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Post by boosters on Oct 6, 2016 13:28:30 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?
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acatalepsy
Junior Member
Not Currently In Space
Posts: 97
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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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Post by ross128 on Oct 6, 2016 14:18:38 GMT
They work well against small formations, but they struggle to keep up with large ones because of how their targeting works.
By turning "ignore range" on, just about any high-RoF railgun can kill a missile by saturating the area. The problem is the targeting system won't lay off the first target until it's dead, and it won't be dead until the rounds get there (by which time the gun will have easily fired ten times more bullets than it actually needed). So you waste a lot of time firing at a target that is already dead but doesn't know it.
The result is it kills missiles reliably but not quickly. The real advantage of lasers is because their travel time is negligible, they start doing damage immediately and can change targets quickly when the first one pops. They're less lethal, but they don't waste time on overkill.
That said, sometimes killing the target reliably is more important than killing it quickly. Railguns are an excellent defense against large, high-yield nukes because those launch in relatively small formations by necessity. There is no reasonable missile armor that could ever keep them alive against a railgun barrage, where as basalt fiber and silica aerogel can make large missiles nearly immune to lasers. In that situation, railguns come out the clear winner.
Against flak missiles though, they're not very effective because those are typically fired in formations of 40+. With that many targets, the seconds wasted on overkill add up. If you need to defend against large formations of flak missiles, it's worthwhile just mass enough lasers to pop them (or just run them out of delta-V before they can intercept).
Railguns would be a lot better at point defense if they had a "point defense mode" though, that caused it to sweep the whole formation instead of focusing on a single missile. All it really needs is a good targeting algorithm.
Edit: As mentioned above though, intercepting missiles with your own ordinance is generally preferable to any point-defense, since that will reduce or eliminate the formation with zero risk to your ships and you'll get kills simply by setting off the enemy missiles' proximity fuses, rendering silica aerogel and basalt fiber irrelevant.
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Post by elouda on Oct 6, 2016 14:37:53 GMT
If flak rounds reliably detonated before passing their targets, a lower velocity coilgun firing flak rounds that split into thousands of gram or small chunks might make a very effective defence.
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Post by captinjoehenry on Oct 6, 2016 15:59:02 GMT
Ok here! This is for a super dreadnaught that I have made. As such it's power draw, mass and cost are irrelevant. Performance wise it can easily engage gunships at over 300km and stock flack missiles at 40.1 km. And 50 missiles against the broadside of these ships with 6 of these per broadside kills all of them while they are still over a kilometer out.
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Post by elouda on Oct 6, 2016 16:53:12 GMT
Its also a glitched design.
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Post by blothorn on Oct 6, 2016 18:18:10 GMT
Yes---for 1g@35km/s, a 100% efficient 1GW railgun should fire once every .6 seconds. At 50km/s, every 1.25 seconds. I suspect that at that rate of fire, residual inaccuracy prevails over muzzle velocity.
Not to mention that the integrator bug is giving unrealistic acceleration; if it were fixed achieving those velocities would require a much larger gun.
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Post by boosters on Oct 6, 2016 18:21:09 GMT
Hmm, so, how can I tell if a rail gun or coil gun design is unrealistically effective? What are the theoretical maximum muzzle velocities for these kinds of weapons, or how can I calculate them?
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Post by captinjoehenry on Oct 6, 2016 18:26:49 GMT
Yes---for 1g@35km/s, a 100% efficient 1GW railgun should fire once every .6 seconds. At 50km/s, every 1.25 seconds. I suspect that at that rate of fire, residual inaccuracy prevails over muzzle velocity. Not to mention that the integrator bug is giving unrealistic acceleration; if it were fixed achieving those velocities would require a much larger gun. Well that's a gosh darn shame. I really wish that bug could get more thoroughly fixed so I don't end up with these super guns. Oh well. Still the performance is really good while the glitch is there
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Post by ross128 on Oct 6, 2016 18:34:38 GMT
A quick and simplistic way is to simply compare power in to power out. Because energy is conserved and power is energy over time, if power in is less than power out you have a problem (or you have a ZPE generator hidden in your turret). Power in is the rated power of course, and power out is (velocity^2)*mass/(2*reload_time). Your base units are meters per second, kilograms, and seconds respectively. So captinjoehenry's gun for example would have (35300^2)*0.001/(2*0.0035)=~178MW power out for 10MW of power in. You'll notice that your fire rate (or its inverse, your reload time) is a factor in the "power out" equation, but that up to a point you can juice your loader to arbitrarily change it with absolutely no change to "power in". Under normal physical constraints the equation is basically "muzzle energy, power efficiency, rate of fire: pick two". Right now we can have all three because rate of fire has no impact on power consumption. Whether you'd prefer to gleefully exploit this or do the sanity checks yourself is up to you. (edit: well technically his gun actually uses over 250MW of power, but almost all of that is going into the turret's reaction wheels and shouldn't be ending up in the projectile! )
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Post by jakjakman on Oct 6, 2016 19:42:55 GMT
Hmm, so, how can I tell if a rail gun or coil gun design is unrealistically effective? What are the theoretical maximum muzzle velocities for these kinds of weapons, or how can I calculate them?
Compare power out of the gun vs power into the gun.
Power out is the kinetic energy per second the gun spits out: ( 0.5 * (projectile mass in kg) * (velocity in m/s) ^ 2 ) * shots per second.
If that power turns out to be more than the power you're supplying the gun then it's unrealistic. I think you can nerf your own design by playing with the reloader power to bring the firing rate down.
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Post by tukuro on Oct 6, 2016 23:37:48 GMT
I use railgun drones to intercept missiles swarms. It's very cost effective and safer than trying to destroy them during a fleet intercept. This is a prototype I've been working on. It fires 1 gram projectiles at 6.64 km/s. It easily counters silicon aerogel armoured missiles, but it strangely has a problem dealing with graphite, so I might go with a heavier and longer projectile. The deltaV also isn't impressive, so I'll be changing fuel and engines too to keep the size down. I also haven't calculated whether this violates any laws of physics like a lot of the designs.
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Post by blothorn on Oct 7, 2016 0:06:21 GMT
Very pretty. But can they actually take down an equal-to-superior number of missiles before they reach the drones? My experience is that you can reliably stop missiles with drones, but not without losing the drones (if facing nuclear missiles)--and trading drones for missiles is not going to end well in the long run.
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Post by tukuro on Oct 7, 2016 0:16:49 GMT
Very pretty. But can they actually take down an equal-to-superior number of missiles before they reach the drones? My experience is that you can reliably stop missiles with drones, but not without losing the drones (if facing nuclear missiles)--and trading drones for missiles is not going to end well in the long run. Well, I mostly use these to counter larger missiles. As long as the swarm costs more than the drone, I'll send a drone to intercept it (Which are expendable). If the swarm is small enough that a drone would not be worth sending I'd probably be able to take it out with a few dozen laser drones at the main fleet intercept. Of course, the drone could also be countered by a laser drone, but even the smallest lasers drones I've seen are more expensive than this drone. And in the future we might have access to retractable turrets, which would also make these drones more resistant to lasers. Alternatively, I could use a flak MIRV drone.
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Post by blothorn on Oct 7, 2016 0:31:18 GMT
I would classify the AI's sending an entire launch of missiles against a single drone a bug--the smart policy would seem to be to kill the drone with a small number of missiles and continue the intercept with the rest.
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