Author Topic: Sea Dragon class LV thead  (Read 83031 times)

Offline neilh

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Re: Sea Dragon class LV thead
« Reply #165 on: 07/26/2010 09:16 PM »
One question - if the Sea Dragon model reduces cost by an order of magnitude, and it seems to scale down well, then why isn't it being seriously pursued by *somebody*?

I can see an issue with going after the full-scale Sea Dragon - no one needs that much launch capacity, or even 10% of it.  But why not a smaller scale Sea Snake or Sea Crocodile or Sea <insert your creature here>?

Seriously, what's the fly in the ointment?  The showstopping problem?  Is it technological, political, or something else?

I've sometimes wondered if this is a route that SpaceX could optionally pursue in the future. Their engines are already apparently designed to survive seawater immersion, although launching underwater is of course presumably a different issue. Also, they seem to have put a lot of effort into minimizing the launch infrastructure needed.
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Offline go2mars

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Re: Sea Dragon class LV thead
« Reply #166 on: 07/30/2010 02:58 PM »
I don't think spacex will go sea launch.  At the Boulder CO. Mars Society convention, someone in the crowd asked Elon if he would ever consider a Sea Dragon type of approach.  His response was something to the effect of "I prefer solid ground launches". 


Offline JasonAW3

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Re: Sea Dragon class LV thead
« Reply #167 on: 08/10/2010 05:52 AM »

 I actually consideredt that possibility at one time.  An inflatable torus, continious, with docking hubs at each spoke point, a curved rigid structure would be rigged to the outside of the torus, with cable rigging back to the central hub supporting them, much like on a suspension bridge.
     One issue that had occured to me; A rotating torus would tend to wobble as mass is moved from one side of the torus to another.  I had considered the use of water tanks under the walking surface using computer controlled pumps to transfer water between tanks on the opposite side of the torus from the offcenter mass, to compensate for and counteract the wobble.

Jason

Bit like this you mean?

There was a paper in the December 1991 issue of the Journal of the British Interplanetary Society by Michael A Minovitch of Phaser Telepropulsion Inc proposing the building of rotating 2001 type stations 100 metres diameter for at least 150 crew by using automatic wrapping machines rotating round inflated Kevlar torus’ to wind thin layers of aluminium until the required thickness had been made.

The rotating toroidal living section would have a major and minor radii of 100m and 2m while the two central column cylinders with labs etc and constructed in the same way would each be 100m long x 10m diameter. The two column cylinders would connect into a pre-fabricated central hub into which three spokes 100m long x 4m diameter also constructed in the same way would be fitted to join the hub to the toroidal living section.

The station also served as the basis for a 'cycling' ship and would take about 10 HLLV (assuming 100 tons/launch) or 14 Shuttle-C launches and 1 STS flight with minimal EVA.

Costs were about $400 billion for an Earth orbit station, a Mars orbit station and a cycling ship


     
     Could you get me a link to this?  I am kind of curious about this.

     It occurs to me that constructing a dual wheel station, ala 2001, could be done for much less than $400 billion, via the use of the upperstages of the Sea Dragon, being used dry for wet, as hub and spokes, and boosting up the materials with those stages, to actually build the wheels.
     By including the upperstages as part of the payload, you reduce the overall cost of the station signifigantly.  The large spokes themselves would have different levels of gravity, as you go up, closer to the Hub.  This could prove useful for both scientific and medical purposes.
     I'm in the camp of having too much available usaeble volume is far better than not having enough usable volume, as this space, on a station, could be rented out, while on a manned Mars mission, one could store redundant supplies and raw materials for Cad/CAM and 3d printing systems, to manufacture parts as needed during the mission.  (Obviously
  some mission critical parts should be kept for safety's sake, but creating new toold or parts to augment the mission, would be of great value on such a flight.

Jason
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Offline PMN1

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Re: Sea Dragon class LV thead
« Reply #168 on: 08/10/2010 06:42 PM »

     Could you get me a link to this?  I am kind of curious about this.

   

Unfortunately not, the only place it seems to exist in the the paper JBIS article.

I've had a look for the author on google but nothing much turned up.

The system was also proposed in the same article for building bases on Mars.

Offline ciscosdad

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Re: Sea Dragon class LV thead
« Reply #169 on: 11/11/2010 10:12 PM »
This whole concept reminds me a lot of the old studies that came out of Orion (nuclear pulse propulsion). It seems to me that this idea has the same advantages (as mentioned by various posters here). The construction methods there were a lot more akin to shipbuilding than "rocket science". For that reason I would avoid any use of Liq H2 or anything else exotic. There should be enough margin to make both stages Lox/RP1 and still get 100's of tons to orbit.
I haven't done the maths though
Has anyone seen any studeies that focus more on the payloads, especially taking advantage of the huge weights available and the possibility of "low tech" equipment on the payloads?
500 tons in orbit in one go allows for an awful lot of leeway in almost everything.

You could build something right out of Buck Rogers!

Offline Obsidian

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Re: Sea Dragon class LV thead
« Reply #170 on: 11/14/2010 08:59 PM »
I am new to this forum, and I am a bit out of my element here.  I am a student of public policy, not an engineer, though I have a reasonable literacy when it comes to science and technology.  I have been interested in the Sea Dragon concept for the last two years, ever since I stumbled upon the Truax Engineering Multimedia Archive while researching a report on the economic feasibility of solar power satellites. 

My question is as follows.  According to the Truax site (http://neverworld.net/truax/), the numbers are quite different than what everyone has been citing.  The estimated payload to LEO is 1,000 tons (~900 metric tons) instead of the 550 metric tons that has been cited.  The estimated cost in 1983 dollars was $20 per pound which, in 2010 dollars, translates to roughly $440 per kilogram (assuming a 400% inflation between 1983 and 2010) instead of the $1000 per kilogram that had been cited.  Could someone please explain these discrepancies? 

Offline Jorge

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Re: Sea Dragon class LV thead
« Reply #171 on: 11/14/2010 09:20 PM »
The estimated cost in 1983 dollars was $20 per pound which, in 2010 dollars, translates to roughly $440 per kilogram (assuming a 400% inflation between 1983 and 2010)

Think you might want to rerun those numbers. 400% inflation would turn $20 into $100, not $440.
JRF

Offline kch

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Re: Sea Dragon class LV thead
« Reply #172 on: 11/14/2010 10:07 PM »
The estimated cost in 1983 dollars was $20 per pound which, in 2010 dollars, translates to roughly $440 per kilogram (assuming a 400% inflation between 1983 and 2010)

Think you might want to rerun those numbers. 400% inflation would turn $20 into $100, not $440.

And converting from pounds to kilograms would take it up to $220 (not $440).

Offline Obsidian

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Re: Sea Dragon class LV thead
« Reply #173 on: 11/15/2010 12:58 AM »
Yes, I looked at my number and I transferred them incorrectly, thank you for the correction.  With the correction, that would be $220/kilogram.  Still, that is even a larger difference from the numbers that were given earlier in the forum.

Offline Max_Peck

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Re: Sea Dragon class LV thead
« Reply #174 on: 11/15/2010 01:38 AM »
SD was proposed before the F-1 got on the test stand and revealed the problems with large engines and combustion instability. The guarantee of combustion instability on a single-bell 80 million pound thrust first stage engine, or a 7 million pound thrust upper stage engine is simply ridiculous.

The cost is also prohibitive. How expensive was the 1 million pound thrust RS-84 was going to be? How expensive is the quarter-million pound thrust J-2X? Warp drives would be cheaper to develop than an 80 million pound single-bell engine.

That amount of power in the ocean will kill everything within miles. Environment groups will make it illegal long before the first test flight ever came close.

Nice idea. Totally impractical.

-MP.
« Last Edit: 11/15/2010 01:42 AM by Max_Peck »

Offline kkattula

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Re: Sea Dragon class LV thead
« Reply #175 on: 11/15/2010 02:03 AM »
So you put 30 F-1 class engines on it and launch from the Dead Sea.

Problem solved.  ;)

Offline Sparky

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Re: Sea Dragon class LV thead
« Reply #176 on: 11/15/2010 04:17 AM »
So you put 30 F-1 class engines on it and launch from the Dead Sea.

Problem solved.  ;)

Putting what is probably the world's largest man made vessel of combustible material afloat in a lake in one of the most fought-over regions on Earth. What could go wrong? :P

Offline go4mars

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Re: Sea Dragon class LV thead
« Reply #177 on: 11/16/2010 03:59 PM »
http://www.astronautix.com/lvs/ur700m.htm

Zhang Guitian (Apparently a Chinese "acamedician") was talking at a conference in 2006 referring to Chinese plans to build something on the scale the UR-700M.  That's more payload mass than my beloved Sea Dragon!

Does anyone know more about this/able to verify/dispel it?  Or know where it was discussed on another thread?

Thanks in advance. 
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Offline go4mars

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Re: Sea Dragon class LV thead
« Reply #178 on: 07/20/2011 07:57 PM »
Will SpaceX borrow half of the Sea Dragon idea?

SpaceX has talked about making their rocket sea-water resistant.  When I was picturing the fully-reusable future SpaceX launcher, I was picturing a first stage which after separation, turns around, re-ignites some or all of its engines with residual fuel, and boosts back to the launch pad for a propulsive landing.  Might SpaceX instead just propulsively slow it down above the ocean enough to slip in without sustaining damage, to be pulled up, perhaps by an amphibious erector tower or tow-cable to be taken back to the pad? 

Is one of the reasons for building a new Texas pad a range rule against boosting your stages back in the direction of a Florida pad?   
« Last Edit: 07/20/2011 07:59 PM by go4mars »
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline Jim

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Re: Sea Dragon class LV thead
« Reply #179 on: 07/20/2011 08:02 PM »

Is one of the reasons for building a new Texas pad a range rule against boosting your stages back in the direction of a Florida pad?   

Same rule would apply to Texas.  Also, TX pad is a rumor

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