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So far all the ideas for nuclear rockets (except my own) seem to be based around a bomb being dropped out of the back of the craft, going off, and a thick plate stopping the explosion blowing the craft up, with the craft riding the explosion. That is so inefficient. It would surely be much more efficient to turn the plate into a tunnel and direct all the nukes force outwards, so energy doesn't get sent off in directions where it won't be utilised.
Use what is abundant and build to last
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Hello? Anyone there?
Use what is abundant and build to last
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yes, and both ideas wouldn't work... if anything you would need to use the neuclear reactor to power something that would help propel it. a blast would need force to push you and being in space the only force you could attain is to have something in the nuke to push you. (from any style blast) so your best bet is to do a type of solar sail and project high speed particles against it of some sort. I have to admit i'm not that good with this stuff yet but i have been trying to learn more about it.
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yes, and both ideas wouldn't work... if anything you would need to use the neuclear reactor to power something that would help propel it. a blast would need force to push you and being in space the only force you could attain is to have something in the nuke to push you. (from any style blast) so your best bet is to do a type of solar sail and project high speed particles against it of some sort. I have to admit i'm not that good with this stuff yet but i have been trying to learn more about it.
The original Orion nuclear pulse propulsion system incorporated low molecular mass materials within the pulse units, which atomised to form a sort of propellant which would then impact the pusher plate. the atomic charges were focused, to ensure that a disproportionate amount of the blast energy was directed at the pusher plate. Nuclear explosives have such a high energy density that it almost doesn't matter how efficient the propulsion system is in terms of energy capture, for interplanetary missiosn at least.
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What about a modified reactor, so instead of using the heat to create stea, it's open-ended, directing all the pressure and energy from the reactor outwards?
Use what is abundant and build to last
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What about a modified reactor, so instead of using the heat to create stea, it's open-ended, directing all the pressure and energy from the reactor outwards?
not just that but i think a neuclear reactor would work awesome out in space since you dont have to worry about cooling all that much... not to mention the ammount of power you would have for how long of a time... there are other ways but it adds mass and isn't as powerful.
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yes, and both ideas wouldn't work... if anything you would need to use the neuclear reactor to power something that would help propel it. a blast would need force to push you and being in space the only force you could attain is to have something in the nuke to push you. (from any style blast) so your best bet is to do a type of solar sail and project high speed particles against it of some sort. I have to admit i'm not that good with this stuff yet but i have been trying to learn more about it.
The original Orion nuclear pulse propulsion system incorporated low molecular mass materials within the pulse units, which atomised to form a sort of propellant which would then impact the pusher plate. the atomic charges were focused, to ensure that a disproportionate amount of the blast energy was directed at the pusher plate. Nuclear explosives have such a high energy density that it almost doesn't matter how efficient the propulsion system is in terms of energy capture, for interplanetary missiosn at least.
ie, NERVA. This idea was first thought of in the 1940s. The problems can be summarised as follows:
1) The operating temperature of the reactor is limited by the melting point of its internals;
2) The power of the reactor is limited by the rate of heat transfer by conduction through the fuel and into the proellant at the fuel-propellant boundary.
Both of these problems limit the specific impulse of a nuclear rocket engine to about 1000 seconds, even if very low molecular mass propellants are used (ie, hydrogen).
Orion gets around this problem by basically exploding the reactor(s) at the rear of the vehicle. This allows the proellant to reach much higher temperatures (100s of thousands of degrees) and also gets around the neccesity for heat transfer between the fuel and propellant, which tends to limit the power to weight ratio of nuclear thermal rocket engines. Orion is therefore much more efficient in ISP terms than a NERVA rocket engine and achieves much high mass ratios.
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wouldn't you have to worry about radiation alot more then? and you would be using the power made by the neuclear rocket to move the vehicle instead of powering the vehicle its self.
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wouldn't you have to worry about radiation alot more then? and you would be using the power made by the neuclear rocket to move the vehicle instead of powering the vehicle its self.
I'm not quite sure that I understand what you are asking here. Why would you need to worry about radiation more? In an Orion type vessel, the pusher plate would be many feet thick and would shield the vessel from the majority of the raditaion. And the standoff distance woulod be in the order of 100 meters, even for the smallest pulse units.
In both Orion and NERVA concepts the reactor provides propulsion, which is by far the most energy demnading function.
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I've been thinking about this idea. How about having a reactor providing energy for a Nuclear Thermal Rocket. The waste would be recycled in Breeder reactors. Then the waste from the breeder reactors decays and the energy taken from that. Interstellar gases could be scooped up to provide fuel for the NTR.
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I've been thinking about this idea. How about having a reactor providing energy for a Nuclear Thermal Rocket. The waste would be recycled in Breeder reactors. Then the waste from the breeder reactors decays and the energy taken from that. Interstellar gases could be scooped up to provide fuel for the NTR.
Most NTRs use weapons grade Uranium or Plutonium, so there isn't very much fertile material in the core to support breeding. More likely, breeder reactors on the ground could be used to provide excess plutonium for NTR manufacture. Generally speaking, it would not be safe or economic to return an NTR to Earth in order to recover the unspent fuel following final burnout.
As for the idea of using interstellar gases as 'fuel', this is only practical in advanced fusion powered systems, which can extract enormous amounts of energy from relatively small amounts of hydrogen/helium gas. In an NTR, the interstellar gas serves as propellant, not fuel. The effective ISP is far too low to consider gathering gas from hundreds of square kilometres of space and the exhaust velocity of rocket is generally too low to support high velocities when countered by the drag induced by the inter-stellar gas.
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Of the fission type rocket engine, I understand that there are two basic types of engines. One that goes with nuclear explosions behind the rocket with a pusher to absorb the shock wave from reaching the passenger compartment and then there is the compartment type of explode a bomb inside a chamber. Then use a jet nozzle to get the thrust. The one that your using a compartment to explode your mini nuclear bomb it, you could use it to generate electricity, you would also have to have some type of containment to keep those nuclear gases from making contact with compartment and the pusher, because of the high temperature involved in the nuclear reaction. Then there the Fission type rocket that would work more like a reactor type, which we could also use to generate electricity too. Of these two basic types, it we choose to build them, we could probably build them in three to five year time frame after the decision was make to build them. There are no major new technologies that we need to develop that we could not over come in that time frame.
Fusion was also mentioned, now that might take twenty years or longer to develop, because the technology to built something like that is still in it infancy and new technologies need to be developed to make it happen. So for the time being this type is on hold for anything that we are planning to do in the next ten to twenty years or so. But, this would be our preferred choice when it should be developed, because of the energy output and the speed that we could get to Mars with if we are caring people.
Larry,
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We can initiate fusion, we just can't control it. A modified pusher plate idea could explode Hydrogen bombs instead.
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We can initiate fusion, we just can't control it. A modified pusher plate idea could explode Hydrogen bombs instead.
A hydrogen bombs occurs when they use a smaller fission bomb is used to start the change reaction in the hydrogen. So that would add complexity to our nuclear fuel supply that we are trying to use to drive our ship to Mars. So we would have to have a micro fission nuclear bomb to detonate a slightly bigger fusion bomb which would not be practical to do and defeats the whole purpose in going fusion powered rocket. For fusion to be used as the fuel that we are interested in, we need to have a continual chain reaction through out the entire hydrogen on a controlled bases to push our space ship. We would be able to draw of electrons to generate electricity and we would have a powered rocket vs on that has to be sling shot from Earth orbit to Mars orbit taking six to seven months to get there or come back to Earth orbit. A controlled fusion powered rocket, could fly to Mars in say 7 days or so and doesn't have to wait 2 1/2 years for the orbits of the Earth and Mars to line up for that window. Blowing up a fission bomb so we can blow up a fusion bomb doesn't give us that kind of control that we need for the purpose that we intent to use it for.
Larry,
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Of the fission type rocket engine, I understand that there are two basic types of engines. One that goes with nuclear explosions behind the rocket with a pusher to absorb the shock wave from reaching the passenger compartment and then there is the compartment type of explode a bomb inside a chamber. Then use a jet nozzle to get the thrust. The one that your using a compartment to explode your mini nuclear bomb it, you could use it to generate electricity, you would also have to have some type of containment to keep those nuclear gases from making contact with compartment and the pusher, because of the high temperature involved in the nuclear reaction. Then there the Fission type rocket that would work more like a reactor type, which we could also use to generate electricity too. Of these two basic types, it we choose to build them, we could probably build them in three to five year time frame after the decision was make to build them. There are no major new technologies that we need to develop that we could not over come in that time frame.
What terraformer was proposing was a nuclear thermal rocket engine. This produces thrust by passing hydrogen (or some other propellant) through a high temperature nuclear reactor and venting it out the rear as reaction mass. The reactor DOES NOT explode, merely gets very hot (~2000degC) and and heats the hydrogen, which acts as a propellant. Note that the fuel in this case is the uranium embedded within the reactor, not the hydrogen, which does play any part in the energy production, but just gets heated and dumped out the back.
What you are describing are two variants of bomb-propelled space craft, which were developed under the US Orion programme in the 1950s and 60s. Orion propulsion concepts greatly exceed the specific impulse that could ever be provided by a nuclear thermal rocket because the reactor is allowed to reach its maximum posible temperature and power density by allowing it to explode at the rear of the ship. The downside is that in a nuclear thermal rocket the fission products and the unspent fuel are neatly contained within the ship, whereas Orion atmomises them and vents them into the environment. This is a problem if the propulsion system is intended to be used in the vicinity of a planet (especially Earth). This, and the atmoic test ban treaty, pretty much put the lid on the Orion project and all further development of nuclear propulsion focuses on nuclear thermal rockets, in spite of their significantly lower performance.
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