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Chemical rockets would require to much fuel and Fission rockets would spread radioactive materials everywhere. So Fusion would be the only way to go. Any more ways it could happen?
(This is assuming Anti-Gravity isn't invented.)
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I doubt it. Nuclear fusion reactors simply require too much reactor mass per amount of power they produce, they will never be light enough to get a rocket into space.
Chemical rockets don't have the efficiency to get all the way to orbit, but they could make a perfectly fine TSTO (two stage) fully reusable vehicle. Or alternatively, an advanced air-breathing engine, where the engine gets its oxidizer and much of its reaction mass from the atmosphere, are far more efficient than chemical rockets.
Unless of course somebody comes up with a way to make cyclic ozone or stable monoatomic liquid hydrogen, then a conventional-style rocket modified for superhigh temperature operation would make a SSTO easy.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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Again, many many tonnes of machinery which produce only small amounts of power (relatively speaking). To put things in perspective, the Space Shuttle's main engine, the famous "SSME," generates about nine gigawatts of power (nine billion W) while weighing only around 8 metric tonnes.
NTR engines simply pose too large of a safety risk, and are only efficient if they use liquid hydrogen, making the vehicle extremely bulky.
I maintain that an SSTO, with near-term materials, will only be practical with air-breathing engines or exotic superhigh performance chemical fuels (cyclic ozone, monoatomic hydrogen).
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Methane is denser and cheaper, but because it is heavier it gets poorer performance than Hydrogen. Generally it isn't worth the trade off for large rockets, which is why nobody uses it except small Russian satellite launchers.
NTR rockets are not acceptable for launch vehicles:
-First of all, the propellant must flow in very close proximity to the nuclear reactor to efficiently transfer heat, which generally leads to the propellant carrying bits of the intensely radioactive reactor core out and into the exhaust stream. This is an inherently difficult problem.
-Second, the shielding required to protect the vehicle from the massive radiation flux will be quite heavy, thus reducing the efficiency benefit from NTR.
-Thirdly, the engine will remain intensely hot (as in temperature) and radioactive after firing for months as a result of decay heat, so if there were an accident and the reactor was damaged before reaching orbit the fallout would be catastrophic. It could very well be the equal of Chernobyl... you will find no stronger supporter of space nuclear power than me, but this is silly.
-Fourth, handling the NTR engines on the ground between firing would be very dangerous and very expensive, ruining much of the cost benefit of the technology. (See USAF nuclear-powered bomber).
-Fifth, the only efficient fuel for NTR (liquid hydrogen) has extremely low density, which makes its tanks very large. A big problem for an SSTO vehicle where volume is at a premium.
And, don't forget, that NTR engines only have about 50% better performance than chemical engines, once you adjust for the difference in fuel density. Its just not worth it.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Oh, and to put things in perspective... a commercial nuclear power reactor requires a few inches of steel, several feet of water and concrete to keep the radiation dose low, right? Such a reactor typically operates at ~2-3 gigawatts (thermal), while an NTR engine would need to run as much as ten times as high. The radiation output from such a reactor is truly terrible and massive!
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Hydrogen has the lowest molecular mass of any stable substance possible, and oxygen is not far behind as practical oxidizers go.
As far as pure rockets, we could play with slushed Hydrogen, which would give an improvement in density anyway. It might make an SSTO personnel shuttle possible.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Here's the deal. While the amount of thrust you get per unit of fuel (specific impulse/ISP) is of critical importance to interplanetary travel, the rate at which that power can be safely released, and the amount of mass it takes to generate that rate (specific power/thrust) are very important during lift-off as well.
While most sorts of nuclear engines (be they NTR, GCNR, VASMIR, Fusion, whatever) may have superb ISP, their specific power/thrust is poor to downright terrible. Whats more, there is a limit to the rate at which most of these engines can safely release their energy due either to heat dissipation (VASMIR and others) or radiation (anything involving Fission).
Thats why none of these is suitable for a first or second stage engine for an Earth-side lift-off. Chemical or air-breathing really are the only options, (with chemical being the best in my book). I wouldn't be so quick to count out other chemical fuels though. H2OH, CH4, C2H6, and Keresone all have lower impulse than the LOX+LOH combo use in the shuttle, but they all are denser which can give you an advantage in tankage size (which is critical for SSTO).
He who refuses to do arithmetic is doomed to talk nonsense.
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What's slushed Hydrogen, and what's Cyclic Ozone? I know Ozone is O3, but how would that help?
I'm only 13.6 and interested in Biotech, not chemistry. I don't tend to search out info on the net about chemistry.
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If you get liquid hydrogen cold enough, you can actually freeze the stuff into a solid, and if you finely grind the solid and mix it with liquid, the combined slurry will flow well enough to be pumped into a rocket engine perhaps. If you do that, you can cram 20-30% more (reportedly) into the same sized tank as you would the liquid alone. It is also ideal for spiking with small amounts of highly active (aluminum or lithium powder) substances to boost the specific impulse a little.
Cyclic ozone is a variant of regular O3 ozone, which theoretically is fairly stable and contains much more energy per gram than its ordinary sibling. However, nobody has figured out how to make the stuff yet in any quantity.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Could Nascent Hydrogen be freezed into an unreactive solid for storage? Then mix it with Aluminum powder a little and stick it in Liquid Hydrogen? and use Cyclic Ozone for the Oxidizer?
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assemble the fusion reactor spacecraft in space
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We're talking about SSTOs. Not Spacecraft to other planets. SSTO- Single Stage To Orbit.
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Could Nascent Hydrogen be freezed into an unreactive solid for storage? Then mix it with Aluminum powder a little and stick it in Liquid Hydrogen? and use Cyclic Ozone for the Oxidizer?
Solid hydrogen isn't some unstable exotic matter like monoatomic hydrogen or something, but it would have to be kept exceedingly cold. That plus cyclic ozone for an oxidizer would give you NTR-like performance using chemical fuels. That ought to make an SSTO space vehicle pretty easy, once you came up with an engine that could take the heat.
I do discount the viability of low performance high density fuels (kerosene, methane, peroxide) for an SSTO, they just don't have the necessary punch. A really robust, effective, reliable and cost effective SSTO vehicle needs margin, it doesn't just have to work but it needs to have the extra mass to be built strong. A reusable SSTO that crashes every hundred flights or can't carry much is pretty worthless. This is, of course, barring a revolution in composite and reusable heat shield materials.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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We're talking about SSTOs. Not Spacecraft to other planets. SSTO- Single Stage To Orbit.
Okay..... but it still is in the 'interplanetary transportation' section.
If the Fusion can't power an SSTO of the ground, perhaps a large fusion craft can be built in orbit that never lands, only transports orbitally between planets and asteroids, using other vehicles for surface operations
Perhaps a Fusion powered railgun/mass driver could launch the vehicles into orbit?
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But that orbital craft still needs a Shuttle for surface operations.
Are there any catalysts that would turn H2 into 2H?
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Okay..... but it still is in the 'interplanetary transportation' section.
This section is the best one for discussions about launch vehicles and propulsion.
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Are there any catalysts that would turn H2 into 2H?
Not to my knowledge: one problem is that the 2H would immediately recombine into H2 upon leaving the catalyst (as they are in close proximity), and the second is the rather large amount of energy needed to break the H-H bond.
Making monoatomic Hydrogen isn't so much the difficulty, the trouble is with storing it so that it doesn't spontaneously recombine to H2 before you can use the stuff as fuel.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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SSTO is achievable with ground assist.
Mass driver acceleration track + rocket engines fired once clear of the track.
(Or at megaengineering scales -- probably not in our lifetimes -- just the former would be sufficient.)
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I don't see anybody counting the extra assist from the low latitudes at Kourou as one more stage. If it's on the ground, separate from the vessel going to orbit, I don't see why it should be counted.
You're just fudging semantics because you apparently don't want to accept it as a SSTO.
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What was that Gaetano - sorry, Samy?
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