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Lasers
Oct 5, 2016 16:41:19 GMT
Post by concretedonkey on Oct 5, 2016 16:41:19 GMT
Nice , elouda , so you have good results with 300W ? Would you be willing to share the design ? I'm quite sure mine are rubbish , my 200W was able to fight off drones only at quite short ranges and I was wondering what I'm doing wrong. You use the same laser on the big drone ? Why not scale it up ? Edit: I've just come up with this 1MW miniaturised copy of the stock 13MW one. I haven't tested it properly.. do you think there is something outrageously wrong with it ? Attachments:
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Lasers
Oct 5, 2016 17:45:17 GMT
Post by elouda on Oct 5, 2016 17:45:17 GMT
Design is as follows;
LaserModule 300 kW Nd:YAG Green Laser ArcLamp GasComposition Krypton EnvelopeComposition Diamond PowerSupplied_W 3e+005 Radius_m 0.028 CavityWallComposition Silver CavityCoolantComposition Hydrogen CavitySemimajorAxis_m 0.57 CavitySemiminorAxis_m 0.56 GainMedium Nd:YAG OpticalNodes 900000 LasingRodRadius_m 0.041 Mirror Composition Silver OutputCoupler Composition Fused Quartz CoolantTurbopump Composition Amorphous Carbon PumpRadius_m 0.063 RotationalSpeed_RPM 400 CoolantInletTemperature_K 1200 FrequencyDoubler NonlinearOptic Composition Silver Gallium Selenide OpticLength_m 0.02 OpticRadius_m 0.00055 ApertureRadius_m 0.31 FocusingMirror Composition Silver Turret InnerRadius_m 0.67 ArmorComposition Basalt Fiber Composite ArmorThickness_m 0.021 ReactionWheels Composition UHMWPE RotationalSpeed_RPM 620 EngagementRange_km 20 TargetsShips true TargetsShots true
I could have put a more powerful one on the big drone, but big drone is mainly just more fuel and not much else, and I want to keep cross section down as there are already at risk from 11mm railguns at closer ranges. Generally I will want to scatter once I get to 7-8km to flow around the target, looking for engines or other non-laser resistant target. A group of 10 of these will cut into the side of most stock designs armour to get at the engines at ranges under 10 km. You can also manually order them to fire beyond that, they can still knock out weak components like the 286mm guns after a while.
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acatalepsy
Junior Member
Not Currently In Space
Posts: 97
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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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tuna
New Member
Posts: 33
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Post by tuna on Oct 5, 2016 18:44:39 GMT
The problem with that approach is that the radiators of the lasers themselves get really huge really quickly, due to the low temperature. I keep trying to build lasers that can run a little hotter, but silver is just too good compared to all the other reflective materials. I wonder if something can approach it at some other wavelength than the V/UV I usually build at.
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Lasers
Oct 5, 2016 19:05:29 GMT
Post by blothorn on Oct 5, 2016 19:05:29 GMT
I would actually expect that optimization by weight would favor relatively low-powered lasers with exceptional optics. Particularly if you believe in armored radiators with 2N redundancy, they can considerably outmass the laser itself. On the other hand, better optics means larger sizes, particularly of the turret itself--which means more vulnerability to railguns.
And yes, I have put a fair amount of effort into high-temperature lasers too and have not come up with something remotely effective. I would probably rejoice at an 2000K laser at only half the efficiency, but the falloff from silver/aluminum is steep indeed. (And I have gone up to green; for reasons that I expect would be clear if I knew more about laser optics, the Nd:YAG worked a lot better than titanium:sapphire at the Solar Flare's 1.5m width.)
Edit: doing some research, it seems tungsten (I recall that being the high-temperature non-transparent mirror choice?) is a decent reflector of IR. (Gold and copper become good reflectors somewhat earlier, but do not afford much melting point advantage.) Molybdenum should be better, but I do not recall it being an option.
Edit 2: And Osmium is supposedly an excellent reflector of UV, but I am fairly certain it is not an option.
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Lasers
Oct 5, 2016 19:38:17 GMT
Post by apophys on Oct 5, 2016 19:38:17 GMT
My first stab at it:
LaserModule 1.000 GW Nd:YAG Green Laser ArcLamp GasComposition Krypton EnvelopeComposition Diamond PowerSupplied_W 1e+009 Radius_m 0.01 CavityWallComposition Molybdenum CavityCoolantComposition Hydrogen CavitySemimajorAxis_m 1 CavitySemiminorAxis_m 0.99 GainMedium Nd:YAG OpticalNodes 4000000 LasingRodRadius_m 0.022 Mirror Composition Molybdenum OutputCoupler Composition Diamond CoolantTurbopump Composition Boron PumpRadius_m 0.9 RotationalSpeed_RPM 400 CoolantInletTemperature_K 2200 FrequencyDoubler NonlinearOptic Composition Silver Gallium Selenide OpticLength_m 0.026 OpticRadius_m 0.025 ApertureRadius_m 0.5 FocusingMirror Composition Silver Turret InnerRadius_m 2.2 ArmorComposition Boron ArmorThickness_m 0.06 ReactionWheels Composition Lithium RotationalSpeed_RPM 320 EngagementRange_km 100 TargetsShips true TargetsShots true
Screw efficiency, 2240K or bust (which is the limit set by the Nd:YAG). Produces 19.6 MW output, weighs 15.9 tons.
Coincidentally, the weight is close to the 15.6t of the reactor to feed it. Not sure about radiators though.
Update: Irradiance table:
5km off the chart 10km 13100 20km 3400 30km 1490 40km 840 50km 541 60km 375 70km 275 80km 211 90km 166 100km can't see because the scrollbar's in the way, ~135
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acatalepsy
Junior Member
Not Currently In Space
Posts: 97
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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 20:13:46 GMT
Post by apophys on Oct 5, 2016 20:13:46 GMT
Added. But that's with an aperture of 0.5m ; if you're fine with a smaller targeting angle than 70 degrees you can arbitrarily increase the aperture (and the turret once it gets too big for that) for crazy irradiance.
Doubling the aperture and doing minor tweaks, I get 670 at 90km range. But targeting angle drops to 47 degrees.
Probably worth it, now that I think about it...
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Lasers
Oct 5, 2016 20:28:39 GMT
Post by concretedonkey on Oct 5, 2016 20:28:39 GMT
So I have two contestants that are both reasonably effective. I guess I can get away with twice less power if I can afford just a bit larger turret... and the other way around. btw hellfire drones drop like flies if you target the gun... same with stingers... is it some kind of construction flaw or the game simulates explosion of the gun itself ? Attachments:
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Post by apophys on Oct 5, 2016 21:59:23 GMT
Big upgrade. The effect of aperture is way bigger than I expected. I grew it from 0.5 to 2.4 meters, changing basically nothing about the lasing components (grew the turret to match; that made it 6 times heavier at 89.8t, and the diameter 10.3m).
This is now a proper siege laser.
Distance Irradiance (MW/m^2) 20km >60,000 30km 34,600 40km 19,600 50km 12,600 60km 8,650 70km 6,400 80km 4,900 90km 3,840 100km 3,150 110km 2,590 120km 2,160 130km 1,860 140km 1,600 150km 1,380 160km 1,230 170km 1,080 180km 961 190km 868 200km 781 210km 712 220km 647 230km 590 240km 545 250km can't see... :P
That's about 4 times the irradiance of the 1GW stock laser while being ~6,550 times lighter and ~480 times smaller cross section.
6 irradiance per ton at 240km, and the small radiator area it needs, makes it practical.
New lasersnipe meta? xD
LaserModule 1.000 GW Nd:YAG Green Laser ArcLamp GasComposition Krypton EnvelopeComposition Diamond PowerSupplied_W 1e+009 Radius_m 0.01 CavityWallComposition Molybdenum CavityCoolantComposition Hydrogen CavitySemimajorAxis_m 1 CavitySemiminorAxis_m 0.99 GainMedium Nd:YAG OpticalNodes 5000000 LasingRodRadius_m 0.023 Mirror Composition Molybdenum OutputCoupler Composition Diamond CoolantTurbopump Composition Boron PumpRadius_m 0.9 RotationalSpeed_RPM 400 CoolantInletTemperature_K 2200 FrequencyDoubler NonlinearOptic Composition Silver Gallium Selenide OpticLength_m 0.026 OpticRadius_m 0.025 ApertureRadius_m 2.4 FocusingMirror Composition Silver Turret InnerRadius_m 5.1 ArmorComposition Boron ArmorThickness_m 0.06 ReactionWheels Composition Iridium RotationalSpeed_RPM 73 EngagementRange_km 250 TargetsShips true TargetsShots true
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Post by ross128 on Oct 5, 2016 22:21:00 GMT
There's generally three approaches you can take with lasers, from what I've seen.
1: Pump power into it until the optics melt. Some of the super-reactor designs floating around on the forum make this pretty viable.
2: Put a massive aperture on it. Obviously this is reserved for stations or really big ships that won't mind having the Overwhelmingly Large Telescope mounted on them. That said, shooting people with the Overwhelmingly Large Telescope is highly effective even at low power levels, though your reaction wheels will put a pretty hard floor on how low you can go.
3: Bring a Redundant Array of Inexpensive Lasers. Module targeting is the key to this: if your target modules, the gunnery AI will focus ALL the lasers in your fleet on one module at a time, combining your entire fleet's firepower into a single super-laser. If you don't, the lasers will rake randomly across the hull and be useless. Probably a good way to use this is actually to go over to the enemy fleet while combat is paused, and target ALL their modules so that the targeting computer won't run out of targets. Just to keep the lasers focused. RAIL arrays (yes, I know, the "A" stands for "array", refer to the "R") also work well against drones because they're so small, the fleet targeting a drone will achieve sufficient concentration anyway.
Taking lasers in rings of 6 or more is a good way to implement #3 on large ships. Because their typical firing arc is about 70-80 degrees, a four-laser ring can only point one laser at the enemy at a time. But a six-laser array can point three of them because they're only spaced 60 degrees apart, so you can utilize 50% of your lasers in any direction instead of 25%. Main downside to RAIL arrays is, outside of drones, they're crew-intensive.
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Post by Zerraspace on Oct 5, 2016 22:29:34 GMT
Mine from the design thread: It's too heavy to reasonably pack onto most ships (I made the uber-sized 862 m long Virgil craft just to carry it), but that's because I went with giant elements - 800 million optical nodes, 3.5 meter radius aperture, 16 meter radius turret... but look at the irradiance! Distance Irradiance (MW/m2) 20 km >800000 30 km 479000 40 km 278000 50 km 175000 60 km 124000 70 km 89600 80 km 69500 90 km 54400 100 km 43700 110 km 36500 120 km 30400 130 km 26100 140 km 22400 150 km 19700 160 km 17200 170 km 15100 180 km 13600 190 km 12100 200 km 11000 210 km 9960 220 km 9120 230 km 8310 240 km 7670 250 km <7670 I somehow doubt anything that could carry it needs other weapons. LaserModule 1.000 GW Titanium:Sapphire Violet Laser ArcLamp GasComposition Xenon EnvelopeComposition Diamond PowerSupplied_W 1e+009 Radius_m 0.86 CavityWallComposition Silver CavityCoolantComposition Hydrogen CavitySemimajorAxis_m 7.5 CavitySemiminorAxis_m 6.5 GainMedium Titanium:Sapphire OpticalNodes 800000000 LasingRodRadius_m 2.6 Mirror Composition Molybdenum OutputCoupler Composition Fused Quartz CoolantTurbopump Composition Silicon Nitride PumpRadius_m 2 RotationalSpeed_RPM 400 CoolantInletTemperature_K 1230 FrequencyDoubler NonlinearOptic Composition Potassium Dihydrogen Phosphate OpticLength_m 0.016 OpticRadius_m 0.0016 ApertureRadius_m 3.5 FocusingMirror Composition Aluminum Turret InnerRadius_m 16 ArmorComposition Boron Carbide ArmorThickness_m 0.1 ReactionWheels Composition Silicon Nitride RotationalSpeed_RPM 10 EngagementRange_km 250 TargetsShips true TargetsShots true
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Lasers
Oct 5, 2016 23:04:51 GMT
Post by apophys on Oct 5, 2016 23:04:51 GMT
Very awesome.
That 74.7 kt weight though... makes it 0.1 irradiance per ton at 240km . I wonder how much the radiators weigh, too...
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acatalepsy
Junior Member
Not Currently In Space
Posts: 97
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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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Lasers
Oct 5, 2016 23:44:27 GMT
Post by Zerraspace on Oct 5, 2016 23:44:27 GMT
I never said it was practical - though I got the third version of that ship to field four of them. Radiator mass is 855 tons, using my own custom-made armored diamond radiators - but with how heavy the laser is, this barely registers. More than half the mass is in the titanium sapphire rods and the silver mirror melts if temperature goes any higher, so shaving any mass off would require a total redesign. I was just proud that I'd shave the original's mass down eightfold and gotten 7%+ efficiency - I'm a sucker for high efficiency, even though I'm almost certainly losing out due to mass in the long run. I kind of wonder if an intermediate between ours is possible - something with my irradiance but closer to your mass. Most likely some tweaking of your design would get there, though the turret will probably still be inordinately heavy.
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