine it's like somebody setting off a fire trucks siren next to you while eating dinner. Sonar is high frequency. Rocket engines are mostly low frequency.


Johnneyhinbos. If you're listening, you're our go to guy on this type of question.

Having worked on sonar systems, I can assure you that sonar systems are not necessarily high frequency. Depends on the purpose.

Offline rsdavis9

Instead of transport back to launch site by boat. I think that refuel and hop might become an easier option. Platform could have the small amount of fuel necessary.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline oiorionsbelt

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #13 on: 12/28/2020 09:44 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

A while back I was talking with someone about launching Starships from ocean platforms. A nearby little birdie laughed at the idea that it would bypass environmental concerns.
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Offline Nevyn72

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #14 on: 12/28/2020 09:57 pm »
Use both barges and a platform.

Land SS & SH on barges, gives the benefit of flexibility of landing location.

Move the barges to beside the dedicated launch platform and crane onto the launch mount.

Advantages:
- no risk of damage to launch facilities during landing.
- you can land downrange saving on boost back burn -> increased load to orbit?
- you can queue up SS & SH for launch in rapid succession while previous vehicles are returning.
- If work is required the barge can head directly to a maintenance facility rather than tying up the launch/landing platform.
- cargo integration becomes a separate location, thus freeing up launch platform. (ie. Land -> cargo integration facility -> launch platform)

The main disadvantage is the need for multiple landing/transport barges and a separate cargo integration/maintenance facility and dedicated launch facility.
Over all it's much more capital intensive although much lower risk to overall operational continuity.

Offline DigitalMan

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #15 on: 12/28/2020 10:06 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

A while back I was talking with someone about launching Starships from ocean platforms. A nearby little birdie laughed at the idea that it would bypass environmental concerns.
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

That is very interesting. It's hard to know what might be necessary. I'm looking forward to seeing what any potential concerns are.

If P2P is going to become a thing, hopefully the costs can be minimized at the same time as protecting resources.

Offline Lar

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #16 on: 12/28/2020 10:22 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
« Last Edit: 12/28/2020 10:23 pm by Lar »
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Offline butters

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #17 on: 12/28/2020 11:01 pm »
The combination of terrestrial launch and marine landing should be seen as an interim arrangement, in my opinion, because while it probably makes things "sooner," it pretty much rules out the kind of turnaround cadence envisioned for the Starship system. Droneship landing implies F9-like cadence. That seems fine for prototype flight-testing and acceptable for the Starlink launch campaign, but it would be a bummer for propellant tanker campaigns (HLS or Mars cargo), and it would blow up the schedule for NASA human-rating Starship by flying it hundreds of times.

The only way a SS/SH pair launches several times a week is if they both land very close to the launch pad. Even a fixed launch platform with a mobile droneship landing pad positioned a short distance away would significantly complicate operations, but 2-3 weekly launches seems possible in this mode. The F9 droneship experience shows that there's a significant risk of loss-of-vehicle associated with a vertical rocket stage on a pitching deck. The price they pay for a mobile landing platform is the need for something Octograbbery and probably still some risk of losing the vehicle after a nominal landing.

Since they need the Octograbbery solution for the terrestrial launch + droneship landing mode anyway, it would make sense to build the fixed launch platforms with provisions for landing in the future, and continue using droneships for landing until they're confident enough to land on the launch platform. They should probably minimize their investments in droneships and ideally avoid building any launch-only offshore platforms, because this is not viable as permanent infrastructure for a high-rate reusable launch system.

Offline born01930

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #18 on: 12/28/2020 11:07 pm »
Having been on a submarine launching a couple SLBM’s I can say they are quite loud even a hundred + feet under water.

Elon mentioned no legs on SH, maybe caught with a derrick while hovering next to the platform. No need barge or transfer crane. I suggested this in jest many years ago on Selenian Boondocks

Offline punder

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #19 on: 12/29/2020 12:46 am »
Having been on a submarine launching a couple SLBM’s I can say they are quite loud even a hundred + feet under water.

Elon mentioned no legs on SH, maybe caught with a derrick while hovering next to the platform. No need barge or transfer crane. I suggested this in jest many years ago on Selenian Boondocks
Elon read your post, it sat in his subconscious for years and then came back, meaning you helped form spaceflight reality. Not being sarcastic. One can always dream!   ;D

So you are one of those crazy submariners. That’s pretty impressive. I’d just curl up in a ball and die of fright.

Offline steveleach

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #20 on: 12/29/2020 12:38 pm »
People are talking about the environmental issues being potentially no less for sea launch, but I got the impression from Elon's tweets that the primary reason for it was to move the noise away from population centres.

Offline DigitalMan

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #21 on: 12/29/2020 04:31 pm »
That sounds like a great reason to me, particularly if the environmental issues are manageable.

Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #22 on: 12/29/2020 05:41 pm »
The benefit of off-shore operations (nearly nobody and nothing around you) is also the biggest hassle.
As we've seen at Boca Chica, operations can be conducted with almost entirely off the shelf equipment. Buy some tanks, truck them in, mount them on concrete. Fill the tanks? Truck the propellant in, commercial suppliers will drive to your door. Need to lift your spaceship? Rent a crane. Crane needs to be bigger? Stop renting it, rent a bigger one. Etc. Startup cost is extraordinarily low, ongoing costs only on-go while you're actually doing something.

Offshore, you need to bring everything you need with you. Tanks? Need ones that don't rust while being blasted with salt water. Not available off the shelf? Whoops, better design bespoke ones ($$$ + lead time) or purchase an LNG tanker. Whaddaya mean nobody builds LOX tanker vessels?! Ugh, more lead-time! Need a crane? Whoops, either build a custom one that can survive being left on the pad next to the rocket, or hire one of the vanishingly few sea-lift cranes with sufficient height (if any exist). Whaddaya mean there's only one it's pre-booked for the next few years! etc.

It's not just the rig(s) themselves that form a big up-front paywall before you can actually start operations, it's all the ancillary infrastructure, equipment and commodities that aren't off the shelf or available for cheap and short notice rental that needs to be bought and paid for up-front and well in advance.

We will probably see a larger drone-ship for down-range landings during testing so they can fly non-RTLS profiles. But it will almost certainly be 'just' a barge that gets hauled back to land for any further operations like the existing ASDSes. Doing any processing - much less actually launching - from off-shore is a whole different ballgame. With the pace SpaceX likes to iterate at, and how averse they are to being locked into a bad design (e.g. CF), I can't see them locking themselves into the large costs and lead-times for a Minimum Viable Product off-shore launch platform until they have been operating Starship & Superheavy for long enough to iron the bugs out.

Offline goretexguy

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #23 on: 12/29/2020 06:18 pm »
I can't see them locking themselves into the large costs and lead-times for a Minimum Viable Product off-shore launch platform until they have been operating Starship & Superheavy for long enough to iron the bugs out.

...buuut, when they do get things worked out, SpaceX has a demonstrable tendency to establish a manufacturing process to cheaply make bespoke items. This tendency may extend to offshore launch/landing platforms as seen in the point-to-point Starship video.

So, while I heartily agree that SpaceX will avoid substantial seagoing facilities for as long as possible, at some point they will reach an inflection point in operations which requires them to produce these Off-Shore Launch And Landing Platforms (OSLAPs, or 'oh-slaps', you heard it here first) in significant numbers. If SpaceX is to go to Mars in the numbers that Musk envisions, I don't see any way to achieve these launches without numerous OSLAPs around the world.


Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #24 on: 12/30/2020 05:55 pm »
The benefit of off-shore operations (nearly nobody and nothing around you) is also the biggest hassle.
As we've seen at Boca Chica, operations can be conducted with almost entirely off the shelf equipment. Buy some tanks, truck them in, mount them on concrete. Fill the tanks? Truck the propellant in, commercial suppliers will drive to your door. Need to lift your spaceship? Rent a crane. Crane needs to be bigger? Stop renting it, rent a bigger one. Etc. Startup cost is extraordinarily low, ongoing costs only on-go while you're actually doing something.

Offshore, you need to bring everything you need with you. Tanks? Need ones that don't rust while being blasted with salt water. Not available off the shelf? Whoops, better design bespoke ones ($$$ + lead time) or purchase an LNG tanker. Whaddaya mean nobody builds LOX tanker vessels?! Ugh, more lead-time! Need a crane? Whoops, either build a custom one that can survive being left on the pad next to the rocket, or hire one of the vanishingly few sea-lift cranes with sufficient height (if any exist). Whaddaya mean there's only one it's pre-booked for the next few years! etc.

It's not just the rig(s) themselves that form a big up-front paywall before you can actually start operations, it's all the ancillary infrastructure, equipment and commodities that aren't off the shelf or available for cheap and short notice rental that needs to be bought and paid for up-front and well in advance.

We will probably see a larger drone-ship for down-range landings during testing so they can fly non-RTLS profiles. But it will almost certainly be 'just' a barge that gets hauled back to land for any further operations like the existing ASDSes. Doing any processing - much less actually launching - from off-shore is a whole different ballgame. With the pace SpaceX likes to iterate at, and how averse they are to being locked into a bad design (e.g. CF), I can't see them locking themselves into the large costs and lead-times for a Minimum Viable Product off-shore launch platform until they have been operating Starship & Superheavy for long enough to iron the bugs out.
You paint a dismal picture. Agreed, moving ops off shore is expensive. It seems necessary if P2P becomes a reality (long term projection). It might be forced on SX for environmental and safety reasons (short or medium projection).


There is truth in many of the specifics you point out but some are a bit overblown. At BC SX is building a rocket, building a launch facility and building a manufacturing facility, while figuring out what they need on the fly. Only the launch/landing would move off shore and then it would carry some legacy with it. The longer it's put off, the more developed that legacy.


Starting with landing only, is a beginning where they already have F9 experience. That beautiful swan dive and acrobat flip of SN8 started with a stainless steel plate water tower. If he has to, Elon has the talent to finesse a landing barge into an entire off shore infrastructure at a price point that will drive captains of industry to babbling envy.


Ten years ago who would have thought that the cost of an off shore launch/landing facility would be seen as major issue in a return to the moon or HSF to Mars?
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

Offline Surfdaddy

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #25 on: 12/31/2020 03:33 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
« Last Edit: 12/31/2020 03:33 am by Surfdaddy »

Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #26 on: 12/31/2020 03:40 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
yes.
the liquid  nitrogen required for subchill is made at the same time as the liquid  oxygen.
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Offline Vanspace

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #27 on: 01/01/2021 04:59 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
yes.
the liquid  nitrogen required for subchill is made at the same time as the liquid  oxygen.

And the boil off can power the bubble curtain.

To be fair, the 5000 tons of propellant Starship uses is not considered a very large amount by marine transport standards. The average LNG tanker carries around 75,000 tons with the big ones around 150K tons.
"p can not equal zero" is the only scientific Truth. I could be wrong (p<0.05)

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #28 on: 01/03/2021 02:48 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
yes.
the liquid  nitrogen required for subchill is made at the same time as the liquid  oxygen.

And the boil off can power the bubble curtain.

To be fair, the 5000 tons of propellant Starship uses is not considered a very large amount by marine transport standards. The average LNG tanker carries around 75,000 tons with the big ones around 150K tons.
I hope you're talking about LN2 boiloff and not CH4.


I've got a picture in my head of a group of launch platforms, each with small top off GSE tanks and serviced by two of the older and smaller LNG tankers, one converted to LOX to do servicing runs.


Refueling a fleet of mars bound ships will call for ~5 tanker launches for each outbound ship. Four ships, 20 tanker launches. Eight ships, 40 launches. Do a launch, play orbital catch-up for 6 hours, transfer fuel and wait for reentry alignment ~12 hours after launch. One turnaround per day per tanker, SH and pad if everything goes perfect. This assumes an ideal of truly minimal servicing needs. One platform just wouldn't be adequate.


What would be needed to convert an LNG tanker to LOX?

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Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #29 on: 01/03/2021 04:01 am »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #30 on: 01/03/2021 07:05 pm »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
That brings up another issue with platforms. Power. A cable can be run. That's not only big time expensive but can be damaged by drag netting. There's a lot of shrimping down that way. And underwater telecom cables have a lot of loss. Can't see power being much different.


Alternatives I come up with are wind, solar, tidal and thermal differential. Somehow big wind turbines and rocket exhaust don't seem to mix all that well. Hmm, maybe there is a synergy there.


Solar makes sense and and floating an array of panels both generates power and would keep peak water temps down a bit, reducing energy input to storms. Would the fish mind? Probably.


Don't know much about tidal and thermal differential. ISTM one of those platforms with a very deep draft might be an ideal place to play with this. 
« Last Edit: 01/03/2021 07:08 pm by OTV Booster »
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Offline dchenevert

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #31 on: 01/03/2021 10:04 pm »
Has Sea Launch (the company) already been raked over in this forum?

They launched rockets and caught helicopters back in the day. Not that SpaceX should buy this old hulk--but it is an existence proof of ??? something similar.

https://www.spaceflightinsider.com/space-flight-news/sea-launch-reduces-staff-due-lull-launches/

Offline dchenevert

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #32 on: 01/03/2021 10:08 pm »
Enough power for propellant-related chemistry? Yeah that's a lot of power.

If power is only needed to pump propellant around, and keep the cameras and radios running, wouldn't a few tons of grid-battery-storage do the job?

If a lot of power is needed...  All the cool kids are pouring their $-billions into offshore wind. Most of this is fixed-platform but 'floating-platform' is up and coming.

https://www.ge.com/renewableenergy/wind-energy/offshore-wind/haliade-x-offshore-turbine#:~:text=Introducing%20Haliade%2DX%2C%20the%20most,competitive%20source%20of%20clean%20energy.

Purports to provide "13 GWh/year", probably in a high-wind environment.

A few km of separation might be workable; and/or move the windmill or the launch platform away during launches and landings, then move it back.

Or... put the windmill on the same platform, separated by 100 meters or whatever, and lock it down during launches and landings.
« Last Edit: 01/03/2021 10:19 pm by dchenevert »

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #33 on: 01/03/2021 10:16 pm »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
That brings up another issue with platforms. Power. A cable can be run. That's not only big time expensive but can be damaged by drag netting. There's a lot of shrimping down that way. And underwater telecom cables have a lot of loss. Can't see power being much different.

Whether you (a) manufacture LOX/LNG on land and ship it to the platform or (b) manufacture on-platform is a simple cost equation.  Ignoring tech that doesn't practically exist, given suitably large amounts of $$$ manufacture on-platform can be achieved using off-the-shelf diesel gen-sets, but there are very high real-estate and maintenance costs to be factored in also.

Unless your platform is a really long way off-shore, ISTM it would be significantly cheaper to send all of your supplies - food, water, diesel.. (oh, and LN2, LOX, LNG, Helium, Welding gases also) out on a supply ship every launch or so.
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.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #34 on: 01/03/2021 10:24 pm »
Unless your platform is a really long way off-shore, ISTM it would be significantly cheaper to send all of your supplies - food, water, diesel.. (oh, and LN2, LOX, LNG, Helium, Welding gases also) out on a supply ship every launch or so.

If this launch facility is to be there long term, it would be worth the expense to run piping along the sea bed for the propellants and other liquid necessities, fed from a shore facility.
« Last Edit: 01/03/2021 10:25 pm by clongton »
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Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #35 on: 01/03/2021 11:28 pm »
Unless your platform is a really long way off-shore, ISTM it would be significantly cheaper to send all of your supplies - food, water, diesel.. (oh, and LN2, LOX, LNG, Helium, Welding gases also) out on a supply ship every launch or so.

If this launch facility is to be there long term, it would be worth the expense to run piping along the sea bed for the propellants and other liquid necessities, fed from a shore facility.

Maybe.  Remember, undersea pipelines have to start somewhere, and enter the water somewhere, so there is land to be purchased, beach access to be negotiated, HV power provided, trenching (both above and below the high tide mark), permits, notices, signage, on-going maintenance, etc.

Again, it depends exactly how far off-shore we are talking about.. and, if you're talking pipelines, what particular shore also.
« Last Edit: 01/03/2021 11:29 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 Asteroza

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #36 on: 01/04/2021 03:16 am »
Having been on a submarine launching a couple SLBM’s I can say they are quite loud even a hundred + feet under water.

Elon mentioned no legs on SH, maybe caught with a derrick while hovering next to the platform. No need barge or transfer crane. I suggested this in jest many years ago on Selenian Boondocks

Hrm, Saipem 7000 is getting a little long in the tooth, wonder if she's coming up for sale...

Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #37 on: 01/04/2021 04:11 am »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
That brings up another issue with platforms. Power. A cable can be run. That's not only big time expensive but can be damaged by drag netting. There's a lot of shrimping down that way. And underwater telecom cables have a lot of loss. Can't see power being much different.
...
Offshore wind turbines run power cables just fine.
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Offline danneely

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #38 on: 01/04/2021 05:08 am »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
That brings up another issue with platforms. Power. A cable can be run. That's not only big time expensive but can be damaged by drag netting. There's a lot of shrimping down that way. And underwater telecom cables have a lot of loss. Can't see power being much different.

The development of affordable HVDC hardware has made underwater power cables much more feasible than they used to be.  AC (and data over wires is AC) suffers from capacitive losses that are avoided with DC.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #39 on: 01/04/2021 07:49 am »
I remember this being discussed some years back, but it's hard to search for:

What are the tradeoffs for building a causeway out to an ocean platform?

You gain the convenience of road access for spacecraft and equipment, and can run all power, coms, lox/ch4 pipes alongside, out of the water. The only downside I can see is cost (both capital and ongoing maintenance).

Offline DistantTemple

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #40 on: 01/04/2021 10:25 am »
Has Sea Launch (the company) already been raked over in this forum?

They launched rockets and caught helicopters back in the day. Not that SpaceX should buy this old hulk--but it is an existence proof of ??? something similar.

https://www.spaceflightinsider.com/space-flight-news/sea-launch-reduces-staff-due-lull-launches/
Yes, extensively. Well documented: https://forum.nasaspaceflight.com/index.php?topic=34112.280#lastPost etc

Its not considered a hulk by its proud new guardians, and looks quite pristine on a walk-through video.
« Last Edit: 01/04/2021 10:27 am by DistantTemple »
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #41 on: 01/04/2021 11:16 am »
I remember this being discussed some years back, but it's hard to search for:

What are the tradeoffs for building a causeway out to an ocean platform?

You gain the convenience of road access for spacecraft and equipment, and can run all power, coms, lox/ch4 pipes alongside, out of the water. The only downside I can see is cost (both capital and ongoing maintenance).
Unless there are very expensive high bridges (overpasses? I'm not sure of the word) to allow ship traffic there will be some mighty frakked people out there. Not a deal killer but the expense has to be part of the equation.


We can only guess what launch tempo would justify this.
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #42 on: 01/04/2021 11:32 am »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
That brings up another issue with platforms. Power. A cable can be run. That's not only big time expensive but can be damaged by drag netting. There's a lot of shrimping down that way. And underwater telecom cables have a lot of loss. Can't see power being much different.
...
Offshore wind turbines run power cables just fine.
The whole point of an offshore wind farm is the cable. It has to be there. Cable installation and maintenance costs are part of the business case. The case for a launch platform doesn't have to include a cable although that can be a factor in choice of location. Wasn't saying it couldn't be done but think that alternatives are a consideration.
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Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #43 on: 01/04/2021 11:32 am »
The only downside I can see is cost (both capital and ongoing maintenance).
And pissing off everyone else wanting to use the waterway you've just dragged an effective wall across. For Boca Chica as an example, anyone wanting to head south from Brownsville or South Padre Island would need to detour around your however-many-miles-long pier.

Plus there's hurricanes. The Mulberries at Omaha & Arromanches only survived with the aid of large additional breakwaters, and even they had trouble in the relatively mild summertime Channel environment. If you want to put something out at sea, it either needs to be extraordinarily sturdy, or it won't be there for long.

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #44 on: 01/04/2021 04:41 pm »
Having been on a submarine launching a couple SLBM’s I can say they are quite loud even a hundred + feet under water.

Elon mentioned no legs on SH, maybe caught with a derrick while hovering next to the platform. No need barge or transfer crane. I suggested this in jest many years ago on Selenian Boondocks

Hrm, Saipem 7000 is getting a little long in the tooth, wonder if she's coming up for sale...
Whoo, that is one impressive piece of hardware. [size=78%]https://en.m.wikipedia.org/wiki/Saipem_7000[/size]


And it can lay pipe up to 24".

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Offline Bananas_on_Mars

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #45 on: 01/04/2021 06:15 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Offline Asteroza

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #46 on: 01/05/2021 06:46 am »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...

Offline Bananas_on_Mars

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Starship Ocean Platform; Advantages and Difficulties
« Reply #47 on: 01/05/2021 05:21 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
« Last Edit: 01/05/2021 05:24 pm by Bananas_on_Mars »

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #48 on: 01/05/2021 07:35 pm »
The only downside I can see is cost (both capital and ongoing maintenance).
And pissing off everyone else wanting to use the waterway you've just dragged an effective wall across. For Boca Chica as an example, anyone wanting to head south from Brownsville or South Padre Island would need to detour around your however-many-miles-long pier.

Plus there's hurricanes. The Mulberries at Omaha & Arromanches only survived with the aid of large additional breakwaters, and even they had trouble in the relatively mild summertime Channel environment. If you want to put something out at sea, it either needs to be extraordinarily sturdy, or it won't be there for long.
If memory serves, the storm that took out the British mulberry and damaged the American was unprecedented for that time of the year, which doesn't minimize the rack and ruin a hurricane can unleash. Has a semi submersable rig ever been taken out by storm?

Here's an overview of semi submersible platforms. https://en.m.wikipedia.org/wiki/Semi-submersible_platform

"The operating deck can be located high above the sea level owing to the good ship stability of the design, and therefore is kept well away from the waves."
« Last Edit: 01/05/2021 07:36 pm by OTV Booster »
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Offline Bananas_on_Mars

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #49 on: 01/05/2021 08:28 pm »
Has a semi submersable rig ever been taken out by storm?

Alexander L. Kielland, capsized in north sea, 1980

Ocean Ranger, sank in a storm, 1982

Offline Garrett

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #50 on: 01/06/2021 09:19 am »
For this discussion, I think some data on seafloor depth would be useful. As far as I can find, the seafloor has a very small slope and is still only about 50 meters deep 50 km out to sea from Boca Chica.
https://woodshole.er.usgs.gov/project-pages/mobility/images/gmex.png
https://charts.noaa.gov/PDFs/11301.pdf

Would this not make tunnels a viable option, particularly given Elon being a fan of them. Either a Boring Company tunnel, or a prefabricated tunnel laid down on the seabed (like the Transbay Tube for the BART).

Bridges are possible, but I would assume much more troublesome to build. An example that springs to mind is the Řresund Bridge, linking Denmark and Sweden:
https://en.wikipedia.org/wiki/%C3%98resund_Bridge

Also, given such small depths, why would any platform be floating, rather than directly fixed on the seafloor?

Edit: spelling
« Last Edit: 01/07/2021 12:05 pm by Garrett »
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Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #51 on: 01/06/2021 10:52 am »
Seabed-laid tunnels (or any seabed-laid infrastructure like cables or pipes) are vulnerable to damage from anchor dragging and other hazards. Boca Chica is immediately next to a major port, and large vessels anchored just offshore is a very common sight (and visible in many local photos and videos of SpaceX sites). A lot of underwater infrastructure is now buried on install in coastal regions for this reason.

Offline philw1776

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #52 on: 01/06/2021 04:40 pm »
For this discussion, I think some data on seafloor depth would be useful. As far as I can find, the seafloor has a very small slope and is still only about 50 meters deep 50 km out to sea from Boca Chica.
https://woodshole.er.usgs.gov/project-pages/mobility/images/gmex.png
https://charts.noaa.gov/PDFs/11301.pdf

Would this not make tunnels a viable option, particularly given Elon being a fan of them. Either a Boring Company tunnel, or a prefabricated tunnel laid down on the seabed (like the Tansbay Tube for the BART).

Bridges are possible, but I would assume much more troublesome to build. An example that springs to mind is the Řresund Bridge, linking Denmark and Sweden:
https://en.wikipedia.org/wiki/%C3%98resund_Bridge

Also, given such small depths, why would any platform be floating, rather than directly fixed on the seafloor?

Agree heartily. At these shallow depths fixed seafloor platforms are the simpler solution.
Long bridges block access and environmental political review would take ages and most likely fail review.
Anyone know what the feature ~12 miles offshore on the noaa chart near he Mexican ocean border labeled (2) is? 
Could is be a shallow seamount? Size?
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« Last Edit: 01/06/2021 05:02 pm by rsdavis9 »
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #54 on: 01/07/2021 12:37 pm »
Just for context for this thread, Elon previously mentioned that platforms would need ~30km / 18 miles clear area for noise.
https://twitter.com/elonmusk/status/1298019842356703232?s=20

So offshore from Boca Chica that would mean a depth of 50 m max, and maybe even only 30 m.

I would feel pretty confident in betting that they will build a Boring Company tunnel (or tunnels more likely) for access to an offshore platform and also for piping propellant and transporting electricity.

At current prices and tunneling speeds, they could probably build an initial service tunnel for a few $100 million, over 2 years. Short term that is a massive waste of money, but I think in the long term it would be cost effective.
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #55 on: 01/07/2021 01:47 pm »
Don't fall for the fallacy that the Gulf Coast is a pristine marine environment, that the seafloor bed is uncluttered, or that a platform at any location or in any condition is difficult to obtain.

The Gulf may be a big place, but it has thousands of active platforms, thousands of inactive platforms, and thousands of miles of undersea servicing pipes and pipelines. 

You can literally pick your preferred spot and make an offer.

https://skytruth-org.carto.com/tables/offshore_platforms_not_removed/public

As I posted in another thread, I think the active orbital launch facilities will be right off-shore from Galveston because it has better on-shore support and transfer facilities.
« Last Edit: 01/07/2021 01:48 pm by sghill »
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Offline philw1776

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #56 on: 01/07/2021 07:00 pm »
Offshore Galveston would overfly too many crewed oil platforms. 
They would also overfly too many ships for near daily flight cadence.
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #57 on: 01/08/2021 04:11 pm »
Offshore Galveston would overfly too many crewed oil platforms. 
They would also overfly too many ships for near daily flight cadence.

I've thought about that.  If this thing is going to be a crew rated point-to-point spacecraft, it's going to need to have the reliability and corresponding FAA clearances approaching if not equal to airliners. We need to stop thinking about this spacecraft in terms of one-off launches.

Daily launches means daily refueling, passenger processing, and cargo operations; as well as the means, reliability, and clearances to fly over stuff.

First Principles tell us it can't be so remote as to preclude the former in order to accommodate an absence of the later. The business case (daily or hourly flights) won't support it.

Besides, there is a HUGE empty space southeast of Galveston where there is nothing for hundreds of miles before you get to the next line of platforms (which are not anywhere near each other for the most part even though the map makes it look like they are). Perfect for a launch area.
« Last Edit: 01/08/2021 04:24 pm by sghill »
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #58 on: 01/08/2021 04:26 pm »
And what inclinations can you actually launch to from Galveston without one hell of a dogleg?

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #59 on: 01/08/2021 05:08 pm »
And what inclinations can you actually launch to from Galveston without one hell of a dogleg?

Not sure what inclinations they'd correspond to, but this is roughly the allowable launch vectors.  The black lines show the gap between Mexico and Cuba, the red line appears to thread its way between all the islands.  The orange lines overfly the Bahamas and the Dominican Republic; if it's going fast enough at that point to safely overfly populated areas is more than I can say, it's farther downrange than Cuba in the dogleg SSO corridor from the Cape; but I'm not sure what the relative population densities are (and those matter as much as how fast it's going for the risk assessment).

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #60 on: 01/08/2021 05:30 pm »
For this discussion, I think some data on seafloor depth would be useful. As far as I can find, the seafloor has a very small slope and is still only about 50 meters deep 50 km out to sea from Boca Chica.
https://woodshole.er.usgs.gov/project-pages/mobility/images/gmex.png
https://charts.noaa.gov/PDFs/11301.pdf

Would this not make tunnels a viable option, particularly given Elon being a fan of them. Either a Boring Company tunnel, or a prefabricated tunnel laid down on the seabed (like the Tansbay Tube for the BART).

Bridges are possible, but I would assume much more troublesome to build. An example that springs to mind is the Řresund Bridge, linking Denmark and Sweden:
https://en.wikipedia.org/wiki/%C3%98resund_Bridge

Also, given such small depths, why would any platform be floating, rather than directly fixed on the seafloor?

Agree heartily. At these shallow depths fixed seafloor platforms are the simpler solution.
Long bridges block access and environmental political review would take ages and most likely fail review.
Anyone know what the feature ~12 miles offshore on the noaa chart near he Mexican ocean border labeled (2) is? 
Could is be a shallow seamount? Size?

Google Earth gives a discussion quality map of depths in the gulf.  It's not particularly deep 25 miles out from shore.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #61 on: 01/08/2021 06:15 pm »
Also, We can put some boundaries on just how far off-shore a Gulf of Mexico-based point-to-point launch operations platform can be in order to remain competitive with air travel.

And I will repeat, there is no point to point Starship travel without overflights permitted. None.

First, let's make four assumptions:

1) Only the total trip time matters for this exercise. Leaving one City and Arriving in another.
2) The cost and/or priority need for this exercise is not an obstacle.
3) We are assuming one launch site from the US for this exercise in the Gulf of Mexico.
4) None of this particularly matters for orbital or BEO space launches.

In other words, we are looking at an apples to apples comparison of how long it will take a passenger to leave their home city and arrive at their destination city.

Using Net Present Value thinking, if the travel time time for Starship is one minute longer than the conventional jet travel time, there is no business case.  Why am I bringing this up? Because it is exactly the same economic problem that killed Concorde flights. They were fast and expensive flights, but they were so rare between flights that you could have arrived at your destination on the next 747 flight long before Concorde even left London for New York on its twice daily flight- irrespective of that cost and speed. Anyway, back to Starship...

We need a formula for comparison to give us the Max distance off-shore the launch operations can function while retaining the value proposition favorable for point to point travel. We need to identify the common elements and the variable values.

Now, I am ignoring cargo and disembarking times at the final destination, and I am also ignoring any non-direct airline flights because for this exercise they don't matter. They are either shared or they don't matter.  Also, I am ignoring cities where the hub and spoke means of travel come into play because no one flies from Fayetteville to New York City to THEN get on a Concorde to London. Let's just look at the cities where the travel time by airliner would be the shortest and also the likelihood of travel to the destination city by a traveler with the means and need for Starship travel is greatest.

So what we need is the SUM of all Starship's variables to be less than the sum of the jet airliner's variables for the business case to work.

What the table below shows is that there are lots of elements of Starship travel that are unavoidable (unless you ALREADY happen to live in Houston and want to fly to Tokyo on Starship). What is variable is the length of time it takes to get out to the Starship launch platform, and also the cargo and passenger handling time on the ground.

Starship Variables:   Values in hours
A) Boarding and loading time in origin city (LA or New York) to departure city (private flight to Galveston)    0.5
B) Flight time from origin city to Galveston (private direct flight).   4
C) Transfer and Pre-Boarding time for flight out to the to Launch Platform   1
D) Surface or air transport travel time out to Launch Platform   0.5
E) Cargo Loading and Pre-boarding time for Starship (Also making the assumption that fueling has already occurred, or is occurring simultaneously)   1
F) Starship launch and flight time   0.25
G) Disembarking and cargo unloading at landing platform   1
H) Surface or air transport travel time away from landing platform to receiving city (London, Tokyo, or Seoul)   0.5
Total Travel Time:   8.75
   
Airline Travel Variables: LA to Tokyo   
A) Boarding and loading time in origin city   3
B) N/A   
C) N/A   
D) N/A   
E) N/A   
F) Jet airliner taxi and flight time   12
G) N/A   
H) N/A   
Total Travel Time:   15
   
Airline Travel Variables: NYC to London   
A) Boarding and loading time in origin city   3
B) N/A   
C) N/A   
D) N/A   
E) N/A   
F) Jet airliner taxi and flight time    7
G) N/A   
H) N/A   
Total Travel Time:   10


The lesson is, the launch platform transfer and ground handling costs enough time that Point to Point passenger flights for a passenger from the New York area to London don't make sense unless there is a launch platform accessible directly from New York- even if money is no object. They make a little more sense from LA to Tokyo. And I had my thumb heavily in Starship's favor on these scales by not using commercial airport boarding and transfer times to make the flight to Houston and then to the platform, assuming direct flights, and assuming very fast flight times in the destination city from the landing platform.

They make a lot more sense for LA to Abu Dhabi or some other ridiculously long-haul flight. Concorde could barely make the trans-Atlantic flight (it had to carry fewer passengers on the East-bound leg), so it's price premium could not meet the time cost penalty for such a short flight. Starship, on the other-hand, can cover a hemisphere. It needs lots of launch and landing platforms with super rapid transfer, but if they regularly carry enough passengers, I think there is a business model to be made here.

« Last Edit: 01/08/2021 06:18 pm by sghill »
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Offline philw1776

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #62 on: 01/08/2021 07:46 pm »
You're on the P2P Starship flow where by definition overflights aren't a problem. I'm considering this decade's possible ocean launch sites for Mars transport through the early 30s.  In this view overflights of Galveston, etc. shipping lanes and offshore platforms are likely a big issue.
I see P2P as very late 2030s at earliest but there's a separate topic for that discussion.
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Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #63 on: 01/11/2021 12:31 am »
The lesson is, the launch platform transfer and ground handling costs enough time that Point to Point passenger flights for a passenger from the New York area to London don't make sense unless there is a launch platform accessible directly from New York- even if money is no object. They make a little more sense from LA to Tokyo. And I had my thumb heavily in Starship's favor on these scales by not using commercial airport boarding and transfer times to make the flight to Houston and then to the platform, assuming direct flights, and assuming very fast flight times in the destination city from the landing platform.

From what you've posed and as I see it, the key issue with ocean launch platforms doing PTP flights really has nothing at all to do with the technology - as discovered by airport planners a century ago, they simply don't make economic sense unless you happen to be living nearby.

Case in point:  One reason for the invention (and demise) of the A380 was a widely-advertised plan for a 'hub and spoke' model of global air transportation.  For many reasons, a few years back it was thought it might be more efficient (economically and time-wise especially) for people to fly from their local to a major international hub and be transported to another international hub before travelling on to their destination.  The problem here was that (a) depending upon where the hub is, it turned out that for smaller numbers of people it's actually more efficient to travel from their home town direct to their destination and (b) it seems folks don't especially like taking three flights when they can take one - which is quicker door-to-door anyway - and (c) large numbers of passengers arriving at the same time created headaches for everyone with long delays in security processing and baggage collection at both ends.

What that means is, for this proposal to be anything other than a novelty (like the A380 ultimately is) there needs to be lots of these platforms, ideally one close to each major city - but no matter how close you get by sea, you simply aren't going to be able to compete economically with the same set-up anywhere on dry land, which is always going to be both closer (quicker to get to) and cheaper and more readily accessible by road, train and air (not just expensive sea and air).  For this reason IMHO even if it can be make to work somehow, we'll see it travel the way of the A380: ie. it will take years to develop, costing a small fortune in the process; it will be a great novelty for a while; and it will, a few years after inception, be replaced by launch pads on dry land.
     
« Last Edit: 01/11/2021 12:39 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 Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #64 on: 01/11/2021 01:13 am »
Not sure I agree with that. There are some unique aspects of rocket travel that make ocean platforms better. Arms control, mass production of very weird, custom GSE, and especially the need to be like >15 miles away from any houses.

I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.
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Offline Zed_Noir

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #65 on: 01/11/2021 12:31 pm »
<snip>
I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.

The US Air Mobility Command might operated P2P Starships for movements between logistics hubs. Since that is only the way the DoD can get enough surge logistics capacity without buying a lot more air transports and aerial tankers plus ground side infrastructure expansion. Maybe even pressed all available transport variants of the Starship into service for the duration of an emergency.

Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #66 on: 01/11/2021 02:15 pm »
Starship won't be flying anywhere that doesn't have an LCH4 & LOX retanking facility (or you'd never get it back). It absolutely won't be flying into anywhere that doesn't have total control of the local airspace, as it is incredibly vulnerable throughout all stages of flight, and even when landed for offloading.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #67 on: 01/11/2021 04:18 pm »
Starship won't be flying anywhere that doesn't have an LCH4 & LOX retanking facility (or you'd never get it back). It absolutely won't be flying into anywhere that doesn't have total control of the local airspace, as it is incredibly vulnerable throughout all stages of flight, and even when landed for offloading.

It'd definitely need new infrastructure, but similar constraints on airspace safety also apply to C-17/22/130 transport aircraft.  In some ways though Starship would actually be less vulnerable to hostile fire in transit.  While it's limited in there effectively only being a single flight path between any two points except at takeoff/landing it's beyond the reach of hostile fighter aircraft and conventional AA systems.  Some ABM/ASAT systems would have the reach to engage it mid-flight; but they're far less common than conventional SAMs.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #68 on: 01/11/2021 04:48 pm »
<snip>
I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.

The US Air Mobility Command might operated P2P Starships for movements between logistics hubs. Since that is only the way the DoD can get enough surge logistics capacity without buying a lot more air transports and aerial tankers plus ground side infrastructure expansion. Maybe even pressed all available transport variants of the Starship into service for the duration of an emergency.

Another thing to consider is that SpaceX looks like a much more reliable supplier of air/space craft for a given cost than the current aircraft manufacturer incumbents.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #69 on: 01/11/2021 08:16 pm »
Not sure I agree with that. There are some unique aspects of rocket travel that make ocean platforms better. Arms control, mass production of very weird, custom GSE, and especially the need to be like >15 miles away from any houses.

I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.
P2P for irregular and unscheduled priority cargo makes more economic sense than for passengers. Either way, ISTM that a Star Ship Light would better serve. Same construction techniques, same engines, smaller diameter. Maybe 4or 5m (guess). There are probably good engineering arguments that show a lower efficiency but the rocket is only one part of the system.


If a smaller version can use land facilities that is its own efficiency. I think there's another thread for SS variants for any who want to go into the details but exploring the impact of a variant seems fair game for this thread.
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #70 on: 01/11/2021 09:12 pm »
<snip>
I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.

The US Air Mobility Command might operated P2P Starships for movements between logistics hubs. Since that is only the way the DoD can get enough surge logistics capacity without buying a lot more air transports and aerial tankers plus ground side infrastructure expansion. Maybe even pressed all available transport variants of the Starship into service for the duration of an emergency.
Interesting idea on the surface. It's down in the weeds that problems show up. Unless there are propellants available at the destination it'll be a one way trip. Maybe a P2P tanker? Not impossible, but if it takes 5 tankers to get one SS back I think I see a leetle problem.


A one way trip can be justified to solve a high priority problem. Something like staging an army to England to liberate Europe, assuming England can make return propellant. Then a slap bang one way jump across the channel to kick things off. Well, maybe a bigger operation than what you meant.


I've been long time fascinated by military logistics and my reading shows two modes. Push and Pull. Push is when things are pushed to the theater automatically based on the number of bellies to be filled and clothed and estimated fuel and ammo expenditure rates. Pull is when the estimates are off and you requisition laser toner that never got pushed. Think of all the little things you use every day that will not be there when a military force arrives.


In Desert Storm they used hand scanners and modern stocking procedures (with Walmart as a major adviser IIRC) and they established a priority system to fly things over expedited. The system was abused and clogged. Clogging aside, putting hands on the material, getting it to an airfield then getting it distributed after arrival took more time than the transit itself.


The troops went over by air. The tanks and other heavy equipment by ship. The initial non bulk push logistics went by air. Food was purchased on the local economy as much as possible. IIRC, the fall of the wall allowed European stocks to be transferred. Some interesting factoids: food was less than 2% of the total logistics load. Most of the rest was fuel (Saudi supplied) and ordinance. An armored division (~15k-16k troops and a butt load of iron) consumed 1200-1600 tons per day while engaged in operations. A stripped down military flatbed or tanker semi carries ~50-55 tons.
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Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #71 on: 01/11/2021 10:08 pm »
Another thing to consider is that SpaceX looks like a much more reliable supplier of air/space craft for a given cost than the current aircraft manufacturer incumbents.

That's a bit harsh.. For one thing, they're in totally different markets and the current spacecraft market isn't affected by a COVID-induced downturn to quite the same extent as the aircraft market.  If Starship were flying passengers right now, maybe things would be different - but they aren't and won't be for a very long time to come.
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Offline spacenut

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #72 on: 01/11/2021 10:41 pm »
If point to point is expensive, then for quicker times paying for a private jet flight might be just as quick.  You avoid check in time and screening at an airport which can be as much as two hours. 

My wifes son lived in Milwaukee a few years ago.  We had to drive 90 minutes to Atlanta, go through check in about 2 hours early, have a flight to Chicago for about 1.5 hours in the air, then get picked up by her son and drive another 90 minutes to where he lives.   This always was about 6-1/2 to 7 hours.  We could drive it in about 11-12 hours and that is stopping a few times for a meal, gas, and bathroom breaks.  Then we could take a load of say Christmas presents.  It would have been harder on a plane especially checking luggage or taking a chance of lost luggage.  Sometimes slower is better and many times cheaper, especially if we had to leave our car in Atlanta. 

Then using the internet and computers for business meetings, long distance business flights may never return to pre-covid levels.  I agree with many here that point to point may involve the military or special cargo more than business flights.  It all depends on cost. 

And then there is hypersonic planes people are working on.  This may be a direct competition with point to point. 

SpaceX first has to master the belly flop landings. 

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #73 on: 01/12/2021 10:34 am »
In some ways though Starship would actually be less vulnerable to hostile fire in transit.  While it's limited in there effectively only being a single flight path between any two points except at takeoff/landing it's beyond the reach of hostile fighter aircraft and conventional AA systems.  Some ABM/ASAT systems would have the reach to engage it mid-flight; but they're far less common than conventional SAMs.
Starship during the post-entry bellyflop is moving low supersonic to subsonic, in a nice straight path (with very little aerodynamic manoeuvre capability relative to aircraft), while glowing brightly in the IR regime, and with an extremely thin and delicate monocoque semiballoon construction. A single manpad would find popping a Starship trivial. It is far more vulnerable than even the ponderous C-5, and those are already restricted from some tasks due to their vulnerability.
There is also the issue that there are few adversaries who actually demand staging 100 tons of materiel to the other side of the planet within single-digit hours (rather than the tens of hours of existing airlift), that also do not have the capability to intercept high-speed vehicles at high altitudes, or even outright ABM capability.

Starship is not going to be landing in (or even flying over when possible) anything other than very friendly territory.

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #74 on: 01/15/2021 08:14 am »
Kinda Off Topic: Concorde was killed by faulty maintenance, a few errors and a flight instability that was exacerbated by the fuel tank rapidly emptying. Basically, the plane was doomed because the center of gravity moved too far aft when it was going slow. The fire was survivable, the center of gravity moving too far aft was near certain doom due to the flight instability. A good article on it: https://askthepilot.com/untold-concorde-story/

On Topic: I thoroughly expect people will reschedule travel to take a Starship flight for the dimple reason of avoiding time cooped up in the air. If you haven't flown a lot you won't understand. I was a sometimes Concorde flyer when I was young. Most often for emergencies where it took longer to get one of the biz jets to me, than waiting for and taking the next Concorde flight. I loved that I could go from DC to Paris in 4 hours gate to gate, or NYC to London in 3.5 hours. People scheduled their travel to fly them to avoid 4 to 5 more hours in the air. The biz jets took 8 to 9 hours so I often flew overnight and slept the flight away. An advantage the biz jets had over Concorde was they usually went much closer to where I wanted to go.
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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #75 on: 01/15/2021 09:36 am »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?
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Offline rsdavis9

Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?

And a catamaran.
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Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #77 on: 01/07/2022 04:10 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?
Which torpedo?
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Offline Asteroza

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #78 on: 01/08/2022 03:40 am »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?
Which torpedo?

I'm gonna assume they were thinking of a Shkval

https://en.wikipedia.org/wiki/VA-111_Shkval

But that uses a supercavitating bubble for propulsion purposes, not destructive purposes. Most conventional torpedos use their explosive to make a single large gas cavity bubble under the keel which promptly collapses, stressing the keel of the ship too hard and breaking it's back. I can't recall a torpedo with a water foaming warhead though...

Offline RedLineTrain

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #79 on: 08/03/2022 04:44 pm »
Just did some trawling through LinkedIn and SpaceX's job board and it's clear that at the end of last year, SpaceX started an offshore launch program referred to as either "Starship Offshore" or "Starship Offshore Engineering" and based in Cape Canaveral.

It looks like a modestly-sized engineering program for now.  Maybe a handful of engineers.  The team includes those who designed and built A Shortfall of Gravitas and at least one with long drill rig experience at Valaris.

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