Cheap heavy launcher - can it be done at all

Euler · 2004-08-16 14:44:58

We have talked about every thing but the manned portion of the rocket. As every one has noted it is fairly easy to design something to lift materials or other items to almost anywhere that we would want.

That is because this is a thread about heavy lift launch vehicles. The manned launches will probably use a capsule design on top of existing expendable light or light-medium launchers.

ANTIcarrot. · 2004-08-16 16:30:02

The idea of light payloads launched by reuseable vehicles or assembly-line supercheap rockets is folley...

Except the zenit is currently one of the cheepest launch systems around. If it's a case of putting up the most weight for the least cost then it is the best solution. And the question was heavy lift, not heavy lift to a fixed location. ^.^ Such a site would ideally be located at/V-near the equator to minimise rondezvous problems.

SeaDragon is a pretty crazy concept... I don't think it could be done in such a fasion that it would be practical, since the thing simply isn't going to turn around fast, mostly because of the trouble of building and handling and assembling somthing that big, and it is so big that it has very limited utility with its lack of granularity. Much higher risk of dooming the whole project if there is a launch failure too if you launch your whole ship in only 1-2 shots.

It's an ELV. What turn around are you talking about? We build and handle things like that all the times. They're called 'ships'. That's why I said it's most suitable for projects in the 10,000ton+ range; which would require 20+ launches.

ANTIcarrot.

Euler · 2004-08-16 16:55:44

Except the zenit is currently one of the cheepest launch systems around. If it's a case of putting up the most weight for the least cost then it is the best solution.

Not really. It does have the advantage of being made in Ukraine (so it is helped by exchange rates), and it can lift more mass due to being launched at the equator. However, according to Astronautix.com, it can only launch 5,250 kg to GTO at a cost of $90 million. Some versions of Atlas V and Delta IV have a lower cost/kg than that, as does Ariane V. Zenit also can not launch much more than 6MT to LEO due to structural problems with it's third stage.

GCNRevenger · 2004-08-16 17:00:51

Sure you can buy alot of $50M Zenit-II rockets for the price of a $500M HLLV shot, but would you want to? Ten 15MT payloads that have to fit in a 3-4m faring versus a single 150MT payload with a 9m faring? The cost of sending up a large object, lets say a 300MT Mars ship or a 450MT space station, is much cheaper to build on the ground and tested on the ground and no docking hardware needed for each little piece, weighs much less for comperable volume so you can afford more equipment mass and carry more fuel per-flight, and does not need any tugs or robot arms or human assembly... just dock 2-3 big pieces. The advantage of HLLV for building objects of this scale is clear, even if it costs more for the launcher; to focus only on the pounds-per-dollars is shortsided and wrong, it leads down the road to silly ideas like DH-1 and SeaDragon...

Oh, nor can Zenit deliver any practical mass directly to Earth-escape trajectories, so you have to buy additional upper stage engines and tankage for them too.

As for SeaDragon, it will take an awful long time to build such a large object I would guess, and frankly I don't think they can be built at a reasonable rate. The expense of handling a giant bomb that has to work 98% of the time, survive high G-loads, extreme vibration, and the stages fit together perfectly within a fraction of an inch water-tight... and then having to wait to tow and assemble and erect and fuel and all that down time will also hurt the flight rate and the cost, since salaries are fixed no matter how many you fly. Further, there is the problem of payload granularity limiting its utility, when you only need 60-80-100MT and you need it at a specific time (like a probe launch window or space station freight), you might be out of luck. SeaDragon is also not suited for escape velocity shots as previously mentioned.

A concern about going Shuttle-dervied, is that I doubt the vehicle can be pushed much past 120MT payload, which will quite possibly kill any MarsDirect style plan if there is any weight creep.

GCNRevenger · 2004-08-16 17:03:54

I think Anti is referring to the Zenit-II, which can put ~15MT into LEO for (reportedly) $50M a pop.
http://www.astronautix.com/lvs/zenit2.h … zenit2.htm

Euler · 2004-08-16 17:51:48

I think Anti is referring to the Zenit-II, which can put ~15MT into LEO for (reportedly) $50M a pop.

I guess that is cheaper, but only due to exchange rates and inflation. It also can't send payloads much beyond LEO, and a 20% failure rate is hardly something to be proud of.

GCNRevenger · 2004-08-16 18:22:43

Probability of sucess for a 300MT mission
HLLV that is 98% reliable: 96%
Zenit-II that is 80% reliable: your gonna lose two shots.

Just hope those aren't the ones with the $3Bn Hab module?

Euler · 2004-08-16 18:33:08

Probability of sucess for a 300MT mission
HLLV that is 98% reliable: 96%
Zenit-II that is 80% reliable: your gonna lose two shots.
Just hope those aren't the ones with the $3Bn Hab module?

Yeah, at that rate the insurance costs alone for the Zenit will be more than the total launch costs of the HLLV.

ANTIcarrot. · 2004-08-16 18:34:29

As for SeaDragon, it will take an awful long time to build such a large object I would guess, and frankly I don't think they can be built at a reasonable rate.

About 40 days if you held races. Look up the term 'liberty ship' some time.

The expense of handling a giant bomb that has to work 98% of the time,

Wielded steel tanker trucks carry explosive liquids all over the world with a success rate much higher than 98%.

survive high G-loads, extreme vibration, and the stages fit together perfectly within a fraction of an inch water-tight...

Again, making things that don't leak isn't really a serious technical challange for a ship yard.

and then having to wait to tow and assemble and erect and fuel and all that down time will also hurt the flight rate and the cost, since salaries are fixed no matter how many you fly.

Eh? Okay, first it's unlikely the HHLV will be built in a factory right next to the launch site, so a lot of this will aply to any design. Second on a continual production rate you don't need to wait for anything. You have 5 ship lanes build them, five ships towing them, and a couple of ex-navy ships fueling them. With a sensible launch rate everyone could be kept busy at a continual basis. The only significant cost will be patrolling the 'launch site' and keeping a 20 mile circle clear of shipping. Though this could be offset against the problems of building and maintaining a launch pad et all for your super EELV.

Further, there is the problem of payload granularity limiting its utility,

If you're using it to build SSPSs (or some other major project) then you simply buy a percentage of the cargo hold. They'll be going up on a regular basis. It'll be no different from buying cargo-space on any other 'charter' flight.

SeaDragon is also not suited for escape velocity shots as previously mentioned.

So? SeaDragon is designed to put a sealed 500ton cargo pod in LEO. There's no reason that 500ton cargo pod couldn't be a third-stage.

Besides, as you say yourself...
The advantage of HLLV for building objects of this scale is clear.The cost of sending up a large object, lets say a 300MT Mars ship or a 450MT space station, is much cheaper to build on the ground and tested on the ground and no docking hardware needed for each little piece, weighs much less for comperable volume so you can afford more equipment mass and carry more fuel per-flight, and does not need any tugs or robot arms or human assembly

Why bother messing around with measily 100ton modules, which then require (shudder! horror!) assembally in orbit, when you can put everything up at once?

You can't argue with that logic. It's your own after all...

ANTIcarrot.

GCNRevenger · 2004-08-16 20:12:00

Oh come on, you aren't seriously comparing a rocket of any kind to a WW2 undersized underpowerd antique freighter are you? Uhh, you do know that SeaDragon is a bit bigger, right? The SeaDragon is two hundred meters long including launch platform, which is almost as big as many oil tankers. They're big, real big, unreasonably big. Double the size of Saturn-V at least...

And which freighters do you know are designed to withstand multi-G stresses? Bolt-popping, people-liquifying vibration? Restarting the 2nd stage of that size for orbital circulization? The seal around the main engine nozzle at launch? And having to glue two or three of these massive vessels together to build the rocket, which must fit with extreme precision, and be water-tight to avoid interstage flooding without welding like in a shipyard. Making somthing this big that doesn't leak is an issue.

The idea of running multiple shipyards full-tilt all the time is a terrible idea because of the cost involved. It would just cost too much. That kind of parallel construction would employ far too many people and require far too much infrastructure if large-scale production is needed for economy... I also bet you didn't know that the pieces for Energia were transported by air? The Zenit rockets today are still shiped from the factory by air. Say we can build two 200MT HLLV rockets as quickly as one SeaDragon, as its just a core the size of Shuttle's with recycled boosters and an upper smaller than a Delta rocket? The HLLV might actually not be more expensive.

But the biggest reason not to try the grand experiment to build SeaDragon, the worlds' first water-borne spaceship and made from steel, is that there isn't any good reason to. The risk of the SeaDragon concept failing I think is high enough that without the need for 2000-3000MT/year loads of extremely low granularity, that its not worth the trouble since conventional rockets are more certain to work. The idea of forcing smaller payloads to "hitch a ride" with a large is silly too, some launch windows are down to the second and relying on somthing that big is not an option, especially if the trajectory for the main payload into orbit is different for the probe out of orbit...

Nor can you pack the thing with two dozen commertial satelites and fire it off every few years, since they need to go to different places around the globe, and not wait on the others to be launched either. Time spent on the ground is money lost. Then there is chance of the SeaDragon failing and taking tens of billions of dollars with it is not practical. The only thing its good for is launching extremely large payloads now and then, and SSPS is such a technicly shakey proposition, there simply isn't much for it to do. The limited utility of a rocket that size should be more obvious than the exsistence of your nose on your face... smaller rockets are sometimes worthwhile thanks to their utility, lower efficency or no.

Futher, exploration missions and space stations, though becoming more efficent as they get larger by the decreased surface area, there is a limit. A 9m 150MT payload is quite simply big enough for most things currently (especially with inflatable HABs), the trouble of making such a large spaceship on the ground, giant delicate hydrogen tanks or spacious living quarters and all, now becomes signifigant. Why, the payload faring must be 75m tall! You want to put together a Mars ship thats 25 stories tall? Objects in space need not be as strong as on the ground, yet if they are built on the ground, then they are unessesarrily strong. And, the bigger the object, the more true this becomes - A little on-orbit assembly can save some headache and mass in actuality.

SpaceNut · 2004-08-16 20:32:37

When I think of heavy lift I do not assume only cargo or of very large size modules. As I noted before I was referencing the need for more than a few astronauts with enough materials to maybe transfer into any such earlier launched Habitat modules.

The Progress is currently carrying to the Iss about 2.5 tons of food, water, propellant, and other supplies for its two-man crew.

How long do you think those supplies will last with a real size crew for exploration to mars or to the moon.

Just think about how many people would be on this journey and for how many months that the journey wil be fore not to mention the number of months they will be there in addition to the return trip.

If one does puny little capsulse for a max of 3. What then leave them parked in orbit for the four or 5 yearfor the round trip. I would hope not. I also do not see that many docking ports on a habitat module either. Not to mention bringing those capsules all the way to Mars or the moon, One would be bad enough.

Sorry If I am way off topic of cargo lift only.

Euler · 2004-08-16 23:20:14

Double the size of Saturn-V at least...

Actually, it is 6 times as large as Saturn V.

And which freighters do you know are designed to withstand multi-G stresses? Bolt-popping, people-liquifying vibration? Restarting the 2nd stage of that size for orbital circulization? The seal around the main engine nozzle at launch? And having to glue two or three of these massive vessels together to build the rocket, which must fit with extreme precision, and be water-tight to avoid interstage flooding without welding like in a shipyard. Making somthing this big that doesn't leak is an issue.

Not to mention the fact that it has giant fuel tanks under 32 atmospheres of pressure, and it will be compressed by 36 million kg of force during launch.

It is not a valid argument to say that since heavy lift is good, super heavy must be even better. That is like saying that since 747s move people around efficiently, we should go and build an airplane 10 times larger.

If one does puny little capsulse for a max of 3. What then leave them parked in orbit for the four or 5 yearfor the round trip. I would hope not. I also do not see that many docking ports on a habitat module either. Not to mention bringing those capsules all the way to Mars or the moon, One would be bad enough.

Existing light-medium launchers are easily powerful enough to launch a 6-8 person capsule up to the vehicle that you are assembling in orbit. You have a couple of pilots that ferry the crew up to the Mars ship and then return to Earth. Then when the Mars ship returns to Earth after its journey, you send up more capsules to ferry them back down to Earth. You don't want to send up the crew in the HLLV because then you would have to man-rate it, adding unnecessary expenses.

ANTIcarrot. · 2004-08-17 07:12:45

Oh come on, you aren't seriously comparing a rocket of any kind to a WW2 undersized underpowerd antique freighter are you?

SeaDragon is effectively a flying ship. And you did asked how quickly they *could* be built. Liberty ships were also designed to be successful if they worked *once*, so the comparison isn't that far off. Point is it is possible to quickly build large disposable sea-worthy steel ships, and to do so in a reasonably econimical fashion.

And which freighters do you know are designed to withstand multi-G stresses? Bolt-popping, people-liquifying vibration?

How many fully loaded rockets can you name that can withstand being placed sideways and supported at each end without snapping in the middle? That's pretty standard for sea-worthiness. I would also like to see your reference for how bad the vibration would be oboard SeaDragon. As you point out, it isn't built anything like a conventional rocket.

The seal around the main engine nozzle at launch?

In the real world (where most of us live) we have these little things called 'bilge pumps'. Pumping part of the air out of the interstage would also create a reasonably good seal by forcing the stages together. There are solutions to this problem, and all the others you raise. And once the rocket's upright this effectively stops being a problem.

The idea of running multiple shipyards full-tilt all the time is a terrible idea because of the cost involved.

Yessss... Because as we all know, mass production *always* drives unit price up!

I also bet you didn't know that the pieces for Energia were transported by air?

And how exactly do they transport the core section without cutting it up? It won't fit on a C-5, AN-225, or Beluga.

The HLLV might actually not be more expensive.

Much of SeaDragon can be built at any shipyard world wide as a contract. Wielded steel is after all not a classified technology. How many aerospace factories in America can build your 200MT HLLV? Two or three? Or do you plan to build your own factory?

And even if you could build two 200MT HLLVs, you'd still be 100MT light of a single SD launch.

The risk of the SeaDragon concept failing I think is high enough that without the need for 2000-3000MT/year loads of extremely low granularity, that its not worth the trouble since conventional rockets are more certain to work.

Yes, thank you for repeating what I have already said. SD is practical for large projects only. However I'd guess max lift capacity for seadragon at more like 6000MT-12000MT per year.

some launch windows are down to the second and relying on somthing that big is not an option,

With the kind of lift capacity discussed in this thread some kind of orbital infrastructure is probably in place already or soon will be. In which case it will often make little sense to launch directly to the destination. And launches down to the second are usually mandidated by DeltaV/fuel limitations. Those don't really exist with something like SD. At least not for small payloads.

Then there is chance of the SeaDragon failing and taking tens of billions of dollars with it is not practical.

<sigh> We've been over this before. Much of a satellite's cost is combating weight creep. Allow weight creep and satelites become much cheaper. A boeing study indicated a 50% reduction in costs for a 30% growth in weight; and that wasn't an optimised stopping point for such growth.

You want to put together a Mars ship thats 25 stories tall?

Why not? Most of it will be fuel tanks you realise. Besides, do you really think you'll colonise mars or luna in thirty ton modules?

SeaDragon is not a generic fix-all for all applications, but neither is it entirely impractical. If you check back you'll find I've sung the praises before of the kind of SDV/ELV hybrids you're proposing now. But they're not a generic fix-all for all applications either.

For Mars Direct style applications, your idea is good enough. But for serious explotation of space resources you need something much more capable.

Besides which you can always build *smaller* BDB designs. 40MT into LEO for $120/kg anyone?

ANTIcarrot.

BWhite · 2004-08-17 08:00:48

A good launch cost http://www.futron.com/pdf/FutronLaunchCostWP.pdf]link.

GCNRevenger · 2004-08-17 08:08:11

"Point is it is possible to quickly build large disposable sea-worthy steel ships, and to do so in a reasonably econimical fashion."

I contest that you cannot. Not somthing this large. It is many times the size of the old Liberty ship, and around a dozen times larger or so the amount of steel at least. Given the higher quality of assembly you must accomplish relative to an oceangoing ship, this is not credible.

As far as the vibration is concerned, it is going to be pretty extreme, as SeaDragon has a high thrust/weight ratio and a single pressure-fed (turbulent) engine of many millions of pounds of thrust. The simple fact that it weighs so much loaded, the engine must therefore by truely gargantuan, which is going to put off some major. major vibration. Saturn-V's F-1 engines were at the limits of tolerable.

"Yessss... Because as we all know, mass production *always* drives unit price up!"

Ah, but you wouldn't be mass-producing them. They would take so long to build because of their size, several times over more surface area than any rocket that has come before and with as much surface area as most oil supertankers, that you just can't build them that fast. Hence, you will need massive parallel construction, which other than the materials involved, is going to cost about double to build two rockets instead of one. Two factories, two shipyards, two construction crews, two "launch fleets." Its called being "unscaleable."

Michoud can crank out at least 5-6 Shuttle ETs a year. Boeing can build 20 CBCs. Put the two technologies together, throw in reusable Atlas/Zenit boosters, and a fat Centaur and thats it. All you really have to build new is the core and the upper, which is way, way smaller than SeaDragon, which you have to throw away in its entirety. The higher construction rate for a 200MT HLLV possible with a single factory and a single launch complex plus booster reuseability would mostly offset the larger size of SeaDragon, and could quite possibly be less expensive.

Don't forget the mass penalty for Earth-hardening large objects compared to smaller ones.

The old giant kerosense first stage + big upper all expendable of the Saturn-V style, like SeaDragon, is obsolete and uneconomical versus an Energia style arrangement.

"...some kind of orbital infrastructure is probably in place already or soon will be. In which case it will often make little sense to launch directly to the destination. And launches down to the second are usually mandidated by DeltaV/fuel limitations. Those don't really exist with something like SD. At least not for small payloads."

A big assumption, how much will this "orbital infrastructure" cost? And what happens if you need a 60-80MT payload launched between the months or year required for SeaDragon and the other payloads to be readied?

"Much of a satellite's cost is combating weight creep."

No, actually, I don't think you know what you are talking about. Space satelites are expensive not so much because of their low weight, but because they are really complicated. Even if you make the thing's chassis out of pig iron, the gobs of electronics, the hypergolic or ion engines, the solar cells... all these things aren't going to be loads cheaper.

"For Mars Direct style applications, your idea is good enough. But for serious explotation of space resources you need something much more capable.
Besides which you can always build *smaller* BDB designs."

Really? Why do we need somthing "much more capable?"

And no, you can't build smaller BDBs, not out of steel. That is why SeaDragon is practical you know, that it is so big that the reduced surface area per-volume of tankage is small enough that making it out of steel is not going to be a big performance hit. Making a tiny one, and there is just no way you can make it "at a shipyard, cheap!"

SpaceNut · 2004-08-17 09:50:26

Thanks BWhite for the cost link to Space Transportation Costs
of Futron Corporation for the other thread on Rocket Business model for shuttle delta IV atlasV, and others good or bad.

SpaceNut · 2004-08-17 13:37:04

Falcon rocket rides slow road toward flight
SpaceX deals with hurdles associated
with engine and environmental rules

http://www.msnbc.msn.com/id/5725500/

ANTIcarrot. · 2004-08-17 17:24:06

Liberty ship weight (empty): 7000tons.
SeaDragon weight (empty): 2000tons.

So much for SD needing more steel. Or construction time.

Launching underwater is a very different enviroment to Pad 39. In fact I'd imagine the information about it is also rather heavily classified, since that's how nuclear sub missiles launch... So god knows where're you're getting your information.

Ah, but you wouldn't be mass-producing them.

I assure you I can find shipyards that can build multiple 200m long 2000ton 'steel balloons' without any great difficulty.

The launch rate for a major project would be one or two SDs a month - minimum. Not one every few years, which is your made up sugggestion. Such a rate is *very* scalable as it maximizes the use of the launch ships.

No, actually, I don't think you know what you are talking about.

Really? Boeing (the study I referenced) doesn't know what it's talking about? Boeing the REALLY REALLY big aerospace giant doesn't know anything about space craft? Are you listening to yourself?

And no, you can't build smaller BDBs, not out of steel.

So Chrysler, McDonnel Douglas, Rockwell, Martin Marietta, TRW & of course Boeing all got it wrong when it came to the BDB/MCD concept?

Really? Why do we need somthing "much more capable?"

I'm sorry - why are you here again?

ANTIcarrot.

GCNRevenger · 2004-08-17 18:00:36

I really doubt that Liberty ships were built such that they could withstand the high internal pressures of pressure-fed engines, the high G-loadings even when fueled, the vibration, the atmospheric pressure change, supersonic air friction, and all that fun stuff.

And the rocket itself, albeit weighing less, is still going to be bigger than Liberty ships, its going to be much more fragile, its still going to have to be built, assembled, and handled with greater precision. And I assure you that it will still take many months to build one SeaDragon vehicle, and this alone has the potential to make it a more expensive and inferior launch vehicle. A month or two each indeed, nonsense... You will therefore need additional shipyards to match the tons/year capacity of HLLV, which will destroy the economics of the whole proposition.

Actually no, submarine missiles are not launched underwater. Their engines do not fire until after they have reached the surface. But even if it were launched in water, there would still be massive vibration any which way simply from the sheer thrust.

What stuff you listed earlier? Yes signifigant portions of the cost go to minimize vehicle mass, but even if you had unlimited mass budget to play with (within reason) there is no way your are going to avoid a price-tag in the 8-9 digit range for satelites. Its just not going to happen.

"So Chrysler, McDonnel Douglas, Rockwell, Martin Marietta, TRW & of course Boeing all got it wrong when it came to the BDB/MCD concept?"

The concept for a steel or other commodity metal booster that trades mass fraction for simplicity of design and sheer size only works for a giant booster because of the reduced tankage area. It HAS to be big, or it won't work... And given the difficulty of making a rocket this size versus making more numerous relativly tiny Aluminum tanks with modern mass-produced engines and reuseable boosters (!), yeah, I think it is quite possible they would reject the notion of BDB out of hand today given its very low utility.

HLLV can actually be better than a BDB with double the payload, it certainly won't be much worse, and it will be a much MUCH more flexable solution.

ANTIcarrot. · 2004-08-18 15:57:27

Its just not going to happen.

In your personal peerless unvarified opinion.

It seems a personal belief of yours that rocket technology cannot possibly get better. Lords know why as this is not reflected in practice.

ANTIcarrot.

GCNRevenger · 2004-08-18 17:52:30

Rocket technology can and will improve. It has come along way since large practical rockets had their heyday in the 60's... but SeaDragon is NOT an improvement... it is not... it is simply a scaling up of traditional more primitive technologies in the hope that simple/expendable/big can overcome the tank mass and complexity penalties of high-Isp/(semi)reuseable/modest...

And it could, on a cost-per-pound basis. I will grant you that... but that does not make it the best solution to today's needs. We need a launcher that can go up several times per year per factory/pad, that Shuttle has proven is within the realm of reason. It would be a great benefit to have a launcher that can handle medium sized payloads rather than super giant mega ones (JIMO?). Rediculous 500MT, 70m payloads would suffer from signifigant structure, engine, and fuel mass penalties due to Earthly construction for spacecraft. High risks in building very very large rockets (that mistakes would be made and missed too), unproven launch strategy, low flight rate, poor payload-matching utility, poor escape velocity utility, zero payload granularity... you get the idea.

With reuseable boosters, such as Energia's RD-170 boosters good for ~10-20+ flights each at only a few million per flight in overhead, surrounding a core that is fairly easy to build powerd by a small number of large Cryogenic engines (under $200M is quite possible), and modest Cryogenic upper stages that are reasonably priced can deliver all this for fairly low sums.

Specialty telecomm & control computer hardware, not commodity Pentiums and DDR memory, space rated... $
Gallium Arsenide doped crystalline Silicon cells, radiation and micrometeoroid resistant...$
Appropriate power control hardware and eclipse batteries good for a decade or so, solar-flare resistant...$
Multiple highly accurate (possibly gimbaled) trancievers...$
Tankage for toxic, corrosive, and extremely dangerous Hypergolic propellants, under pressure...$
Engines for Hypergolic propellants...$
Trained engineers on the ground to assemble, test, and integrate the satelite for launch...$
Trained ground control engineers and associated facilities...$

Would you please point out how these items will suddenly become two or three orders of magnetude cheaper with more mass budget? ...Oh, and don't forget, that as the vehicle gets heavier, it will need more fuel and larger engines, growing exponentialy larger. Think about it, the tens or hundreds of millions for a satelite go in large part to the expensive construction, handling, and launch staff; you sure aren't going to build a satelite with Bob the Machineist who makes household appliances or Karl the electrician who builds houses no matter what its made with. This is why Proton and Zenit-II cost a third of comperable American launchers, not because their rockets are far superior, but because the builders are so comperably underpaid.

Would it cost less if you could build it from steel, with copper wiring, with heavy radiation/meteroid shielding, and all that? Sure it would, but thats not going to make it cost less than several millions of dollars, because competant aerospace engineers can demand high wages, and because many of the componets will be of similar cost simply because they are inherintly complex and made in small number, not because they are expensive to build light weight.

Euler · 2004-08-18 18:13:39

It seems a personal belief of yours that rocket technology cannot possibly get better. Lords know why as this is not reflected in practice.

It is not a belief that rocket technology cannot get any better; clearly it can through lighter materials, cheaper and more reliable engines, etc. However, the belief is that there are reasonably competent and intelligent aerospace engineers that design the rockets. This means that the rockets will be pretty well optimized to do their job as cost effectively as possible, and that therefore there will not be orders of magnitude improvement without improvement in technology.

SpaceNut · 2004-08-19 08:07:09

Most design work and workers usually do not care about cost of parts or of labor to make items. There usual goal is to just make it work and that it is someone elses problem for cost. The only way to change that mind set is to reduce the available design funds. Forcing the designers to finally give a care.

quasar777 · 2004-08-19 08:17:57

i haven`t visited the Sea Dragon site yet, so forgive if i`m a bit off. wouldn`t it be easier to build a "smaller" Sea Dragon? i had a similar idea to this & i`d go a bit further & possibly even more "esoteric". it appears that while the Space equipment isn`t being used it could be used underwater & this would include spacesuits.

GCNRevenger · 2004-08-19 09:38:21

No, and no

As far as SeaDragon or other "Big Dumb Booster" concepts (emphasis on the big part), the bigger you make a rocket, the less fuel tank surface you need per gallon of fuel, and since the fuel tank accounts for the majority of the rockets' weight, the less it weighs the better. So, SeaDragon et al. came along and cooked up a rocket of such terrible size, 200m tall and nearly 50m across, that its tank area was so small compared to its fuel volume, that making it out of steel didn't kill the payload, even with an engine with inferior efficency. A smaller rocket, built the same way SeaDragon is out of cheap metal in a shipyard or a large hanger, would have much more surface area per gallon of fuel, so its tanks would weigh too much and the payload would be nil, particularly with the low specific impulse engine.

And no, you can't use space suits underwater really, because space suits are designed to be inflated to keep air in under higher pressure than space (a vacuum), not to keep higher water pressure out (underwater).

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Re: Cheap heavy launcher - can it be done at all

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Re: Cheap heavy launcher - can it be done at all

#32 2004-08-16 18:22:43

Re: Cheap heavy launcher - can it be done at all

#33 2004-08-16 18:33:08

Re: Cheap heavy launcher - can it be done at all

#34 2004-08-16 18:34:29

Re: Cheap heavy launcher - can it be done at all

#35 2004-08-16 20:12:00

Re: Cheap heavy launcher - can it be done at all

#36 2004-08-16 20:32:37

Re: Cheap heavy launcher - can it be done at all

#37 2004-08-16 23:20:14

Re: Cheap heavy launcher - can it be done at all

#38 2004-08-17 07:12:45

Re: Cheap heavy launcher - can it be done at all

#39 2004-08-17 08:00:48

Re: Cheap heavy launcher - can it be done at all

#40 2004-08-17 08:08:11

Re: Cheap heavy launcher - can it be done at all

#41 2004-08-17 09:50:26

Re: Cheap heavy launcher - can it be done at all

#42 2004-08-17 13:37:04

Re: Cheap heavy launcher - can it be done at all

#43 2004-08-17 17:24:06

Re: Cheap heavy launcher - can it be done at all

#44 2004-08-17 18:00:36

Re: Cheap heavy launcher - can it be done at all

#45 2004-08-18 15:57:27

Re: Cheap heavy launcher - can it be done at all

#46 2004-08-18 17:52:30

Re: Cheap heavy launcher - can it be done at all

#47 2004-08-18 18:13:39

Re: Cheap heavy launcher - can it be done at all

#48 2004-08-19 08:07:09

Re: Cheap heavy launcher - can it be done at all

#49 2004-08-19 08:17:57

Re: Cheap heavy launcher - can it be done at all

#50 2004-08-19 09:38:21

Re: Cheap heavy launcher - can it be done at all

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