C# Aurora Changes Discussion

[Elouda]

Um. Already ingame.
[image]

Except this requires you to launch all of them at once, instead of being able to fire them as desired.

[Person012345]

Well, plasma is not a gas technically, but Tsiolkovsky rocket equation doesn't mind if you tossing out plasma or very hot gas.

I don't know if that was at me, but nuclear pulse propulsion doesn't involve "tossing out" plasma either and although plasma is involved, throwing things out the back isn't what has the propulsive effect (which is what was implied by the post I was quoting). It involves throwing a nuke out the back and riding the explosion.

[sloanjh (OP)]

Well, plasma is not a gas technically, but Tsiolkovsky rocket equation doesn't mind if you tossing out plasma or very hot gas.

I don't know if that was at me, but nuclear pulse propulsion doesn't involve "tossing out" plasma either and although plasma is involved, throwing things out the back isn't what has the propulsive effect (which is what was implied by the post I was quoting). It involves throwing a nuke out the back and riding the explosion.

I think the point that was being made was that "riding the explosion" consists of letting "stuff" from the explosion hit the back of your thing-being-propulsed and letting it bounce off, transferring momentum to your thing-being-propulsed, which is morally equivalent to tossing things out the back of the thing-being-propulsed.

There is one subtlety here that might require a modification to the rocket equation : if the stuff being thrown out the back end is being thrown out at a relativistic velocity (e.g. is comprised of photons), then some of the assumptions in the classical derivation break down and you have to be careful with relativistic effects.  This might be dealt with here https://en.wikipedia.org/wiki/Relativistic_rocket, but I'm not sure if even that derivation deals with exhaust whose rest mass is zero (and whose velocity is the speed of light, i.e is comprised of photons). 

In any event, figuring out how to have all your fuel converted into photons all of which go straight out the back is going to be the most efficient rocket you can get, and that probably CAN be analyzed using the classic Tsiolkovsky equation using an "effective" V_exhaust  defined by delta_momentum_of_ship/delta_mass_used_to_get_that_delta_momentum.

[EDIT]  Now that I think of it, there's another aspect of efficiency:  in the photon drive case if you could arrange to consume all the fuel simultaneously then you could probably do better than the Tsiolkovsky equation, since you wouldn't be accelerating any of the fuel.  This would be hard to do in practice though. Also, "photon drive" gave me a better search term, so here's a discussion of the photon drive case: https://en.wikipedia.org/wiki/Photon_rocket[/EDIT]

For chuckles and grins: I have a memory from my undergraduate days working in a relativity hydrodynamics group of someone saying "X has a saying that there's two kinds of stuff in the universe: gamma = 5/3 stuff (non-relativistic) and gamma = 4/3 stuff", where I don't remember who X is (but he was well known), and gamma is the adiabatic index.  What he meant was that when the temperature of a gas gets so high that the thermal energy is significantly higher than the rest energy (i.e. the thermal velocities are relativistic), then the thermodynamic properties change and you have to redo the derivation, BUT the difference can be absorbed into a generalization of the adiabatic index.  I suspect it's a similar effect for V_exhaust and the rocket equation.  For a better discussion of the relativistic adiabatic index, see the 1st and 2nd full paragraphs on page 4 here:
https://websites.pmc.ucsc.edu/~glatz/astr_112/lectures/notes6.pdf

John

[Person012345]

Fair enough, though I don't think that's what was implied by the original post.

[iceball3]

@Steve Walmsley Hmm, quick question. Is there a rationale for railguns and plasma carronades having such a low tech cutoff compared to mesons, lasers, and particle beams?
Because at the max tech caps, the largest lasers are outright bigger than the largest carronades, and tailguns have a very low end point on it's tech tree.
Meanwhile a lot of the higher tech levels for mesons, particle beam range, etc are completely redundant and are significantly larger than the maximum fire control range in the whole game.

[serger]

nuclear pulse propulsion doesn't involve "tossing out" plasma either and although plasma is involved, throwing things out the back isn't what has the propulsive effect (which is what was implied by the post I was quoting). It involves throwing a nuke out the back and riding the explosion.

Ermmm... do you think, that nuke is not tossing some plasma back?.. 
There is a momentum conservation law - you cannot change your momentum forward, if you don't toss smth back.
In a nuclear pulse propulsion drive you can have an open propulsion camera, but you still have absolutely the same principle: some part of propulsion mass must bump against your drive camera or reflector, and another part of propulsion mass will simply fly away without bumping at any of your ship hard part.

[Iranon]

@ iceball3: Railguns cease to be worthwhile when your capacitor tech can't keep up; 50cm is pushing it. Rule of thumb: RP-hungry and expensive for the capability with RoF 10, markedly inferior to lasers with similar single-shot-damage at RoF 15. 50cm railguns may be halfway competitive because they're a big bump up from 45cm.

Particle beams don't quite reach maximum fire control range, and the very high end has some theoretical applications for attempted instant-kills at very long range (more so once lances are available). Small ones may be more practical most of the time (decent DPS at range, on a budget), but there are cool and flashy things you can do with large ones.

The larger Meson sizes appear to be pointless though.

[Bremen]

@ iceball3: Railguns cease to be worthwhile when your capacitor tech can't keep up; 50cm is pushing it. Rule of thumb: RP-hungry and expensive for the capability with RoF 10, markedly inferior to lasers with similar single-shot-damage at RoF 15. 50cm railguns may be halfway competitive because they're a big bump up from 45cm.

Particle beams don't quite reach maximum fire control range, and the very high end has some theoretical applications for attempted instant-kills at very long range (more so once lances are available). Small ones may be more practical most of the time (decent DPS at range, on a budget), but there are cool and flashy things you can do with large ones.

The larger Meson sizes appear to be pointless though.

Larger mesons have increased range, but not increased damage. There's some value there in planetary assault scenarios (where mesons can be fired both from and at planetary bases, if you're unable or unwilling to use missile bombardment) since if a ship based Meson outranges a planet based one you can pick apart planetary meson bases at will. Overall it's probably not a commonly used tech line, though.

I've often thought particle beams have a role in skirmisher type long range beam ships with shields, capable of absorbing long range beam fire while pounding their opponent with high damage at range. But the current supremacy of missile combat means I've never really tested them out.

[Barkhorn]

Does anyone else find it strange that orbital stations have to have an Orbital Habitat module, even if the station isn't actually meant to house any people?

Why do I need to have a habitat on a sorium mining platform if I want to build it with my factories?  I don't need a habitat to have sorium harvesters on a ship, why do I need one on a station?

[83athom]

Does anyone else find it strange that orbital stations have to have an Orbital Habitat module, even if the station isn't actually meant to house any people?

Why do I need to have a habitat on a sorium mining platform if I want to build it with my factories?  I don't need a habitat to have sorium harvesters on a ship, why do I need one on a station?

And where do you propose those miners stay on their 120 year or so mission?

[iceball3]

@ iceball3: Railguns cease to be worthwhile when your capacitor tech can't keep up; 50cm is pushing it. Rule of thumb: RP-hungry and expensive for the capability with RoF 10, markedly inferior to lasers with similar single-shot-damage at RoF 15. 50cm railguns may be halfway competitive because they're a big bump up from 45cm.

Particle beams don't quite reach maximum fire control range, and the very high end has some theoretical applications for attempted instant-kills at very long range (more so once lances are available). Small ones may be more practical most of the time (decent DPS at range, on a budget), but there are cool and flashy things you can do with large ones.

The larger Meson sizes appear to be pointless though.

Hmm. Guess I was mistaken about the particle beams.
You're definitely right about the mesons though, as they max out on range far before the max size mesons are even close to useful.
That said, I would argue that railguns might have some use for alpha-strike purposes compared to lasers because of the extra damage per ton. Maybe if railguns were given size reduction tech, too?...
Still, that's no excuse to cut the max range tech on railguns, too, it's just not fair at that point.

[iceball3]

Does anyone else find it strange that orbital stations have to have an Orbital Habitat module, even if the station isn't actually meant to house any people?

Why do I need to have a habitat on a sorium mining platform if I want to build it with my factories?  I don't need a habitat to have sorium harvesters on a ship, why do I need one on a station?

I imagine it is some manner of "City-in-the-sky" sized structural supports and compartmentalization that allows the object to be built in the first place, and with the sheer mass, the living spaces are sort of rolled up into it for the heck of it.

[Barkhorn]

And where do you propose those miners stay on their 120 year or so mission?

Where do they stay if I build it in a shipyard?

[alex_brunius]

Where do they stay if I build it in a shipyard?

In the ships crewquarters, which are added automatically?

[Barkhorn]

And why can't they do that if I build it in factories?  Its not like the design has any fewer crew quarters if I include a habitat module.  In fact, it has MORE.

This is not build-able in a factory:

Code: [Select]

New Class #4213 class Terraforming Base    25 750 tons     110 Crew     629.6 BP      TCS 515  TH 0  EM 0
1 km/s     Armour 1-77     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 1     PPV 0
MSP 15    Max Repair 500 MSP
Intended Deployment Time: 3 months    Spare Berths 0   
Terraformer: 1 module(s) producing 0.0015 atm per annum


This design is classed as a Commercial Vessel for maintenance purposes

This IS build-able in a factory:

Code: [Select]

New Class #4213 class Terraforming Base    277 700 tons     140 Crew     1140.2 BP      TCS 5554  TH 0  EM 0
1 km/s     Armour 1-379     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 1     PPV 0
MSP 3    Max Repair 500 MSP
Intended Deployment Time: 3 months    Spare Berths 2   
Habitation Capacity 50 000   
Terraformer: 1 module(s) producing 0.0015 atm per annum


This design is classed as a Commercial Vessel for maintenance purposes
This design is classed as an Orbital Habitat for construction purposesIf I need a habitat module to support the terraformer/sorium-harvester/asteroid-mine workers on the version that's made in a factory, why don't I need one on the version that's made in a shipyard?  If the 110 crew of the shipyard version is enough to man a terraformer, why do I need a habitat module if I want to build it with factories?

I think the only answer is that its a way to nerf factory-produced stations.  But I don't really think they NEED nerfed.  The fact that they need a tug is a big enough nerf.