| written by Zixinus on May 24, 2007 14:49 |
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What you see above you is a picture of a Saturn-5. This is the same rocket that allowed Man to kick some dust of Luna.
Size: 111 meters tall
Fuels: RP-1 (kerosene) and liquid oxygen
Thrust (first stage): 1.5 million pounds
Payload to orbit: 129,300 kg
Dry mass: 187, 78724118 kilograms (414,000 pounds)
Use-once. Multi-stage.
The Saturn-5 is an impressive piece of engineering. It never failed.
What you see below is a similar concept representation of a rocket along the idea of the Saturn-V. With one crucial difference.
Size: 115 meters
Fuels: Uranium for the gas cores, hydrogen for propellent
Thrust: 8.7 million pounds with all seven engines, 6 million if only five.
Payload to orbit: 907, 18474 tons (200000 pounds)
Dry mass: 725, 747792 tons (1600000 pounds)
Fully reusable. SSTO. Exhaust is hydrogen.
The difference: nuclear. Chemicals can give you only so much energy. Nuclear can give you allot more.
Safety? The craft pictured here is conceived with redundancy (you would only need 5 engines, you carry two extra just in case) and radioactive waste is dealt with within outer space (it is literally shot towards the Sun while circularization). Shielding is included to the mass shown.
I believe the numbers speak for themselves. | |  | |  |
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  | written by Naavis on May 24, 2007 15:10 |
 | |  | | ![]() Umm, it's still a rocket. It can't land back on Earth. I don't know if it can be called reusable. Unless it means that just the nuclear gas core is reusable. | |  | |  |
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| written by Zixinus on May 24, 2007 15:15 |
| written by Naavis on May 24, 2007 15:27 |
| written by Pomelos on May 24, 2007 16:35 |
| written by Zixinus on May 24, 2007 19:33 |
| | | | ![]() Yes and no.
It is not NERVA or solid core at all. It uses fission yes, but the fission works at such a hot temperature that its gas. The entire reactor area is gas infact.
It is a thermal rocket in sense that it uses heat created by fission to propel the propellent.
I'll explain how it works:
Inject fission fuel at high temperatures. It undergoes fission, more heat is generated. Inject hydrogen, and it will be propelled outwards. This is an open-cycle gas core. It gives great performance (especially compared to chemical performances), but not desirable due to the small little fact that radioactive fuel and waste will escape with the exhaust. 
However there is a way around this:
Contain the reactor in fused silica.
The fuels are so hot that it emits its heat in the ultraviolet region, instead of infra-red. The fused silica is transparent to ultraviolet, so in effect, the heat emitted will heat the propellent. The propellent will also cool the container. The propellent becomes so hot in the process that it will give significant thrust, with higher velocity then what chemical engines can give.
This is called a closed gas cycle system, or "nuclear lightbulb". In essence, yes it is a nuclear thermal rocket, but not your usual one.
Exhaust velocity is an important measure of rocket performance. The best chemical rockets can give about 4500 m/s. This baby could give you about 20 000 m/s.
 | Naavis said: | | Apparently no one's building it yet, it's only a proposition. |
| Zixinus said: | | What you see below is a similar concept representation of a rocket along the idea of the Saturn-V. |
The idea is to tell people that nuclear-powered spacecrafts are okay, and are superior to chemical rockets.
Here is a site talking about realistic spaceships: http://www.projectrho.com/rocket/index.html | | | | |
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└> last changed by Zixinus on May 24, 2007 at 19:50
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| written by Naavis on May 24, 2007 20:15 |
| | | | ![]() As far as I know, nuclear-powered spacecraft have always been okay. That specific concept could be a bit more credible if it was mentioned in more places than just a short forum post and a single, obscure article. And no one still explained the reusability-issue. The article says "It flies to space with a thousand tons of cargo, and flies back using some gentle aero-braking and its thrusters with another thousand tons of cargo." but according to the picture it's a rocket. A rocket lacks the control surfaces needed to maneuver well enough in Earth's atmosphere, not to mentioned the lack of landing gear and such. That's why shuttles were invented. | | | | |
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| written by Zixinus on May 24, 2007 20:31 |
| | | | ![]()  | Naavis said: | | As far as I know, nuclear-powered spacecraft have always been okay. |
No, they haven't. They were, in fact, only okay in the 50's.
With the increase of nuclear-hysteria (see Godzilla, and pretty much any Hollywood film touching anything nuclear), even Cassini-Hyden was protested againts. This is a spaceprobe, not even manned or meant to come back to Earth. Most protesters most can't comprehend anything beyond "NU-KU-LAR = BAAAAHD!".
But they don't care. NASA has gently tried to nudge government towards realizing the fact that relying on chemical rockets in like trying to fly a coal-fuelled steam engine for a biplane.
The USA had a NTR program that was shut down, partly for financial reasons, party for political reasons. It has not been restarted.
| Naavis said: | | That specific concept could be a bit more credible if it was mentioned in more places than just a short forum post and a single, obscure article. And no one still explained the reusability-issue. The article says "It flies to space with a thousand tons of cargo, and flies back using some gentle aero-braking and its thrusters with another thousand tons of cargo." but according to the picture it's a rocket. A rocket lacks the control surfaces needed to maneuver well enough in Earth's atmosphere, not to mentioned the lack of landing gear and such. That's why shuttles were invented. |
You are thinking along the lines of an aeroplane, rather then a rocket. It does not need to manoeuvre that much. It only needs to spin, so the engines face the ground. Then, apply trust gently.
It would manoeuvre in atmosphere the same way it manoeuvres in space. Small manoeuvring rockets.
It has more then enough propellent for it.
Such a landing system has been demonstrated with chemical rockets. The name fails me though. | | | | |
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| written by Pomelos on May 24, 2007 20:43 |
| | | | ![]() | Zixinus said: | No, they haven't. They were, in fact, only okay in the 50's.
With the increase of nuclear-hysteria (see Godzilla, and pretty much any Hollywood film touching anything nuclear), even Cassini-Hyden was protested againts. This is a spaceprobe, not even manned or meant to come back to Earth. Most protesters most can't comprehend anything beyond "NU-KU-LAR = BAAAAHD!". |
I guess the low success rate of space rockets had nothing to do in the final decision.
I'm astonished, here. We're living in a free-market world, where opportunity costs pretty much decide what is and what's not, it has been that way for 200 years, and you're still thinking that way?
Couldn't it occur to you that, maybe, since such a rocket looked so damned efficient, there might be some hidden cost you're not taking into account? | | | | |
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| written by Naavis on May 24, 2007 20:55 |
| | | | ![]() | Zixinus said: | | You are thinking along the lines of an aeroplane, rather then a rocket. It does not need to manoeuvre that much. It only needs to spin, so the engines face the ground. Then, apply trust gently. |
Easier said than done with a 115-meter giant weighing at 700 tonnes. | | | | |
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 | |  | | ![]() As far as landing goes, I imagine they'd likely touch down in the ocean, with something like a parachute system to slow their descent. The space shuttle's solid rocket boosters each weigh nearly 100 tons when empty, and return for re-use using that method.
I'd say the most obvious flaw with this design is the fact that it requires nuclear fuel. While you might consider it "nuclear hysteria", the fact remains that nuclear waste cannot be easily cleaned up, and can make an area uninhabitable for thousands of years. With the relatively high failure rate of space missions, putting a significant amount of highly radioactive material on a rocket is only asking for trouble. | |  | |  |
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| | | | There's an answer to that: don't let it touch the ground at all. Build it in orbit, and have it dock with a station. Or build it on the moon.
This has the advantage that the required thrust can be smaller since it doesn't have to battle as much with gravity. | | | | |
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| written by Azuraun2 on May 25, 2007 06:01 |
 | |  | | It'd probably be even worse if the rocket blew up above earth. IT'S RAINING RADIOACTIVE WASTE! AHHH!!! XD | |  | |  |
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| written by Zixinus on May 25, 2007 06:50 |
| | | | ![]() | Pomelos said: | | I guess the low success rate of space rockets had nothing to do in the final decision. |
The final decesion was to luanch Cassini-Hyden. It was a success. And what low succes rate? Most space rockets worked well.
The Saturn-5 never had a failure for example.
| Pomelos said: | | Couldn't it occur to you that, maybe, since such a rocket looked so damned efficient, there might be some hidden cost you're not taking into account? |
Maybe, just maybe, you haven't tried to see people's reaction when it comes to anything nuclear?
Again, Cassini-Hyden was protested againsts, and it was just a RTG. Envariomental protestors don't care what they are protesting againts, they just protest mindlesly.
| Naavis said: | | Easier said than done with a 115-meter giant weighing at 700 tonnes. |
So is combining three different vehicle behaviours into one craft, like the Space Shuttle. From an engineering standpoint, it is actually more simple. From the pilot standpoint, you merely have to aim the nose of the craft towards the sky.
| Cryoburner said: | | As far as landing goes, I imagine they'd likely touch down in the ocean, with something like a parachute system to slow their descent. |
No, I've detailed the landing plan already. It might land in a big pool of water though. But I'm not sure that it would float.
| Cryoburner said: | | While you might consider it "nuclear hysteria", the fact remains that nuclear waste cannot be easily cleaned up, and can make an area uninhabitable for thousands of years. With the relatively high failure rate of space missions, putting a significant amount of highly radioactive material on a rocket is only asking for trouble. |
And sticking to steampower for aeroplanes is asking for brains. Chemical rockets will simply not work in the long run, and you "wait till the right technology is developed" isn't an answer either. We could build this thing.
The waste issue is dealt within space. The craft is planned with safety and reduncicy in mind. Hence the two extra engines.
| Xenomorph said: | | There's an answer to that: don't let it touch the ground at all. Build it in orbit, and have it dock with a station. Or build it on the moon. |
Then you will want nuclear-electric. Ion, MPD or VASIMR drives powered by nuclear power. No, solar will not cut it.
And to build this thing in orbit or on the moon, you will need either way a booster that transports all the materials, personal and equipment to its destenation. This craft could transports 900 tons into orbit. Most likely more then enough for the Moon.
Also, such a craft would be unable to land.
| Azuraun2 said: | | It'd probably be even worse if the rocket blew up above earth. IT'S RAINING RADIOACTIVE WASTE! |
The waste issue is dealth with. And why would it blow up? This is an engine, not a bomb.
Besides, the waste would quickly scatter in orbit and all around of Earth. By the time it arrives, it will burn up and scatter even more. You'll get a few grams of the stuff in several cubic kilometres. Consider that there is uranium and radon in coal (and that you are constantly bombarded by cosmic rays), and that by coal-buring power plants, you get allot more radioactive stuff in the air. | | | | |
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| written by Pomelos on May 25, 2007 07:12 |
| | | | ![]() | Zixinus said: | | Pomelos said: | | Couldn't it occur to you that, maybe, since such a rocket looked so damned efficient, there might be some hidden cost you're not taking into account? |
Maybe, just maybe, you haven't tried to see people's reaction when it comes to anything nuclear? |
You're having it all backwards, here.
You're loving that nuke rocket, you want it to be made. Since it hasn't, you're relying on paranoia and conspiracy to explain why. (Yup, that's paranoia and conspiracy, the green flavoured ones.)
And, you know, discarding every argument against you by saying "it's completely safe, you're just some nuclear fearing tree-huggers" won't bring you any closer to convince people. There's some nuclear danger, there. Rockets do explode. (oh, hell yeah, they do.) And, appart from civil reactors and military ships, there's hardly anything nuclear powered in this world. That could be because it's not safe. Or because it's too expensive to build safe, Or because it's not efficient, regardless of what theories say. Or whatever.
As for myself, I only see this: it has never be built, and not even considered by actual rocket design agencies for the last 40 years. | | | | |
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