Talk:Size of Infrastructure
The assemblers need not be nano. Self-replicating factories will at first be very big. A good way to simplify the replication process is to have shared componentsmarsp.
As for HLVs, do not fixate on Ares V, constellation and NASA. One example is Sea Dragon. Sea Dragon had a payload capacity of 500 tons or so. HLVs have ~100, MLVs, say, ~20 tons. How hard would it be to scale down Sea Dragon to the size of an HLV or MLV?
If it is not vital to have a HLV for lunar return, it would certainly be preferred. Just not a NASA monstrosity. T.Neo 09:39, 7 September 2008 (UTC)
- As far as I know there is no need for HLVs to start a lunar colony. The costs of maintaining launch facilities for HLVs are outsized just as the rockets are outsized. Since HLVs are infrequently launched, the annual maintenance costs are spread over few launches making HLVs expensive per pound of payload. Eliminating an entire unneeded class of launch vehicle results in savings that should not be missed.--Farred 14:24, 22 October 2008 (UTC)
- Robert Bigelow has said that he plans to assemble mutiple Bigelow modules in LEO, then land them on the moon. For non-inflatable, rigid shell habitats, HLV's may be necessary. Using less costly, commercially available rockets is one of the advantages of the Bigelow approach. - Jarogers2001 15:16, 22 October 2008 (UTC)
- I see your point, Farred. However, the whole concept behind BDB (Big Dumb Boosters) like Sea Dragon is to reduce those costs throught simplicity. For example, how about using room temperature propellants such as H2O2 and kerosine/hydrocarbon instead of cryogenics like Lox/LH2? I do think, However, that below a certain point, sea launch becomes too costly, and it would probably be better to do a conventional land launch. We ship cargo in bulk on huge container ships, not one-by-one on rowboats.
We also need smaller launchers, I am not saying that we don't. It is a pity BDB was never applied to smaller launchers. T.Neo 22:35, 22 October 2008 (UTC)
- The problem with H2O2 is its instability. The safeguards to protect against/prevent violent decomposition tend to be more expensive than going with LOX. BDB should probably be applied with LOX/Kerosene. SpaceX is trying to take this route. - Jarogers2001 00:59, 23 October 2008 (UTC)
Not even "real" kerosine. I am talking about something more like Jet A. The OTRAG project used plain gasoline, if I remember correctly. What about propane/MAPP gas/natural gas? Could these be used as room temperature, self pressurizing propellants? With room temperature oxidisers, nitrogen tetroxide is used often, and nitric acid of several varieties have been considered. These two are toxic and volatile, so how do they stand up to H2O2? Which is cheaper: Lox/H2O2?
- Cost per litre
- Cost of handling equipment
- Cost of maintaining handling equipment
- Cost in weight, of fill/drain and other handling systems on board the LV
- Cost in terms of Hi-tech materials used both on the pad and on the vehicle
- Also, if empty stages were to spill residual propellants, or the rocket went off course, H2O2 would quickly dilute into the water into low levels thatare tolerable. N204/Nitric acid would do terrible things, but LOX would just go boom.
SpaceX disappoints me with the amount of "Hi-Tech" components on their LVs, like the turbopump driven Merlin (First stage Falcon1, both stages Falcon9) and the niobium nozzle on the Kestrel engine. I am talking "down and dirty" technology, rugged, off the shelf, cheap. Like OTRAG.
A big dumb booster concept, the Beal BA-2, used jet fuel/H2O2 in all stages. It failed because, like I said before, it started out too big. T.Neo 08:23, 23 October 2008 (UTC)
- something from --Farred 00:48, 27 October 2008 (UTC) follows.
- There have been merchant vessels such as the Edmund Fitzgerald which carried 26000 tons of ore to the bottom of Lake Superior and rowboats have been economically important, but these craft have nothing more to do with rockets than a garbage truck does. In spite of any watercraft examples, eliminating launch facilities for HLVs would save money.
- Sea Dragon was an interesting design that might have been the cheapest way to launch very large payloads, but it was never built. It may be that there was some difficulty that was found during development of specifications for production that discouraged production. It may have been decided that there was simply no need for such a large rocket. In any case, it is not needed now.
- OTRAG’s Common Rocket Propulsion Units might have allowed the benefits of mass production to lower launch costs some, but OTRAG never launched to orbit. There is a reason that upper stages use higher specific impulse fuels than lower stages. Saving a pound on a third stage makes a bigger difference in the gross takeoff weight than saving a pound on a booster.
- I have no objection to propane and liquid oxygen; or RP1 and liquid oxygen as a first stage propellant. The thing that is unneeded is the size of a Saturn V.
- The Chinese seem to be building something big in the line of rocketry. Perhaps they intend to go to Mars and aspiring Martians should learn Chinese. It may take fifty years for financial returns to start coming in from industrial developments on Luna. We still need more information about available lunar resources to figure that out. It will take much more than fifty years to see the first financial returns from Mars. --Farred 00:48, 27 October 2008 (UTC)
OTRAG had low Isp upper stages. It sacrificed efficiency for a reason, lower production cost. However, there are some uses for which there must be a high Isp. Things like Earth Departure stages, and landers, etc. Look, for example at a VASIMR lunar tug. It sacrifices production and operating costs for Isp and efficiency. Use lox/kerosine if you want. H2O2 might be inferior to Lox, but compared with other room temperature propellants, it comes out safer then N2O4.
To make space travel a real possibility, and to branch out of LEO, we need to leave behind the old NASA way of thinking. We need our launchers to be rugged and strong, simple and effective. We must reserve liquid hydrogen and turbopumps for moon landers. We must adopt simple methods of construction.
End of rant. T.Neo 07:46, 27 October 2008 (UTC)