Kaputnik - 7/9/2007 3:15 AM
There's no need for 400mt+ boosters. It would be much better to develop a smaller booster suitable for lunar missions which can then fly three to five times to build up a Mars mission.
Your IMLEO estimates are far too high, IMHO. A Mars mission can be done for under 500t total.
Kaputnik - 7/9/2007 7:15 PM
There's no need for 400mt+ boosters. It would be much better to develop a smaller booster suitable for lunar missions which can then fly three to five times to build up a Mars mission.
Your IMLEO estimates are far too high, IMHO. A Mars mission can be done for under 500t total.
kkattula - 7/9/2007 11:10 AMDoes the passenger survive in this plan?QuoteKaputnik - 7/9/2007 7:15 PM
There's no need for 400mt+ boosters. It would be much better to develop a smaller booster suitable for lunar missions which can then fly three to five times to build up a Mars mission.
Your IMLEO estimates are far too high, IMHO. A Mars mission can be done for under 500t total.
Ask Richard P. Speck of Micro-Space. He thinks he can put 1 man (or 2 petite women) on Mars using one Falcon 9. Not a heavy either, just a regular.
How?Use the search function, have some effort yourself.
tnphysics - 7/9/2007 3:53 PM
How?
Sorry.
You must surround the entire living quarters with shielding that has the same effectiveness as five feet of water in a tank. This requirement should be used for all mass calculations for extremely long duration missions. Lighter elements are more effective per unit mass, so using liquid hydrogen gives the lightest shield. A thin layer of boron-10 would be needed as a neutron absorber.
It is not possible to get away with less shielding, owing to the fact that the incoming cosmic rays have enough energy to create electron-positron pairs. These pairs are called secondary radiation, and they, too, must be stopped. However, these, in turn, create more electron-positron pairs until their energy drops below 1.1 MeV (the minimum energy needed to create an electron-positron pair) (At some point, each positron will annihilate an electron, producing two gamma rays). Because, for a given total energy of ionizing radiation, alpha radiation is more damaging than beta radiation which is more damaging than gamma rays, and lower frequency (longer wavelength) gammas are more damaging than shorter wavelength gammas, a thinner shield would actually be counterproductive, so far as cosmic rays are concerned.
tnphysics - 9/9/2007 1:34 AMSorry.
You must surround the entire living quarters with shielding that has the same effectiveness as five feet of water in a tank. This requirement should be used for all mass calculations for extremely long duration missions. Lighter elements are more effective per unit mass, so using liquid hydrogen gives the lightest shield. A thin layer of boron-10 would be needed as a neutron absorber.
It is not possible to get away with less shielding, owing to the fact that the incoming cosmic rays have enough energy to create electron-positron pairs. These pairs are called secondary radiation, and they, too, must be stopped. However, these, in turn, create more electron-positron pairs until their energy drops below 1.1 MeV (the minimum energy needed to create an electron-positron pair) (At some point, each positron will annihilate an electron, producing two gamma rays). Because, for a given total energy of ionizing radiation, alpha radiation is more damaging than beta radiation which is more damaging than gamma rays, and lower frequency (longer wavelength) gammas are more damaging than shorter wavelength gammas, a thinner shield would actually be counterproductive, so far as cosmic rays are concerned.
Kaputnik - 8/9/2007 11:23 AM
I'm not an expert on this, but what's the difference in radiation exposure between LEO and the Earth-Mars interplanetary space?
Christine - 10/9/2007 7:50 AM
The best way to shield from solar protons during a flare in my mind would be to put a giant water filled polyethylene tank on the sun-facing side of your habitat.
tnphysics - 11/9/2007 9:58 PM
In principle, why couldn't you make the spacecraft able to withstand launch loads without a fairing?
kkattula wrote: "Basically, if you take a bunch of smokers, send them to Mars and back over 3 years, (without cigarettes), their life expectancy on return would be higher than if they'd stayed on Earth and continued smoking."
If you take a bunch of smokers and put them into a small aluminum can together on a trip to Mars, without cigarettes . . .and I guarantee their life expectancy will be no more than 2 weeks. They'll all kill each other! :laugh:
Kaputnik - 11/9/2007 6:06 PM
No reason other than that it is usually more mass-efficient to have a disposable fairing than a toughened spacecraft. ... it will also increase the aerodynamic drag on the vehicle, reducing performance.
bad_astra - 13/9/2007 9:10 AM
Unless you're building an Oneal colony from Earth Materials (exactly the opposite of how it should be built, anyway), there is no reason, ever, for a Sea Dragon.
How many launches of this kind of vehicle could be needed by one country in one year? One? Maybe one every 2? You still need standing army to maintain it, it's prep facilities, etc during the off time so you really get no savings from having such a monster. And if you LOSE a Sea Dragon, how many years are you unable to go to space at all because you bet the farm on one LV and killed off the rest of the competition?
What is far more reasonable and robust is a diverse lv's with high flight rates.
tnphysics - 19/9/2007 6:14 PM
Sea Dragon was intended to use a "brute force" approach to acheving large payloads.
What about a more clever approach?
Pump-fed reusable LRBs. Pump fed (but no more expensive) reusable core stage. Nuclear upper stage.
khallow - 11/9/2007 3:50 PM
I think it's a terrible idea to ignore the economies of scale from using small LVs launched more frequently.
Michael Bloxham - 13/11/2007 8:07 PMb
What about clustering smaller rockets in parallel to allow for the occasional oversized payload?
Boeing envisions this for the Delta IV: A first stage consisting of 7 CBC's clustered together is their ultimate configuration. A configuration like this might be capable of lifting more than 7-times as much as a Delta IV Medium with just one CBC ("more than" due to the advantages of parallel staging).
I used this as inspiration for my PARIS VII rocket, which envisions a cluster of 7 Ares V-derived tanks to allow for payloads of over 500 tonnes:
http://cleanslate.editboard.com/free-chat-f1/paris-launch-system-t11.htm
meiza - 2/11/2007 1:38 PM
Just mentioning that bigger is not always the most cost effective approach. It depends on a lot of details.
Michael Bloxham - 14/11/2007 11:07 AM
Boeing envisions this for the Delta IV: A first stage consisting of 7 CBC's clustered together is their ultimate configuration. A configuration like this might be capable of lifting more than 7-times as much as a Delta IV Medium with just one CBC ("more than" due to the advantages of parallel staging).
publiusr - 16/11/2007 11:17 AMQuotemeiza - 2/11/2007 1:38 PMAnd smaller is certainly not always the most cost effective approach--otherwise we'd ship oil on thousands of bass boats than in supertankers--that may very well be a harder build than Sea dragon--a simple tube. We just have to get rid of this bias that LVs cannot grow in size--while airplanes and ships continue to grow.
Just mentioning that bigger is not always the most cost effective approach. It depends on a lot of details.
tnphysics - 9/9/2007 1:34 AM
Higher frequency gammas are much more damaging than lower.
Has anyone thought of the problems involved in designing an LAS for a spacecraft to go on top of Sea Dragon?
I don't think that you can pull someone from on top of a medium-sized nuclear weapon to safety in about two seconds.
It will be cool if someone would build something like the Sea Dragon. I don't think it's fair to say that it is too big just because the Saturn V and Space Shuttle have no market. Obviously, those are both really complex and thus expensive launch vehicles which are made even more so because they are intended to carry human cargo.I believe that a pintle injector was to be used, but that's just based on similar (but much, much smaller) rocket designs such as the Apollo LM DPS.
I would suggest, though, that those two vehicles didn't last because they are in the wrong payload lift range. They are too big for all current applications, yes, but they are too small and too expensive to make a first generation space based industry feasible. If you could put 2 million pounds into LEO with one of these things at a cost of 200 million dollars, and launch twelve of them per year, then space based solar power would suddenly be a lot more reasonable. This is an option that is every bit as cheap as using propellant depots if your goal is eventually to mine gold and vanadium out of asteroids.
On another note, for as many formal analyses as were done on this, and for as much enthusiasm as some people have for this rocket, I can find precious little documentation regarding it. I have seen the Wikipedia entry, the Encyclopedia Astronautica entry, the Truax website, and some page that says "Lots of pictures. Loads slowly, but worth it." But none of these sites seem to include any information on the method of guidance and control, for example. Was this vehicle supposed to use liquid injection for thrust vectoring? I doubt an engine that big was supposed to gimbal.
How were the engines to be cooled, if at all?
What type of propellant injector was assumed?
I've known about this concept for over a decade, but these are things (mostly about the engines) I have just never been able to find with a casual internet search.
SeaDragon Documents
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880069339_1988069339.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880069340_1988069340.pdf
1. One of the big charges lobbed at me is that I am more in love with the rocket than with the payload.
2. This charge is actually a better critique of the enemies of big dumb boosters who want LVs to be overly complex for their own sakes.
3. Same with Ares V. Ares allows large simple payloads, and anti-HLLV forces tell lies about Ares V craft being more complex--when complexity is all but forced upon smaller vehicles due to smaller shrouds and lower lift capability.
4. More complex engines and more launches are what drive costs up.
SeaDragon Documents
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880069339_1988069339.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880069340_1988069340.pdf
It's the sea launch component of Sea dragon that has always bugged me. Have any serious investigations been done into land launched options? I'm not convinced enough study has been done of land based systems to commit to a sea based launch and the attendent transportation problems being the best of all available options for a booster of that class. I'm also not convinced that there is as much advantage as people might imagine in using an existing ship yard to do build the item.
The Excalibur that I linked above is a reduced scale Sea Dragon about the size of a Saturn V that could fit the VAB building and not have to be sea launched, but it only lifts 55 tons. It is reusable though. If a 3rd stage could be added it could probably lift more.
I can't understand why the leaders at NASA will not use a "Sea Dragon" type vehicle. If it is a low pressure engine, and pressure fed, no turbopumps etc. It can't be that expensive to build out of sheet steel at a navy shipyard. We could then concentrate on a reusable flyback lifting body craft that is smaller than shuttle with a flyback booster. Then we could build large spacecrafts to fly between Earth and Moon, Mars etc. Just use the smaller craft to ferry people between Earth and the spacecraft.
So, this 550 ton launching reusable rocket would launch how many times per month?
But why would you? It is the sea launch that allows you to have so little launch infrastructure. That would be major part in its low cost. Shipyards already exist capable of building structures on that scale. Large seagoing support vessels are easily available. (no need for a carrier) And launching from the seas is great... Ballast the thing to vertical, and go...
Or you can imagine a land-based launch facility. KSC scaled up 5-10x?
But why would you? It is the sea launch that allows you to have so little launch infrastructure. That would be major part in its low cost. Shipyards already exist capable of building structures on that scale. Large seagoing support vessels are easily available. (no need for a carrier) And launching from the seas is great... Ballast the thing to vertical, and go...
I thought the reason for suggesting a carrier was that they would use electricity from it's nuclear reactor to electrolize seawater for the LOX (astronautix). Without the nuclear reactor I suspect you're left looking for a towing vessel that can carry all that LOX. I don't have figures for the total launch mass of LOX. Also I don't know how long it takes to tow it to site and prepare for launch. Boil off is going to be fairly significant isn't it?Or you can imagine a land-based launch facility. KSC scaled up 5-10x?
I think it's pretty clear you can't scale up what they have at KSC with the seperate VAB, the Crawler, and bringing in entire dry stages by barge. That isn't anything like what I was suggesting. The fact that the infrastructure at Kenedy can't be scaled up doesn't mean there aren't alternative ways to organise fabrication/integration/launch of a super booster on land without adopting this extra design constriant of emersing your vehicle and all the support equipment in brine.
If you start from the pressumption that the thing is immovable until launch and must be built already raised in it's launch orientation then a big hole in the ground seems to me the simplest of all solutions. Maybe concrete lined shafts of this diameter have already been dug for mining? I suspect the technology and experience is available.
I really started thinking about this when I saw how N1 was welded up inside the MIK and thought about how Orion would have to have been built at launch site (can't exactly move one around!).
I just have this suspicion that the cart has been placed before the horse on this one and that a sea launch only make sense if you are the US navy. Otherwise it might make more sense to start your own "shipyard" in a desert somewhere rather than to acquire and opperate an expensive and highly specialised support vessel and to design your booster so it has to be a boat as well as a rocket.
I am really convinced that a sea-landing is far easier accomplished than a land-landing. As the vehicle becomes larger, it seems that this becomes more and more the case, since you only need to protect the outer layer of material from seawater (i.e. If you need to protect a brick from seawater, you need a certain thickness of material around the brick. That thickness stays the same as the brick becomes larger, but the volume of the brick grows faster than the surface area of the brick.)
Honestly, what's the big deal with being in seawater?
and to design your booster so it has to be a boat as well as a rocket.
and to design your booster so it has to be a boat as well as a rocket.
You've got to do that anyway. Ocean splashdown and recovery of the stages is an important part of the cost structure of this scheme. So all you really need is a nuclear reactor...
...or a Polywell, but if you've got a Polywell there may be better ways to build cheap reusable Nova-class space launchers...
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?
You don't need a nuclear reactor. You could use any electrical source, as long as you could connect to the grid.
You don't need a nuclear reactor. You could use any electrical source, as long as you could connect to the grid.
I was talking about the requirements for a standard ocean launch of a Sea Dragon. If you can connect to the grid, you're far too close to a lot of expensive shoreline properties to launch something with an 80 Mlb kerolox engine.
I was never envisaging that the thing would be reusable. I thought the baseline version of Sea Dragon was supposed to be expendable. Never figured for landing the vehicle. It just seems like more complexity. It's better to keep the production line busy by commiting to being expendable than to try to recover the dead stage a few times and insert lengthy stand-downs into your production?
The Excalibur that I linked above is a reduced scale Sea Dragon about the size of a Saturn V that could fit the VAB building and not have to be sea launched, but it only lifts 55 tons. It is reusable though. If a 3rd stage could be added it could probably lift more.
I can't understand why the leaders at NASA will not use a "Sea Dragon" type vehicle. If it is a low pressure engine, and pressure fed, no turbopumps etc. It can't be that expensive to build out of sheet steel at a navy shipyard. We could then concentrate on a reusable flyback lifting body craft that is smaller than shuttle with a flyback booster. Then we could build large spacecrafts to fly between Earth and Moon, Mars etc. Just use the smaller craft to ferry people between Earth and the spacecraft.
A Nimitz-class supercarrier costs about $4.5B according to Wikipedia. It might be substantially cheaper to build a dedicated nuclear-powered support ship or two, and considering what you'd probably have to spend on payloads to make Sea Dragon worthwhile, a couple billion on a one-off isn't all that much money...
The USS Enterprise, the oldest active combat vessel in the Navy as of 2009, had been scheduled to be decommissioned as late as 2014. On April 6, 2009 Admiral Gary Roughead, Chief of Naval Operations, stated that he would be seeking a congressional dispensation to speed up the process. Under this new timetable, the ship would complete one final deployment before being decommissioned in late 2012 or early 2013.
As for a support ship for a Seadragon class LV why not modify a LNG tanker?
http://en.wikipedia.org/wiki/LNG_carrier
Just a note: Sea Dragon's upper stage runs LOX/LH2. The reactor is needed for electrolysis, not just refrigeration.
Enterprise was the CV depicted in that Sea Launch painting from the early 1960s meaning that would have been an appropriate choice.
I've never bought into the idea that fuel depots are an enabling step for crewed RLV development and deployment as I believe a Sea Dragon class vehicle would be able to deliver fuel to LEO for a fraction of the cost of a crew capable RLV.
I've never bought into the idea that fuel depots are an enabling step for crewed RLV development and deployment as I believe a Sea Dragon class vehicle would be able to deliver fuel to LEO for a fraction of the cost of a crew capable RLV.
Hmmm. Perhaps the SSTO Sea Dragon could "be" the depot, and instead of filling it on orbit, it arrives full, and when emptied, deorbits itself for refilling and reuse to be replaced by another "reusable" depot. Just thinking.
What the Sea Dragon concept does (IMHO) is invalidate claims that LEO fuel depots will facilitate crewed RLV development - if those crewed RLVs are intended to act as fuel tankers filling such depots.
You could also loft a great many Bigelow habitats, all connected to a central hub, in a single throw creating a large capacity station or a ginormous Earth departure vessel.
500,000 kilograms @$10,000 per kilogram = $50 billion dollars. Unless I slipped some decimal places. ;-)
Because of low reliability, don't send your lunar lander via Sea Dragon, just the fuel needed for that lunar lander.
At Falcon 9 price levels, a fully disposable Sea Dragon would seem far less expensive and if the Sea Dragon were reusable -- even less expensive than that.
At Falcon 9 price levels, a fully disposable Sea Dragon would seem far less expensive and if the Sea Dragon were reusable -- even less expensive than that.
Sea Dragon was designed to be reusable 20-30 times. Even if the original article cost 2 times the Falcon, the AeroJet study said that it could be refurbished and re-launched for 7% of the replacement cost.
Just for comparison, Falcon 9 is priced at $44 million a copy. So if the Dragon cost twice that, or $88 million each, and can be re-launched for 7% of that, then each subsequent launch would cost $6.16 million. So 20 Falcon 9 launches would cost $880 million, but flying the one Dragon 20 times would cost $205 million, a savings of $675 million, or $10.25 million per flight, $33.75 million less than the $44 million Falcon. Impressive.
Like Robotbeat said, this thing would be so cheap that it wouldn't matter if you didn't use the full capacity of the launcher or not. Launch it for $10.25 million per launch and put whatever you wanted into orbit, without regard to the mass.
This is a perfect example of how economies of scale, using a RLV, beat launchrate economies hands down. Can't touch this.
The RLV people have been shoveling against the tide by keeping their designs too small. Make it huge (and extraordinarily simple) and suddenly everything drops into place.
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.
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 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.
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?
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?
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.
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.
What does Elon have to do with the price of tea in China?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.
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.
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.
...
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.
Yes, which helps enable the Sea Dragon to float as RP-1 is lighter than water. I was thinking of the second stage when talking of the LH2...
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.
Nitpick: Sea Dragon first stage was LOX / RP-1
Liquid Hydrogen is a LOT lighter than water. There's no way Sea Dragon wouldn't float, even if the first stage fuel was denser than water. In fact, with the RP-1 it needed ballast tanks to sink the base and bring it vertical. They were to be discarded at launch.
I'm a little uncomforatable with using N2 to pressurize the tanks:
1) It's a lot heavier than Helium. I suppose that much He might be too expensive, although it could be recovered from the spent first stage and re-used.
2) Nitrogen tends to disolve in LOX causing combustion instabilities.
If I was designing a Sea Dragon today, I might consider using He or N2 to drive a pistonless pump. (See Flowmetrics). The driving gas could even be produced by a gas generator.
This would have the advantage of reducing the weight of the main tanks, while increasing the combustion chamber pressures, without requiring expensive, complicated turbo-pumps.
Even 30 to 50 psi would give the tanks an awful lot of strength.
For a cylinder that ratio will mostly be equal to the depth of propellant in the tank. Sea Dragon's tanks are fairly squat, and at the end of the burn, won't have much depth. OTOH, I'm not an expert on exactly how N2 disolves in LOX. Could be some weird chemistry. I've heard anecdotal evidence of problems with N2 pressure fed rockets. Pump fed ones don't seem to have as many problems with N2 pressurization, because the pressure is about 1/10th as much. YMMV.
Yes, quite easily.
The problem isn't that it could do that, the question is how do you pay for all that hardware to go fly on a single rocket -- that laundry list you suggest is worth billions and billions! More importantly: Do you really want to risk putting all those eggs in a single basket?
If anything happened to that launch, you would lose everything in your entire *program* not just a single element.
A Sea Dragon could just-about launch the equivalent mass of two International Space Station's in a single shot.
While we would have loved to have had that capability ten years ago when we started lifting all those modules, there isn't much in the way of payloads around today -- or even planned in the next 20 years -- which would fill a single Sea Dragon each year -- and Sea Dragon's cost benefits required it to have a decent flight rate around 12 flights per year (just like every other launcher).
If you didn't have that many launches, then the same old rules come into effect and the infrastructure costs start dominating the cost of each flight -- making the system non-viable again.
The entire world's launch requirements -- government, military and civilian combined -- amounts to just a very small fraction of the 6,600mT of LEO lift capability which this system needed to make it worthwhile.
And it's one hell of a gamble to go pay all the money needed to develop this in the hope that "if you build it they will come". That approach failed to work out very well for either EELV, did it?
This needs a totally different business model to have any chance at all -- and I personally don't think NASA would ever choose to fly anything on it.
Ross.
I never thought of stringing a few of them together like that for the rotational gravity at greater radius. An elegant solution!
Another way to slow down the middle one further for docking/unloading would be have 7 of them, the central one, and attach 2 more end-to end so they go in 400 foot long spokes from the central point. With fairly short rotation. Gravity could almost feel natural at the bottom of those.
Here's an interesting document I found...
http://neverworld.net/truax/Truax_Engineering.pdf
I wonder how rigid Bigelow's inflatables will be... Perhaps a long inflatable habitat tube could touch the tips of all these tanks and keep them in proper alignment. Air pressure can provide a lot of rigidity. It would look like a bike tire with really really fat spokes and a big fat hub.
This would enable useful volume at higher G's and connect access to the tips. You could go jogging along the entire outside wall of the inflatable tube. Mission duration is less relevant if you have lots of volume for astronaughts to roam at higher g-force.
If they were attached stage to stage for the extra length, perhaps you could weld or bolt the nozzles together. That would provide even more space. Agreed that some well placed cables would be highly desirable.
Central hub tank would have docking ports, nuclear reactor, and engines (perhaps vasimr). Or polywell drive...
Good idea. Water also is a good insulator for radiation. It can be cracked for fuel with solar power attached.
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
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 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.
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)
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.
So you put 30 F-1 class engines on it and launch from the Dead Sea.
Problem solved. ;)
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?
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?
Sea Dragon is not needed.You only measure to LEO. To BEO, it crushes everything else.
It's $300 per kg to orbit in 1963 is $2160 per kg in 2011 dollars, which means it would be competing with Russian rockets (Zenit) and Falcon Heavy on a cost per kg basis.
Why was Sea Dragon so much more efficient at BEO?
Aerojet did some fantastic engine work and doesn't get the credit like the bigger boys LM, Boeing etc.
Wait till you see the finished performance of the AJ-500.
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.
-MP.
If you change Sea Dragon to use an aerospike, it's almost Direct P2.s
From my understanding, Ross left cstar earlier this year, and this is a different venture.If you change Sea Dragon to use an aerospike, it's almost Direct P2.s
Haha, it looks like I needed to pay more attention to what Ross, Chuck, et al are up to these days. So is this what C-Star is doing?
Several people have mentioned their concern over developing a large rocket engine due to combustion instabilities. With modern software/analytical tools, is combustion instability still considered a practically insurmountable challenge for developing really big engines?
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.
Note exactly :) See the "problem" is the amount of payload one of these things could lift. Short of a sudden "emergency" colonization program, need for a super asteroid/comet defense system or solar power satillite program the SD is simply too BIG to be viable. It has such a huge payload capabilty that you can't really justify a "viable" use for a single flight, let alone the multiples that the "program" would have required.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.I should probably point out that as knowledge was gained in the F1 program the design was changed to several combustion chambers feeding a single nozzle so it wasn't "actually" a single engine design :)QuoteThe 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.The last design upgrade I recall had the engines being developed from the F1 it self so the design costs were a lot less than expected overall.QuoteThat 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.Engine "burp" or simply fireing up the turbopumps will clear the area in a hurry. A couple of "sounding-charges" (big band, little actual blast) would effectivly clear out all the life within a couple of square miles within seconds. IIRC there is actually a Navy procedure number for such an operation :)QuoteNice idea. Totally impractical.
Ok,
Quick fix.
Plug Nozzel for the first stage and about 10 to 15 F-1 engines on the second stage. Problem solved.
If fact, such a launcher, pound for pound (or kilogram for kilogram, if you will) would be a couple of orders of magnitude cheaper than any current launcher, including the Falcon 9.
However; If this could be made as a reliable TSTO craft that either could have both stages reusable, OR the first stage reusable and use the upper stage as a .5 stage, (Doing Dry-for-wet) as part of either a space station or as a part of a Mars Exploration Vessel, then I think that it would more than justify the cost.
Actually they DID "think" about it, I recall a section of the original report on that subject :) The first stage seemed "doable" but the economics weren't really clear. As I recall, reuse only made "sense" if you had a pretty hefty flight rate which no "normal" case would justify. The conclusin that I recall was that "reuse" was pretty much a non-starter but "salvage" was a very possible set up.However; If this could be made as a reliable TSTO craft that either could have both stages reusable, OR the first stage reusable and use the upper stage as a .5 stage, (Doing Dry-for-wet) as part of either a space station or as a part of a Mars Exploration Vessel, then I think that it would more than justify the cost.
No, it wouldn't. Reuseability negates the whole idea of Sea dragon. It is designed to be built cheap and robust, not for reuse. Also, return of huge stages is unthinkable
You don't have to actually "agree" with me, however both NASA and others pointed out this issue in the discusions and reports on the SeaDragon. Truax never "bought" the arguments but neither as far as I can tell could he actually manage to refute them either. :)QuoteNote exactly :) See the "problem" is the amount of payload one of these things could lift. Short of a sudden "emergency" colonization program, need for a super asteroid/comet defense system or solar power satillite program the SD is simply too BIG to be viable. It has such a huge payload capabilty that you can't really justify a "viable" use for a single flight, let alone the multiples that the "program" would have required.
It's an "issue" I wish we didn't have, but it is still the main issue with a SDLV type vehicle :)
Not exactly sure I agree with you on this.
Yes, the payload, currently, is excessive. However; If this could be made as a reliable TSTO craft that either could have both stages reusable, OR the first stage reusable and use the upper stage as a .5 stage, (Doing Dry-for-wet) as part of either a space station or as a part of a Mars Exploration Vessel, then I think that it would more than justify the cost.The payload was ALWAYS "excessive" and while it is possible ot "justify" the cost its a limited launcher without a massive and intensive NEED for materials on-orbit. And even then the projected flight rate was low enough that the costs began to dominate again just as in most "normal" launcher options
Is this issue less problematic for very large pintle-injection engines? How might the challenges be minimized?Several people have mentioned their concern over developing a large rocket engine due to combustion instabilities. With modern software/analytical tools, is combustion instability still considered a practically insurmountable challenge for developing really big engines?
It's not insurmountable, it's just extremely expensive. We know more than we knew during the days of the F1, but you're still looking at a very test-intensive program to get it right. Models of combustion stability have to take into account the coupled interactions of combustion kinetics, acoustics, and multi-phase fluid mechanics. Models of any one of these are happy to get within 10-20% of the real world values. Computational acoustics in particular is in its infancy.
Geez,It takes off from the ocean, it would have to land in the ocean.
I just had a sick thought. What if you sacrificed about 30% of your total throw mass for both stages and added landing gear to the stages like on the Reusable Falcon 9? It COULD be recoverable then, still have a HUGE throw mass, and be reusable.
But where the heck would you land such a monster? It'd be like trying to land a 25 story building for each stage!
YEIKES!
Of course landing one on MARS could prove... Interesting. A ready, semi insulated structure that could be used dry for wet as a Mars COLONY, not just a Base. Save any reisidual O2 from the oxidizer tanks, scrub or otherwise neturalize the kerosene from the fule tanks, having already designed in hatchways into the tanks, go inset up gridwork floors and inflate habitat segments per floor, (For further insulation amd privacy) and you have a pretty good Mars colony to start.If we get to point of settling Mars, it would seem a Sea Dragon could become viable.
Jason
What if you sacrificed about 30% of your total throw mass for both stages and added landing gear to the stages like on the Reusable Falcon 9? It COULD be recoverable then, still have a HUGE throw mass, and be reusable.Texas near the Mexican border I assume.
But where the heck would you land such a monster?
I vaguely remember some arguments that combustion instability becomes easier to solve at Sea Dragon engine sizes.I would too, but I'm not sure your references exist. I should just make an 80 million pound of thrust engine in my garage. Figure out if combustion stability is easier. Too many naysayers. ;D
Would love some references to back up that claim :P
Geez,
I just had a sick thought. What if you sacrificed about 30% of your total throw mass for both stages and added landing gear to the stages like on the Reusable Falcon 9? It COULD be recoverable then, still have a HUGE throw mass, and be reusable.
But where the heck would you land such a monster? It'd be like trying to land a 25 story building for each stage!
YEIKES!
Of course landing one on MARS could prove... Interesting. A ready, semi insulated structure that could be used dry for wet as a Mars COLONY, not just a Base. Save any reisidual O2 from the oxidizer tanks, scrub or otherwise neturalize the kerosene from the fule tanks, having already designed in hatchways into the tanks, go inset up gridwork floors and inflate habitat segments per floor, (For further insulation amd privacy) and you have a pretty good Mars colony to start.
Jason
<p>Sorry.</p><p> You must surround the entire living quarters with shielding that has the same effectiveness as five feet of water in a tank. This requirement should be used for all mass calculations for extremely long duration missions. Lighter elements are more effective per unit mass, so using liquid hydrogen gives the lightest shield. A thin layer of boron-10 would be needed as a neutron absorber.
It is not possible to get away with less shielding, owing to the fact that the incoming cosmic rays have enough energy to create electron-positron pairs. These pairs are called secondary radiation, and they, too, must be stopped. However, these, in turn, create more electron-positron pairs until their energy drops below 1.1 MeV (the minimum energy needed to create an electron-positron pair) (At some point, each positron will annihilate an electron, producing two gamma rays). Because, for a given total energy of ionizing radiation, alpha radiation is more damaging than beta radiation which is more damaging than gamma rays, and lower frequency (longer wavelength) gammas are more damaging than shorter wavelength gammas, a thinner shield would actually be counterproductive, so far as cosmic rays are concerned. </p><p> </p>
My question is from a slightly different angle.
It seems we have a history of building "right-sized" rockets, that then suffer weight increases and/or performance shortfalls, then we have to optimize the crap out of them to get the job done.
Is a really big, dumb booster more expensive than all the effort expended on optimization & advanced materials?
Is there harm in overkill? Granted, if we tried to build something with 30 F-1 engines, now we're hit with high engine expense, and duplicated complexity.
My question is from a slightly different angle.
It seems we have a history of building "right-sized" rockets, that then suffer weight increases and/or performance shortfalls, then we have to optimize the crap out of them to get the job done.
Is a really big, dumb booster more expensive than all the effort expended on optimization & advanced materials?
Is there harm in overkill? Granted, if we tried to build something with 30 F-1 engines, now we're hit with high engine expense, and duplicated complexity.
Matt, with 30 engines you run into SIGNIFICANT timing and fuel routing issues. (An example of this is the Soviet N-1 moon rocket).(Technically somewhere between 45 and 53 engines if using F1B or F1-upgraded motors respecivily for a "full-up" Seadragon, fewer for the Excalibur and "Sub-Caliber" models that NASA thought were STILL to big :))
There are also a couple of significant issues with the Sea Dragon design. (While I am infavor of this design, I am having to play Devil's advocate here for a minute).
First, it is designed to be launched from the ocean with all shipping and air traffic to be cleared out for at least a five mile radius. (Not impossible, but difficult) Should the craft suffer a catostrophic failure during any part of the ascent, it would detonate with the force of a small nuclear weapon and scatter debris over a VERY large area. (The higher it got the larger the area)
Also, due to the Sea launch set up, it would rove a significant danger to sea life in the immediate vicinity. (Boiled shark soup with a side of broiled whale anyone?)
Fueling the first stage with Kerosene would be possible at shore, but should leaks develope, signifcant envionmental damage could occure.
The noise of such a launch would FAR exceed any OSHA standards and the shockwave over water is likely going to be able to travel a significant distance with little diminimishment.
Fueling the hydrogen for the second stage and the LOX for both First and Second stage would be very tricky using specialized cryogenics ships, similar to the current LNG tankers. Even with a dedicated Nuclear Reactor for fuel seperation from sea water and cryogenic cooling of both LOX and Hydrogen, we are talking a significant time to fully fuel such a craft, during which storms could develope endangering both the craft and the ocean vessels.
Assuming development of large plug nozzle systems for such craft, it MAY be possible to stretch the first stage and eliminate the second stage as plug nozzles tend to reconfigure their exhaust according to atmospheric pressure and do not require a specialized exhaust bell for low or zero pressure environments. This would also facilitate the recovery of such a craft for reuse, but it would again, endanger sea life where it landed.
However, even with these issues, I think that this is still a very viable launch system.
This guy briefly outlines some features of Sea Dragon (high level).
the sea dragon had a core diameter of 75 feet, if you built a can with a 75 dia and put a tub in it like the tub inside your close dryer and gave it a spin of 4-10 revolutions per minute you would have all the centrifical force created artifical gravity you would need for sleep chambers on a trip to mars. it would not be 1g but it would be more than enough to offset zero g effects enough on a 5-7 month voyage.Ah, so you're suggesting that just a part of the interior would spin. Maybe just a ring in the middle somewhere. Interesting thought. I had assumed the whole business could rotate (or maybe a tether to some mass) but this "seems" simpler.
Actually after the rocket lifts from the water it tends to take a parabolic shape which directs the noise upwards instead of out. Once it gets a couple of hundered feet up though the sound is going to be rather awsome in every meaning of the word :)Wouldn't the water absorb (not reflect) a lot of the acoustic energy? Also, if the focal point of your parabola is behind a supersonic rocket plume (or large grouping of convergent rocket plumes), seems like it would be hard for the rocket to acoustically destroy itself from the ground reflection. What am I missing?
Actually after the rocket lifts from the water it tends to take a parabolic shape which directs the noise upwards instead of out. Once it gets a couple of hundered feet up though the sound is going to be rather awsome in every meaning of the word :)Wouldn't the water absorb (not reflect) a lot of the acoustic energy? Also, if the focal point of your parabola is behind a supersonic rocket plume (or large grouping of convergent rocket plumes), seems like it would be hard for the rocket to acoustically destroy itself from the ground reflection. What am I missing?
However; If this could be made as a reliable TSTO craft that either could have both stages reusable, OR the first stage reusable and use the upper stage as a .5 stage, (Doing Dry-for-wet) as part of either a space station or as a part of a Mars Exploration Vessel, then I think that it would more than justify the cost.
No, it wouldn't. Reuseability negates the whole idea of Sea dragon. It is designed to be built cheap and robust, not for reuse. Also, return of huge stages is unthinkable
However; If this could be made as a reliable TSTO craft that either could have both stages reusable, OR the first stage reusable and use the upper stage as a .5 stage, (Doing Dry-for-wet) as part of either a space station or as a part of a Mars Exploration Vessel, then I think that it would more than justify the cost.
No, it wouldn't. Reuseability negates the whole idea of Sea dragon. It is designed to be built cheap and robust, not for reuse. Also, return of huge stages is unthinkable
However; If this could be made as a reliable TSTO craft that either could have both stages reusable, OR the first stage reusable and use the upper stage as a .5 stage, (Doing Dry-for-wet) as part of either a space station or as a part of a Mars Exploration Vessel, then I think that it would more than justify the cost.
No, it wouldn't. Reuseability negates the whole idea of Sea dragon. It is designed to be built cheap and robust, not for reuse. Also, return of huge stages is unthinkable
Actually after the rocket lifts from the water it tends to take a parabolic shape which directs the noise upwards instead of out. Once it gets a couple of hundered feet up though the sound is going to be rather awsome in every meaning of the word :)Wouldn't the water absorb (not reflect) a lot of the acoustic energy? Also, if the focal point of your parabola is behind a supersonic rocket plume (or large grouping of convergent rocket plumes), seems like it would be hard for the rocket to acoustically destroy itself from the ground reflection. What am I missing?
IIRC experiments showed that a water surface, (unlike sprayed) acts more like a solid object to heavy sound waves and you get very little absorbtion. I doubt you'd have to worry about acoustic's damaging the rocket given the way the exhaust plume is supposed to shape the water's surface the "focus" would be behind the rocket once the surface calmed from the rather awsome "bubble-burst" of the rocket breaking free in the first place.
The only time the "parabolic" effect was mentioned that I recall was in dealing with the ROMBUS lift off which was done over an artifical lagoon for specifically acoustical reasons. The SeaDragon is going to create a huge gas bubble beneath it that will cause so much surface distortion thre a parabolic surface would never happen in the first place. I was talking more of the ROMBUS case than the SeaDragon case. Sorry if that wasn't clear.
Randy
If you have any questions, there are a number of books I can recommend on acoustics and acoustical properties of various materials.Yes please!
If you have any questions, there are a number of books I can recommend on acoustics and acoustical properties of various materials.Yes please!
Also, in your reply #223 on this thread, ...Bigelow modules within the tanks? I'm not following the rationale.
Hi,Raptor makes me wonder if we'll ever see a giant engine - many smallish good ones has advantages.
I just did comparaison photos of Sea Dragon to Saturn V and the F-1 engine, quite impressive. When you look at it and think of what you could do, it's awesome.
Hi,Raptor makes me wonder if we'll ever see a giant engine - many smallish good ones has advantages.
I just did comparaison photos of Sea Dragon to Saturn V and the F-1 engine, quite impressive. When you look at it and think of what you could do, it's awesome.
Is it an idea that is done?
I still like the Sea Dragon concept of operations more than what I see out there getting built. Is the assumption simply that barnacles and crud adding mass and risk? Or is there more to the story?
My guess is that sea-based launches are still worth exploring for a variety of reasons, but it only makes sense if the rocket is designed to be seaworthy. For example, there's a startup in Norway called Ripple Aerospace that aims to launch rockets that can be fabricated in Norwegian shipyards.
https://rippleaerospace.com/ (https://rippleaerospace.com/)
Salinity is not kind to aerospace alloys. Designed to be seaworthy is an interesting comment, not sure how to accomplish that for flight hardware. No doubt possible, would be interesting to see practical examples.
Rocket equation is unforgiving. 8mm steel is not immune to corrosion. Surplus nuclear aircraft acrriers are not easy to aquire.
Hi,Raptor makes me wonder if we'll ever see a giant engine - many smallish good ones has advantages.
I just did comparaison photos of Sea Dragon to Saturn V and the F-1 engine, quite impressive. When you look at it and think of what you could do, it's awesome.
Although many smaller engines seems a good idea on the surface, having too many not only risks a higher potential for failure, (the plumbing get pretty complicated. Ask the Russians about the N-1) they also wind up massing more than a fewer number of larger more powerful engines.
That said, the design shown for the ITS seems to be a fair compromise between larger engines, and complicated systems.
Rocket equation is unforgiving. 8mm steel is not immune to corrosion. Surplus nuclear aircraft acrriers are not easy to aquire.
Starship 2.0 is planned to be the same diameter as sea dragon, or more. I remember at the 2008 Mars Society Conference in Boulder, someone in the audience had a long question about Sea Dragon. Elon mentioned he preferred solid ground. But with Starship 2.0, from sea to sea point to point and transorbital, this idea seems to have come around.What is your source on Starship 2.0?
Starship 2.0 is a Sea Dragon Class LV!
Starship 2.0 is planned to be the same diameter as sea dragon, or more. I remember at the 2008 Mars Society Conference in Boulder, someone in the audience had a long question about Sea Dragon. Elon mentioned he preferred solid ground. But with Starship 2.0, from sea to sea point to point and transorbital, this idea seems to have come around.What is your source on Starship 2.0?
Starship 2.0 is a Sea Dragon Class LV!
The 18m speculation has degraded since a more recent elon post suggesting 9m is actually a little too large, once you figure in ground handling for rapid reuse.
Stainless is more resistant to corrosion than aluminum, generally speaking.Rocket equation is unforgiving. 8mm steel is not immune to corrosion. Surplus nuclear aircraft acrriers are not easy to aquire.
Corrosion is ALWAYS an issue. It simply wouldn't be as much of an issue as for a aluminium or lithium based structure.
And yes, nuclear aircraft carriers wouldn't be as available as, say a floating solar farm, but I guess you take what you can get...
What are your suggestions on 440+ tons to LEO LVs?Gotta point out that the original ITS/BFR/Starship would've gotten 500 tons expendable to orbit, similar to some Sea Dragon variants.
My favorite would be Sea Dragon built out of aluminum. What would its payload be?
And why does Sea Dragon-2 have only 320 Isp? That sounds too low for even a pressure-fed oxyhydrogen engine.
The application would be manned Mars missions (about 1200 tons IMLEO, 500 tons of which is radiation shielding against cosmic rays, using NTP for TMI).
In the end, the final nails in the coffin for the concept were 1) that the heavy pressure fed metal tank raw material costs dramatically outweighed the modern costs of developing a high performance turbopump - for all propellant combinations, and 2) the impact of firing a large rocket engine underwater - even with extensive sound mitigation efforts such as multiple bubble curtains - would have killed all manner of sea creatures for *miles* around.
In the end, the final nails in the coffin for the concept were 1) that the heavy pressure fed metal tank raw material costs dramatically outweighed the modern costs of developing a high performance turbopump - for all propellant combinations, and 2) the impact of firing a large rocket engine underwater - even with extensive sound mitigation efforts such as multiple bubble curtains - would have killed all manner of sea creatures for *miles* around.
In the end, the final nails in the coffin for the concept were 1) that the heavy pressure fed metal tank raw material costs dramatically outweighed the modern costs of developing a high performance turbopump - for all propellant combinations, and 2) the impact of firing a large rocket engine underwater - even with extensive sound mitigation efforts such as multiple bubble curtains - would have killed all manner of sea creatures for *miles* around.
I had a discussion about sea launch with a marine biologist a long time ago, the impact is definitely something that would have to be sorted out. Not that it is impossible, but if someone had an idea that they could just go out there and not worry about it, they are probably going to be disappointed.
In the end, the final nails in the coffin for the concept were 1) that the heavy pressure fed metal tank raw material costs dramatically outweighed the modern costs of developing a high performance turbopump - for all propellant combinations, and 2) the impact of firing a large rocket engine underwater - even with extensive sound mitigation efforts such as multiple bubble curtains - would have killed all manner of sea creatures for *miles* around.
I had a discussion about sea launch with a marine biologist a long time ago, the impact is definitely something that would have to be sorted out. Not that it is impossible, but if someone had an idea that they could just go out there and not worry about it, they are probably going to be disappointed.
This reminds me of my long gone grandfather way of mixing fishing and hunting. Took his riffle, fired it in the water. The detonation shockwave / pressure was enough to kill fishes that come floating dead on the surface. Just pick them up.
In fact the detonation overpressure blew this part of fish anatomy https://en.wikipedia.org/wiki/Swim_bladder - and that's why they died and floated up.
I can only imagine what a Sea Dragon would do in similar conditions... as seen on the video above. Fish swim bladders (or whatever you call that in english language - blame Google translate !) would definitively NOT appreciate Truax rocket.
I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
The Bikini Atoll is still radioactive, but it is also teaming with life in the lagoon. PBS had a show about it. You would be amazed at what's in there.I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
That might be politically sensitive to the government of the Marshall Islands.
This is true of many areas where circumstances have excluded humans, such as Chernobyl, many military weapons ranges, and areas around launch sites. I suspect that the area around Boca Chica will see a richer ecosystem as more human residents are excluded. It is less true of areas with more severe long-term ecological devastation, especially agricultural areas.The Bikini Atoll is still radioactive, but it is also teaming with life in the lagoon. PBS had a show about it. You would be amazed at what's in there.I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
That might be politically sensitive to the government of the Marshall Islands.
The Bikini Atoll is still radioactive, but it is also teaming with life in the lagoon. PBS had a show about it. You would be amazed at what's in there.I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
That might be politically sensitive to the government of the Marshall Islands.
The Bikini Atoll is still radioactive, but it is also teaming with life in the lagoon. PBS had a show about it. You would be amazed at what's in there.I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
That might be politically sensitive to the government of the Marshall Islands.
I appreciate that, and I'm not saying that Bikini is some kind of radioactive wasteland, but it is still hazardous for extensive human activity, like resettling the indigenous people. That damage has already been done. This proposal is just a way of turning lemons into lemonade. I'm saying that if one were to pursue a Sea Dragon class LV then the potential environmental impact would be mitigated in this location as opposed to off the coast of say Florida, or out in the open Pacific.
The Bikini Atoll is still radioactive, but it is also teaming with life in the lagoon. PBS had a show about it. You would be amazed at what's in there.I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
That might be politically sensitive to the government of the Marshall Islands.
I appreciate that, and I'm not saying that Bikini is some kind of radioactive wasteland, but it is still hazardous for extensive human activity, like resettling the indigenous people. That damage has already been done. This proposal is just a way of turning lemons into lemonade. I'm saying that if one were to pursue a Sea Dragon class LV then the potential environmental impact would be mitigated in this location as opposed to off the coast of say Florida, or out in the open Pacific.
I suspect the government and people of the Marshall Islands would be far more sensitive to environmental impacts on Bikini than off the coast of Florida! I think there's the possibility of a strong reaction to the idea of foreigners causing more environmental damage to Bikini.
The Bikini Atoll is still radioactive, but it is also teaming with life in the lagoon. PBS had a show about it. You would be amazed at what's in there.I too was fascinated by the Sea Dragon concept, but the impact on marine life would never be tolerable...if launched in the open ocean. But what if there was a way of launching that wouldn't be in the open ocean? My answer was launch it from Bikini Atoll.
That might be politically sensitive to the government of the Marshall Islands.
I appreciate that, and I'm not saying that Bikini is some kind of radioactive wasteland, but it is still hazardous for extensive human activity, like resettling the indigenous people. That damage has already been done. This proposal is just a way of turning lemons into lemonade. I'm saying that if one were to pursue a Sea Dragon class LV then the potential environmental impact would be mitigated in this location as opposed to off the coast of say Florida, or out in the open Pacific.
I suspect the government and people of the Marshall Islands would be far more sensitive to environmental impacts on Bikini than off the coast of Florida! I think there's the possibility of a strong reaction to the idea of foreigners causing more environmental damage to Bikini.
Since Bikini (and Kwajalein) are uninhabited, they might be tolerant of this idea, if we were to offer them something in return. I'm optimistic that some kind of quid pro quo can be found.
Kwajalein is not uninhabited, the inhabitants are 'relocated' onto Ebeye Island.
Very crowded, on the satellite photo it looks a bit like Gaza strip.
https://commons.wikimedia.org/wiki/File:Ebeye_Island.jpg
https://en.wikipedia.org/wiki/Ebeye_Island