acatalepsy
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Post by acatalepsy on Oct 25, 2016 6:31:00 GMT
My experience so far is that missiles hold an extremely dominant position, and armoring against them tends to prove futile. So ship armor and that armor's layout is rarely relevant at all. This is true against AI ships, because AI has no idea how to fight against missiles. Right now the missile algorithm is so poor as to render most missiles useless against an even half-awake target - and even if that wasn't so, existing solutions, from countermissiles to decoys provide ample 'hard counters' to missile spam. My current paradigm does make use of missiles (and coutermissiles, and even a few drones), but mostly as a way of keeping the other person honest and forcing them to expose vulnerable weapons and drones to long-range laser fire. The bulk of my mass/credits is spent on very, very big lasers. EDIT: To be clear, this has a bunch of problems, not the least of which is 'what if they have non-terrible turret designs'. When that happens, much of this paradigm goes out the window.
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acatalepsy
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Post by acatalepsy on Oct 24, 2016 21:27:57 GMT
One thing that's worth pointing out on needleship survivability - its predicated on an ability to point it's armored front unerringly at the source of incoming fire. That's all well and good, but what happens if the enemy has more than one source of incoming fire? One broadside versus one needle might be in favor of the needle...but fleets usually have more than one combat spacecraft. Not to mention missiles and drones deployed on off-axis attack vectors. Broadside designs have a lot more freedom to maneuver at and near the point of engagement, and even a few kilometers separation in the opposing fleet could make things very bad for a group of needleships.
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acatalepsy
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Post by acatalepsy on Oct 18, 2016 19:15:49 GMT
It's worth pointing out that needle ships have much more limited manuevering options. In a long range duel, sure, it doesn't have as big of a profile, but a broadside ship with even halfway-decent acceleration can generate a miss regardless just buy thrusting out of the way of incoming fire. A needle ship can accelerate towards an opponent, and...that's it. This is especially important for dealing with missile swarms, at least until the algorithm is improved.
Also, if you want to avoid an engagement and still have defensive fire, you're kind of screwed.
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acatalepsy
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Post by acatalepsy on Oct 18, 2016 18:53:14 GMT
These are some excellent points I feel. One thing that could be done to aid in getting into orbit is making the braking burn at a long distance from the target and inserting into a highly elliptical orbit. Not only would this make interference with the burn more difficult it would also give the greatest flexibility to the invasion fleet to decide what their final orbit will be. In addition the final breaking stage of an invasion stage could be fairly well armored to protect against this type of attack. Yes, armored (from the front at least) 'final' invasion stages are a decent idea. I've been considering how you could armor a nuclear rocket from behind- it's not easy, but it is possible, especially if the number of places that they can shoot at you from is limited, and your main concern is lasers rather than solid projectiles. Another one is to go on offense, with at least one (unarmored, unmanned) craft filled with missiles and maybe a few drones that doesn't decelerate at all, but rather exists to destroy and disrupt any placed defenses or attempted intercept during the braking manuevers. I think the question of "how soon must they brake to avoid taking long range fire" is a very interesting one, especially since it's at the edge of what a lot of questions the simulation isn't set up to avoid answering. If they do it too early, they're not even in an elliptical orbit, and will need to spend real thrust to get to where they need to go. If they break too late, they're exposed to all sorts of nastiness - including defensive (potentially stealthy, at least until the last possible minute) railguns, pre-placed missiles and drones, very big lasers, and more - when they absolutely cannot afford it. Prudence suggests erring on the side of caution, and bringing a (relatively) armored, manueverable tanker so you can fight your way in slowly. It's worth noting that, in terms of fighting near most belt bodies, I imagine there's no such thing as a "safe" ellipitical orbit (simply too little gravity). Another thing worth considering is reinforcements. An interplanetary invasion many not be not "one and done", but a whole stream of attacks launched as logistics and construction are completed back at home. Having a fleet in a high orbital gives you time to assess the opponent's strength in detail, direct waves of hypervelocity attacks coming in behind you, and shoot down-well at targets of opportunity while the rest of your reinforcements come in. I don't know if an "orbithead" could be a real thing, but I don't see why it couldn't be.
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acatalepsy
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Post by acatalepsy on Oct 18, 2016 15:48:23 GMT
I think the big problem, the one that CoaDE basically sidesteps, is intercepting interplanetary transfers. And there's a lot of complexity there, that gets into places where the simulation is weak, at the edges of its assumptions on speed, sensor resolution, etc. If you damage or destroy the by-necessity-unarmored propellant tanks (the "invasion stages") before the craft has completed their braking maneuvers, you've mission killed that spacecraft for the purposes of anything other than a flyby; it's going on a nice long trip to nowhere...which suggests that (multistage) flak missile swarms are a reasonably effective anti-invasion defense. Even forcing incoming spacecraft to spend time and dV dodging missiles threatens to make their mission a failure by simply missing the target or not having enough dV to orbitally insert (or fight against ground fire if they do).
This depends of course on how accurate missiles can be against targets closing at speeds greater than 10 km/s. But I don't think this an utterly insurmountable problem with properly designed missiles and good targeting algorithms; point defense can be rendered basically a non-factor by sheer speed. The best defense is dispersion and possibly countermissiles or drone defense screens, but these things could detonate/fragment at fairly extreme range and still be reasonably accurate.
There's also the borderline - the place *where* the incoming fleet needs to decelerate to do an insertion burn. This almost the perfect place to attack, especially with long range weapons like lasers, drones, and missiles that can try to shoot the exposed, vulnerable engines while the braking is going on and manuevering options are limited (or even do so with long range coilgun/railgun bombardment, aimed at preventing a successful braking maneuver). Or send out combatants (with tankers, etc) to try to intercept and match the incoming fleet on the way in, again to force the incoming fleet to do breaking manuevers early and waste lots of dV.
Not to say that countermeasures to this don't exist. It's possible fuel tanks will be sufficiently self-healing that fragments can't really damage them or reduce dV. Or that (multi-stage) drone interceptors with extreme dV might be able to engage and destroy the command vehicle for a missile swarm, or that dispersion across distances of hundreds to hundreds of thousands of kilometers makes interception threats difficult or counterproductive. But it's a fertile field that pushes the boundary of what the simulation can do.
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acatalepsy
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Post by acatalepsy on Oct 6, 2016 14:17:09 GMT
So, I made a very heavy ~55km/s muzzle velocity railgun that fires very light ammunition and stuck it on the nose of a ship. It's accurate for attacking ships out at extreme ranges, well over 300km, but can also start taking out stock missiles at about 100km, which I had never been able to achieve before. If it orients towards an incoming volley, it can intercept right around 20 missiles with 5 seconds to impact for the last one. I feel like I could do even better, here, and maybe get away from using lasers (and their heavy radiators) for this job. Does that seem plausible? What are your best railgun designs for long-range missile interception? This seems like it's taking advantage of the railgun integration bug to get better-than-physically-possible performance. The best long range missile interception, by the way, is another missile or decoy mounted on a missile chassis.
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acatalepsy
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Lasers
Oct 6, 2016 1:47:55 GMT
Post by acatalepsy on Oct 6, 2016 1:47:55 GMT
I'm trying to see if I can get a Near Ultraviolet laser going - the advantage is that, for a give aperture, and output power, it seems to have a higher intensity at any given range. The catch is that it's less efficient overall. I don't really understand how the arc lamp spectra or pumping efficiency is calculated, so....
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acatalepsy
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Post by acatalepsy on Oct 6, 2016 0:52:35 GMT
Okay, now this is funny. Take one 50MW Titanium:Sapphire Laser, derived, as such things are, from tuna's design:
LaserModule 50.0 MW Titanium:Sapphire Violet Laser ArcLamp GasComposition Xenon EnvelopeComposition Fused Quartz PowerSupplied_W 5e+007 Radius_m 0.043 CavityWallComposition Silver CavityCoolantComposition Hydrogen CavitySemimajorAxis_m 1.9 CavitySemiminorAxis_m 1.8 GainMedium Titanium:Sapphire OpticalNodes 10000000 LasingRodRadius_m 0.083 Mirror Composition Silver OutputCoupler Composition Fused Quartz CoolantTurbopump Composition Copper PumpRadius_m 0.28 RotationalSpeed_RPM 56 CoolantInletTemperature_K 670 FrequencyDoubler NonlinearOptic Composition Lithium Niobate OpticLength_m 0.03 OpticRadius_m 0.0025 ApertureRadius_m 7.9 FocusingMirror Composition Aluminum Turret InnerRadius_m 17 ArmorComposition Graphite ArmorThickness_m 0.022 ReactionWheels Composition UHMWPE RotationalSpeed_RPM 13 EngagementRange_km 250 TargetsShips true TargetsShots true
Run the following experiment. Reduce the aperture to a set value. Then then reduce the size of the turret until it is just barely big enough to hold the laser. Record the mass of the laser turret, and its intensity at 200 km. Record the ratio between those two numbers. You'll get the following result:
aperture (m) mass (tons) intensity@200km (MW/m^2) ratio 0.5 7.86 6.34 0.806615776 1 12.8 25.4 1.984375 2 27.3 101 3.6996337 3 45.2 228 5.044247788 4 61.4 406 6.61237785 5 464 634 1.36637931 6 493 913 1.851926978 7 435 1240 2.850574713 7.8 1260 1540 1.222222222 7.9 774 1580 1.222222222 8 262 1620 6.183206107 9 3110 2050 0.659163987
Notice that something really weird is going on in the vicinity of the 8m aperture. As near as I can tell, what's happening is that the lens aperture and the reaction wheel for the turret are competing for space; if you increase the size of the aperture you will decrease the amount of mass in the reaction wheel. If the 8m aperture is a tighter 'fit' for the turret than the 7m aperture is for the smallest turret that will it it, the 7m one will be heavier even if it's smaller. You'll also lose turret speed, but you don't need a lot of turret speed to engage targets that are 200 km away. But this highlights what a big design problem the turrets themselves are, even independently from the laser.
In any case, my general finding would be that you want to make turrets in the range of 4m across, but that this is heavily dependent on the turret having the right "fit".
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acatalepsy
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Post by acatalepsy on Oct 5, 2016 23:37:24 GMT
The biggest problem I'm having is the turret. The reaction wheel design is actually really terrible for things like lasers; simple mechanical actuators would open a whole new design space in "stupendously large laser cannons".
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acatalepsy
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Post by acatalepsy on Oct 5, 2016 19:49:45 GMT
Screw efficiency, 2240K or bust (which is the limit set by the Nd:YAG). Produces 19.6 MW output, weighs 15.9 tons. The output isn't the only relevant factor; can you provide the intensity at different distances? Compare, for example, tuna's 60MW violet laser to the stock 100 MW laser: range My 60MW Stock 100MW 5km 11600 5760 10km 4320 1440 20km 1080 365 30km 480 163 35km 353 120 40km 270 - 50km 173 - 60km 120 - You can find tuna's full 60MW design here. The intensity at range is what matters; a 1GW laser that can kill you in a heartbeat at 30km away is no good if it's not powerful enough to stop you from murdering it from 65km away with a railgun.
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Lasers
Oct 5, 2016 18:33:45 GMT
Post by acatalepsy on Oct 5, 2016 18:33:45 GMT
So, I think my next project is to start taking a hard look at total power at a given distance per weight. And by that I mean, that the total power per square meter at distances of 250, 200, 150, and 50 km, divided by the total weight of the system - the weight of both the laser itself, and the weight of the power + radiators per megawatt, plus the weight of radiators needed to dissipate heat from that laser. I suspect, given how cheap we've been able to drive power, it will be about building the maximum possible size laser - perhaps Rick Robinson's "laserstars".
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Post by acatalepsy on Oct 4, 2016 21:29:08 GMT
I don't know what about anything I said suggested that there wouldn't be a chain of command, or a commander, or job roles? I'm having a hard time figuring out what you're even talking about at this point. Like, our military rank structure has evolved from stuff in the past. It will continue to evolve in the future. There's at least some acknowledgement of the fact that the model for how units are commanded and operate differs between land, sea, and air units. I'd like to discuss how it might evolve to fit a space combat environment, and had a couple of thoughts on it (one of which is that perhaps unlike navy ships, spacecraft will have no enlisted crew). Another is that there might be a big operational/career path/rank divide between the actually deployed spacers, due to their small number.
I'm not sure what about that is difficult?
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Post by acatalepsy on Oct 4, 2016 21:14:58 GMT
That sounds like a level of burnt earth that is... somewhat counterproductive. Most of the products needed as fleet consumables are going to also be needed for civilian infrastructure, things like fuel and remass, victuals, water, air, etc. People are going to have a real low sense of humor about their military messing with those. Scorched earth policy for a war that is undeclared. Might be hard to swing that one. What undeclared war? Like, if you have combat spacecraft slinging nuclear missiles at each other, it's on, and if your unofficial official policy is "war crimes are okay as long as we win" and "lets plan on raining nuclear death on our enemies until they unconditionally surrender and make ourselves lords of the solar system for all time", you have to figure that your opponent is not going to be keen on giving you any advantage, even if it hurts a great deal. At the very least, you cannot rely on such, because if you do and it turns out your enemy is in fact willing to play scorched earth, you are, in a word, screwed. So you need a plan B, and that plan be can be bringing enough infrastructure to start living off the land, or have home sending sufficient tankers and reinforcements to continue combat operations in the face of opposition.
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Post by acatalepsy on Oct 4, 2016 19:50:21 GMT
On some level, it depends on what's cheaper. On the other, if you lose the fight, your tankers and/or refining equipment are now property of the enemy. Well, tankers would be able to at least abort the orbit and maneuver for friendly space; not fun, but they're not going to be captured. In some ways this gets into the heart of a problem of CoaDE; spacecraft in CoaDE exist largely to fight each other. Whether or not it's even viable for defending spacecraft to simply decline an engagement - or whether a hostile fleet taking up orbit over a world can force its surrender, or whether or not those defending spacecraft will be forced to defend vital space installations - shipyards, habitats, skyhooks, etc - are very unanswered. CoaDE assumes that you have two limits - credits, and mass, and that you can't go over either. But is that a good approximation? What does an "extended campaign" in hostile territory entail? More directly technically - do you think it's possible to produce deuterium (for fusion, and more importantly for our purposes hydrogen deuteride, which is amazing stuff for NTR propellant) on site? Given how nuclear reactor happy these spacecraft are, it seems possible, but I don't know what that would look like.
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acatalepsy
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Post by acatalepsy on Oct 4, 2016 19:24:21 GMT
Remember that most of these solar bodies you are talking about are already colonized .. heavily in many cases (200 million people on Mars for example). I think the issue with that is that no enemy is going to leave ISRU infrastructure intact for you to use if they can help it, and with months or even years of warning, they generally can help it. And with potentially years before reinforcements arrive, if you want to be able to rely on ISRU, you need to bring your own. I think the question is really whether there's that level of stability to combat that bringing in processing is a better alternative than just bringing a tanker.
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