Post by darthroach on Jan 16, 2017 20:49:46 GMT
I decided to make this thread in the science discussion section rather than in suggestions because I am not exactly an expert, and am more interested in seeing some discussion on this subject. And considering that lots of you guys here are a hell of a lot smarter than me, this is as good a place as any for it.
I don't think I have to make any introductions to the idea since pretty much everyone playing this game has been to AtomicRockets at some point in their lives, and mr Chung has gone into a fair bit of detail about the specific engine design here:
Open Cycle Gas Core NTR
The gist of it is that instead of the engine temperature (and therefore exhaust velocity) being limited by the melting point of the solid fuel nuclear reactor parts, the fission reaction takes place in a cloud of Uranium plasma. Around this hydrogen or other propellant (doped with radiation-scattering dust) is channeled, getting superheated by the ongoing nuclear reaction in the center. That way, the temperature is limited by our ability to cool the combustion chamber's walls, which is considerably higher. The reaction is confined by cleverly arranging the surrounding propellant flow to keep the central vortex in for as long as possible, and is started by any number of AND THEN A MIRACLE HAPPENS proposals. Some of the fission fuel inevitably goes out the back end, of course, and pointing the thing at a surface launchpad will slag the county. But thankfully CoaDE's setting does not require us to pay any attention to the environment.
Now it seems some people from NASA or related have done a fair bit of theoretical consideration on this already. In short:
Pros:
I don't think I have to make any introductions to the idea since pretty much everyone playing this game has been to AtomicRockets at some point in their lives, and mr Chung has gone into a fair bit of detail about the specific engine design here:
Open Cycle Gas Core NTR
The gist of it is that instead of the engine temperature (and therefore exhaust velocity) being limited by the melting point of the solid fuel nuclear reactor parts, the fission reaction takes place in a cloud of Uranium plasma. Around this hydrogen or other propellant (doped with radiation-scattering dust) is channeled, getting superheated by the ongoing nuclear reaction in the center. That way, the temperature is limited by our ability to cool the combustion chamber's walls, which is considerably higher. The reaction is confined by cleverly arranging the surrounding propellant flow to keep the central vortex in for as long as possible, and is started by any number of AND THEN A MIRACLE HAPPENS proposals. Some of the fission fuel inevitably goes out the back end, of course, and pointing the thing at a surface launchpad will slag the county. But thankfully CoaDE's setting does not require us to pay any attention to the environment.
Now it seems some people from NASA or related have done a fair bit of theoretical consideration on this already. In short:
Pros:
- Isp in the 3000-7000 range (limited by the need to keep the combustion chamber walls solid)
- Thrust comparable to solid core NTRs, which is to say, a whole damn lot
- Cool
Cons:
The pros are such that they make normal NTRs look rather weak and obsolete in comparison. The cons are mostly the lack of real engineering work done to make this work. Going by the general philosophy of the game, there is more than enough information to implement this as a workable engine family - we know how it will perform if it works, the things we don't understand have more to do with actually making the engine work in the first place. So the question is whether you guys think something like this could ever actually be built and perform to spec.
- No one has actually tried to confine a fission reaction inside a vortex of gas moving at supersonic speeds
- Starting the engine could prove a rather difficult task
- Will ruin the day of anyone sitting in the way of the exhaust. Maybe not the best idea for a fleet of battleships in close formation.
The pros are such that they make normal NTRs look rather weak and obsolete in comparison. The cons are mostly the lack of real engineering work done to make this work. Going by the general philosophy of the game, there is more than enough information to implement this as a workable engine family - we know how it will perform if it works, the things we don't understand have more to do with actually making the engine work in the first place. So the question is whether you guys think something like this could ever actually be built and perform to spec.