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#26 Re: Human missions » Space Initive Launch Vehicle » 2004-09-09 13:44:52
It is perfectly safe as long as you don't mistreat it.
So are nuclear power stations. Accidents still happen. Probably nothing we can do to stop that but I still believe this is a foolish risk.
which will not be a big deal for a NASA launch vehicle.
Hmm. Which hopefully will not...
a real VTOL rocket would have to carry landing fuel.
A properly designed space shuttle would also carry landing fuel. The orrigonally intention was to give it jet engines. The reasons will still be valid for shuttle-II.
Return by parachute or aerofoil does not make it as practical to turn around as a vehicle which soft-lands in flyable shape.
You refused to believe that a space vehicle could land in a flyable state when we were discussing the DH-1. Fitting a new parachutte will probably not be a turn around limiter, as it'll take less time than the other tasks that need to be done; for either design.
A lift body can be built in such a fasion that it will naturally right itself during reentry even dead-stick
And it's kinda hard to design a cone that *doesn't* do that. Most capsules enter dead-stick and all slow down to safe ejection speeds long before hitting the ground.
Finally, a little size comparison...
By all means. By your numbers the DC-I would be smaller than the X-30 NASP, since a 747 is much bigger than 40m.
In any case, I'm the twit who favours the DH-1 remember 
That'd be about as small as the DC-I and comes apart into two pieces for easy handling. 
ANTIcarrot.
#27 Re: Human missions » Space Initive Launch Vehicle » 2004-09-09 11:20:14
I think that you are missing the point, at least in part Anti,
Oh I see. So what you want is a shuttle, built to fly into space, owned only by America, operated only by NASA, which will be of an all new, innovative design to replace those silly old fashioned ELV rockets.
Hmm. You know, that sounds vaguely familiar... I can't think, where have I heard that before?
it will be much more complicated than a conventional style rocket... but that doesn't make it inherently inferior, and a real order-of-magnitude reduction in launch costs is possible with sufficient demand.
Funny, you never accepted either argument for the DH-1.
I also don't think you have given enough credit to the RCC materials
RCC was what failed on Columbia. Up until then it was seen as a indestructible wonder material. NASA viewed it as the one part of the shuttle that could be hit repeatedly with a hammer and still certified for flight. And true, it *is* amazingly tough. But also true, it was smashed into uselessness by a piece of foam that I could crush in my hand.
It will work fine up until it hits something. Just like Concorde's wheel's worked fine until some stupid fog-leg twit left a piece of jagged metal on the runway that was as long as my arm.
Having such a vital part of the reentry shield face forward during flight is, I believe, fundamentally unsafe and a fundamentally bad idea.
can partially overcome the loss of mass fraction
If it's several times larger than a 747, yes.
you get your spaceplane back more easily and safely with its inherintly gentler dynamics
With an inherently more complex heatshield, with inherently longer reentry times and inherently higher heatshield temperatures.
DC-I with its puny Delta-II sized payload
VTVL SSTO does not equal HTOL TSTO! You cannot use such an argument to say HTOL carries more payload because multiple stages will almost always produce a higher mass ratio.
and if the engines fail?
What if your hydraulics fail?
A large VTOL would probably have 4 or more engines. Probably tending to much more. Small VTOLs will probably be fitted with parachutes or aerofoils. Even in a full mechanical/electronics failure, I'd rather be in the VTOL, as I don't need a runway to land safely in that.
Wings do add complexity to the shape and frame, but not as much as you think to the mechanical complexity.
As a studied aerospace engineer I can quite happily say, yes they do. They also add orders of magnitude to development complexity, time, and cost.
Bingo, that the Shuttle was designed to please everyone...
Very true. But the other flaw with the shuttle was that it was all new.
*New engines.
*New heatshield.
*New method of launch.
*New method(s) of recovery.
*New and complex shape.
All new (and especially complex, high performance all new) doesn't always work too well.
ANTIcarrot.
#28 Re: Human missions » Space Initive Launch Vehicle » 2004-09-09 05:53:18
The bennefit of using wings on a space ship is that it is easier to make it reuseable than a ballistic rocket.
That has been the standing assumption for amny years. But that doesn't make it true.
Aircraft type spacecraft will need large airports and large runways. These will not be cheap. They will need to fly through the atmosphere at high speed. Permission for that won't be easy. And they'll always be vaulnerable to a columbia style problem with the leading edge. And they are fundimentally a design compromise. When getting into space is as hard as it is at present, compromising on any aspect of the 'space' bit is shooting yourself in the foot in terms of cost and complexity.
Ballistic spaceships will also need a large areas. But launch pads take up less space than 5000m long runways, (so you can have more backups) and you aren't over-flying land outside your airport. You will not be building a super-concorde so you'll not face that class of political oposition. VTOL designs are by definition, pure rockets with sometimes a deployable aerofoil and landing legs. Yes this adds to the complexity, but nearly so much as wings do.
ANTIcarrot.
#29 Re: Human missions » China The Dominant Superpower In 20 Years..... - What does this mean for US? » 2004-09-08 05:13:22
An observation:
You all seem to be concentrating on the nuclear power plants, and forgeting about the system that supports them.
If there are lots of small pebble beds scattered over the country, then that's going to need several new nuclear processing facilities. Possibly bigger ones than at present.
The fuel will need to be shipped around more. This will increase security problems. Armoured convoys are being taken to pieces in Iraq. The same is easily possible in America.
Since it's 'perfectly safe' people might stop treating the threats so seriously. "Oh why not trim the budget a little? It's not like the stuff can be turned into a bomb or anything!"
Most obvious way a terrrorist could attack such a system would be to steal a small shipment of pebbles, grind them up into fine dust using any metal work shop, and then incorporate it into a dirty bomb. Or just dump the powder off a tall building in New York.
Engineers were quite satisfied that the Twin Towers could survive an aeroplane impact. And they were correct, for about an hour or so. Then they stopped being correct; mainly because they had never thought to acount for an aviation fuel fire. Columbia suffered a similar fate because the writers of a piece of software never thought to add a little tag saying, "Not suitable for calculating damage for foam pieces larger than 5cm!"
I can't help but wonder what the pebble bed enthusiasts have never thought to account for. 
And humbug to hydrogen cars! All electric ones are much better.
ANTIcarrot.
#30 Re: Human missions » Space Initive Launch Vehicle » 2004-09-08 04:39:41
I'm still not certian of the merits of sticking wings on rockets. Especially since the R&D costs are so much higher than for a VTOL design, with little operational benifit.
ANTIcarrot.
#31 Re: Science, Technology, and Astronomy » ISS cutbacks » 2004-09-06 06:32:08
Mad Grad Student to GCNR:
You go off on how idiotic the shuttle and the ISS are, then turn around and attack anyone who thinks NASA isn't performing up to par. Do you support NASA unconditionally as it is now?
Here's the thing: The shuttle was designed by comittee. But NASA has been flying it for twenty years. Though they cannot be held fully responsable for how it turned out, you can ask some very pointed questions as to why they haven't been improved upon, and how they managed to lose two of them in just over 100 missions.
True, the science rack won't fit through a progress hatch (do they fit through the shuttle hatch?!) but again, that's NASAs fault for designing them that way, and going to great lengths to ensure there's only one way to launch them. Ditto for all the other ISS components.
And then low and behold, to everyone's great shock, amazement, and complete surprise, the house they built on the sand fell over.
It's kinda hard to blaim anyone but NASA for that.
ANTIcarrot.
#32 Re: Human missions » Post central for information on CEV 2 - ...continue here. » 2004-09-05 08:57:06
The Desert Challenge thingie with the autonomous jeeps WERE GPS guided.
But, and here's the bit you missed, they were not following a known safe route. They had to cope with bolders, fences, and ditches strewn across their path and do so at 30mph+.
And they didn't do too bad when you remember most of them couldn't detect objects beyond a dozen meters. Many humans wouldn't do too much better if they only had two seconds warning between an obstical appearing, and it hitting the front of their car.
The 8 second delay sounds at least in part a computer problem. Better software and hardware could go along way to solving it.
ANTIcarrot.
#33 Re: Human missions » Delta IV Heavy and Beyond » 2004-09-02 10:48:22
The real problem probably won't be man rating the rocket, but man rating the launch facilities and procedures. NASA's hit and miss obsession with safety could wreck the launch utility of the most reliable rocket.
ANTIcarrot.
#34 Re: Human missions » Kerry's position on space - any one know were Kerry stands » 2004-09-02 08:45:32
It allows us to fight entire wars with far lower casulties than were common in a single day in times past.
And how are those expensive tanks, aircraft, ships and missiles helping you in the cities of Iraq? All those things can help you smash the enemy, but to take and hold the ground you need soldiers. It's always worked that way and it always will, even long after the soldiers stop being human.
You also need someone in charge who understands the realities of warfare and of the reigon they are attacking. And a people willing to back you and your soldiers.
If you won't comit the needed numbers of soldiers, if you don't understand what you're doing, if the people don't back you, then the most advanced technological toys in the world won't help you.
And quite frankly I'm a little curious - what is this country that's going to suddenly pose a serious technological threat to the US military?
ANTIcarrot.
#35 Re: Human missions » Cheap heavy launcher - can it be done at all » 2004-08-24 06:02:21
Be cautious about letting students draw conclusions such as "the computer I paid $1,500 for last month would have cost about $342 if I bought it 30 years ago" or "a gallon of gasoline that costs $1.57 today would have cost 24 cents in 1952." First off, re-emphasize that, while statements such as those about some products might be true, most goods do not “follow inflation” that exactly. Additionally, we cannot compare the buying power of computers in that way because computers were not available to consumers 30 years ago. And, as for gasoline, there are many variables that such a statement does not consider, including:
-from a guide to teaching inflation to high school students.
For example, based on the cost of a Model T Ford in the 1920s, a modern car should cost $3000. It doesn't. New materials, new technology, new manufacturing techniques, market size, and foreign competition all affect prices.
Wright Brothers aeroplane - New technology
I assure you the airofoil was in use long before the Wright brothers were born. That would make it old technology. The petrol engine was also not new technology. The only thing they actually invented (as proven by the patents they filed) was their control system.
You have done nothing but parrot the Traux brochure because their idea runs counter to armies of professional engineers, and come up with strawmen galore trying to defend it, with an article from a lone USAF officer for garnish...
The Wright brothers beat a similar army of professional engineers and scientists back in the 1900s. The army in this case is run by bosses who know they're paid on a cost plus baisis, and that profit is linked directly to the cost of the rocket.
And I haven't heard a satisfactory response about the really really lousy flexability of such a huge booster
Mention a single non-human payload or mission it couldn't accomadate, and I'll explain how it could.
with an article from a lone USAF officer for garnish...
...Which just so happens to support everything I say.
Half of the boat's construction IS the hull. <snip> I don't see how you can claim with a straight face its going to be loads easier.
Because I have provided evidence in addition to arguement, and you haven't. Until then you're just blowing hot air.
Euler
The real problem is that there is no market for such a booster.
True. Like any rocket you'd have to invent the need at the same time you'd invent the rocket. (SaturnV/Apollo style) The rocket couldn't and shouldn't be built without a big project to justify it.
ANTIcarrot.
#36 Re: Human missions » Funding human missions - Lets chat basics » 2004-08-24 04:37:19
Nobody has ever done anything like that before, and could present a whole range of issues beyond simply hitting the target from hundreds of kilometers away.
A proof of concept couldprobably be launched for a few hundred million. ISS solar panel truss + microwave transmitter + attitude control. Such a mission would probably answer a lot of questions.
and how about transmitting the power down the cable by HTSC wire?
IIRC, the physics are against that. Superconductors only work below thier tempreature limit AND below a certian level of power flow per unit area cross section.
Value of asteroid materials:
Based on NASA space colony design study. 10,000ton linear accelerator tug starting in LEO. 6,000tons of that is reaction mass. (EG: ground up propellent tank, waste, etc.) Including main tank, an SDV can put ~130tons into orbit per launch. This would require about 76 launches. Say 80 for convenience. ming a launch rate of 12 per year this woudl take under seven years. At $250M per launch this would represent an investment of $20B dollars in launch costs. Add another $10B for R&D + construction. Total system cost: $30B. Tug returns 500,000 ton asteroid to earth a few years later.
Asteroid material is worth: $60/kg.
100tons 'useful cargo' SDV: $2,500/kg.
That's before refining of course. But there is a possibility here for the material to be made into something worthwhile in earth orbit for less than the cost of launch an equivolent amount of material from earth.
Space manufacturing:
There are two issues here. Can things be built in zero G that are exportable to earth? Can spinning create a good enough emulation of gravity to make normal earth style manufacturing practical, and therefore illeminate the requirement for R&D & it's cost.
A common material claim for the future is 10 times less weight for any given strength. (Glassy metal, nano-tube reinforced metal, etc.) Assuming this is true and that the material had to be made in space, there are a few potential buyers.
A 'super material' F-18 would weigh 1,400kg. It could accelerate forward and bank ten times harder than it could at present. You'd have to nail it down on a windy day to stop it flying away, but you could also operate it from the deck of a frigate's helicopter pad. 
An aerospace company would be more than willig to pay several thousand dollars a kilo for such a material. Unless there were apparent disadvantages, or it could be made on earth for less.
A 5GW SSPS that lasts for 20 years before major servicing will generate $96B of electricity at $0.11/kWh. Since electricity in the US sells for $0.12/kWh you could improve the lives (or at least power bills) of tens of millions of registered voters. Who would then (in theory) support you and your space programme.
ANTIcarrot.
#37 Re: Human missions » Cheap heavy launcher - can it be done at all » 2004-08-23 18:18:34
increase linearly with surface area
Quite possibly, but I don't have the costs for a military submarine pressure hull to hand. I doubt you do either. I put it to you however that the pressure hull will be a small portion of the over all cost. Say, $10,000,000?
handling and welding thicker plates of steel for submarines costs less than welding three thinner plates, because it takes three times as much manpower.
That does not follow. A plate twice as thick can take twice as long to wield, or twice as many people to wield in the same amount of time. But it doesn't automatically take three times as many men to wield an arbitary thickness of steel than it does for another arbitary thickness of steel. Which is what you've said.
the two huge, gargantuan, monsterous rocket engines
Since it's a pressure fed system, the pressure in the engines cannot exceed the pressure in the tanks. There will be problems with tempreature, and spredding the propellent to all the combustion chambers evenly, but ptrobably nothing that can't be over come.
expanding exit cone for the second,
Where does it say this is a feature of the SeaDragon design?
In fact, it seems a common theme in the AltSpace zealots, that they are obviously much more clever than the "old geezers" of rocketry.
Funnily enough, at the time it was the altspace zealots who wanted to build the shuttle and bring costs down, and the old fashioned engineers who wanted to take advantage of the cube/square law.
Then NASA's budget was slashed and there was no need for HLLVs of any type, since they wouldn't be going anywhere or doing anything for the foreseeable future.
And as I am sure you will attack me over, I am going to invoke the rule you don't seem to be able to accept... that if this were such a good idea, so much better than what we've been doing, then somebody would have done it already.
Apply the rule to Kitty Hawk. Or the computer. Or for that matter, the wheel. "Why bother building any of these things," your sacred rule would argue, "because if there was any point to them, it would have always been done."
It's a stupid rule invented by a stupid, petty, small minded person who lacked the imagine to realise what its application would truely mean: the abolition of all progress and invention.
unless the program is run by the military.
And that part *would* be under military control. As I clearly said in my post. We'd only be paying transport & electricity costs at a fixed $30M/year. At *any* time they like they can sail away from the deal, for a proportional loss of income. It's unlikely they would, purely from the prestiege they'd ganer from out-manouvering the USAF. Or the Americans, if we rented russian/french.
$500,000,000 each is probobly being too generous
If you had absolutely any evidence or proof it would cost that much you would have posted it. You haven't, so you don't, so it wouldn't. $265M is a good maximum. Chances are it would cost much less than that.
ANTIcarrot.
#38 Re: Human missions » Funding human missions - Lets chat basics » 2004-08-23 17:09:28
Solar power stations are getting to be practical in terms of cost invested/cost returned - barely.
The killer is build time though. Even with sea dragons going up 4 times a month that's only 24,000tons/year, and a 5GW SSPS weighs 100,000tons. So you're talking about a 4 year minimum build time and it'd be difficult to build them in parallel. With 10 DH-1 launches a day it'd take 12 years.
You also need to invest heavily up front. Build costs for direct launch can be as high as $60B, and even if the eventual return is $100B companies are reluctant to make the initial investment.
Asteroid or moon-built SSPSs cost less on paper (say $20 up front + $5B per SSPS) but you're gambling that the mineral resources are there and that you can get at them easily. since there's no proof that they are, Halliburton contine to invest in oil and political brides.
ANTIcarrot.
#39 Re: Human missions » Kerry's position on space - any one know were Kerry stands » 2004-08-23 07:09:05
Why can't you build the new power station right on top of where the old one use to be.
Because much of the power station itself counts as radioactive waste, and it's much easier to leave it where it is rather than knock it down and contain the resultant fallout.
ANTIcarrot.
#40 Re: Human missions » MarsDirect or Mars Sustained ? » 2004-08-23 05:13:35
If we show a long term development approach with returns in the short term ( 3-10 years ) into the long term exploration of space by humanity then the public will allow the expansion of the exploration.
The post apollo applications programme showed a long term development approach with returns in the near term and settlement in the long term. The public didn't care as they knew that 'settlement' means 'settlement by scientists'.
The public will always care more about issues closer to home. Unless a space programme can have a positive effect on tens of millions of people they will not be interested. This is why they like TV satellites, and are willing to *volintarily* pay for them through license fees, and why they kinda like Hubble. All those pretty pictures don't you know.
Why would they like Mars Direct, or any variation? And more to the point, why would they like a second Mars Direct? Single cell life will only hold their interest so long.
ANTIcarrot.
#41 Re: Human missions » Kerry's position on space - any one know were Kerry stands » 2004-08-22 10:58:51
There is not really all that much nuclear waste,
There may not be a lot of fuel-rod waste, but it is my understanding that each power station has to be shut down after about fifty years and then left alone for the next 500. Another reactor also has to be built to take its place.
Wouldn't a pure nuclear policy end up with ten dead power stations for every active one?
ANTIcarrot.
PS: And I believe NASA costs around $15 per person in America.
#42 Re: Human missions » Cheap heavy launcher - can it be done at all » 2004-08-22 09:56:18
Cost:
I believe that even if SeaDragon is possible, that its costs will be much higher than its proponents think. The vehicle itself would take a long time to build, limiting flight rate from a single factory, which idles the launch staff for long periods and prevents launching of payloads when you need them, forcing you to wait months between launches.
Sorry for the poor quality. I never could get this kind of printed work to scan properly...
Anyway, in the above picture you can see three Vanguard nuclear submarines, with space for a forth. Each is 150m long and 13m wide. Allowing that each sub is half the width, but the right length, it's quite demonstratable that the 'drydock' can accommodate two complete sea dragon rockets, or three or more partially complete ones. This represents the capacity of one building in one shipyard owned by one company that is based on a island of no great size located off the northern shores of continental Europe.
With four buildings like this you could build 8 sea dragons at the same time. Alternatively 2 container-ship/oil-tanker dry-docks would do as well. So even if it took 8 months to build (and I'd disagree that it would take so long) you could still launch them at a rate of one per month. Taking the Virginia as a model, it takes 16 months to build one on a limited production line. Assuming a linear relationship between weight and time, this would translate to a period of about 4 months for SeaDragon. Assuming a similar linear relationship between mass and using the LA as a model each SeaDragon would cost $260M to build.
These are fairly conservative estimates, because the SeaDragon would not need the complexities of an acoustic stealth systems, sensitive sonar systems, life support for 9000 man days, internal decking or sub compartments, weapons load out, or a nuclear reactor. Based upon these estimates, the single building in the picture above could crank them out at a rate of one every two months.
You'd need something like s sea launch Assembly and Command Ship, a nuclear reactor to desalinate and crack the sea-water, and a tug or two to move them from the ship-yard slip-ways to the nearest patch of 20mile wide area of open sea. (NB: A fully loaded SeaDragon will be the equivalent of 1/4-1/3 of the Hiroshima bomb if it explodes full loaded. You need a big open area!) If you wanted to recover the first stage you'd also need to tow it back to the launch site.
No idea how much it costs to move large objects around at sea, but we could always rent decommissioned LA class subs from the US DoD. (Say, $30M/year/sub.) We'll need at least one on site. With six launches a year it might as well double as a tow-boat as well. So that's now $265M per launch.
The original concept assumed a nuclear aircraft carrier, but an LA sub with modifications would do as well. Such an arrangement would not be unusual, as DoD regularly rents out its hardware and/or personnel to anyone or anything that would put them in a good light. The navy in particular would likely be very interested in, as it would allow them to break the USAF's monopoly on US space assets, and to keep a 'reserve fleet' of LAs active at zero cost. The US DoD Will probably want to keep a close eye on us anyway.
If not we rent Russian for a similar cost. Since we’d only be buying transport, electricity, and minor labour there’d be nothing illegal about such an arrangement. Or even worse, we could rent from France!
There'll probably be a few million in misc costs on top of that, but that looks like a good ball-park figure. It's also close to the optimistic costs for a single SDV in the 100ton class, and roughly twice the maximum estimated cost for the Delta IV heavy. As near as I can tell GCNR's super EELV will put 100tons in LEO for around $100M minimum. That it however a minimum cost. A maximum would be ... what? $150M-$200M?
Payload technology
The principle requirement for aerospace computers is for them not to interfere with other delicate aerospace components. Of course if you're using commercial hardware you don't need to worry. My computer does affect my mobile phone beyond a few meters. Shielding from radiation would be a simple matter of dunking it in the water-tanks (also useful for cooling) with a suitably water tight container. A commercial computer in a modded case could probably work quite happily inside a space station for a few thousand dollars extra. But you still wouldn't want to use Pentium IVs are they're not particularly reliable on the ground.
Use normal solar cells. Build SSPS at the same time to bring costs of cells down. Build cells perpendicular to solar radiance, with thick shield along one edge facing the sun and a mylar sail above.
Commercial UPS systems. Integrate as LRUs.
Use sat-TV dish linked to star-tracker telescope and GPS receiver. One can receive high bandwidth signals from 30,000km away, the second can aim very accurately and can get its starting position from the last.
Tankage for methane and oxygen. Under pressure, but not corrosive. Use of ion-drive for minor correction. Use of heavy reaction wheels for low cost attitude control.
KISS satellite requires someone with college level understanding of computers and some mechanical knowledge. Plug A into slot B. These would be family cars not F-1 racing cars and the people working on them would be trained appropriately.
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 that’s not going to make it cost less than several millions of dollars, because competent 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.
If it was made out of steel and copper wiring only a complete moron would pay aerospace engineers to build it. You'd use electricians, plumbers, and wielders. And highly qualified artisans are all kept far away in the factories that produce the parts needed.
No, and no
Wrong and wrong. At least according to every single aerospace company in America, who all believe that yes, it *can* be done. None of the smaller designs get close to SeaDragon costs, but they all report a substantial reduction in launch costs. They also agree that such a reduction in launch costs would have a knock on effect on cheaper satellite construction.
ANTIcarrot.
References:
Sea Dragon Rocket
Length: 150m
Width: 20m
Weight (empty): 2,000MT
GLOW: 18,000MT
Payload: 500MT to LEO.
http://www.astronautix.com/lvs/searagon … aragon.htm
LA class attack submarine
Construction cost: $900,000,000
Operating cost per year: £21,000,000
Weight: 7,000MT
Power generated: 35,000shp
Pressure capacity: Greater than 24 atmospheres of pressure at ~800feet
"Between 1998 and 2001 the US will retire 11 Los Angeles class submarines that have an average of 13 years left on their
30-year service lives."
http://www.fas.org/man/dod-101/sys/ship … sn-688.htm
Virginia class attack submarine
Weight: 7,800
Construction schedule: Four subs in five years.
http://www.fas.org/man/dod-101/sys/ship … p/nssn.htm
Launch costs for a few vehicles (cera 1990)
http://www.futron.com/pdf/FutronLaunchC … CostWP.pdf
http://www.ecsel.psu.edu/~sqm110/XST/Ap … ST/App.htm
Delta IV rocket launch costs from an estimated $70 million to $140 million dollars.
LEO On the cheep
"Yes rockets can be built for less."
http://www.dunnspace.com/leo_on_the_che … _cheap.htm
Fin.
#43 Re: Human missions » Cheap heavy launcher - can it be done at all » 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.
#44 Re: Human missions » Cheap heavy launcher - can it be done at all » 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.
#45 Re: Human missions » Cheap heavy launcher - can it be done at all » 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.
#46 Re: Human missions » Cheap heavy launcher - can it be done at all » 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.
#47 Re: Human missions » Cheap heavy launcher - can it be done at all » 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.
#48 Re: Human missions » Cheap heavy launcher - can it be done at all » 2004-08-16 13:16:39
Define 'heavy'. You say around 100tons per launch, but where's it going? Is the idea to put up lots of ISS size stations? Send huge 60mt probes off to mars et all? Build something *really* big, like an SSPS? Or just put a huge amount of fuel or small parts/people into orbit?
For the first two, some kind of SDV like Zeus, Shuttle-C or Shuttle-II (space island group) would be good. For the last, something on the scale of DH-1 or a mass produced zenit (literally launch them as they roll off the production line) might be better and cheaper to operate. For the third, something like SeaDragon really is the way to go; especially for projects in the 10,000ton plus range.
It all depends on how much you want to put up and how quickly. Just remember that the more you put up and the more often you launch the cheaper it all becomes.
ANTIcarrot
#49 Re: Human missions » Opening space to Individual or private industry - Space CHASE Act » 2004-08-16 06:03:08
The USA is not going to listen to any non-US organisation Comstar3. The government has difficulty enough listening to the will of the people, as demonstrated by the scandle in Florida four years ago.
You can set it up if you like, and maybe China would show interest, but everyone from ESA, USA, and RSA is going to see it as a waste of time and all the smart ones will try desperately to avoid it. So only the old, the foolish and the young will get in, which will undermine it's reputation even more.
As for handing $15B a year over to any organisation that is not controlled rigidly (or does not rigidly control) congress is simply not going to happen. They won't evven give that *cough* 'large' a sum to a company like McDD to build something like the DC-X. What chance has a UN derived organisation have?
ANTIcarrot.
#50 Re: Human missions » Opening space to Individual or private industry - Space CHASE Act » 2004-08-15 17:18:33
But, as far as to why the space does not seen to be sustainable, we should look at NASA history of who affected it. You would have to follow what Kennedy did and what Wall Street did along with the Federal Reserve System and the banking system.
I believe the costs of the Vietnam war also had something to do with it. Strange that the US government claims it couldn't afford a peaceful space programme, but could afford to start a war with a country that was asking America for help.
Of course now we're in a similar situation, with another somewhat mismanaged war, and another space programme. Though in this case the space programme is just starting, and is somewhat mismanaged as well.
Gee, I wonder where the money's going to go this time?
ANTIcarrot.