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Towards the Future

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Look, all we're asking is that you do everything we say and surrender your nukes and guns. Oh and your food... (And gimme your boots as well)
 
[X] Plan: The Smell of Burning Flesh

We voted to unify the world in a destructive war and by jove we'll do it!
Rolen von Keng said:
...And your motorcycle, your leather jacket, your lives, and oh! Your very future too, please?
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Very good idea. Gotta make them give up their punk gear so they turn into civilized post-apocalyptic folk and don't become an ungovernable Mad Maxistan.
 
I do think that demanding annexation or total surrender is counterproductive here. They have second-strike capabilities, they have the sort of high command who were picked for reliability in a nuclear war, and they have seen their nation burn down around their ears. They are not stable, and one cannot expect them to think wholly in terms of 'this is best for the species, we lost'. A total surrender demand is just as if not more likely to be met with a volley of nukes and a resumption of what is now a broken-backed war. Which will then smoothly lead to extinction of civilization on the planet and societal collapse.
I'd advise caution here.
 
I really don't think we should be demanding full annexation, if they see us as uncompromising they might as well decide to do a 4th strike to fuck us over before we roll in with the tanks, which means game over at that point.

It's a really high risk for something we can achieve in the future anyway by accepting the negotiated peace, we can centralize later, but we won't be able to survive if they don't buckle. Launching first is an option that's probably less likely to mean game over even.

Don't forget our character is an avowed nationalist war criminal, we really shouldn't be taking his lead here, he has zero idea of the situation on the ground. It reeks of a trap option, which Blackstar has alluded there being aplenty in this quest, here are her words exactly:

"Now I would give you about a 50/50 survival chance"

"Instead of the 30/70 from pre last turn"

"This includes your opinions on the likely hood of us picking stupid shinies right"

"Those will just kill you"

Like, this is a final war scenario, in which we're at the tail end of a world war that lasted 7 years and a nuclear apocalypse (in which initial estimates predicted 98% of the population to die). We are far from being past the danger zone, losing this game is a very real possibility. Picking shinies, which I highly suspect full annexation to be, can and will kills us.

With that in mind, what to vote for is pretty clear to me:

[X]Plan: Pick the Best of a Raw Bunch + War Criminal
[X]Plan: Pick the Best of a Raw Bunch
 
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[X] Plan: Pick the Best of a Raw Bunch + War Criminal
[X] Plan: Pick the Best of a Raw Bunch
 
General_Urist said:
We voted to unify the world in a destructive war and by jove we'll do it!
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Not quite. Our faction overthrew the old government specifically because we were tired of war and didn't want the world to end in nuclear fire. Alas, we were too late and we now have to pick up the pieces. Peace here is the wisest of all courses because it will let us conserve the most valuable resources, food and manpower, while giving us access to what's left of our (hopefully former) opponents' assets.

Say 'No!' to war, give peace a chance!
Edit: and I think it's necessary to consider that our opponents have nuclear weapons. They're puffing a pretty good desperation deal.
[X]Plan: Pick the Best of a Raw Bunch + War Criminal
[X]Plan: Pick the Best of a Raw Bunch
 
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Topic in Focus: Starships
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    • Topic in Focus: Starships

    The design of every modern starship can be split into four separate categories, each important and each need particular attention paid to them. Warships have yet another category: weapon systems, but they will not be mentioned outside of a relative side note for this exploration. These four categories can be split up fairly easily: the electrical system, the heat management system, the drive system, and the structure of the ship. Of course, this only includes the propulsion bus and its support sections while ignoring the various payload sections, but given the flexibility of the general layout, any attached section is more limited by tonnage than anything else.

    The Electrical System:

    The first and most important of categories is the electrical system that powers the propulsion bus for any form of long-distance travel. A high-temperature gas core pebble bed reactor is used as the primary thermal source on any modern ship, with a general "hot" coolant loop temperature of 1300 degrees Kelvin. This high-temperature helium is then run through a Brayton cycle turbine system constructed near the core structure. After going through the turbine, the gas is further cooled via a 900K radiator system, enabling it to return to the core and produce more power. Due to the power densities involved in any such operation, the core and turbine system themselves are comparatively small relative to the massive radiator systems used to keep them at an acceptable temperature. The presence of a hot nuclear core also requires several precautions to be taken for radiation exposure, as when operating at full power, a massive quantity of radiation is released into the surrounding space.

    This massive quantity of radiation necessitates the use of a boron shadow shield and placing the propellant tanks and cargo section between the reactor and the crew section. However, such a setup does not compensate for the need to dock at stations, necessitating full reactor shutdowns and precise maneuvering to ensure that safe docking procedure can be followed. The reactor cores themselves also require a team of trained engineers to accompany them on every single ship, as an issue with the reactor core can rapidly translate to being trapped in a lethal trajectory, necessitating some form of sprinter ship to be sent out for a rescue, the crew fixing the issue, or accepting their inevitable demise. So far in the operation of the orbital fleet, there have only been two full core failures that have occurred, both of which occurred in low orbit due to issues in cooling rather than in mid-flight.

    The other significant concern of reactor operation has been the necessity for refueling cores in orbit without needing the entire assembly to be sent down from orbit. Unlike first-generation fast reactors, current models of pebble beds are all designed for the use of underway refueling through the replacement of their standardized fuel particles. Generally, such an operation is only attempted on a fully cold reactor in an already docked ship, but most civilian designs and all of the military ones have provisions for filling the core with fresh fuel during full-power operation. These pellets are made of a mixture of Uranium 233 and Uranium 238, though more exotic compositions have been used previously. The current robust breeding infrastructure has ensured that the easy production of U233 from Thorium can be maintained for a low cost and with a relatively small footprint, even in theory allowing the ISRU production of fuel elements, though no facilities have been constructed for that task yet.

    The Heat Management System:

    The ultimate issue caused by basic thermodynamics is that every object produces some heat, and that heat is a massive problem in space where only radiative dispersal is an option. For a reactor core, this is a bit less of an issue, as the hot temperature of the cold loop serves to minimize the number of radiators in use, but the situation is incredibly different for any inhabited section. The dissipation of heat from a reactor loop that has run through a turbine is a comparatively simple matter. After the coolant is run through, it is pumped into a massive surface area of angled radiator surface on the sides of any craft. From there, it is run through the drive ward side of the radiator and then the other, ensuring that it can deposit as much of its heat as possible. Both sides are utilized to take advantage of the limited transmissive capacity of heat-pipe systems, allowing a cross-section of almost twelve meters per panel. However, the radiator system for the crew section has one major difference as a two-loop system is used. Instead of a direct transfer of coolant, it is instead processed through a heat pump to enable an external 400K system, saving on a massive amount of radiator tonnage.

    The Drive System:

    Generally speaking, regardless of their qualities, drives can be split into three categories, with a fourth theoretical category that has only been theorized. As "torch ships" are only a theoretical concept so far, their mention will be avoided, as they break much of the common conceptions, and none have yet been constructed. As a general rule of the rocket equation, primary drives have two issues with few exceptions. Either they are thrust limited, or they are efficiency limited. As an example of the former, both the older ion drives and the newer MPD have high Isp's at a relatively low quantity of thrust. The best example of the latter category is the ever-dependable chemical thruster, as it has no fundamental power limitation for thrust, but its efficiency is too subpar to be used for most orbital roles.

    The first truster and the one seen in some variety on every current spacecraft in orbit is the humble magnetoplasmadynamic thruster. Every single model runs off the power provided to it by the reactor core and can generally manage to move most reasonably designed vessels at around 2.5 mm/s2​. Currently, the optimal propellant that has nearly been universally utilized due to its sheer versatility has been methane. While not as efficient as hydrogen and more problematic to use than argon due to electrode corrosion, methane offers a comparative balance of positive qualities. Methane is storable without the constant risk of boiloff, only moderately corrodes thruster electrodes, can be used in an NTR, and still provides reasonable ISP's. This does cause a reliance on Sabatier process stations all across the system, but as water is a component of most other fuels and carbonaceous rock is extremely common, it has become fairly easy to source locally. Current drives can offer Isp's of almost six thousand seconds at an acceptable efficiency, making them the default tool for any long-distance trip.

    The second thruster and commonality across all militarized spacecraft is the solid core nuclear thermal rocket. Drawing from the same reaction mass supply as the MPD's, the drives provide a rapid ability to maneuver, move out of gravity wells, and evade enemy ordinance. Even with more modern high-temperature designs, the engines can only reach an Isp of 630 seconds. Such a comparatively low efficiency with methane is compensated for by the massive amount of thrust the engine can produce, enabling craft equipped with them to accelerate at almost a full g. Due to the added issues with radiation and the lack of necessity for most civilian orbital craft, the engines are simply not used on any freighters, as they add additional complexity and further increase crew requirements. Of course, military craft and larger missile bus systems take advantage of them, as both systems have proven themselves to be incredibly useful in all simulated space engagements.

    The third type of truster is not a primary drive and, by technicality, combines two discrete thruster systems with slightly different uses depending on the conditions a ship finds itself in. When the reactor cannot be brought online or has some form of energy limitation, the RCS system is used as a conventional chemical system, utilizing inefficient hydrazine monopropellant. When there is spare power, though, the reaction control system is used as an arcjet mode, improving on older resistojet systems and providing a massive improvement in efficiency while enabling the use of more conventional reaction mass. Of course, either use is far from the most efficient way to drive a ship, but as anything involving the nuclear core produces too much radiation to spread evenly across the ship, these dual systems have been used as universal maneuvering thrusters.

    The Structure of the Ship:

    Any civilian ship is built along with a simple principle: what is the smallest amount of mass that can endure acceleration when near dry and have a healthy durability margin? The answer to this question has primarily come from various aerospace alloys of aluminum forming a centralized truss structure with a propulsion bus on the very back, followed by attached cargo, followed by the crew section. In practice, such designs look more like long sticks with massive glowing radiators, but as there is no atmosphere to worry about and few to care about specific appearances, this optimal shape has become the most common across any civilian design. However, military sensibilities are entirely different, as compactness and point defense coverage become far higher priorities instead of mass efficiency. Due to such concerns, ships are constructed as cylinders with an expanded central section, enabling a minimal quantity of radiators to survive in the "shadow" of the ship and presenting as small as possible of a profile to missiles. The general order of components is the same except for any craft carrying NTR-powered missile buses, as those are stored behind a second radiation shield to prevent any excess radiation from harming the crew.

    Citations:

    https://inldigitallibrary.inl.gov/sites/sti/sti/3311067.pdf (Pebble bed design minutia)

    https://sci-hub.se/10.1016/j.ijhydene.2015.01.141 (Thorium Breeding Rates)

    https://www.google.com/books/edition/Review_of_Advanced_Radiator_Technologies/W4Q4AQAAIAAJ?hl=en&gbpv=0 (Radiator Design)

    https://sci-hub.se/10.2514/3.25766 (MPD fuel selection/efficiency graphs)

    https://ntrs.nasa.gov/api/citations/19910012833/downloads/19910012833.pdf (NTR efficiencies)
     
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    • How is the military set up? What are the ranks and how many people/vehicles do they command? Are there Military Academies for Officer Candidates?
     
    One issue with ion engines is that because you can't use open-cycle cooling, in order to get comparable thruster power to a nuclear thermal rocket you need massive radiators to deal with all the waste heat, which is going to load down your spacecraft with a lot of extra dry mass and partially cancel out the gains from better ISP.
     
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    Arcus said:
    One issue with ion engines is that because you can't use open-cycle cooling, in order to get comparable thruster power to a nuclear thermal rocket you need massive radiators to deal with all the waste heat, which is going to load down your spacecraft with a lot of extra dry mass and partially cancel out the gains from better ISP.
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    No one is making an MPD with the same amount of thrust as a nuclear thermal, MPD's are explicitly only moving ships at 2-3 mm/s^2. Unlike Nuclear thermals that can go to almost a full g.
     
    Blackstar said:
    Citations:
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    I just wanted to explicitly praise your efforts in running this quest (and your other quest, but this is here)! People say they want a fey-themed race, you diligently make everything fey or at least Irish-themed. The technology is realistic and insightful; the effort you put in is both impressive and worthwhile. The events are all highly believable. Thank you for running this!
     
    Blackstar said:
    No one is making an MPD with the same amount of thrust as a nuclear thermal, MPD's are explicitly only moving ships at 2-3 mm/s^2. Unlike Nuclear thermals that can go to almost a full g.
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    I specified thruster power (the energy per second outputted by the thruster in its exhaust) and not thrust, though I suppose I wasn't clear enough about that.


    Hmm. Assuming a 1 kiloton spacecraft that can accelerate at 2.5mm/s^2 under MPD thrust, you need the engine to be capable of 2.5kN of thrust and assuming we take the exhaust velocity to be in the range of 60km/s, so you'd need an MPD thruster with a thruster power of 75 MW. If we assume the thruster is 80% efficient (the upper limit for existing ion thrusters) you'd need a 90 MW reactor to supply the required electrical power.

    Assuming a power density of 1 kg/kW of reactor (apparently this is what VASIMR calls for) you'd need a reactor weighing 90 tons, before factoring in the radiator system. If we're being very optimistic we can assign a thermal efficiency of 55% to the reactor, so that's about 75 MW of waste heat that needs to be dealt with. OTOH, this is apparently extremely ambitious and a reactor power density of, say, 10kg/kW would leave us with literally no spare mass to work with. And you know, we don't actually have 1000 tons of dry mass to work with. If we target for a mass ratio of 3 (which gives our spacecraft about 60km/s of dV) that means we only actually have 333 tons of dry mass to work with.

    A theoretically ideal radiator with an operating temperature of 2500K would be capable of radiating 2.2 MW/m^2, so you'd need 34 m^2 of radiator panels. If we go with NASA's target of 2 kg/m^2 for radiator density that works out to a mere 68 kg, but this is being absurdly generous because there's literally no way you can get a reactor efficiency of 55% and a radiator temperature of 2500K without insane reactor operating temperatures (blame the Carnot cycle), realistically you'd have to settle for much lower efficiency or lower outlet temperatures.

    On the other hand, low coolant temperatures compromise the efficiency of your radiators. With a radiating temperature of 1500K you'd need 250 m^2 of radiators instead. 1300 m^2 of radiator at 1000K. The ISS radiators actually have a density of 8kg/m^2 so that would work out to 10 tons. Which isn't too bad compared to the reactor mass, actually, but note the massive increase in radiator area for lower temperatures. Also this is assuming the radiators are completely unarmoured.

    EDIT: If we go with the provided specs (1300K hot - 900K cold) then the reactor efficiency should cap at about 30%, which translates into approximately 210 MW of heat that needs to be dissipated at 900 K temperature, so you'd actually need 5600m^2 of radiator panels, or between 10 to 40 tons of radiator.

    For comparison with an NTR like NERVA you're looking at a 10 ton engine assembly that can output 50 kN at 8 km/s (200 MW). Note that earlier on I didn't even factor in the mass of the MPD thruster itself, which is a pretty glaring omission considering that most electromagnetic/electrostatic thrusters have absolutely godawful thrust to weight ratios.
     
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