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Post by blothorn on Sept 29, 2016 8:10:33 GMT
Things I would try: pure boron--better tensile strength (and speed of sound) than boron carbide. UHMWPE--best S/W ratio in the game. Basalt fiber--also seems to be extremely good vs. lasers, the leading cause of turret death in my game.
What material are you using for Whipple shields? (And just putting all layers outside your main armor?)
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Post by blothorn on Sept 29, 2016 8:02:29 GMT
Actually, with no neutron reflector I would think it so far sub-critical as to be an RTG---critical mass of unconstrained U235 is about 15kg, and it would be spread out (somewhat) in a reactor. Both reactors and NTRs seem to ignore the neutron reflector for the reactor calculations (only using it for radiation emission calculations).
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Post by blothorn on Sept 29, 2016 7:55:16 GMT
I decided to get some actual data on missile armor---made a space station with a 100MW laser and timed how long it took to destroy groups of five of my standard frag missile with different armoring options (all the same mass, +/- 0.2kg). For consistency, I made all interceptions at 100m/s (+/- 5m/s) and started the time when the station began firing (as different geometries had notably different times for the initial turret traverse). Most groups are the average of 3 rounds like that, to attempt to smooth over remaining variances. Armor | Average time (s) | Notes | 5mm amorphous carbon | 31 | My expected winner, at least for "homogenous" armor. | 3mm diamond | 6 | Conductivity does not win you much without good specific heat... | 4.7mm graphite | 45 | Still puzzled why this beats amorphous carbon, which seems to have better stats. | 5mm boron | 26 | My standard bulk kinetic armor; included to see how much it gives up to the carbon-based armors. | 6mm reinforced carbon-carbon | 8 | This might explain the comments about lasers being overpowered vs. stock ships... | 4mm amorphous carbon, 2.7cm graphite aerogel | 32 | The logic is that the aerogel can act as a thermal transfer layer for the amorphous, but it is hampered by the low melting point of the aerogel. Not worth the (considerable) bulk. | 1.9mm diamond, 1.9mm amorphous carbon | 29 | Tries to use amorphous carbon as a heat-sink for the conductive diamond. I am surprised how close this was to homogenous amorphous carbon, given the poor performance of diamond. | 0.8mm basalt fiber, 4mm amorphous carbon | 143(!) | I meant to put the basalt on the inside, to see if insulating the inside components from the armor helps. Putting the basalt on the outside is the best mistake I have made in a while... | 4mm amorphous carbon, 0.8mm basalt fiber | 39 | So much for my initial theory---the performance advantage here is more than explained by the superiority of basalt fiber. | 3.9mm basalt fiber | 223(!) | All five missiles passed the target and were destroyed by fire to their unprotected rear. |
The spectacular results for basalt fiber were surprising---it has a mediocre melting point and specific heat capacity, and one of the lowest thermal conductivities of a solid. I am not entirely certain what is happening, but the results are convincing (if you can stomach the price tag). The big caveat here is that these are thin layers of armor on small targets, and I expect that to work very differently from thicker armor. OTOH, I do not see lasers as very viable in capship fights except for module sniping; I should attempt an experiment on turret armor. (Even if they are the king of close-range combat, as claimed, I have never seen a capital survive trying to close the range that far.) Drones are harder to generalize about, since they are usually killed by weapon/radiator damage, not armor penetration, and options there vary heavily by class.
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Post by blothorn on Sept 29, 2016 1:43:09 GMT
Try putting it in a low-angle turret; that should allow you to distinguish between target prediction errors and maneuver errors.
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Post by blothorn on Sept 29, 2016 1:41:07 GMT
My realism concern was just the extreme temperature differentials---this reactor has listed 371K and 3097K components coexisting within the same .193m^3. I am not an expert on thermal insulation, but I would think that would be a colossal task.
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Post by blothorn on Sept 28, 2016 19:15:11 GMT
RA2lover---for drones, especially, I would definitely go with high-output-temperature reactors. The only reason I know of to chase efficiency is to keep your heat generation down for cheaper flares, and ATM I do not know of anyone using missiles against drones (and if they do, the large radiators used by low-temperature reactors are probably the greatest vulnerability).
And yes, I definitely think something is wrong with the physical model to be allowing these, even ignoring radiation. I think I made a 1MW reactor that fits in a 1m cube...
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Post by blothorn on Sept 28, 2016 17:04:10 GMT
Check the details---he is running his reactor at about 3100K, dropping 400 degrees to a 2700K output (basically at the melting points for the hottest fuel and thermocouple materials available). The radiators are 36 times more effective at 2700K than at 1100K, which adds up quickly.
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Post by blothorn on Sept 28, 2016 16:58:40 GMT
I have not tried flak/nukes as point defense yet---I suspect that flak is not going to help much because hit rates will be relatively low and missiles tend to be quite well-armored from ahead (although as you say, this will be reduced by target prediction---but it is extremely difficult to hit a missile off-bore while it is thrusting, even in a straight line). Nukes would be relying primarily on radiation heating, and given that most missiles are primarily armored against thermal damage I suspect that is tough going.
Defense railguns work, but suffer heavily from flight time (and scale very poorly with ship size). Even with 100% kill rates, a 10km/s railgun will only kill a missile every two seconds at 20km, and below 10km you start taking radiator damage if they are well-aimed. Distributed point defense (multiple ships) is advantageous here too, because they may choose different targets; a bunch of railgun drones with a brief "scatter" at the start of the engagement are probably even better. I think I mentioned it elsewhere, but it would be really nice if point-defense guns selected distinct targets.
And yes, laser component sniping seems incredibly powerful ATM---I should build a ship with proper anti-laser armoring (diamond? I wish that you could put composite armor on turrets...), and see how much better that holds up than the stock components (which I recall being largely metal-armored).
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Post by blothorn on Sept 28, 2016 16:30:27 GMT
Oops... that does change the calculus substantially. And high temperatures seem particularly important for drones, who have the most trouble protecting radiators and the least need for keeping heat low...
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Post by blothorn on Sept 28, 2016 9:07:39 GMT
Unfortunately, I am still seeing superguns: my calculations have this gun imparting 2MW to its projectiles. (On the other hand, I rather doubt that a 2x64mm projectile is going to much bother anybody.)
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Post by blothorn on Sept 28, 2016 7:36:12 GMT
Do note that railgun/coilgun mechanics are broken in the corner cases due to numeric integration issues; your gun, if it worked at 100% efficiency, would need over 60GW of power!
Otherwise, quite neat---I really like the "all or nothing" armor idea.
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Post by blothorn on Sept 28, 2016 7:20:02 GMT
It turns out that the cooling design on that reactor was terrible---working on that a bit gives a rather nifty 268MW at 31.2% efficiency in a 3.9m/10.2m package: And this scales up: who needs to hide emissions when you can hit incoming missiles with a 2GW laser?
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Post by blothorn on Sept 28, 2016 6:19:42 GMT
Here is a stab: It sacrifices the high output temperature for efficiency, but if I am doing the math correctly it only needs about 10% more radiator area (and 1100K gives you more material options, or a considerably larger overhead for resisting battle heating). You can cut the price down to ~850 kc by replacing the thermocouple with tungsten/nickel chromium iron, but they are a poorer thermal expansion match so efficiency drops a bit. The downside is that this is huge---reshuffling the dimensions to be closer to yours, I get 25m height/6.9m radius, vs. 24.7/3.7. On the other hand, this reactor scales up in power with little loss of efficiency by increasing size and neutron flux--want an 831MW, 31.1% efficiency reactor? But given that space is mass once you consider armor, I suspect you are better off scaling it down and using multiples---the weight penalty is negligible on propellant scales. I can get power out of Amorphous Carbon/Nickel Chromium Iron. I thought it would be worth checking because they are a thermal expansion match, but there is still a lot of expansion stress and efficiency is poor. Graphite/Nickel Chromium Iron also works, albeit very badly.
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