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Post by ironclad6 on Sept 3, 2017 22:12:26 GMT
Yes but further reading suggests that it might be possible to get to about half this figure. That would be good, I fugured out that to create an 1TW p-B11 fusion you need 57GW Ion accelerators to produce sufficant 500kev protons. This means an 80% MHD can extract 7.2x times more energy out of this reaction then it requires as input. How would this compare performance wise against either an MPDT or simply using a magnetically confined fusion rocket? Can you give me a really detailed breakdown of what would be involved? I've really no idea what you are talking about. |
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Post by ironclad6 on Sept 4, 2017 0:31:21 GMT
Okay, Morokweng, Goyathley, Ravel, Tchaikovsky and Galahad are all finished. Golden Monarch and Dragonfly are done. Whisker, Valkyrie AGDA and SPIKE are all finished. The dynamic balance I was looking for is all worked out. Thanks for your help especially Kerr and Matterbeam. |
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Post by matterbeam on Sept 4, 2017 2:24:36 GMT
The nozzle requires 100GW for 1TW thrust power? Yes but further reading suggests that it might be possible to get to about half this figure. Please, a link to what you are reading! |
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Post by Kerr on Sept 4, 2017 4:07:59 GMT
That would be good, I fugured out that to create an 1TW p-B11 fusion you need 57GW Ion accelerators to produce sufficant 500kev protons. This means an 80% MHD can extract 7.2x times more energy out of this reaction then it requires as input. How would this compare performance wise against either an MPDT or simply using a magnetically confined fusion rocket? Can you give me a really detailed breakdown of what would be involved? I've really no idea what you are talking about. My vacation ended, I am gonna give you the detailed breakdown later this day, or for you tomorow. |
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Post by ironclad6 on Sept 4, 2017 6:27:12 GMT
Yes but further reading suggests that it might be possible to get to about half this figure. Please, a link to what you are reading! I'm sorry I am having a hell of a job finding it again. To be fair it wasn't a solid scholarly source. |
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Post by ironclad6 on Sept 4, 2017 7:04:02 GMT
I have had to accept roughly a fifth of the acceleration I initially wanted and the Composer class just turned out to be completely unworkable. The upside is that this keeps the level of plausibility very high and the only piece of this propulsion plant I can't explain is the magnetic confinement nozzles. It's weird how fast things get stupid when you start speculating about super high tech radiators and things like that. Basically the performance I wanted would have required Trek level technology and at that point wouldn't it just be easier to make it all up?
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Post by Kerr on Sept 4, 2017 12:05:10 GMT
I have had to accept roughly a fifth of the acceleration I initially wanted and the Composer class just turned out to be completely unworkable. The upside is that this keeps the level of plausibility very high and the only piece of this propulsion plant I can't explain is the magnetic confinement nozzles. It's weird how fast things get stupid when you start speculating about super high tech radiators and things like that. Basically the performance I wanted would have required Trek level technology and at that point wouldn't it just be easier to make it all up? Give me the performance you want to have for your Composer class and I'll work it out. In a hard sci fi you can't have everything, there is no ultimate option for all your needs. High exhaust velocities come with the price of low thrust. High thrust comes with the price of low exhaust velocity. Same goes for everything else. |
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Post by Kerr on Sept 4, 2017 12:11:33 GMT
That would be good, I fugured out that to create an 1TW p-B11 fusion you need 57GW Ion accelerators to produce sufficant 500kev protons. This means an 80% MHD can extract 7.2x times more energy out of this reaction then it requires as input. How would this compare performance wise against either an MPDT or simply using a magnetically confined fusion rocket? Can you give me a really detailed breakdown of what would be involved? I've really no idea what you are talking about. If I remember correctly your fusion drives use ion beams to induce fusion, or did you reckon it? This is just the performance of your MCF Rockets. Using M-Nozzle and Ion beam power requirements to estimate how much more power your fusion drives produce (Thrust power) compared to Input. Using near 100% Ion accelerators and that 50GW/1TW Nozzle your fusion gain (Input-output ratio of fusion) you get an fusion gain of 9. Using 57% Efficient Ion beams and 100GW/1TW Nozzles you still get an fusion gain of 4,5. |
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Post by ironclad6 on Sept 4, 2017 20:12:32 GMT
My literary dilemma is really simple. The only real performance limitation on an open cycle fusion engine once you nail magnetic confinement down is radiator capacity and the strength of the magnetic field you can generate. If you hand-wave those away suddenly you are catapulted into star trek levels of performance and speculation. This is okay as long as you are okay with your ships glowing into the UV spectrum. I think simply don't have my tech level consistent.
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Post by Kerr on Sept 4, 2017 20:28:02 GMT
I know this might seem like a stupid question, but this seems like a good place to ask it anyway. There are several fusion proposals I've seen that use liquid propellant like Liquid Hydrogen or Lithium as reaction mass, and the fusion reaction as the "fuel" that provides energy to heat up the reaction mass as exhaust. The discovery proposal comes to mind in particular (https://ntrs.nasa.gov/search.jsp?R=20050160960). Is there any benefit to this arrangement over using a fusion reaction itself with no propellant or thrust beyond that which comes from the fusion pellet or plasma? The only thing that I could think of would be that the liquid propellant could be a kind of active cooling that could help to absorb some of the waste heat or energy that would otherwise have to be absorbed by the ship and expelled via radiators. Is there any truth to this claim? I do know that it would probably increase thrust and reduce exhaust velocity though. Most often it is used to increase thrust. Because in the "near" future fusion drives would have Gigawatt performance at most. And you don't want to be out accelerated by an snail. Another reason when in context with D-T and DD is neutrons, the neutron radiation a simple fusion drives emits is enormous. Flowing some lithium over your fusion fuel drastically reduces neutron flux while also making use of the neutrons which otherwise would be simply wasted. Lithium can also be used as an conductor for Z-pinch drives, to reduce wearing and erosion on the Anodes and Cathodes. Also, speculative, using Lithium-6 could provide decent amount of energies on it's own. If Lithium-6 is hit by an sufficiently energetic neutrons it undergoes fission. Releasing an Alpha particle and tritium travelling at 3% of C. |
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Post by Kerr on Sept 4, 2017 20:42:16 GMT
My literary dilemma is really simple. The only real performance limitation on an open cycle fusion engine once you nail magnetic confinement down is radiator capacity and the strength of the magnetic field you can generate. If you hand-wave those away suddenly you are catapulted into star trek levels of performance and speculation. This is okay as long as you are okay with your ships glowing into the UV spectrum. I think simply don't have my tech level consistent. What you mean with "If you hand-wave those away"? Why would you want to do that? The limitations of performance on any kind of propulsion is decided on how much you are willing to pay. If you want your fusion drives to have 5x more thrust reduce the burning efficiency by 25x and increase mass flow by 25x. This means your 10Mm/s 1MN engine can produce 5MN at 2Mm/s simply by lowering your input of reducing the amount of energy your particle beams impart on each targets in exchange for more targets. |
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Post by Kerr on Sept 6, 2017 14:38:21 GMT
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Post by ironclad6 on Sept 6, 2017 14:40:23 GMT
Basically once you start messing around with things like dusty plasma radiators thing get really wild.
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Post by Kerr on Sept 6, 2017 14:41:46 GMT
Basically once you start messing around with things like dusty plasma radiators thing get really wild. You know a dusty plasma radiators is just an MPDT shooting out extremely hot plasma. And 10,000K is pretty cold for that, IMO. |
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Post by ironclad6 on Sept 6, 2017 14:49:24 GMT
Basically once you start messing around with things like dusty plasma radiators thing get really wild. You know a dusty plasma radiators is just an MPDT shooting out extremely hot plasma. And 10,000K is pretty cold for that, IMO. Yeah, but the game will only let me go up to 10000K. Basically I'm modelling a couple of different levels of technology at the moment with the only real proviso being that each model has to be internally consistent. At one level I'm looking at fission powered ships driven by MPDTs. In the middle level I'm looking at fusion powered ships, still using a mixture of open cycle fusion and MPDT with no magnetic confinement. That gives me about 5 milligees acceleration for Procellarum and Morokweng. At another level I'm messing with some really exotic tech such as you saw in that picture back there. The ships become really interesting because they are almost more composed of magnetic fields than physical matter. |
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