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Post by newageofpower on Apr 9, 2017 0:15:58 GMT
if you get anything hot enough it will go fast enough Sadly, not even 4510k Graphene makes Mercury go fast. ;_;
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Post by Enderminion on Apr 9, 2017 0:45:50 GMT
maybe if you fed it through a nswr instead?
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Post by nerd1000 on Apr 9, 2017 12:28:32 GMT
maybe if you fed it through a nswr instead? > NSWR mentioned I've been summoned! Mercury in a NSWR? Here we go! Of course the exhaust is somehow even more deadly than the normal NSWR. I hope you're proud of yourself.
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Post by samchiu2000 on Apr 9, 2017 12:48:25 GMT
maybe if you fed it through a nswr instead? > NSWR mentioned I've been summoned! Mercury in a NSWR? Here we go! Of course the exhaust is somehow even more deadly than the normal NSWR. I hope you're proud of yourself. What!? Nuclear mercury rocket?? Sound strange... And using NSWR as SSTO engine should make the launch site radioactive for thousands if not million year to come...
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Post by Enderminion on Apr 9, 2017 13:45:10 GMT
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Post by sevenperforce on Apr 10, 2017 17:02:00 GMT
Smaller thrusters can easily pass 5.5km/s ? For water ? I never got higher than 4.2km/s ish on water NTR's. Mind showing the design ? I suspect that newageofpower increased the the throat radius beyond what was necessary to make the engine function, to allow them to use more of the dissociation energy of the water, which allows for more thrust and exhaust velocity without the need to modify the reactor beyond what is necessary to keep the reactor functional. This might make deep throttling (which is important for SSTO designs) more difficult. Then again, I'm not sure; it's an NTR so combustion instabilities are not an issue.
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Post by ash19256 on Apr 10, 2017 17:48:01 GMT
I suspect that newageofpower increased the the throat radius beyond what was necessary to make the engine function, to allow them to use more of the dissociation energy of the water, which allows for more thrust and exhaust velocity without the need to modify the reactor beyond what is necessary to keep the reactor functional. This might make deep throttling (which is important for SSTO designs) more difficult. Then again, I'm not sure; it's an NTR so combustion instabilities are not an issue. Well, in all honesty deep throttling might well be impossible with NTRs, because you can only dampen the reaction so far without shutting it down all together, and you need to keep the reactor from overheating. Now, it might be possible to use multiple NTRs, and shut some of them down throughout the flight to simulate deep throttling capabilities, but that's going to be less efficient then just being able to deep throttle a single NTR.
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Post by bigbombr on Apr 10, 2017 18:02:37 GMT
This might make deep throttling (which is important for SSTO designs) more difficult. Then again, I'm not sure; it's an NTR so combustion instabilities are not an issue. Well, in all honesty deep throttling might well be impossible with NTRs, because you can only dampen the reaction so far without shutting it down all together, and you need to keep the reactor from overheating. Now, it might be possible to use multiple NTRs, and shut some of them down throughout the flight to simulate deep throttling capabilities, but that's going to be less efficient then just being able to deep throttle a single NTR. You could throttle the propellant flow down, and throttle the reactor down as much as you dare and use radiators to get rid of the rest of the heat.
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Post by sevenperforce on Apr 10, 2017 18:02:54 GMT
This might make deep throttling (which is important for SSTO designs) more difficult. Then again, I'm not sure; it's an NTR so combustion instabilities are not an issue. Well, in all honesty deep throttling might well be impossible with NTRs, because you can only dampen the reaction so far without shutting it down all together, and you need to keep the reactor from overheating. Now, it might be possible to use multiple NTRs, and shut some of them down throughout the flight to simulate deep throttling capabilities, but that's going to be less efficient then just being able to deep throttle a single NTR. I don't know how CDE models it, but AFAIK you can throttle an NTR easily enough simply by decreasing the propellant flow. Unlike a chemical engine, the energy source and the prop flow are separate. Decreasing prop flow runs hotter, since you have less coolant, but specific impulse actually goes up a bit. In contrast, you can push extra propellant through the engine to increase TWR while decreasing specific impulse. The breakpoint would probably be either when the flow chokes at the throat or when the engine overheats due to a lack of coolant.
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Post by Enderminion on Apr 10, 2017 18:22:50 GMT
even then seven, you can insert the control rods more and reduce the reaction cooling the reactor, until you are at the point where any more would shut the reactor down
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Post by newageofpower on Apr 10, 2017 18:30:43 GMT
Well, in all honesty deep throttling might well be impossible with NTRs, because you can only dampen the reaction so far without shutting it down all together, and you need to keep the reactor from overheating. Now, it might be possible to use multiple NTRs, and shut some of them down throughout the flight to simulate deep throttling capabilities, but that's going to be less efficient then just being able to deep throttle a single NTR. I don't know how CDE models it, but AFAIK you can throttle an NTR easily enough simply by decreasing the propellant flow. Unlike a chemical engine, the energy source and the prop flow are separate. Decreasing prop flow runs hotter, since you have less coolant, but specific impulse actually goes up a bit. In contrast, you can push extra propellant through the engine to increase TWR while decreasing specific impulse. The breakpoint would probably be either when the flow chokes at the throat or when the engine overheats due to a lack of coolant. Most players tune their CDE engines to be running at Max ISP. Reductions in coolant flow without throttling the reactor heat will cause meltdown.
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Post by ash19256 on Apr 10, 2017 19:04:55 GMT
Well, in all honesty deep throttling might well be impossible with NTRs, because you can only dampen the reaction so far without shutting it down all together, and you need to keep the reactor from overheating. Now, it might be possible to use multiple NTRs, and shut some of them down throughout the flight to simulate deep throttling capabilities, but that's going to be less efficient then just being able to deep throttle a single NTR. I don't know how CDE models it, but AFAIK you can throttle an NTR easily enough simply by decreasing the propellant flow. Unlike a chemical engine, the energy source and the prop flow are separate. Decreasing prop flow runs hotter, since you have less coolant, but specific impulse actually goes up a bit. In contrast, you can push extra propellant through the engine to increase TWR while decreasing specific impulse. The breakpoint would probably be either when the flow chokes at the throat or when the engine overheats due to a lack of coolant. Well, CDE models it as the turbopump having exactly one setting, and you can set that wherever you want on that scale, depending on what kind of a specific impulse/exhaust velocity you are looking for.
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Post by sevenperforce on Apr 10, 2017 19:20:00 GMT
A quick and dirty build with the Tantalum Hafnium Carbide pellet/liquid fissile metal design allows me to extract 5.44 km/s from plain water at 12 meganewtons while maintaining 260 TWR, while maintaining a core meltdown margin of 10k. I am using a aluminum injector and amco nozzles for safety reasons, and the CoADE simulation does not allow for composite nozzle design, so an IRL NTR could easily surpass this design. I can probably improve this, but as a proof of concept it's proven it's point. Smaller thrusters can comfortably pass 5.52 km/s, but for an SSTO design we need multi-meganewton setups. What does this setup give if we use heavy water?
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Post by Enderminion on Apr 10, 2017 19:42:03 GMT
or Tritiated water
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Post by sevenperforce on Apr 10, 2017 20:48:45 GMT
Tritiated water might be a bit much. Honestly, unless you're actively using a nuclear reactor to synthesize heavy water, semi-heavy water (HDO) is about all you can expect to get from centrifuging plain water.
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