Author Topic: Sea Dragon class LV thread  (Read 187482 times)

Offline clongton

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Re: Sea Dragon class LV thead
« Reply #120 on: 10/18/2009 01:00 pm »

Only the experimental RLV need to be small.  You want parts that can be made using ordinary workshop tools.  A very expensive made-to-measure tool makes implementing design changes difficult.

That was the beauty of the Sea Dragon design. It was designed to be produced in a shipyard using standard tools and basic skills. There is nothing inherently difficult or specialized about it. Other than it's size, this is actually the kind of thing where the basic structure itself could be built by almost any ordinary steel shop in the country, although a shipyard is a better choice because of proximity to the sea. It's size belies its simplicity and extremely low-cost manufacture.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline spacenut

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Re: Sea Dragon class LV thead
« Reply #121 on: 10/18/2009 01:23 pm »
I guess what I was advocating about the Sea Dragon concept is to build a smaller one to launch 50-100 tons to orbit.  Not the big 500 ton one.  It would be able to launch less expensive than a Jupiter, Ares V or sidemount, and be reusable.  Sure it would be big, but not as big as the 500 ton.

I think for human filght a flyback booster would cut the costs and build a robust flyback for the 25 tons or so capacity for the human cargo. 
« Last Edit: 10/18/2009 01:33 pm by spacenut »

Offline clongton

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Re: Sea Dragon class LV thead
« Reply #122 on: 10/18/2009 02:01 pm »
I guess what I was advocating about the Sea Dragon concept is to build a smaller one to launch 50-100 tons to orbit.  Not the big 500 ton one.  It would be able to launch less expensive than a Jupiter, Ares V or sidemount, and be reusable.  Sure it would be big, but not as big as the 500 ton.

I think for human filght a flyback booster would cut the costs and build a robust flyback for the 25 tons or so capacity for the human cargo.

I would not advocate the Sea Dragon, or any variation of it, being a manned launcher at this time.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline A_M_Swallow

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Re: Sea Dragon class LV thead
« Reply #123 on: 10/18/2009 02:09 pm »
Fortunetly we do not need a man rated Sea Dragon in the near future.  We can get people to LEO using the STS.  After that the Falcon 9 and possibly the Taurus II will lift people.

In a decade or so an opportunity may arise to fly a space coach.

Offline MP99

Re: Sea Dragon class LV thead
« Reply #124 on: 10/18/2009 10:33 pm »
I guess what I was advocating about the Sea Dragon concept is to build a smaller one to launch 50-100 tons to orbit.  Not the big 500 ton one.  It would be able to launch less expensive than a Jupiter, Ares V or sidemount, and be reusable.  Sure it would be big, but not as big as the 500 ton.

I think for human filght a flyback booster would cut the costs and build a robust flyback for the 25 tons or so capacity for the human cargo.

I would not advocate the Sea Dragon, or any variation of it, being a manned launcher at this time.

Use Sea Dragon as the EDS launch for DIRECT phase 2 (no depot).

Re-size J-241 JUS for ascent only (say ~100mT payload after margin), and use the EDS (also resized, maybe with multiple J-2X) for TLI, LOI & 75% of Lunar descent (507.5 m/s remaining delta-V, per CARD). Requires ~385mT launch for EDS + fuel.

Delivers 97mT to separation and, with a hypergolic lander, 81mT landed mass (I'd guess maybe 70mT of payload). Of course, the same could be achieved with J-241 CaLV + depot + 16x EELV/ACES-41 launches, although that'd be a coupla billion dollars worth of fuel, I think (4x J-241 tanker/EDS launches would be wa-a-ay cheaper).

cheers, Martin

PS I also think more fuel (still well within that 550mT limit) could brake the lander to a hover at any arbitrary altitude. I suspect that could convert a larger proportion of that initial 97mT into payload.

PPS 550mT of EDS+fuel could push 110mT through TMI and then perform a major pre-EDL braking burn so that a reasonably-sized  heatshield can, maybe, finish the job.

PPPS we now return you to your normal programming.


Edit:
"86mT landed mass" -> "81mT landed mass";
"well over 75mT of payload" -> "maybe 70mT of payload".
« Last Edit: 10/19/2009 10:12 pm by MP99 »

Offline PMN1

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Re: Sea Dragon class LV thead
« Reply #125 on: 10/19/2009 07:53 pm »

I suppose Greenpeace wouldn't be all right with the acoustic effects of a Sea Dragon launch?  How far away would a whale have to be to survive one?

Does anyone know if any of the studies for any kind of sea-launched vehicle have examined the noise issue?

Offline spacenut

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Re: Sea Dragon class LV thead
« Reply #126 on: 10/20/2009 12:12 am »
I was advocating a smaller 50-100 ton sea launch for cargo, and a separate manned launcher with a flyback booster. 

Offline Patchouli

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Re: Sea Dragon class LV thead
« Reply #127 on: 10/20/2009 12:30 am »

I suppose Greenpeace wouldn't be all right with the acoustic effects of a Sea Dragon launch?  How far away would a whale have to be to survive one?

Does anyone know if any of the studies for any kind of sea-launched vehicle have examined the noise issue?

Maybe just avoid the whale migration routes in the first place since they are documented plus employ a means to repel them.
Staying away from the plankton blooms also should help keep you away from any sea mammals.

« Last Edit: 10/20/2009 12:59 am by Patchouli »

Offline spacenut

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Re: Sea Dragon class LV thead
« Reply #128 on: 10/23/2009 01:56 pm »
I still say a Saturn V size Sea Dragon wouldn't have to be towed very far to launch off shore.  Fill at the cape, tow out a few hundred yards, lift and launch.  The Kennedy space center has a location for barges bringing in the shuttle tanks (and in the past Saturn V stages).  Barges exist and could be used to tow and launch them.  Use Kerolox first and second stages for cost effectiveness.  Either load the lox at the center or use a natural gas ship to load the lox.  Since it would be less expensive per lb or Kg to orbit.  It could launch fuel or building supplies and materials to orbit.  If it proves to be reliable, then launch a lunar lander, large telescope, or parts for a fuel depot. 
« Last Edit: 10/23/2009 02:09 pm by spacenut »

Offline William Barton

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Re: Sea Dragon class LV thead
« Reply #129 on: 10/23/2009 02:11 pm »
I've always had this fantasy of using something like Sea Dragon (or bigger) to lift a Project Orion "battlestar" above the atmosphere before lighting off the H-bomb Drive. I guess the EMP effects might still be annoying...

Offline PMN1

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Re: Sea Dragon class LV thead
« Reply #130 on: 10/23/2009 02:54 pm »
Sea Dragon and Excalibur both use a single large engine per stage.

What would br the economics of large pressure fed boosters with multiple engies?

I'm thinking something along the lines of TRW's Low Cost Shuttle Surrogate Booster.

The LCSSB configuration was very similar to the original baseline vehicle in the 1969 NASA study. The booster had three pressure-fed stages, with a first-stage thrust of 30.25 million Newtons (6.8 million pounds). The first stage used four engines, each with a thrust of 7.56 million Newtons (1.7 million pounds). These four engines were identical to the second-stage engine, except that the first-stage engines had a higher chamber pressure and an expansion ratio of 6:l (for sea-level/low-altitude operations), compared with the second-stage engine expansion ratio of 31:l (for high-altitude/vacuum operations). Keeping the designs of the first- and second-stage engines essentially the same would have kept development costs down. The booster had a payload capacity to low earth orbit of 29,756 kilograms (65,600 pounds) when launching due east from Cape Canaveral. When launching into a 90-degree polar orbit, the LCSSB had a lift capacity of 23,178 kilograms (51,100 pounds). The system had a launch cost for production vehicles of $59.2 million per launch (including all launch processing and support costs). This equated to a cost of $1,989 per kilogram ($901 per pound) to LEO, assuming an easterly launch.
« Last Edit: 10/23/2009 02:55 pm by PMN1 »

Offline steve kelsey

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Re: Sea Dragon class LV thead
« Reply #131 on: 10/26/2009 02:56 pm »
Good afternoon all, this is a first time post,  but I am a long time lurker on this excellent site.
I am not sure if this is the right place to ask the following question so Chris please bin this if it's in the wrong place.
I have always liked the simplicity of the Sea Dragon approach and I understand that part of the original Truax approach was to pressure feed the propellant and oxidiser using compressed gas to pressurise the propellant and oxidiser tanks headspace. In theory this avoids the complexity of pumps and therefore potentially increases reliability and reduces cost, the downside being a performance penalty.
My question is would it be possible to generate the tank pressure by bleeding oxidiser into the propellant tank and propellant into the oxidiser tank so that they 'combust' and provide the headspace pressure? If so could this be a way to reduce the complexity even further and generate relatively high pressures? The volume of propellant and oxidiser could be metered to deliver a constant pressure.
No doubt there are big issues with the introduction of combustion into a tank but as the pressure fed system is already designed to handle high pressure it is only the source of the pressure that is changing. Does this make any sense as a proposal?
« Last Edit: 10/26/2009 02:57 pm by steve kelsey »

Offline Jim

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Re: Sea Dragon class LV thead
« Reply #132 on: 10/26/2009 03:03 pm »
Russians did that in some of their missiles.

Offline steve kelsey

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Re: Sea Dragon class LV thead
« Reply #133 on: 10/26/2009 03:06 pm »
Thanks Jim. Only good for one shot then?

Offline Arb

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Re: Sea Dragon class LV thead
« Reply #134 on: 11/21/2009 09:40 pm »
As this thread is somewhat hypothetical, let's suppose for the sake of discussion that a major space colonisation effort is under-way and that Sea Dragon could be man-rated. Given its 550MT capacity, approximately how many people could it lift to LEO in a single launch?

-Arb.

Offline MKremer

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Re: Sea Dragon class LV thead
« Reply #135 on: 11/22/2009 06:25 am »
As this thread is somewhat hypothetical, let's suppose for the sake of discussion that a major space colonisation effort is under-way and that Sea Dragon could be man-rated. Given its 550MT capacity, approximately how many people could it lift to LEO in a single launch?

-Arb.

May be a bit too hypothetical. Your question might also need to include a time frame - within the next year or two, or further out, in which time SpaceX might have been able to fine-tune or even slightly upgrade their booster and stage 2 engines, and possibly further reduce mass in the first or second stages to allow greater mass to LEO. Dragon itself might also be able to lose some mass once several successful flights have taken place and the final data examined (or not, maybe gets heavier).

And there's also the fact that nobody, not even Elon, knows for sure what final mass any cargo or crewed Dragon would have - because none have been flown yet, neither boilerplate or preliminary orbital test final production modules. The final mission launch mass might decrease slightly, or be required to increase drastically to ensure launch and reentry safety.

« Last Edit: 11/22/2009 06:26 am by MKremer »

Offline A_M_Swallow

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Re: Sea Dragon class LV thead
« Reply #136 on: 11/22/2009 07:09 am »
As this thread is somewhat hypothetical, let's suppose for the sake of discussion that a major space colonisation effort is under-way and that Sea Dragon could be man-rated. Given its 550MT capacity, approximately how many people could it lift to LEO in a single launch?

-Arb.

A 550MT payload is sufficient to lift two Boeing 787-9 Dreamliners, each containing 290 passengers.  Since the aircraft lift-off mass includes fuel you can carry a lot more people than that.
http://www.boeing.com/commercial/787family/787-9prod.html

Offline Downix

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Re: Sea Dragon class LV thead
« Reply #137 on: 11/22/2009 10:36 am »
As this thread is somewhat hypothetical, let's suppose for the sake of discussion that a major space colonisation effort is under-way and that Sea Dragon could be man-rated. Given its 550MT capacity, approximately how many people could it lift to LEO in a single launch?

-Arb.

May be a bit too hypothetical. Your question might also need to include a time frame - within the next year or two, or further out, in which time SpaceX might have been able to fine-tune or even slightly upgrade their booster and stage 2 engines, and possibly further reduce mass in the first or second stages to allow greater mass to LEO. Dragon itself might also be able to lose some mass once several successful flights have taken place and the final data examined (or not, maybe gets heavier).

And there's also the fact that nobody, not even Elon, knows for sure what final mass any cargo or crewed Dragon would have - because none have been flown yet, neither boilerplate or preliminary orbital test final production modules. The final mission launch mass might decrease slightly, or be required to increase drastically to ensure launch and reentry safety.


What does Elon have to do with the price of tea in China?

Sea Dragon has nothing to do with the SpaceX Dragon capsule.  The Sea Dragon was a proposed ocean-launched superrocket developed by the NASA Future Projects branch before it was shutdown in the mid 60's.  It was designed to be built using many of the same shipyard tricks used to build submarines.  Its fuel would be seawater cracked into its components hydrogen/oxygen by the tender craft.  It could lift 550mT into orbit.  The second stage of the Saturn V could fit inside of its massive rocket nozzle.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline kkattula

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Re: Sea Dragon class LV thead
« Reply #138 on: 11/23/2009 01:58 am »
As this thread is somewhat hypothetical, let's suppose for the sake of discussion that a major space colonisation effort is under-way and that Sea Dragon could be man-rated. Given its 550MT capacity, approximately how many people could it lift to LEO in a single launch?

-Arb.

About 7,000 average people or maybe 5,000 Americans.

A lot less if you want them alive when they get there. ;)

Seriously, I'd roughly estimate 1,000 kg per person in seat, cabin, life support & personal effects mass.

If you really need to move tens of thousands of people, you should probably just spend the money to build a space elevator.

Offline Bill White

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Re: Sea Dragon class LV thead
« Reply #139 on: 11/23/2009 02:00 am »
As this thread is somewhat hypothetical, let's suppose for the sake of discussion that a major space colonisation effort is under-way and that Sea Dragon could be man-rated. Given its 550MT capacity, approximately how many people could it lift to LEO in a single launch?

-Arb.

About 7,000 average people or maybe 5,000 Americans.

Cold! Too cold!

 ;D
EML architectures should be seen as ratchet opportunities

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